Colorado river

A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.

@article{doi10130674d706462b2111d78648000102c1865d,
    author = "Folk, Robert L. and Ward, W",
    title = "Brazos River bar [Texas]; a study in the significance of grain size parameters",
    year = "1957",
    journal = "Journal of Sedimentary Research",
    abstract = "A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60\% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.",
    url = "https://doi.org/10.1306/74d70646-2b21-11d7-8648000102c1865d",
    doi = "10.1306/74d70646-2b21-11d7-8648000102c1865d",
    openalex = "W2159525271"
}

The Colorado River in its course from central Texas to the Gulf of Mexico carries quartz, chert, and limestone pebbles which can be traced for distances of up to 270 miles from their source. Limestone is so soft that it reaches its limiting roundness in the first few miles and thereafter undergoes no further increase. Harder quartz rounds much more slowly but eventually attains the same high limiting roundness value as limestone. Chert, being brittle, tends to spall and only rounds slightly downstream. A new and more behavioristic measure of equidimensionality, "maximum projection sphericity," is introduced, and a triangular diagram is proposed for analysis of the equant versus disklike versus rodlike aspect of particles, here termed "form." It was hoped that, by limiting the study to pebbles 32-64 mm. in length, the effects of grain size might be eliminated; the data show, however, that, even within this narrow range, particle size has a greater effect on sphericity and form than 200 miles of fluvial transport-larger pebbles tend to have lower sphericity and a rodlike form, while smaller ones are more discoidal. Limestone pebbles remain at constant low sphericity because of their bedding and show no significant change with distance. For quartz, pebbles larger than 54 mm. become more rodlike downstream but show little numerical change in sphericity, hence apparently roll like a rolling pin and wear chiefly on the intermediate axis. Quartz pebbles smaller than 38 mm. show a significant downstream increase in sphericity, chiefly by wear on the long axis, and hence must be carried chiefly in saltation where they bounce randomly along the bottom. Surprisingly, chert pebbles larger than 38 mm. show a striking downstream decrease in sphericity and become more bladed by diminution of the short axis, apparently by preferential splitting parallel with the bedding; but chert pebbles smaller than 38 mm. increase in sphericity in the same manner as do small quartz pebbles. For both quartz and chert, pebbles near the source have similar sphericity and form regardless of size; since large and small sizes wear by opposite mechanisms, there is increasing divergence in sphericity andform between large and small pebbles as they are traced farther from their source. Detailed analysis of the polymodal sphericity frequency distributions reveals the apparent existence of remarkably constant discrete sphericity populations for each rock type. Furthermore, for all rock types the intermediate axis tends to measure very close to halfway between the long and short axes-hence there is a dominance of bladed forms; this is true even for limestone, in which discoidal forms are but slightly more abundant than rodlike forms. Analysis of mean form on the triangular diagram seems to be the most powerful weapon available to attack the problem of particle abrasion. This study shows that sphericity depends most importantly on the inherent abrasional properties of the different rock types, is strongly a function of size as well as distance, and is but little affected by selective sorting.

@article{doi101086626490,
    author = "Sneed, Edmund D. and Folk, Robert L.",
    title = "Pebbles in the Lower Colorado River, Texas a Study in Particle Morphogenesis",
    year = "1958",
    journal = "The Journal of Geology",
    abstract = {The Colorado River in its course from central Texas to the Gulf of Mexico carries quartz, chert, and limestone pebbles which can be traced for distances of up to 270 miles from their source. Limestone is so soft that it reaches its limiting roundness in the first few miles and thereafter undergoes no further increase. Harder quartz rounds much more slowly but eventually attains the same high limiting roundness value as limestone. Chert, being brittle, tends to spall and only rounds slightly downstream. A new and more behavioristic measure of equidimensionality, "maximum projection sphericity," is introduced, and a triangular diagram is proposed for analysis of the equant versus disklike versus rodlike aspect of particles, here termed "form." It was hoped that, by limiting the study to pebbles 32-64 mm. in length, the effects of grain size might be eliminated; the data show, however, that, even within this narrow range, particle size has a greater effect on sphericity and form than 200 miles of fluvial transport-larger pebbles tend to have lower sphericity and a rodlike form, while smaller ones are more discoidal. Limestone pebbles remain at constant low sphericity because of their bedding and show no significant change with distance. For quartz, pebbles larger than 54 mm. become more rodlike downstream but show little numerical change in sphericity, hence apparently roll like a rolling pin and wear chiefly on the intermediate axis. Quartz pebbles smaller than 38 mm. show a significant downstream increase in sphericity, chiefly by wear on the long axis, and hence must be carried chiefly in saltation where they bounce randomly along the bottom. Surprisingly, chert pebbles larger than 38 mm. show a striking downstream decrease in sphericity and become more bladed by diminution of the short axis, apparently by preferential splitting parallel with the bedding; but chert pebbles smaller than 38 mm. increase in sphericity in the same manner as do small quartz pebbles. For both quartz and chert, pebbles near the source have similar sphericity and form regardless of size; since large and small sizes wear by opposite mechanisms, there is increasing divergence in sphericity andform between large and small pebbles as they are traced farther from their source. Detailed analysis of the polymodal sphericity frequency distributions reveals the apparent existence of remarkably constant discrete sphericity populations for each rock type. Furthermore, for all rock types the intermediate axis tends to measure very close to halfway between the long and short axes-hence there is a dominance of bladed forms; this is true even for limestone, in which discoidal forms are but slightly more abundant than rodlike forms. Analysis of mean form on the triangular diagram seems to be the most powerful weapon available to attack the problem of particle abrasion. This study shows that sphericity depends most importantly on the inherent abrasional properties of the different rock types, is strongly a function of size as well as distance, and is but little affected by selective sorting.},
    url = "https://doi.org/10.1086/626490",
    doi = "10.1086/626490",
    openalex = "W1978754515",
    references = "doi101029tr023i002p00621, doi101086622676, doi101086624985, doi101086625559, doi101086626370, doi10130674d704932b2111d78648000102c1865d, doi10130674d706462b2111d78648000102c1865d, doi101306d4268eb92b2611d78648000102c1865d, doi101306d42690f32b2611d78648000102c1865d, doi101306d42695672b2611d78648000102c1865d"
}

@inproceedings{gardner1975the1,
    author = "Gardner, T. W",
    title = "The history of part of the Colorado River and its rivers",
    year = "1975",
    booktitle = "an experimental study: Four Corners Gelogical Society Guidebook, v. 9th Field Conference, p. 87-95",
    note = "talkorigins\_source = {true}; raw\_reference = {Gardner, T. W., 1975, The history of part of the Colorado River and its rivers: an experimental study: Four Corners Gelogical Society Guidebook, v. 9th Field Conference, p. 87-95.}"
}

Abstract Meander incision was studied in a sixty-by-four foot flume in which bedrock was simulated by a kaolinite-sand mixture and overlying alluvium by a silt-sand mixture. The six independent variables controlled during the experiments were base level, bedrock structure, bedrock erodibility, flume (valley) slope, thickness of alluvium and stream discharge. Incision was initiated by a drop in base level after an initial meander pattern had developed in the overlying alluvium. Once incised, only minor modification of the stream pattern occurred. Four distinct forms of incised channels developed under different general conditions: 1) a straight, incised channel developed in response to increasing valley slope or on a bedrock surface sloping in the direction of stream flow, 2) deformed, incised meanders developed on a bedrock surface sloping uniformly upstream, above structural axes and where stream gradients are decreased, 3) superposed meanders developed only on a horizontal bedrock surface overlain by a thin veneer of alluvium, and 4) armouring of the channel bottom and variations in bedrock erodibility caused oblique incision (ingrown meanders). Experimental data duplicate incised meander patterns on the Green and Colorado Rivers in Canyonlands and the San Juan River where it crosses the Monument Upwarp. It is hypothesized that the experimental channels and those rivers have had similar histories. Data from this study provide information on the little known transition phase from alluvial to incised meanders.

@article{openalexw2270285851,
    author = "Gardner, Thomas W.",
    title = "The History of Part of the Colorado River and Its Tributaries: An Experimental Study",
    year = "1975",
    abstract = "Abstract Meander incision was studied in a sixty-by-four foot flume in which bedrock was simulated by a kaolinite-sand mixture and overlying alluvium by a silt-sand mixture. The six independent variables controlled during the experiments were base level, bedrock structure, bedrock erodibility, flume (valley) slope, thickness of alluvium and stream discharge. Incision was initiated by a drop in base level after an initial meander pattern had developed in the overlying alluvium. Once incised, only minor modification of the stream pattern occurred. Four distinct forms of incised channels developed under different general conditions: 1) a straight, incised channel developed in response to increasing valley slope or on a bedrock surface sloping in the direction of stream flow, 2) deformed, incised meanders developed on a bedrock surface sloping uniformly upstream, above structural axes and where stream gradients are decreased, 3) superposed meanders developed only on a horizontal bedrock surface overlain by a thin veneer of alluvium, and 4) armouring of the channel bottom and variations in bedrock erodibility caused oblique incision (ingrown meanders). Experimental data duplicate incised meander patterns on the Green and Colorado Rivers in Canyonlands and the San Juan River where it crosses the Monument Upwarp. It is hypothesized that the experimental channels and those rivers have had similar histories. Data from this study provide information on the little known transition phase from alluvial to incised meanders.",
    url = "https://openalex.org/W2270285851",
    openalex = "W2270285851"
}

A stability analysis of meandering and braiding perturbations in a model alluvial river is described. A perturbation technique, involving a small parameter representing the ratio of sediment transport to water transport, is used to obtain the following results. Under appropriate conditions, the existence of sediment transport and friction are necessary conditions for the occurrence of instability in the flow and on the bed; thus instability is not inherent in the flow alone. An Anderson-type scale relation for longitudinal instability is obtained for meandering. A relation estimating the number of braids and differentiating between meandering and braided regimes is derived. These relations are independent of sediment transport.

@article{doi101017s0022112076000748,
    author = "Parker, Gary",
    title = "On the cause and characteristic scales of meandering and braiding in rivers",
    year = "1976",
    journal = "Journal of Fluid Mechanics",
    abstract = "A stability analysis of meandering and braiding perturbations in a model alluvial river is described. A perturbation technique, involving a small parameter representing the ratio of sediment transport to water transport, is used to obtain the following results. Under appropriate conditions, the existence of sediment transport and friction are necessary conditions for the occurrence of instability in the flow and on the bed; thus instability is not inherent in the flow alone. An Anderson-type scale relation for longitudinal instability is obtained for meandering. A relation estimating the number of braids and differentiating between meandering and braided regimes is derived. These relations are independent of sediment transport.",
    url = "https://doi.org/10.1017/s0022112076000748",
    doi = "10.1017/s0022112076000748",
    openalex = "W2147000014"
}

Continental lithosphere is in unstable mechanical equilibrium because its mantle layer is denser than the asthenosphere. If any process such as cracking, slumping, or plume erosion initially provided an elongated conduit connecting the underlying asthenosphere with the base of the continental crust, the dense lithospheric boundary layer could peel away from the crust and sink. An analytic model for sinking velocities at the critical initial time shows that instability occurs if the effective viscosities of the lower continental crust and the rising asthenosphere are no more than 10 19 P. Analogies to subduction suggest that the mature instability would grow laterally at plate tectonic velocities; however, it would be almost aseismic. Loss of the cold mantle boundary layer would cause uplift, increased heat flow, reduced seismic velocities, and perhaps emplacement of basalt flows, mantle diatremes, and granodiorite sills. A one‐dimensional thermal model of the formation of a new boundary layer predicts a half life of about 3×10 7 years for this thermal anomaly and uplift. As an example, the geologic and geophysical data from the Colorado Plateau are shown to be consistent with the hypothesis that it was uplifted by a delamination event 30 m.y. ago and perhaps a second event about 5 m.y. ago.

@article{doi101029jb084ib13p07561,
    author = "Bird, Peter",
    title = "Continental delamination and the Colorado Plateau",
    year = "1979",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Continental lithosphere is in unstable mechanical equilibrium because its mantle layer is denser than the asthenosphere. If any process such as cracking, slumping, or plume erosion initially provided an elongated conduit connecting the underlying asthenosphere with the base of the continental crust, the dense lithospheric boundary layer could peel away from the crust and sink. An analytic model for sinking velocities at the critical initial time shows that instability occurs if the effective viscosities of the lower continental crust and the rising asthenosphere are no more than 10 19 P. Analogies to subduction suggest that the mature instability would grow laterally at plate tectonic velocities; however, it would be almost aseismic. Loss of the cold mantle boundary layer would cause uplift, increased heat flow, reduced seismic velocities, and perhaps emplacement of basalt flows, mantle diatremes, and granodiorite sills. A one‐dimensional thermal model of the formation of a new boundary layer predicts a half life of about 3×10 7 years for this thermal anomaly and uplift. As an example, the geologic and geophysical data from the Colorado Plateau are shown to be consistent with the hypothesis that it was uplifted by a delamination event 30 m.y. ago and perhaps a second event about 5 m.y. ago.",
    url = "https://doi.org/10.1029/jb084ib13p07561",
    doi = "10.1029/jb084ib13p07561",
    openalex = "W2078181124",
    references = "doi101007bf00388953, doi1010160012825272900384, doi1010160040195178901403, doi101029jb075i020p03941, doi101029jb082i036p05705, doi101029jb083ib10p04975, doi101029jb083ib11p05331, doi101029jz064i010p01521, doi101029me001p0259, doi101111j1365246x1975tb00631x, doi101130001676061974851225somfam20co2"
}

From headwaters to mouth, the physical variables within a river system present a continuous gradient of physical conditions. This gradient should elicit a series of responses within the constituent populations resulting in a continuum of biotic adjustments and consistent patterns of loading, transport, utilization, and storage of organic matter along the length of a river. Based on the energy equilibrium theory of fluvial geomorphologists, we hypothesize that the structural and functional characteristics of stream communities are adapted to conform to the most probable position or mean state of the physical system. We reason that producer and consumer communities characteristic of a given river reach become established in harmony with the dynamic physical conditions of the channel. In natural stream systems, biological communities can be characterized as forming a temporal continuum of synchronized species replacements. This continuous replacement functions to distribute the utilization of energy inputs over time. Thus, the biological system moves towards a balance between a tendency for efficient use of energy inputs through resource partitioning (food, substrate, etc.) and an opposing tendency for a uniform rate of energy processing throughout the year. We theorize that biological communities developed in natural streams assume processing strategies involving minimum energy loss. Downstream communities are fashioned to capitalize on upstream processing inefficiencies. Both the upstream inefficiency (leakage) and the downstream adjustments seem predictable. We propose that this River Continuum Concept provides a framework for integrating predictable and observable biological features of lotic systems. Implications of the concept in the areas of structure, function, and stability of riverine ecosystems are discussed.Key words: river continuum; stream ecosystems; ecosystem structure, function; resource partitioning; ecosystem stability; community succession; river zonation; stream geomorphology

@article{doi101139f80017,
    author = "Vannote, Robin L. and Minshall, G. Wayne and Cummins, Kenneth W. and Sedell, James R. and Cushing, Colbert E.",
    title = "The River Continuum Concept",
    year = "1980",
    journal = "Canadian Journal of Fisheries and Aquatic Sciences",
    abstract = "From headwaters to mouth, the physical variables within a river system present a continuous gradient of physical conditions. This gradient should elicit a series of responses within the constituent populations resulting in a continuum of biotic adjustments and consistent patterns of loading, transport, utilization, and storage of organic matter along the length of a river. Based on the energy equilibrium theory of fluvial geomorphologists, we hypothesize that the structural and functional characteristics of stream communities are adapted to conform to the most probable position or mean state of the physical system. We reason that producer and consumer communities characteristic of a given river reach become established in harmony with the dynamic physical conditions of the channel. In natural stream systems, biological communities can be characterized as forming a temporal continuum of synchronized species replacements. This continuous replacement functions to distribute the utilization of energy inputs over time. Thus, the biological system moves towards a balance between a tendency for efficient use of energy inputs through resource partitioning (food, substrate, etc.) and an opposing tendency for a uniform rate of energy processing throughout the year. We theorize that biological communities developed in natural streams assume processing strategies involving minimum energy loss. Downstream communities are fashioned to capitalize on upstream processing inefficiencies. Both the upstream inefficiency (leakage) and the downstream adjustments seem predictable. We propose that this River Continuum Concept provides a framework for integrating predictable and observable biological features of lotic systems. Implications of the concept in the areas of structure, function, and stability of riverine ecosystems are discussed.Key words: river continuum; stream ecosystems; ecosystem structure, function; resource partitioning; ecosystem stability; community succession; river zonation; stream geomorphology",
    url = "https://doi.org/10.1139/f80-017",
    doi = "10.1139/f80-017",
    openalex = "W2116544104",
    references = "doi1010160022169465901010, doi101126science2004340444, doi101139f69132, doi1015771548844619790040005rasofp20co2, doi1023071296676, doi1023071535983, doi1023071933425, doi1023073817, openalexw202470409, openalexw3164818631"
}

Sediment supplied to the Colorado River within the Grand Canyon has been sorted into distinct deposits of three grain size ranges. The major rapids are formed by boulder deposits from side-canyon tributaries. As a result of a fourfold reduction in peak discharge when Glen Canyon Dam was closed in 1963, new fan debris may increase the gradient through some of the rapids by a factor of 1.8. Cobbles and gravel, transported only during flood stages, are preferentially deposited in the wider sections of the river as bars and riffles and are, for the most part, inactive during post-dam discharges. Fine-grain (largely sandy) terraces occur throughout the canyon, especially along the banks of the large reverse eddies above and below the rapids. The lower terraces are being reworked into beach-like shores by diurnally-varying, post-dam discharges. A slight net lateral erosion of the terraces has resulted. Prior to construction of the dam, sandy bed deposits underwent scour averaging about 1 m during spring floods, balanced by deposition from tributary sources during the summer. Downstream from rapids, decreased turbulence due to lower discharges has resulted in deposition averaging 2.2 m on the bed within the upper portions of the canyon. Differences in rock types along the river determine overall channel morphology. Rocks of low resistance result in a wide valley, a meandering channel, and abundant cobble bars and sand terraces. Narrow channels with rapids and deep pools are most frequent within the sections of the canyon where Precambrian crystalline rocks dominate.

@article{doi101086628592,
    author = "Howard, A. D. and Dolan, Robert",
    title = "Geomorphology of the Colorado River in the Grand Canyon",
    year = "1981",
    journal = "The Journal of Geology",
    abstract = "Sediment supplied to the Colorado River within the Grand Canyon has been sorted into distinct deposits of three grain size ranges. The major rapids are formed by boulder deposits from side-canyon tributaries. As a result of a fourfold reduction in peak discharge when Glen Canyon Dam was closed in 1963, new fan debris may increase the gradient through some of the rapids by a factor of 1.8. Cobbles and gravel, transported only during flood stages, are preferentially deposited in the wider sections of the river as bars and riffles and are, for the most part, inactive during post-dam discharges. Fine-grain (largely sandy) terraces occur throughout the canyon, especially along the banks of the large reverse eddies above and below the rapids. The lower terraces are being reworked into beach-like shores by diurnally-varying, post-dam discharges. A slight net lateral erosion of the terraces has resulted. Prior to construction of the dam, sandy bed deposits underwent scour averaging about 1 m during spring floods, balanced by deposition from tributary sources during the summer. Downstream from rapids, decreased turbulence due to lower discharges has resulted in deposition averaging 2.2 m on the bed within the upper portions of the canyon. Differences in rock types along the river determine overall channel morphology. Rocks of low resistance result in a wide valley, a meandering channel, and abundant cobble bars and sand terraces. Narrow channels with rapids and deep pools are most frequent within the sections of the canyon where Precambrian crystalline rocks dominate.",
    url = "https://doi.org/10.1086/628592",
    doi = "10.1086/628592",
    openalex = "W1984213129"
}

@article{doi1010160191814189900369,
    author = "Lister, Gordon and Davis, G. A.",
    title = "The origin of metamorphic core complexes and detachment faults formed during Tertiary continental extension in the northern Colorado River region, U.S.A.",
    year = "1989",
    journal = "Journal of Structural Geology",
    url = "https://doi.org/10.1016/0191-8141(89)90036-9",
    doi = "10.1016/0191-8141(89)90036-9",
    openalex = "W2138655928",
    references = "doi101007b137431, doi1010160191814182900219, doi1010160191814184900014, doi101029jb088ib05p04183, doi101038291645a0, doi10113000917613198614246dfateo20co2, doi101139e85009, doi101144gsjgs13330191, doi101144gsjgs14050741, openalexw191472345, openalexw2060489052"
}

Baselevel is the imaginary horizontal level or surface to which sub-aerial erosion proceeds. It is sea level. Controversy surrounds the effect of baselevel change on river behavior, the rejuvenation of landscapes, and the delivery of sediment to the shelf-slope depositional system. The effect of baselevel change depends upon many factors, such as rate of change, amount of change, direction of change, river character, and dynamics and erodibility of the sediment source area. In most cases the effects of baselevel change will be moderate, and they can be accommodated by changes of channel pattern, width, depth, and roughness. Therefore, the delivery of large amounts of sediment to a shoreline or continental shelf probably reflects not only baselevel lowering, but significant uplift of the sediment-source area and perhaps climate change.

@article{doi101086648221,
    author = "Schumm, Stanley A.",
    title = "River Response to Baselevel Change: Implications for Sequence Stratigraphy",
    year = "1993",
    journal = "The Journal of Geology",
    abstract = "Baselevel is the imaginary horizontal level or surface to which sub-aerial erosion proceeds. It is sea level. Controversy surrounds the effect of baselevel change on river behavior, the rejuvenation of landscapes, and the delivery of sediment to the shelf-slope depositional system. The effect of baselevel change depends upon many factors, such as rate of change, amount of change, direction of change, river character, and dynamics and erodibility of the sediment source area. In most cases the effects of baselevel change will be moderate, and they can be accommodated by changes of channel pattern, width, depth, and roughness. Therefore, the delivery of large amounts of sediment to a shoreline or continental shelf probably reflects not only baselevel lowering, but significant uplift of the sediment-source area and perhaps climate change.",
    url = "https://doi.org/10.1086/648221",
    doi = "10.1086/648221",
    openalex = "W2074438535",
    references = "doi10100797814612378841, doi1011300016760619881001661fyoss23co2, doi101306703c9af5170711d78645000102c1865d, doi102110pec88010109"
}

Prologue Part I: Evolutionary explanation Demography: age and stage structure Quantitative genetics and reaction norms Trade-offs Lineage-specific effects Part II: Age and size at maturity Number and size of offspring Reproductive lifespan and ageing Appendices Glossary References Author index Subject index.

@article{doi1023075403,
    author = "Benton, Tim G. and Stearne, S.C.",
    title = "The Evolution of Life-histories",
    year = "1993",
    journal = "Journal of Animal Ecology",
    abstract = "Prologue Part I: Evolutionary explanation Demography: age and stage structure Quantitative genetics and reaction norms Trade-offs Lineage-specific effects Part II: Age and size at maturity Number and size of offspring Reproductive lifespan and ageing Appendices Glossary References Author index Subject index.",
    url = "https://doi.org/10.2307/5403",
    doi = "10.2307/5403",
    openalex = "W1544815196"
}

This research was conducted to identify the factors that have permitted Populus—Salix woodland to expand into the formerly active channels of the Platte River and its two major tributaries, the South and North Platte rivers. The research included: pre—settlement vegetation reconstruction based on the General Land Office survey notes, a statistical comparison between historic rates of woodland expansion from aerial photographs and environmental variables, and a field study of seedling demography to isolate the factors controlling recruitment and survival in the modern river. Woodland expansion began in the South and North Platte rivers around 1900 and spread downstream into the Platte River. By the late 1930s, vegetation had occupied most of the former channel area of the South and North Platte rivers and was expanding into Platte River channels. Rates of channel loss in the Platte River have been as great as 10%/yr during droughts. By 1986, channel—to—woodland proportions were relatively uniform throughout the Platte River system. Statistical models indicated that sandbar succession to woodland was regulated by three environmental factors: June flows, summer drought, and ice. June flow regulated seedling recruitment and initial survival because it coincided with the main Populus—Salix seed germination period. Historic reductions in flow at this time for irrigation and to fill reservoirs exposed much of the riverbed and elevated recruitment and seedling survivorship. Late—summer seedling survival was regulated by factors that affect seedling water balance, including river stage, seedling elevation in the riverbed, and rainfall. Winter conditions exerted the largest effect on seedling survivorship. Dominant factors were air temperature, streamflow, and seedling elevation in the riverbed. Lowest survivorship occurred during cold, icy winters with relatively high flow and when most seedlings were growing on low sandbars. The dominant historic trend, of losses in channel area and gains in woodland area, has ceased in recent years. No significant declines in channel area have occurred since 1969; in several reaches channel area has significantly increased since 1969. Comparatively small changes in channel and woodland proportions are expected in the future as long as water use and climate do not change markedly. The steady state has developed because flows have come into balance with active channel area, thereby reducing recruitment and increasing the mortality of tree seedlings. Because of the importance of wide, unvegetated channels to certain avifauna, it may be desirable to manage future flows to ensure no further reduction in channel widths, even if narrowing is only temporary. Dominance by Populus and Salix on new sandbars can be explained by life history characteristics. These include large and dependable seed crops that are effectively dispersed by wind and water to optimal germination sites; rapid germination; rapid root and height growth to withstand flooding, drought, and sedimentation; tolerance of low soil fertility; and the ability of Salix to reproduce vegetatively. Pioneer vegetation and geomorphic processes (principally sedimentation) facilitate succession on floodplains by modifying the highly variable riverbed environment suitable for early successional species into relatively stable surfaces favorable for recruitment of later successional species. Much of the extensive Populus—Salix woodlands that now occupy the Platte River will be replaced by later successional tree and shrub species with lower associated faunal diversity. Maintenance of the current biotic diversity may require artificial regeneration, as is taking place along other river systems in western North America. The response of the Platte River to altered flow differed from that of other rivers. This divergent response despite similar disturbances points out the complex interrelationships among plants and hydrogeomorphic processes operating on floodplains and the difficulties associated with understanding, generalizing, and predicting the effects of human modification of streamflow on natural ecosystems.

@article{doi1023072937055,
    author = "Johnson, W. Carter",
    title = "Woodland Expansions in the Platte River, Nebraska: Patterns and Causes",
    year = "1994",
    journal = "Ecological Monographs",
    abstract = "This research was conducted to identify the factors that have permitted Populus—Salix woodland to expand into the formerly active channels of the Platte River and its two major tributaries, the South and North Platte rivers. The research included: pre—settlement vegetation reconstruction based on the General Land Office survey notes, a statistical comparison between historic rates of woodland expansion from aerial photographs and environmental variables, and a field study of seedling demography to isolate the factors controlling recruitment and survival in the modern river. Woodland expansion began in the South and North Platte rivers around 1900 and spread downstream into the Platte River. By the late 1930s, vegetation had occupied most of the former channel area of the South and North Platte rivers and was expanding into Platte River channels. Rates of channel loss in the Platte River have been as great as 10\%/yr during droughts. By 1986, channel—to—woodland proportions were relatively uniform throughout the Platte River system. Statistical models indicated that sandbar succession to woodland was regulated by three environmental factors: June flows, summer drought, and ice. June flow regulated seedling recruitment and initial survival because it coincided with the main Populus—Salix seed germination period. Historic reductions in flow at this time for irrigation and to fill reservoirs exposed much of the riverbed and elevated recruitment and seedling survivorship. Late—summer seedling survival was regulated by factors that affect seedling water balance, including river stage, seedling elevation in the riverbed, and rainfall. Winter conditions exerted the largest effect on seedling survivorship. Dominant factors were air temperature, streamflow, and seedling elevation in the riverbed. Lowest survivorship occurred during cold, icy winters with relatively high flow and when most seedlings were growing on low sandbars. The dominant historic trend, of losses in channel area and gains in woodland area, has ceased in recent years. No significant declines in channel area have occurred since 1969; in several reaches channel area has significantly increased since 1969. Comparatively small changes in channel and woodland proportions are expected in the future as long as water use and climate do not change markedly. The steady state has developed because flows have come into balance with active channel area, thereby reducing recruitment and increasing the mortality of tree seedlings. Because of the importance of wide, unvegetated channels to certain avifauna, it may be desirable to manage future flows to ensure no further reduction in channel widths, even if narrowing is only temporary. Dominance by Populus and Salix on new sandbars can be explained by life history characteristics. These include large and dependable seed crops that are effectively dispersed by wind and water to optimal germination sites; rapid germination; rapid root and height growth to withstand flooding, drought, and sedimentation; tolerance of low soil fertility; and the ability of Salix to reproduce vegetatively. Pioneer vegetation and geomorphic processes (principally sedimentation) facilitate succession on floodplains by modifying the highly variable riverbed environment suitable for early successional species into relatively stable surfaces favorable for recruitment of later successional species. Much of the extensive Populus—Salix woodlands that now occupy the Platte River will be replaced by later successional tree and shrub species with lower associated faunal diversity. Maintenance of the current biotic diversity may require artificial regeneration, as is taking place along other river systems in western North America. The response of the Platte River to altered flow differed from that of other rivers. This divergent response despite similar disturbances points out the complex interrelationships among plants and hydrogeomorphic processes operating on floodplains and the difficulties associated with understanding, generalizing, and predicting the effects of human modification of streamflow on natural ecosystems.",
    url = "https://doi.org/10.2307/2937055",
    doi = "10.2307/2937055",
    openalex = "W2025182885",
    references = "doi10113000167606195263923dbog20co2"
}

Drainage rearrangement, involving stream piracy (capture), drainage diversion and/or beheading, may be significant for sediment budgets (including sediment provenance) and biotic distributions, as well as for its more usually considered role in landscape evolution. The processes involved in drainage rearrangement are not as self-evident as its abundant literature indicates. This is especially the case with the commonly invoked stream capture. The key process in stream capture, namely, drainage head retreat, is difficult to envisage as a normal part of drainage net evolution, especially in the light of recent findings on drainage hollow evolution. Stream capture may therefore be a relatively rare event in drainage net evolution. This, and uncertainties with interpretations of supposed elbows of capture, mean that stream capture should not be routinely invoked in interpretations of long-term drainage evolution. Further uncertainties associated with the maintenance of drainage lines during the erosion of significant crustal sections, especially in faulted and folded terrains, diminish the likelihood of many supposed examples of stream capture. It is more likely that examples of drainage rearrangement attributed to stream capture were generated by drainage diversion, but even this may involve special conditions.

@article{doi101177030913339501900402,
    author = "Bishop, Paul",
    title = "Drainage rearrangement by river capture, beheading and diversion",
    year = "1995",
    journal = "Progress in Physical Geography Earth and Environment",
    abstract = "Drainage rearrangement, involving stream piracy (capture), drainage diversion and/or beheading, may be significant for sediment budgets (including sediment provenance) and biotic distributions, as well as for its more usually considered role in landscape evolution. The processes involved in drainage rearrangement are not as self-evident as its abundant literature indicates. This is especially the case with the commonly invoked stream capture. The key process in stream capture, namely, drainage head retreat, is difficult to envisage as a normal part of drainage net evolution, especially in the light of recent findings on drainage hollow evolution. Stream capture may therefore be a relatively rare event in drainage net evolution. This, and uncertainties with interpretations of supposed elbows of capture, mean that stream capture should not be routinely invoked in interpretations of long-term drainage evolution. Further uncertainties associated with the maintenance of drainage lines during the erosion of significant crustal sections, especially in faulted and folded terrains, diminish the likelihood of many supposed examples of stream capture. It is more likely that examples of drainage rearrangement attributed to stream capture were generated by drainage diversion, but even this may involve special conditions.",
    url = "https://doi.org/10.1177/030913339501900402",
    doi = "10.1177/030913339501900402",
    openalex = "W2115692443",
    references = "doi101038137179b0"
}

@article{doi101023a1007312524792,
    author = "Bemis, William E. and Kynard, Boyd",
    title = "Sturgeon rivers: an introduction to acipenseriform biogeography and life history",
    year = "1997",
    journal = "Environmental Biology of Fishes",
    url = "https://doi.org/10.1023/a:1007312524792",
    doi = "10.1023/a:1007312524792",
    openalex = "W4239363531",
    references = "doi1010160044848687903218"
}

Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headcut. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood. © 1998 John Wiley & Sons, Ltd.

@article{doi101002sici10969837199807237651aidesp89130co2v,
    author = "Gay, Glenn R. and Gay, Hubert H. and Gay, William H. and Martinson, Holly A. and Meade, Robert H. and Moody, John A.",
    title = "Evolution of cutoffs across meander necks in Powder River, Montana, USA",
    year = "1998",
    journal = "Earth Surface Processes and Landforms",
    abstract = "Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headcut. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood. © 1998 John Wiley \& Sons, Ltd.",
    url = "https://doi.org/10.1002/(sici)1096-9837(199807)23:7<651::aid-esp891>3.0.co;2-v",
    doi = "10.1002/(sici)1096-9837(199807)23:7<651::aid-esp891>3.0.co;2-v",
    openalex = "W2130660102"
}

This chapter contains sections titled: Introduction Stream Power Analysis of River Longitudinal Profiles Profile Analysis of the Upper Noyo River Basin, California A Coupled Bedload Transport and Bedrock Incision Model Discussion Conclusions Notation

@incollection{doi101029gm107p0237,
    author = "Sklar, L. S. and Dietrich, W. E.",
    title = "River longitudinal profiles and bedrock incision models: Stream power and the influence of sediment supply",
    year = "1998",
    booktitle = "Geophysical monograph",
    abstract = "This chapter contains sections titled: Introduction Stream Power Analysis of River Longitudinal Profiles Profile Analysis of the Upper Noyo River Basin, California A Coupled Bedload Transport and Bedrock Incision Model Discussion Conclusions Notation",
    url = "https://doi.org/10.1029/gm107p0237",
    doi = "10.1029/gm107p0237",
    openalex = "W1582979715",
    references = "doi101086628592"
}

1. A view of river basins 2. Fractal characteristics of river basins 3. Multifractal characteristics of river basins 4. Optimal channel networks: minimum energy and fractal structures 5. Self-organized fractal river networks 6. On landscape self-organization 7. Geomorphological hydrologic response 8. References.

@article{doi1010631882305,
    author = "Rodriguez‐Iturbe, I. and Rinaldo, Andrea and Levy, Ohad",
    title = "Fractal River Basins: Chance and Self-Organization",
    year = "1998",
    journal = "Physics Today",
    abstract = "1. A view of river basins 2. Fractal characteristics of river basins 3. Multifractal characteristics of river basins 4. Optimal channel networks: minimum energy and fractal structures 5. Self-organized fractal river networks 6. On landscape self-organization 7. Geomorphological hydrologic response 8. References.",
    url = "https://doi.org/10.1063/1.882305",
    doi = "10.1063/1.882305",
    openalex = "W1963897110"
}

Analyses of flow, sediment‐transport, bed‐topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply‐limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply‐limited to the same degree and that the degree of annual supply limitation increased near the head of Marble Canyon. The predam Colorado River in Grand Canyon displays evidence of four effects of supply limitation: (1) seasonal hysteresis in sediment concentration, (2) seasonal hysteresis in sediment grain size coupled to the seasonal hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4∥ development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Analyses of sediment budgets provide additional support for the interpretation that the predam river was annually supply‐limited with respect to fine sediment, but it was not supply‐limited with respect to fine sediment during all seasons. In the average predam year, sand would accumulate and be stored in Marble Canyon and upper Grand Canyon for 9 months of the year (from July through March) when flows were dominantly below 200–300 m 3 /s; this stored sand was then eroded during April through June when flows were typically higher. After closure of Glen Canyon Dam, because of the large magnitudes of the uncertainties in the sediment budget, no season of substantial sand accumulation is evident. Because most flows in the postdam river exceed 200–300 m 3 /s, substantial sand accumulation in the postdam river is unlikely.

@article{doi1010291999wr900285,
    author = "Topping, David J. and Rubin, David M. and Vierra, L. E.",
    title = "Colorado River sediment transport: 1. Natural sediment supply limitation and the influence of Glen Canyon Dam",
    year = "2000",
    journal = "Water Resources Research",
    abstract = "Analyses of flow, sediment‐transport, bed‐topographic, and sedimentologic data suggest that before the closure of Glen Canyon Dam in 1963, the Colorado River in Marble and Grand Canyons was annually supply‐limited with respect to fine sediment (i.e., sand and finer material). Furthermore, these analyses suggest that the predam river in Glen Canyon was not supply‐limited to the same degree and that the degree of annual supply limitation increased near the head of Marble Canyon. The predam Colorado River in Grand Canyon displays evidence of four effects of supply limitation: (1) seasonal hysteresis in sediment concentration, (2) seasonal hysteresis in sediment grain size coupled to the seasonal hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4∥ development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Analyses of sediment budgets provide additional support for the interpretation that the predam river was annually supply‐limited with respect to fine sediment, but it was not supply‐limited with respect to fine sediment during all seasons. In the average predam year, sand would accumulate and be stored in Marble Canyon and upper Grand Canyon for 9 months of the year (from July through March) when flows were dominantly below 200–300 m 3 /s; this stored sand was then eroded during April through June when flows were typically higher. After closure of Glen Canyon Dam, because of the large magnitudes of the uncertainties in the sediment budget, no season of substantial sand accumulation is evident. Because most flows in the postdam river exceed 200–300 m 3 /s, substantial sand accumulation in the postdam river is unlikely.",
    url = "https://doi.org/10.1029/1999wr900285",
    doi = "10.1029/1999wr900285",
    openalex = "W2090163816",
    references = "doi101086628592"
}

North Atlantic sea surface temperatures for 1856–1999 contain a 65–80 year cycle with a 0.4 °C range, referred to as the Atlantic Multidecadal Oscillation (AMO) by Kerr [2000]. AMO warm phases occurred during 1860–1880 and 1940–1960, and cool phases during 1905–1925 and 1970–1990. The signal is global in scope, with a positively correlated co‐oscillation in parts of the North Pacific, but it is most intense in the North Atlantic and covers the entire basin there. During AMO warmings most of the United States sees less than normal rainfall, including Midwest droughts in the 1930s and 1950s. Between AMO warm and cool phases, Mississippi River outflow varies by 10% while the inflow to Lake Okeechobee, Florida varies by 40%. The geographical pattern of variability is influenced mainly by changes in summer rainfall. The winter patterns of interannual rainfall variability associated with El Niño‐Southern Oscillation are also significantly changed between AMO phases.

@article{doi1010292000gl012745,
    author = "Enfield, David B. and Mestas‐Nuñez, Alberto M. and Trimble, Paul",
    title = "The Atlantic Multidecadal Oscillation and its relation to rainfall and river flows in the continental U.S.",
    year = "2001",
    journal = "Geophysical Research Letters",
    abstract = "North Atlantic sea surface temperatures for 1856–1999 contain a 65–80 year cycle with a 0.4 °C range, referred to as the Atlantic Multidecadal Oscillation (AMO) by Kerr [2000]. AMO warm phases occurred during 1860–1880 and 1940–1960, and cool phases during 1905–1925 and 1970–1990. The signal is global in scope, with a positively correlated co‐oscillation in parts of the North Pacific, but it is most intense in the North Atlantic and covers the entire basin there. During AMO warmings most of the United States sees less than normal rainfall, including Midwest droughts in the 1930s and 1950s. Between AMO warm and cool phases, Mississippi River outflow varies by 10\% while the inflow to Lake Okeechobee, Florida varies by 40\%. The geographical pattern of variability is influenced mainly by changes in summer rainfall. The winter patterns of interannual rainfall variability associated with El Niño‐Southern Oscillation are also significantly changed between AMO phases.",
    url = "https://doi.org/10.1029/2000gl012745",
    doi = "10.1029/2000gl012745",
    openalex = "W2158521569"
}

The abundance of cosmogenic 36 Cl, measured in 41 limestone samples from a 9 m high bedrock fault scarp, allows us to construct the 14 kyr fault displacement history of the Nahef East normal fault, northern Israel (300 m above sea level, N33° latitude). The Nahef East fault is one of a series of fault scarps located along the 700 m high Zurim Escarpment, a major geomorphic feature. Samples at the top of the scarp have the highest nuclide concentrations (79×10 4 atoms (g rock) −1); samples at the base have the lowest (11×10 4 atoms (g rock) −1). Using chemical data from the samples, Nahef East fault scarp geometry, and surface and subsurface production rates for the 36 Cl‐producing reactions, we have constructed a numerical model that calculates 36 Cl accumulation on a scarp through time, given a series of unique displacement scenarios. The resulting model 36 Cl concentrations are compared to those measured in the scarp samples. Faulting histories that result in a good match between measured and modeled 36 Cl abundances show three distinct periods of fault activity during the past 14 kyr with over 6 vertical meters of motion occurring during a 3 kyr time period in the middle Holocene. Smaller amounts of displacement occurred before and after the period of most rapid motion. The episodic behavior of the Nahef East fault indicates that the average displacement rate of this fault system has varied through time.

@article{doi1010292000jb900373,
    author = "Mitchell, Sara Gran and Matmon, Ari and Bierman, Paul R. and Enzel, Yehouda and Caffee, Marc and Rizzo, Donna M.",
    title = "Displacement history of a limestone normal fault scarp, northern Israel, from cosmogenic 36 Cl",
    year = "2001",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The abundance of cosmogenic 36 Cl, measured in 41 limestone samples from a 9 m high bedrock fault scarp, allows us to construct the 14 kyr fault displacement history of the Nahef East normal fault, northern Israel (300 m above sea level, N33° latitude). The Nahef East fault is one of a series of fault scarps located along the 700 m high Zurim Escarpment, a major geomorphic feature. Samples at the top of the scarp have the highest nuclide concentrations (79×10 4 atoms (g rock) −1); samples at the base have the lowest (11×10 4 atoms (g rock) −1). Using chemical data from the samples, Nahef East fault scarp geometry, and surface and subsurface production rates for the 36 Cl‐producing reactions, we have constructed a numerical model that calculates 36 Cl accumulation on a scarp through time, given a series of unique displacement scenarios. The resulting model 36 Cl concentrations are compared to those measured in the scarp samples. Faulting histories that result in a good match between measured and modeled 36 Cl abundances show three distinct periods of fault activity during the past 14 kyr with over 6 vertical meters of motion occurring during a 3 kyr time period in the middle Holocene. Smaller amounts of displacement occurred before and after the period of most rapid motion. The episodic behavior of the Nahef East fault indicates that the average displacement rate of this fault system has varied through time.",
    url = "https://doi.org/10.1029/2000jb900373",
    doi = "10.1029/2000jb900373",
    openalex = "W1992882250",
    references = "doi101016s0169555x9800097x"
}

Developing a quantitative understanding of the factors that control the rate of river incision into bedrock is critical to studies of landscape evolution and the linkages between climate, erosion, and tectonics. Current models of long‐term river network incision differ significantly in their treatment of the role of sediment flux. We analyze the implications of various sediment‐flux‐dependent incision models for large‐scale topography, in an attempt (1) to identify quantifiable and diagnostic differences between models that could be detected from topographic data or from the transient responses of perturbed systems and (2) to explain the apparent ubiquity of mixed bedrock‐alluvial channels in active orogens. Although certain forms of the various models can be discarded as inconsistent with morphological data, we find that the relative intrinsic concavity indices of detachment‐ and transport‐limited systems (defined herein) largely dictate whether the various models can be tied to distinctive steady state morphologies. Preliminary data suggest that no such diagnostic differences may exist, and other methods must be developed to test models. Accordingly, we develop and explore differences in the scaling behavior of topographic relief and the extent of detachment‐ versus transport‐limited channels as a function of rock uplift rate that may allow discrimination among various models. Further, we explore potentially diagnostic differences in the rates and patterns of transient channel response to changes in rock uplift rate. In addition to general differences between detachment‐ and transport‐limited systems our analysis identifies an interesting hysteresis in landscape evolution: “hybrid” channels at the threshold between detachment‐ and transport‐limited conditions are expected to act as detachment‐limited systems in response to an increase in rock uplift rate (or base level fall) and as transport‐limited systems in response to a decrease in rock uplift rate, especially during postorogenic topographic decline. The analyses presented set the stage for field studies designed to test quantitatively the various river incision models that have been proposed.

@article{doi1010292000jb000044,
    author = "Whipple, K. X. and Tucker, Gregory E.",
    title = "Implications of sediment‐flux‐dependent river incision models for landscape evolution",
    year = "2002",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Developing a quantitative understanding of the factors that control the rate of river incision into bedrock is critical to studies of landscape evolution and the linkages between climate, erosion, and tectonics. Current models of long‐term river network incision differ significantly in their treatment of the role of sediment flux. We analyze the implications of various sediment‐flux‐dependent incision models for large‐scale topography, in an attempt (1) to identify quantifiable and diagnostic differences between models that could be detected from topographic data or from the transient responses of perturbed systems and (2) to explain the apparent ubiquity of mixed bedrock‐alluvial channels in active orogens. Although certain forms of the various models can be discarded as inconsistent with morphological data, we find that the relative intrinsic concavity indices of detachment‐ and transport‐limited systems (defined herein) largely dictate whether the various models can be tied to distinctive steady state morphologies. Preliminary data suggest that no such diagnostic differences may exist, and other methods must be developed to test models. Accordingly, we develop and explore differences in the scaling behavior of topographic relief and the extent of detachment‐ versus transport‐limited channels as a function of rock uplift rate that may allow discrimination among various models. Further, we explore potentially diagnostic differences in the rates and patterns of transient channel response to changes in rock uplift rate. In addition to general differences between detachment‐ and transport‐limited systems our analysis identifies an interesting hysteresis in landscape evolution: “hybrid” channels at the threshold between detachment‐ and transport‐limited conditions are expected to act as detachment‐limited systems in response to an increase in rock uplift rate (or base level fall) and as transport‐limited systems in response to a decrease in rock uplift rate, especially during postorogenic topographic decline. The analyses presented set the stage for field studies designed to test quantitatively the various river incision models that have been proposed.",
    url = "https://doi.org/10.1029/2000jb000044",
    doi = "10.1029/2000jb000044",
    openalex = "W2038915357",
    references = "doi101007978146150575412, doi101029gm107p0297, doi102475ajs30145313"
}

A gaging station has been operated by the U.S. Geological Survey at Lees Ferry, Arizona, since May 8, 1921. In March 1963, Glen Canyon Dam was closed 15.5 miles upstream, cutting off the upstream sediment supply and regulating the discharge of the Colorado River at Lees Ferry for the first time in history. To evaluate the pre-dam variability in the hydrology of the Colorado River, and to determine the effect of the operation of Glen Canyon Dam on the downstream hydrology of the river, a continuous record of the instantaneous discharge of the river at Lees Ferry was constructed and analyzed for the entire period of record between May 8, 1921, and September 30, 2000. This effort involved retrieval from the Federal Records Centers and then synthesis of all the raw historical data collected by the U.S. Geological Survey at Lees Ferry. As part of this process, the peak discharges of the two largest historical floods at Lees Ferry, the 1884 and 1921 floods, were reanalyzed and recomputed. This reanalysis indicates that the peak discharge of the 1884 flood was 210,000±30,000 cubic feet per second (ft3/s), and the peak discharge of the 1921 flood was 170,000±20,000 ft3/s. These values are indistinguishable from the peak discharges of these floods originally estimated or published by the U.S. Geological Survey, but are substantially less than the currently accepted peak discharges of these floods. The entire continuous record of instantaneous discharge of the Colorado River at Lees Ferry can now be requested from the U.S. Geological Survey Grand Canyon Monitoring and Research Center, Flagstaff, Arizona, and is also available electronically at http://www.gcmrc.gov. This record is perhaps the longest (almost 80 years) high-resolution (mostly 15- to 30-minute precision) times series of river discharge available. Analyses of these data, therefore, provide an unparalleled characterization of both the natural variability in the discharge of a river and the effects of dam operations on a river.Following the construction and quality-control checks of the continuous record of instantaneous discharge, analyses of flow duration, sub-daily flow variability, and flood frequency were conducted on the pre- and post-dam parts of the record. These analyses indicate that although the discharge of the Colorado River varied substantially prior to the closure of Glen Canyon Dam in 1963, operation of the dam has caused changes in discharge that are more extreme than the pre-dam natural variability. Operation of the dam has eliminated flood flows and base flows, and thereby has effectively "flattened" the annual hydrograph. Prior to closure of the dam, the discharge of the Colorado River at Lees Ferry was lower than 7,980 ft3/s half of the time. Discharges lower than about 9,000 ft3/s were important for the seasonal accumulation and storage of sand in the pre-dam river downstream from Lees Ferry. The current operating plan for Glen Canyon Dam no longer allows sustained discharges lower than 8,000 ft3/s to be released. Thus, closure of the dam has not only cut off the upstream supply of sediment, but operation of the dam has also largely eliminated discharges during which sand could be demonstrated to accumulate in the river. In addition to radically changing the hydrology of the river, operation of the dam for hydroelectric-power generation has introduced large daily fluctuations in discharge. During the pre-dam era, the median daily range in discharge was only 542 ft3/s, although daily ranges in discharge exceeding 20,000 ft3/s were observed during the summer thunderstorm season. Relative to the pre-dam period of record, dam operations have increased the daily range in discharge during all but 0.1 percent of all days. The post-dam median daily range in discharge, 8,580 ft3/s, exceeds the pre-dam median discharge of 7,980 ft3/s. Operation of the dam has also radically changed the frequency of floods on the Colorado River at Lees Ferry. The frequency of floods with peak discharges larger than about 29,000 ft3/s has greatly decreased, while the frequency of smaller floods, with peak discharges between 18,500 and 29,000 ft3/s, has increased substantially. Operation of the dam has greatly extended the duration of smaller floods; for example, each of the four longest periods of sustained flows in excess of 18,500 ft3/s occurred after closure of the dam.

@article{doi103133pp1677,
    author = "Topping, David J. and Schmidt, John C. and Vierra, L. E.",
    title = "Computation and analysis of the instantaneous-discharge record for the Colorado River at Lees Ferry, Arizona — May 8, 1921, through September 30, 2000",
    year = "2003",
    journal = "USGS professional paper",
    abstract = {A gaging station has been operated by the U.S. Geological Survey at Lees Ferry, Arizona, since May 8, 1921. In March 1963, Glen Canyon Dam was closed 15.5 miles upstream, cutting off the upstream sediment supply and regulating the discharge of the Colorado River at Lees Ferry for the first time in history. To evaluate the pre-dam variability in the hydrology of the Colorado River, and to determine the effect of the operation of Glen Canyon Dam on the downstream hydrology of the river, a continuous record of the instantaneous discharge of the river at Lees Ferry was constructed and analyzed for the entire period of record between May 8, 1921, and September 30, 2000. This effort involved retrieval from the Federal Records Centers and then synthesis of all the raw historical data collected by the U.S. Geological Survey at Lees Ferry. As part of this process, the peak discharges of the two largest historical floods at Lees Ferry, the 1884 and 1921 floods, were reanalyzed and recomputed. This reanalysis indicates that the peak discharge of the 1884 flood was 210,000±30,000 cubic feet per second (ft3/s), and the peak discharge of the 1921 flood was 170,000±20,000 ft3/s. These values are indistinguishable from the peak discharges of these floods originally estimated or published by the U.S. Geological Survey, but are substantially less than the currently accepted peak discharges of these floods. The entire continuous record of instantaneous discharge of the Colorado River at Lees Ferry can now be requested from the U.S. Geological Survey Grand Canyon Monitoring and Research Center, Flagstaff, Arizona, and is also available electronically at http://www.gcmrc.gov. This record is perhaps the longest (almost 80 years) high-resolution (mostly 15- to 30-minute precision) times series of river discharge available. Analyses of these data, therefore, provide an unparalleled characterization of both the natural variability in the discharge of a river and the effects of dam operations on a river.Following the construction and quality-control checks of the continuous record of instantaneous discharge, analyses of flow duration, sub-daily flow variability, and flood frequency were conducted on the pre- and post-dam parts of the record. These analyses indicate that although the discharge of the Colorado River varied substantially prior to the closure of Glen Canyon Dam in 1963, operation of the dam has caused changes in discharge that are more extreme than the pre-dam natural variability. Operation of the dam has eliminated flood flows and base flows, and thereby has effectively "flattened" the annual hydrograph. Prior to closure of the dam, the discharge of the Colorado River at Lees Ferry was lower than 7,980 ft3/s half of the time. Discharges lower than about 9,000 ft3/s were important for the seasonal accumulation and storage of sand in the pre-dam river downstream from Lees Ferry. The current operating plan for Glen Canyon Dam no longer allows sustained discharges lower than 8,000 ft3/s to be released. Thus, closure of the dam has not only cut off the upstream supply of sediment, but operation of the dam has also largely eliminated discharges during which sand could be demonstrated to accumulate in the river. In addition to radically changing the hydrology of the river, operation of the dam for hydroelectric-power generation has introduced large daily fluctuations in discharge. During the pre-dam era, the median daily range in discharge was only 542 ft3/s, although daily ranges in discharge exceeding 20,000 ft3/s were observed during the summer thunderstorm season. Relative to the pre-dam period of record, dam operations have increased the daily range in discharge during all but 0.1 percent of all days. The post-dam median daily range in discharge, 8,580 ft3/s, exceeds the pre-dam median discharge of 7,980 ft3/s. Operation of the dam has also radically changed the frequency of floods on the Colorado River at Lees Ferry. The frequency of floods with peak discharges larger than about 29,000 ft3/s has greatly decreased, while the frequency of smaller floods, with peak discharges between 18,500 and 29,000 ft3/s, has increased substantially. Operation of the dam has greatly extended the duration of smaller floods; for example, each of the four longest periods of sustained flows in excess of 18,500 ft3/s occurred after closure of the dam.},
    url = "https://doi.org/10.3133/pp1677",
    doi = "10.3133/pp1677",
    openalex = "W1559275546"
}

The Po Plain is a low-relief area characterised by active shortening accommodated by blind thrust faulting. In this almost flat region depositional rates are similar to tectonic rates and deformation is seldom expressed by noticeable surface anticlines. We adopted a geomorphological approach based on the detailed analysis of the drainage network to identify the location of active thrust faults. A total of 36 anomalies represented by sudden river diversions and shifts in channel pattern were accurately mapped. After comparison with the location of subsurface buried anticlines and of historical seismicity, these anomalies could be related to a tectonic origin and included in a database. Their distribution highlights the activity of the buried outer thrust fronts of both the Southern Alps and the Northern Apennines. Among all the anomalies, we identified one related to the seismogenic source responsible for the 12 May 1802 earthquake (Me 5.7), which struck the Oglio River Valley near Soncino (Cremona). We propose that this earthquake was generated by an east-west trending, north-dipping, blind thrust fault that roots into the Alpine system. If this inference is correct, other faults along the Southern Alpine margin are potentially seismogenic.

@article{doi104401ag3459,
    author = "Burrato, Pierfrancesco and Ciucci, F. and Valensise, Gianluca",
    title = "An inventory of river anomalies in the Po Plain, Northern Italy: evidence for active blind thrust faulting",
    year = "2003",
    journal = "Annals of Geophysics",
    abstract = "The Po Plain is a low-relief area characterised by active shortening accommodated by blind thrust faulting. In this almost flat region depositional rates are similar to tectonic rates and deformation is seldom expressed by noticeable surface anticlines. We adopted a geomorphological approach based on the detailed analysis of the drainage network to identify the location of active thrust faults. A total of 36 anomalies represented by sudden river diversions and shifts in channel pattern were accurately mapped. After comparison with the location of subsurface buried anticlines and of historical seismicity, these anomalies could be related to a tectonic origin and included in a database. Their distribution highlights the activity of the buried outer thrust fronts of both the Southern Alps and the Northern Apennines. Among all the anomalies, we identified one related to the seismogenic source responsible for the 12 May 1802 earthquake (Me 5.7), which struck the Oglio River Valley near Soncino (Cremona). We propose that this earthquake was generated by an east-west trending, north-dipping, blind thrust fault that roots into the Alpine system. If this inference is correct, other faults along the Southern Alpine margin are potentially seismogenic.",
    url = "https://doi.org/10.4401/ag-3459",
    doi = "10.4401/ag-3459",
    openalex = "W37434215",
    references = "doi101016s0040195199000116"
}

@article{doi101023bclim0000013684136211f,
    author = "Christensen, N. S. and Wood, Andrew W. and Voisin, Nathalie and Lettenmaier, Dennis P. and Palmer, Richard N.",
    title = "The Effects of Climate Change on the Hydrology and Water Resources of the Colorado River Basin",
    year = "2004",
    journal = "Climatic Change",
    url = "https://doi.org/10.1023/b:clim.0000013684.13621.1f",
    doi = "10.1023/b:clim.0000013684.13621.1f",
    openalex = "W2084170744",
    references = "doi101007s003820000079, doi1010160921818195000461, doi101023a1010616428763, doi101023bclim0000013685996099e, doi1010292000wr900330, doi1010292001jd000659, doi10102994jd00483, doi1011751520044220000132339nhscva20co2, doi1011751520044220020153237althbd20co2, doi10230720033020"
}

▪ Abstract Bedrock rivers set much of the relief structure of active orogens and dictate rates and patterns of denudation. Quantitative understanding of the role of climate-driven denudation in the evolution of unglaciated orogens depends first and foremost on knowledge of fluvial erosion processes and the factors that control incision rate. The results of intense research in the past decade are reviewed here, with the aim of highlighting remaining unknowns and suggesting fruitful avenues for further research. This review considers in turn (a) the occurrence and morphology of bedrock channels and their relation to tectonic setting; (b) the physical processes of fluvial incision into rock; and (c) models of river incision, their implications, and the field and laboratory data needed to test, refine, and extend them.

@article{doi101146annurevearth32101802120356,
    author = "Whipple, K. X.",
    title = "BEDROCK RIVERS AND THE GEOMORPHOLOGY OF ACTIVE OROGENS",
    year = "2004",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "▪ Abstract Bedrock rivers set much of the relief structure of active orogens and dictate rates and patterns of denudation. Quantitative understanding of the role of climate-driven denudation in the evolution of unglaciated orogens depends first and foremost on knowledge of fluvial erosion processes and the factors that control incision rate. The results of intense research in the past decade are reviewed here, with the aim of highlighting remaining unknowns and suggesting fruitful avenues for further research. This review considers in turn (a) the occurrence and morphology of bedrock channels and their relation to tectonic setting; (b) the physical processes of fluvial incision into rock; and (c) models of river incision, their implications, and the field and laboratory data needed to test, refine, and extend them.",
    url = "https://doi.org/10.1146/annurev.earth.32.101802.120356",
    doi = "10.1146/annurev.earth.32.101802.120356",
    openalex = "W2104300819",
    references = "doi101007978146150575412, doi10102994wr00757, doi101029gm107p0297, doi101038379505a0, doi102475ajs30145313"
}

Rivers differ among themselves and through time. An individual river can vary significantly downstream, changing its dimensions and pattern dramatically over a short distance. If hydrology and hydraulics were the primary controls on the morphology and behaviour of large rivers, we would expect long reaches of rivers to maintain characteristic and relatively uniform morphologies. In fact, this is not the case - the variability of large rivers indicates that other important factors are involved. River Variability and Complexity presents an interesting approach to the understanding of river variability. It provides examples of river variability and explains the reasons for them, including fluvial response to human activities. Understanding the mechanisms of variability is important for geomorphologists, geologists, river engineers and sedimentologists as they attempt to interpret ancient fluvial deposits or anticipate river behaviour at different locations and through time. This book provides an excellent background for graduates, researchers and professionals.

@book{doi101017cbo9781139165440,
    author = "Schumm, Stanley A.",
    title = "River Variability and Complexity",
    year = "2005",
    booktitle = "Cambridge University Press eBooks",
    abstract = "Rivers differ among themselves and through time. An individual river can vary significantly downstream, changing its dimensions and pattern dramatically over a short distance. If hydrology and hydraulics were the primary controls on the morphology and behaviour of large rivers, we would expect long reaches of rivers to maintain characteristic and relatively uniform morphologies. In fact, this is not the case - the variability of large rivers indicates that other important factors are involved. River Variability and Complexity presents an interesting approach to the understanding of river variability. It provides examples of river variability and explains the reasons for them, including fluvial response to human activities. Understanding the mechanisms of variability is important for geomorphologists, geologists, river engineers and sedimentologists as they attempt to interpret ancient fluvial deposits or anticipate river behaviour at different locations and through time. This book provides an excellent background for graduates, researchers and professionals.",
    url = "https://doi.org/10.1017/cbo9781139165440",
    doi = "10.1017/cbo9781139165440",
    openalex = "W2137348668",
    references = "doi101016s0040195199000116"
}

A global overview of dam-based impacts on large river systems shows that over half (172 out of 292) are affected by dams, including the eight most biogeographically diverse. Dam-impacted catchments experience higher irrigation pressure and about 25 times more economic activity per unit of water than do unaffected catchments. In view of projected changes in climate and water resource use, these findings can be used to identify ecological risks associated with further impacts on large river systems.

@article{doi101126science1107887,
    author = "Nilsson, Christer and Reidy, Catherine Ann and Dynesius, Mats and Revenga, Carmen",
    title = "Fragmentation and Flow Regulation of the World's Large River Systems",
    year = "2005",
    journal = "Science",
    abstract = "A global overview of dam-based impacts on large river systems shows that over half (172 out of 292) are affected by dams, including the eight most biogeographically diverse. Dam-impacted catchments experience higher irrigation pressure and about 25 times more economic activity per unit of water than do unaffected catchments. In view of projected changes in climate and water resource use, these findings can be used to identify ecological risks associated with further impacts on large river systems.",
    url = "https://doi.org/10.1126/science.1107887",
    doi = "10.1126/science.1107887",
    openalex = "W2008942529",
    references = "doi10103835002501, doi1016410006356820010510933teotwa20co2"
}

Life history theories attempt to explain the evolution of organism traits as adaptations to environmental variation. A model involving three primary life history strategies (endpoints on a triangular surface) describes general patterns of variation more comprehensively than schemes that examine single traits or merely contrast fast versus slow life histories. It provides a general means to predict a priori the types of populations with high or low demographic resilience, production potential, and conformity to density-dependent regulation. Periodic (long-lived, high fecundity, high recruitment variation) and opportunistic (small, short-lived, high reproductive effort, high demographic resilience) strategies should conform poorly to models that assume density-dependent recruitment. Periodic-type species reveal greatest recruitment variation and compensatory reserve, but with poor conformity to stock–recruitment models. Equilibrium-type populations (low fecundity, large egg size, parental care) should conform better to assumptions of density-dependent recruitment, but have lower demographic resilience. The model's predictions are explored relative to sustainable harvest, endangered species conservation, supplemental stocking, and transferability of ecological indices. When detailed information is lacking, species ordination according to the triangular model provides qualitative guidance for management and development of more detailed predictive models.

@article{doi101139f05040,
    author = "Winemiller, Kirk O.",
    title = "Life history strategies, population regulation, and implications for fisheries management",
    year = "2005",
    journal = "Canadian Journal of Fisheries and Aquatic Sciences",
    abstract = "Life history theories attempt to explain the evolution of organism traits as adaptations to environmental variation. A model involving three primary life history strategies (endpoints on a triangular surface) describes general patterns of variation more comprehensively than schemes that examine single traits or merely contrast fast versus slow life histories. It provides a general means to predict a priori the types of populations with high or low demographic resilience, production potential, and conformity to density-dependent regulation. Periodic (long-lived, high fecundity, high recruitment variation) and opportunistic (small, short-lived, high reproductive effort, high demographic resilience) strategies should conform poorly to models that assume density-dependent recruitment. Periodic-type species reveal greatest recruitment variation and compensatory reserve, but with poor conformity to stock–recruitment models. Equilibrium-type populations (low fecundity, large egg size, parental care) should conform better to assumptions of density-dependent recruitment, but have lower demographic resilience. The model's predictions are explored relative to sustainable harvest, endangered species conservation, supplemental stocking, and transferability of ecological indices. When detailed information is lacking, species ordination according to the triangular model provides qualitative guidance for management and development of more detailed predictive models.",
    url = "https://doi.org/10.1139/f05-040",
    doi = "10.1139/f05-040",
    openalex = "W2167875938",
    references = "doi101023a1008828730759, doi1018900012965820020831490prhcac20co2, doi101890050330"
}

Updated proxy reconstructions of water year (October–September) streamflow for four key gauges in the Upper Colorado River Basin were generated using an expanded tree ring network and longer calibration records than in previous efforts. Reconstructed gauges include the Green River at Green River, Utah; Colorado near Cisco, Utah; San Juan near Bluff, Utah; and Colorado at Lees Ferry, Arizona. The reconstructions explain 72–81% of the variance in the gauge records, and results are robust across several reconstruction approaches. Time series plots as well as results of cross‐spectral analysis indicate strong spatial coherence in runoff variations across the subbasins. The Lees Ferry reconstruction suggests a higher long‐term mean than previous reconstructions but strongly supports earlier findings that Colorado River allocations were based on one of the wettest periods in the past 5 centuries and that droughts more severe than any 20th to 21st century event occurred in the past.

@article{doi1010292005wr004455,
    author = "Woodhouse, Connie A. and Gray, Stephen T. and Meko, David M.",
    title = "Updated streamflow reconstructions for the Upper Colorado River Basin",
    year = "2006",
    journal = "Water Resources Research",
    abstract = "Updated proxy reconstructions of water year (October–September) streamflow for four key gauges in the Upper Colorado River Basin were generated using an expanded tree ring network and longer calibration records than in previous efforts. Reconstructed gauges include the Green River at Green River, Utah; Colorado near Cisco, Utah; San Juan near Bluff, Utah; and Colorado at Lees Ferry, Arizona. The reconstructions explain 72–81\% of the variance in the gauge records, and results are robust across several reconstruction approaches. Time series plots as well as results of cross‐spectral analysis indicate strong spatial coherence in runoff variations across the subbasins. The Lees Ferry reconstruction suggests a higher long‐term mean than previous reconstructions but strongly supports earlier findings that Colorado River allocations were based on one of the wettest periods in the past 5 centuries and that droughts more severe than any 20th to 21st century event occurred in the past.",
    url = "https://doi.org/10.1029/2005wr004455",
    doi = "10.1029/2005wr004455",
    openalex = "W1627286860",
    references = "doi1010079789401578790, doi1010292000gl012745, doi101038scientificamerican057292, doi101126science1102586, doi1011751520045019840230201otavoc20co2, doi1011751520047719980790061apgtwa20co2, doi1023071271101, doi1023071550667, doi1023072287607, openalexw1515936669"
}

The eastern Brazilian coastal drainages are of great biogeographical significance, because of their highly endemic fish faunas. Phylogenetic patterns suggest a close biotic relationship between the rivers that flow into the Atlantic and those on the adjacent upland crystalline shield. However, little has been said on the dynamics of the geological processes causally related to the cladogenetic events between these areas. Distributional and phylogenetic patterns suggest a close association with the geological history of the passive continental margin of South America, from the Cretaceous to the present day. In this area megadome uplifts, rifting, vertical movements between rifted blocks and the erosive retreat of the South American eastern continental margin are hypothesized as the main geological forces controlling the distribution of freshwater fishes. The tectonic activity associated with the break-up of Gondwana and separation of South America and Africa formed six megadomes that control most of the current courses of the main crystalline shield river basins. Except for basins located at the edges of such megadomes, these river systems developed long, circuitous routes over the ancient Brazilian crystalline shield before emptying into the recently opened Atlantic Ocean. Initial cladogenetic events between upland crystalline drainages and Atlantic tributaries were probably associated with vicariant processes, and some ancient basal sister-groups of widespread inclusive taxa are found in these coastal hydrographic systems. Later, generalized erosive denudation resulted in an isostatic adjustment of the eastern margin of the platform. These, along with reactivations of ancient rifts led to vertical movements between rifted blocks and gave rise, in southeastern Brazil, to taphrogenic (rift related) basins. These basins, such as the Taubaté, São Paulo, Curitiba and Volta Redonda basins, among others, captured adjacent upland drainages and fauna. The fossil fishes from the Tremembé Formation (Eocene-Oligocene of Taubaté Basin) exemplify this process. Other taphrogenic systems of Tertiary age were also identified in other segments of the Atlantic continental margin, such as in Borborema province, in NE Brazil, with marked influence over drainage patterns. At the same time, erosive retreat of the eastern margin of the platform successively captured upland rivers, which became Atlantic tributaries evolving associated to main rift systems. The continued nature of these processes explains the mixed phylogenetic and distributional patterns between Atlantic tributaries and the upland crystalline shield areas, especially in the southeastern continental margin, represented by successively, less inclusive sister-groups associated with cladogenetic events from the Late Cretaceous to the present.

@article{doi101590s167962252006000200009,
    author = "Ribeiro, Alexandre C.",
    title = "Tectonic history and the biogeography of the freshwater fishes from the coastal drainages of eastern Brazil: an example of faunal evolution associated with a divergent continental margin",
    year = "2006",
    journal = "Neotropical Ichthyology",
    abstract = "The eastern Brazilian coastal drainages are of great biogeographical significance, because of their highly endemic fish faunas. Phylogenetic patterns suggest a close biotic relationship between the rivers that flow into the Atlantic and those on the adjacent upland crystalline shield. However, little has been said on the dynamics of the geological processes causally related to the cladogenetic events between these areas. Distributional and phylogenetic patterns suggest a close association with the geological history of the passive continental margin of South America, from the Cretaceous to the present day. In this area megadome uplifts, rifting, vertical movements between rifted blocks and the erosive retreat of the South American eastern continental margin are hypothesized as the main geological forces controlling the distribution of freshwater fishes. The tectonic activity associated with the break-up of Gondwana and separation of South America and Africa formed six megadomes that control most of the current courses of the main crystalline shield river basins. Except for basins located at the edges of such megadomes, these river systems developed long, circuitous routes over the ancient Brazilian crystalline shield before emptying into the recently opened Atlantic Ocean. Initial cladogenetic events between upland crystalline drainages and Atlantic tributaries were probably associated with vicariant processes, and some ancient basal sister-groups of widespread inclusive taxa are found in these coastal hydrographic systems. Later, generalized erosive denudation resulted in an isostatic adjustment of the eastern margin of the platform. These, along with reactivations of ancient rifts led to vertical movements between rifted blocks and gave rise, in southeastern Brazil, to taphrogenic (rift related) basins. These basins, such as the Taubaté, São Paulo, Curitiba and Volta Redonda basins, among others, captured adjacent upland drainages and fauna. The fossil fishes from the Tremembé Formation (Eocene-Oligocene of Taubaté Basin) exemplify this process. Other taphrogenic systems of Tertiary age were also identified in other segments of the Atlantic continental margin, such as in Borborema province, in NE Brazil, with marked influence over drainage patterns. At the same time, erosive retreat of the eastern margin of the platform successively captured upland rivers, which became Atlantic tributaries evolving associated to main rift systems. The continued nature of these processes explains the mixed phylogenetic and distributional patterns between Atlantic tributaries and the upland crystalline shield areas, especially in the southeastern continental margin, represented by successively, less inclusive sister-groups associated with cladogenetic events from the Late Cretaceous to the present.",
    url = "https://doi.org/10.1590/s1679-62252006000200009",
    doi = "10.1590/s1679-62252006000200009",
    openalex = "W1979804243"
}

Understanding the mechanisms by which nonnative species successfully invade new regions and the consequences for native fauna is a pressing ecological issue, and one for which niche theory can play an important role. In this paper, we quantify a comprehensive suite of morphological, behavioral, physiological, trophic, and life-history traits for the entire fish species pool in the Colorado River Basin to explore a number of hypotheses regarding linkages between human-induced environmental change, the creation and modification of ecological niche opportunities, and subsequent invasion and extirpation of species over the past 150 years. Specifically, we use the fish life-history model of K. O. Winemiller and K. A. Rose to quantitatively evaluate how the rates of nonnative species spread and native species range contraction reflect the interplay between overlapping life-history strategies and an anthropogenically altered adaptive landscape. Our results reveal a number of intriguing findings. First, nonnative species are located throughout the adaptive surface defined by the life-history attributes, and they surround the ecological niche volume represented by the native fish species pool. Second, native species that show the greatest distributional declines are separated into those exhibiting strong life-history overlap with nonnative species (evidence for biotic interactions) and those having a periodic strategy that is not well adapted to present-day modified environmental conditions. Third, rapidly spreading nonnative fishes generally occupy “vacant” niche positions in life-history space, which is associated either with “niche opportunities” provided by human-created environmental conditions (consistent with the environmental-resistance hypothesis of invasion) or with minimal overlap with native life-history strategies (consistent with the biotic-resistance hypothesis). This study is the first to identify specific life-history strategies that are associated with extensive range reduction of native species and expansion of nonnative species, and it highlights the utility of using niche and life-history perspectives to evaluate different mechanisms that contribute to the patterns of fish invasions and extirpations in the American Southwest.

@article{doi101890050330,
    author = "Olden, Julian D. and Poff, N. LeRoy and Bestgen, Kevin R.",
    title = "LIFE-HISTORY STRATEGIES PREDICT FISH INVASIONS AND EXTIRPATIONS IN THE COLORADO RIVER BASIN",
    year = "2006",
    journal = "Ecological Monographs",
    abstract = "Understanding the mechanisms by which nonnative species successfully invade new regions and the consequences for native fauna is a pressing ecological issue, and one for which niche theory can play an important role. In this paper, we quantify a comprehensive suite of morphological, behavioral, physiological, trophic, and life-history traits for the entire fish species pool in the Colorado River Basin to explore a number of hypotheses regarding linkages between human-induced environmental change, the creation and modification of ecological niche opportunities, and subsequent invasion and extirpation of species over the past 150 years. Specifically, we use the fish life-history model of K. O. Winemiller and K. A. Rose to quantitatively evaluate how the rates of nonnative species spread and native species range contraction reflect the interplay between overlapping life-history strategies and an anthropogenically altered adaptive landscape. Our results reveal a number of intriguing findings. First, nonnative species are located throughout the adaptive surface defined by the life-history attributes, and they surround the ecological niche volume represented by the native fish species pool. Second, native species that show the greatest distributional declines are separated into those exhibiting strong life-history overlap with nonnative species (evidence for biotic interactions) and those having a periodic strategy that is not well adapted to present-day modified environmental conditions. Third, rapidly spreading nonnative fishes generally occupy “vacant” niche positions in life-history space, which is associated either with “niche opportunities” provided by human-created environmental conditions (consistent with the environmental-resistance hypothesis of invasion) or with minimal overlap with native life-history strategies (consistent with the biotic-resistance hypothesis). This study is the first to identify specific life-history strategies that are associated with extensive range reduction of native species and expansion of nonnative species, and it highlights the utility of using niche and life-history perspectives to evaluate different mechanisms that contribute to the patterns of fish invasions and extirpations in the American Southwest.",
    url = "https://doi.org/10.1890/05-0330",
    doi = "10.1890/05-0330",
    openalex = "W2053890762",
    references = "doi101086282697, doi101086283244, doi101086284325, doi101146annurevecolsys32081501114037, doi1016410006356820000500053eaecon23co2, doi1018901051076120000100689bicegc20co2, doi1023071313099, doi1023072257385, doi1023073071998, doi1023075403"
}

Kondolf, G. M., A. J. Boulton, S. O'Daniel, G. C. Poole, F. J. Rahel, E. H. Stanley, E. Wohl, A. Bång, J. Carlstrom, C. Cristoni, H. Huber, S. Koljonen, P. Louhi, and K. Nakamura 2006. Process-based ecological river restoration: visualizing three-dimensional connectivity and dynamic vectors to recover lost linkages. Ecology and Society 11(2): 5. https://doi.org/10.5751/ES-01747-110205

@article{doi105751es01747110205,
    author = "Kondolf, G. Mathias and Boulton, Andrew J. and O'Daniel, S. J. and Poole, Geoffrey C. and Rahel, Frank J. and Stanley, Emily H. and Wohl, Ellen and Bång, Åsa and Carlström, Julia and Cristoni, Chiara and Huber, Harald and Koljonen, Saija and Louhi, Pauliina and Nakamura, Keigo",
    title = "Process-Based Ecological River Restoration: Visualizing Three-Dimensional Connectivity and Dynamic Vectors to Recover Lost Linkages",
    year = "2006",
    journal = "Ecology and Society",
    abstract = "Kondolf, G. M., A. J. Boulton, S. O'Daniel, G. C. Poole, F. J. Rahel, E. H. Stanley, E. Wohl, A. Bång, J. Carlstrom, C. Cristoni, H. Huber, S. Koljonen, P. Louhi, and K. Nakamura 2006. Process-based ecological river restoration: visualizing three-dimensional connectivity and dynamic vectors to recover lost linkages. Ecology and Society 11(2): 5. https://doi.org/10.5751/ES-01747-110205",
    url = "https://doi.org/10.5751/es-01747-110205",
    doi = "10.5751/es-01747-110205",
    openalex = "W2134028032",
    references = "doi101111j13652427200601708x"
}

The Roan Plateau in western Colorado constitutes a natural experiment for studying landscape response to a drop in base level. Late Cenozoic incision of the upper Colorado River led to elevational isolation of the Plateau and initiation of a wave of incision into its southern edge. Knickpoints (oversteepened reaches that contain waterfalls 60–110 m in height) mark the upstream extent of this headward propagating wave. That this incision has occurred in a laterally extensive, well‐stratified, and essentially flat‐lying bedrock and in an area with relatively uniform climate, implies that it should serve as a good test of existing knickpoint propagation models. We predict the locations of knickpoints by using a stream power‐based celerity model, in which knickpoint recession rate is a power function of drainage area and is proportional to rock susceptibility to erosion. Models of the Parachute and Roan drainages (17 and 16 knickpoints, respectively) show expected rapid initial knickpoint propagation rates, which decline as drainage area decreases stepwise at tributary junctions. The modeled positions of knickpoints match well with observed features, using a single combination of parameters to model retreat in both drainage basins. We compare our celerity model results with past studies and explore how longitudinal profile analysis may be used to derive independently the exponent on drainage area in the celerity model.

@article{doi1010292006jf000553,
    author = "Berlin, M. M. and Anderson, Robert S.",
    title = "Modeling of knickpoint retreat on the Roan Plateau, western Colorado",
    year = "2007",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The Roan Plateau in western Colorado constitutes a natural experiment for studying landscape response to a drop in base level. Late Cenozoic incision of the upper Colorado River led to elevational isolation of the Plateau and initiation of a wave of incision into its southern edge. Knickpoints (oversteepened reaches that contain waterfalls 60–110 m in height) mark the upstream extent of this headward propagating wave. That this incision has occurred in a laterally extensive, well‐stratified, and essentially flat‐lying bedrock and in an area with relatively uniform climate, implies that it should serve as a good test of existing knickpoint propagation models. We predict the locations of knickpoints by using a stream power‐based celerity model, in which knickpoint recession rate is a power function of drainage area and is proportional to rock susceptibility to erosion. Models of the Parachute and Roan drainages (17 and 16 knickpoints, respectively) show expected rapid initial knickpoint propagation rates, which decline as drainage area decreases stepwise at tributary junctions. The modeled positions of knickpoints match well with observed features, using a single combination of parameters to model retreat in both drainage basins. We compare our celerity model results with past studies and explore how longitudinal profile analysis may be used to derive independently the exponent on drainage area in the celerity model.",
    url = "https://doi.org/10.1029/2006jf000553",
    doi = "10.1029/2006jf000553",
    openalex = "W2076293507",
    references = "doi101086628592, doi101130001676061978891745eamcda20co2"
}

New tree‐ring records of ring‐width from remnant preserved wood are analyzed to extend the record of reconstructed annual flows of the Colorado River at Lee Ferry into the Medieval Climate Anomaly, when epic droughts are hypothesized from other paleoclimatic evidence to have affected various parts of western North America. The most extreme low‐frequency feature of the new reconstruction, covering A.D. 762‐2005, is a hydrologic drought in the mid‐1100s. The drought is characterized by a decrease of more than 15% in mean annual flow averaged over 25 years, and by the absence of high annual flows over a longer period of about six decades. The drought is consistent in timing with dry conditions inferred from tree‐ring data in the Great Basin and Colorado Plateau, but regional differences in intensity emphasize the importance of basin‐specific paleoclimatic data in quantifying likely effects of drought on water supply.

@article{doi1010292007gl029988,
    author = "Meko, David M. and Woodhouse, Connie A. and Baisan, Christopher and Knight, Troy A. and Lukas, Jeffrey J. and Hughes, Malcolm K. and Salzer, Matthew W.",
    title = "Medieval drought in the upper Colorado River Basin",
    year = "2007",
    journal = "Geophysical Research Letters",
    abstract = "New tree‐ring records of ring‐width from remnant preserved wood are analyzed to extend the record of reconstructed annual flows of the Colorado River at Lee Ferry into the Medieval Climate Anomaly, when epic droughts are hypothesized from other paleoclimatic evidence to have affected various parts of western North America. The most extreme low‐frequency feature of the new reconstruction, covering A.D. 762‐2005, is a hydrologic drought in the mid‐1100s. The drought is characterized by a decrease of more than 15\% in mean annual flow averaged over 25 years, and by the absence of high annual flows over a longer period of about six decades. The drought is consistent in timing with dry conditions inferred from tree‐ring data in the Great Basin and Colorado Plateau, but regional differences in intensity emphasize the importance of basin‐specific paleoclimatic data in quantifying likely effects of drought on water supply.",
    url = "https://doi.org/10.1029/2007gl029988",
    doi = "10.1029/2007gl029988",
    openalex = "W2161896476",
    references = "doi1010079789401578790, doi1010292005wr004455, doi101038369546a0, doi10108000401706197710489581, doi101093forestscience372734, doi101126science1102586, doi1011751520045019840230201otavoc20co2, doi101177095968369500500211, openalexw1515936669, openalexw185908181, openalexw2187518561"
}

Global biodiversity in river and riparian ecosystems is generated and maintained by geographic variation in stream processes and fluvial disturbance regimes, which largely reflect regional differences in climate and geology. Extensive construction of dams by humans has greatly dampened the seasonal and interannual streamflow variability of rivers, thereby altering natural dynamics in ecologically important flows on continental to global scales. The cumulative effects of modification to regional-scale environmental templates caused by dams is largely unexplored but of critical conservation importance. Here, we use 186 long-term streamflow records on intermediate-sized rivers across the continental United States to show that dams have homogenized the flow regimes on third- through seventh-order rivers in 16 historically distinctive hydrologic regions over the course of the 20th century. This regional homogenization occurs chiefly through modification of the magnitude and timing of ecologically critical high and low flows. For 317 undammed reference rivers, no evidence for homogenization was found, despite documented changes in regional precipitation over this period. With an estimated average density of one dam every 48 km of third- through seventh-order river channel in the United States, dams arguably have a continental scale effect of homogenizing regionally distinct environmental templates, thereby creating conditions that favor the spread of cosmopolitan, nonindigenous species at the expense of locally adapted native biota. Quantitative analyses such as ours provide the basis for conservation and management actions aimed at restoring and maintaining native biodiversity and ecosystem function and resilience for regionally distinct ecosystems at continental to global scales.

@article{doi101073pnas0609812104,
    author = "Poff, N. LeRoy and Olden, Julian D. and Merritt, David M. and Pepin, David M.",
    title = "Homogenization of regional river dynamics by dams and global biodiversity implications",
    year = "2007",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Global biodiversity in river and riparian ecosystems is generated and maintained by geographic variation in stream processes and fluvial disturbance regimes, which largely reflect regional differences in climate and geology. Extensive construction of dams by humans has greatly dampened the seasonal and interannual streamflow variability of rivers, thereby altering natural dynamics in ecologically important flows on continental to global scales. The cumulative effects of modification to regional-scale environmental templates caused by dams is largely unexplored but of critical conservation importance. Here, we use 186 long-term streamflow records on intermediate-sized rivers across the continental United States to show that dams have homogenized the flow regimes on third- through seventh-order rivers in 16 historically distinctive hydrologic regions over the course of the 20th century. This regional homogenization occurs chiefly through modification of the magnitude and timing of ecologically critical high and low flows. For 317 undammed reference rivers, no evidence for homogenization was found, despite documented changes in regional precipitation over this period. With an estimated average density of one dam every 48 km of third- through seventh-order river channel in the United States, dams arguably have a continental scale effect of homogenizing regionally distinct environmental templates, thereby creating conditions that favor the spread of cosmopolitan, nonindigenous species at the expense of locally adapted native biota. Quantitative analyses such as ours provide the basis for conservation and management actions aimed at restoring and maintaining native biodiversity and ecosystem function and resilience for regionally distinct ecosystems at continental to global scales.",
    url = "https://doi.org/10.1073/pnas.0609812104",
    doi = "10.1073/pnas.0609812104",
    openalex = "W2146317308",
    references = "doi101016jtree200309010, doi101126science2885467854, doi101890050330"
}

Abstract. Implications of 21st century climate change on the hydrology and water resources of the Colorado River Basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950–1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into three periods: 2010–2039, 2040–2069, and 2070–2099. The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2% for the A2 scenario, and from +1 to −1% for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived April 1 snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38% for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff changes of −1, −6, and −11% for the A2 ensembles, and 0, −7, and −8% for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage and average hydropower production generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 for both emissions scenarios.

@article{doi105194hess1114172007,
    author = "Christensen, N. S. and Lettenmaier, Dennis P.",
    title = "A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin",
    year = "2007",
    journal = "Hydrology and earth system sciences",
    abstract = "Abstract. Implications of 21st century climate change on the hydrology and water resources of the Colorado River Basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950–1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into three periods: 2010–2039, 2040–2069, and 2070–2099. The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2\% for the A2 scenario, and from +1 to −1\% for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived April 1 snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38\% for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff changes of −1, −6, and −11\% for the A2 ensembles, and 0, −7, and −8\% for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage and average hydropower production generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20\% by period 3 for both emissions scenarios.",
    url = "https://doi.org/10.5194/hess-11-1417-2007",
    doi = "10.5194/hess-11-1417-2007",
    openalex = "W2105594811",
    references = "doi101007s003820000079, doi101007s003820050010, doi101023bclim0000013684136211f, doi101023bclim0000013685996099e, doi1010292005wr004455, doi10102994jd00483, doi101038nature04312, doi101126science1139601, doi1011751520044220020153237althbd20co2, doi101175jcli36291, doi101175jcli38271"
}

Summary 1. Temporary rivers and streams are among the most common and most hydrologically dynamic freshwater ecosystems. The number of temporary rivers and the severity of flow intermittence may be increasing in regions affected by climatic drying trends or water abstraction. Despite their abundance, temporary rivers have been historically neglected by ecologists. A recent increase in temporary‐river research needs to be supported by new models that generate hypotheses and stimulate further research. In this article, we present three conceptual models that address spatial and temporal patterns in temporary‐river biodiversity and biogeochemistry. 2. Temporary rivers are characterised by the repeated onset and cessation of flow, and by complex hydrological dynamics in the longitudinal dimension. Longitudinal dynamics, such as advancing and retreating wetted fronts, hydrological connections and disconnections, and gradients in flow permanence, influence biotic communities and nutrient and organic matter processing. 3. The first conceptual model concerns connectivity between habitat patches. Variable connectivity suggests that the metacommunity and metapopulation concepts are applicable in temporary rivers. We predict that aggregations of local communities in the isolated water bodies of temporary rivers function as metacommunities. These metacommunities may become longitudinally nested due to interspecific differences in dispersal and mortality. The metapopulation concept applies to some temporary river species, but not all. In stable metapopulations, rates of local extinction are balanced by recolonisation. However, extinction and recolonisation in many temporary‐river species are decoupled by frequent disturbances, and populations of these species are usually expanding or contracting. 4. The second conceptual model predicts that large‐scale biodiversity varies as a function of aquatic and terrestrial patch dynamics and water‐level fluctuations. Habitat mosaics in temporary rivers change in composition and configuration in response to inundation and drying, and these changes elicit a range of biotic responses. In the model, aquatic biodiversity initially increases directly with water level due to increasing abundance of aquatic patches. When most of the channel is inundated and most aquatic patches are connected, further increases in aquatic habitat and connectivity cause aquatic biodiversity to decline due to community homogenisation and reduced habitat diversity. The predicted responses of terrestrial biodiversity to changes in water level are the inverse of aquatic biodiversity responses. 5. The third conceptual model represents temporary rivers as longitudinal, punctuated biogeochemical reactors. Advancing fronts carry water, solutes and particulate organic matter downstream; subsequent flow recessions and drying result in deposition of transported material in reserves such as pools and bar tops. Material processing is rapid during inundated periods and slower during dry periods. The efficiency of material processing is predicted to increase with the number of cycles of transport, deposition and processing that occur down the length of a temporary river. 6. We end with a call for conservation and resource management that addresses the unique properties of temporary rivers. Primary objectives for effective temporary river management are preservation or restoration of aquatic‐terrestrial habitat mosaics, preservation or restoration of natural flow intermittence, and identification of flow requirements for highly valued species and processes.

@article{doi101111j13652427200902322x,
    author = "Larned, Scott T. and Datry, Thibault and Arscott, David B. and Tockner, Klement",
    title = "Emerging concepts in temporary‐river ecology",
    year = "2009",
    journal = "Freshwater Biology",
    abstract = "Summary 1. Temporary rivers and streams are among the most common and most hydrologically dynamic freshwater ecosystems. The number of temporary rivers and the severity of flow intermittence may be increasing in regions affected by climatic drying trends or water abstraction. Despite their abundance, temporary rivers have been historically neglected by ecologists. A recent increase in temporary‐river research needs to be supported by new models that generate hypotheses and stimulate further research. In this article, we present three conceptual models that address spatial and temporal patterns in temporary‐river biodiversity and biogeochemistry. 2. Temporary rivers are characterised by the repeated onset and cessation of flow, and by complex hydrological dynamics in the longitudinal dimension. Longitudinal dynamics, such as advancing and retreating wetted fronts, hydrological connections and disconnections, and gradients in flow permanence, influence biotic communities and nutrient and organic matter processing. 3. The first conceptual model concerns connectivity between habitat patches. Variable connectivity suggests that the metacommunity and metapopulation concepts are applicable in temporary rivers. We predict that aggregations of local communities in the isolated water bodies of temporary rivers function as metacommunities. These metacommunities may become longitudinally nested due to interspecific differences in dispersal and mortality. The metapopulation concept applies to some temporary river species, but not all. In stable metapopulations, rates of local extinction are balanced by recolonisation. However, extinction and recolonisation in many temporary‐river species are decoupled by frequent disturbances, and populations of these species are usually expanding or contracting. 4. The second conceptual model predicts that large‐scale biodiversity varies as a function of aquatic and terrestrial patch dynamics and water‐level fluctuations. Habitat mosaics in temporary rivers change in composition and configuration in response to inundation and drying, and these changes elicit a range of biotic responses. In the model, aquatic biodiversity initially increases directly with water level due to increasing abundance of aquatic patches. When most of the channel is inundated and most aquatic patches are connected, further increases in aquatic habitat and connectivity cause aquatic biodiversity to decline due to community homogenisation and reduced habitat diversity. The predicted responses of terrestrial biodiversity to changes in water level are the inverse of aquatic biodiversity responses. 5. The third conceptual model represents temporary rivers as longitudinal, punctuated biogeochemical reactors. Advancing fronts carry water, solutes and particulate organic matter downstream; subsequent flow recessions and drying result in deposition of transported material in reserves such as pools and bar tops. Material processing is rapid during inundated periods and slower during dry periods. The efficiency of material processing is predicted to increase with the number of cycles of transport, deposition and processing that occur down the length of a temporary river. 6. We end with a call for conservation and resource management that addresses the unique properties of temporary rivers. Primary objectives for effective temporary river management are preservation or restoration of aquatic‐terrestrial habitat mosaics, preservation or restoration of natural flow intermittence, and identification of flow requirements for highly valued species and processes.",
    url = "https://doi.org/10.1111/j.1365-2427.2009.02322.x",
    doi = "10.1111/j.1365-2427.2009.02322.x",
    openalex = "W2118792424",
    references = "doi101023bclim0000013684136211f, doi1016410006356820020520905upadlo20co2"
}

We describe and apply a method for estimating uplift rate histories from longitudinal river profiles. Our strategy is divided into three parts. First, we develop a forward model, which calculates river profiles from uplift rate histories. Height variation along a river profile is controlled by uplift rate and moderated by the erosional process. We assume that the erosional process can be represented by a combination of advection and diffusion, which are parameterized using four erosional constants. Second, we have posed and solved the geologically more interesting inverse problem: which uplift rate history minimizes the misfit between calculated and observed river profiles? The inverse algorithm has been tested on synthetic river profiles, which demonstrates that uplift rate histories can be reliably retrieved. Our tests show that the erosional process is dominated by advection (i.e., knickpoint retreat) and that changes in lithology and discharge play a secondary role in determining the transient form of a river profile. Finally, we have inverted river profiles from a series of African topographic swells, namely the Bié, South African, Namibian, Hoggar, and Tibesti domes. Fits between calculated and observed river profiles are excellent. Calculated uplift rate histories suggest that these domes grew rapidly during the last 30–40 million years. Uplift rate histories vary significantly from dome to dome but cumulative uplift histories agree closely with independent geologic estimates.

@article{doi1010292009jb006692,
    author = "Roberts, G.G. and White, Nicky",
    title = "Estimating uplift rate histories from river profiles using African examples",
    year = "2010",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "We describe and apply a method for estimating uplift rate histories from longitudinal river profiles. Our strategy is divided into three parts. First, we develop a forward model, which calculates river profiles from uplift rate histories. Height variation along a river profile is controlled by uplift rate and moderated by the erosional process. We assume that the erosional process can be represented by a combination of advection and diffusion, which are parameterized using four erosional constants. Second, we have posed and solved the geologically more interesting inverse problem: which uplift rate history minimizes the misfit between calculated and observed river profiles? The inverse algorithm has been tested on synthetic river profiles, which demonstrates that uplift rate histories can be reliably retrieved. Our tests show that the erosional process is dominated by advection (i.e., knickpoint retreat) and that changes in lithology and discharge play a secondary role in determining the transient form of a river profile. Finally, we have inverted river profiles from a series of African topographic swells, namely the Bié, South African, Namibian, Hoggar, and Tibesti domes. Fits between calculated and observed river profiles are excellent. Calculated uplift rate histories suggest that these domes grew rapidly during the last 30–40 million years. Uplift rate histories vary significantly from dome to dome but cumulative uplift histories agree closely with independent geologic estimates.",
    url = "https://doi.org/10.1029/2009jb006692",
    doi = "10.1029/2009jb006692",
    openalex = "W2158346779",
    references = "doi101007s001900050480z, doi1010160040195192902599, doi1011300091761320002843riodir20co2"
}

The hydrological budget of Himalayan rivers is dominated by monsoonal rainfall and snowmelt, but their relative impact is not well established because this remote region lacks a dense gauge network. Here, we use a combination of validated remotely‐sensed climate parameters to characterize the spatiotemporal distribution of rainfall, snowfall, and evapotranspiration in order to quantify their relative contribution to mean river discharge. Rainfall amounts are calculated from calibrated, orbital, high‐resolution Tropical Rainfall Measurement Mission data, and snow‐water equivalents are computed from a snowmelt model based on satellite‐derived snow cover, surface temperature, and solar radiation. Our data allow us to identify three key aspects of the spatiotemporal precipitation pattern. First, we observe a strong decoupling between the rainfall on the Himalayan foreland versus that in the mountains: a pronounced sixfold, east‐west rainfall gradient in the Ganges plains exists only at elevations <500 m asl. Mountainous regions (500 to 5000 m asl) receive nearly equal rainfall amounts along strike. Second, whereas the Indian summer monsoon is responsible for more than 80% of annual rainfall in the central Himalaya and Tibetan Plateau, the eastern and western syntaxes receive only ∼50% of their annual rainfall during the summer season. Third, snowmelt contributions to discharge differ widely along the range. As a fraction of the total annual discharge, snowmelt constitutes up to 50% in the far western (Indus area) catchments, ∼25% in far eastern (Tsangpo) catchments, and <20% elsewhere. Despite these along‐strike variations, snowmelt in the pre‐ and early‐monsoon season (April to June) is significant and important in all catchments, although most pronounced in the western catchments. Thus, changes in the timing or amount of snowmelt due to increasing temperatures or decreasing winter precipitation may have far‐reaching societal consequences. These new data on precipitation and runoff set the stage for far more detailed investigations than have previously been possible of climate‐erosion interactions in the Himalaya.

@article{doi1010292009jf001426,
    author = "Bookhagen, Bodo and Burbank, Douglas W.",
    title = "Toward a complete Himalayan hydrological budget: Spatiotemporal distribution of snowmelt and rainfall and their impact on river discharge",
    year = "2010",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The hydrological budget of Himalayan rivers is dominated by monsoonal rainfall and snowmelt, but their relative impact is not well established because this remote region lacks a dense gauge network. Here, we use a combination of validated remotely‐sensed climate parameters to characterize the spatiotemporal distribution of rainfall, snowfall, and evapotranspiration in order to quantify their relative contribution to mean river discharge. Rainfall amounts are calculated from calibrated, orbital, high‐resolution Tropical Rainfall Measurement Mission data, and snow‐water equivalents are computed from a snowmelt model based on satellite‐derived snow cover, surface temperature, and solar radiation. Our data allow us to identify three key aspects of the spatiotemporal precipitation pattern. First, we observe a strong decoupling between the rainfall on the Himalayan foreland versus that in the mountains: a pronounced sixfold, east‐west rainfall gradient in the Ganges plains exists only at elevations <500 m asl. Mountainous regions (500 to 5000 m asl) receive nearly equal rainfall amounts along strike. Second, whereas the Indian summer monsoon is responsible for more than 80\% of annual rainfall in the central Himalaya and Tibetan Plateau, the eastern and western syntaxes receive only ∼50\% of their annual rainfall during the summer season. Third, snowmelt contributions to discharge differ widely along the range. As a fraction of the total annual discharge, snowmelt constitutes up to 50\% in the far western (Indus area) catchments, ∼25\% in far eastern (Tsangpo) catchments, and <20\% elsewhere. Despite these along‐strike variations, snowmelt in the pre‐ and early‐monsoon season (April to June) is significant and important in all catchments, although most pronounced in the western catchments. Thus, changes in the timing or amount of snowmelt due to increasing temperatures or decreasing winter precipitation may have far‐reaching societal consequences. These new data on precipitation and runoff set the stage for far more detailed investigations than have previously been possible of climate‐erosion interactions in the Himalaya.",
    url = "https://doi.org/10.1029/2009jf001426",
    doi = "10.1029/2009jf001426",
    openalex = "W2048329679"
}

The waters of the Colorado River serve 27 million people in seven states and two countries but are overallocated by more than 10% of the river's historical mean. Climate models project runoff losses of 7-20% from the basin in this century due to human-induced climate change. Recent work has shown however that by the late 1800s, decades prior to allocation of the river's runoff in the 1920s, a fivefold increase in dust loading from anthropogenically disturbed soils in the southwest United States was already decreasing snow albedo and shortening the duration of snow cover by several weeks. The degree to which this increase in radiative forcing by dust in snow has affected timing and magnitude of runoff from the Upper Colorado River Basin (UCRB) is unknown. Here we use the Variable Infiltration Capacity model with postdisturbance and predisturbance impacts of dust on albedo to estimate the impact on runoff from the UCRB across 1916-2003. We find that peak runoff at Lees Ferry, Arizona has occurred on average 3 wk earlier under heavier dust loading and that increases in evapotranspiration from earlier exposure of vegetation and soils decreases annual runoff by more than 1.0 billion cubic meters or ∼5% of the annual average. The potential to reduce dust loading through surface stabilization in the deserts and restore more persistent snow cover, slow runoff, and increase water resources in the UCRB may represent an important mitigation opportunity to reduce system management tensions and regional impacts of climate change.

@article{doi101073pnas0913139107,
    author = "Painter, T. H. and Deems, J. S. and Belnap, Jayne and Hamlet, Alan F. and Landry, Christopher C. and Udall, B.",
    title = "Response of Colorado River runoff to dust radiative forcing in snow",
    year = "2010",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The waters of the Colorado River serve 27 million people in seven states and two countries but are overallocated by more than 10\% of the river's historical mean. Climate models project runoff losses of 7-20\% from the basin in this century due to human-induced climate change. Recent work has shown however that by the late 1800s, decades prior to allocation of the river's runoff in the 1920s, a fivefold increase in dust loading from anthropogenically disturbed soils in the southwest United States was already decreasing snow albedo and shortening the duration of snow cover by several weeks. The degree to which this increase in radiative forcing by dust in snow has affected timing and magnitude of runoff from the Upper Colorado River Basin (UCRB) is unknown. Here we use the Variable Infiltration Capacity model with postdisturbance and predisturbance impacts of dust on albedo to estimate the impact on runoff from the UCRB across 1916-2003. We find that peak runoff at Lees Ferry, Arizona has occurred on average 3 wk earlier under heavier dust loading and that increases in evapotranspiration from earlier exposure of vegetation and soils decreases annual runoff by more than 1.0 billion cubic meters or ∼5\% of the annual average. The potential to reduce dust loading through surface stabilization in the deserts and restore more persistent snow cover, slow runoff, and increase water resources in the UCRB may represent an important mitigation opportunity to reduce system management tensions and regional impacts of climate change.",
    url = "https://doi.org/10.1073/pnas.0913139107",
    doi = "10.1073/pnas.0913139107",
    openalex = "W1973517598",
    references = "doi1010292005jd005776, doi1010292005wr004455, doi1010292006jd008003, doi1010292007gl029988, doi10102994jd00483, doi101029rg020i001p00067, doi101038nature04141, doi101038ngeo156, doi101073pnas2237157100, doi101126science1102586, doi101146annureves23110192000431, doi101175bams86139, doi105194hess1114172007"
}

The present two‐part review aims to put the different phenomena that have been called “beta diversity” over the years into a common conceptual framework and to explain what each of them measures. The first part (Tuomisto 2010) discussed basic definitions of “beta diversity”. Each arises from a different way of combining a definition of “diversity” with a definition of its alpha component and with a mathematical relationship between the alpha and gamma components. This second part assumes that an appropriate basic definition of a beta component (which may or may not be true beta diversity) has been chosen, and the focus here will be on how to quantify it for a given dataset. About twenty different approaches have been used for this purpose. It turns out that only two of these approaches accurately quantify the selected beta component: one does so for the entire dataset, and the other for two sampling units at a time. The other approaches actually quantify other phenomena, such as mean species turnover between sampling units, compositional gradient length (with or without reference to an external gradient), distinctness of a focal sampling unit, rate of species accumulation with increasing sampling effort, rate of compositional turnover along an external gradient, or the rate of decay in compositional similarity with increasing geographical distance. Although most of these phenomena can be expressed as a function of a beta component of diversity, they do not equal a beta component of diversity. Many of these derived variables are not even numerically correlated with the beta component on which they are based, which needs to be taken into account when interpreting the results. The effects of sampling decisions when results are extrapolated beyond the available data will also be discussed.

@article{doi101111j16000587200906148x,
    author = "Tuomisto, Hanna",
    title = "A diversity of beta diversities: straightening up a concept gone awry. Part 2. Quantifying beta diversity and related phenomena",
    year = "2010",
    journal = "Ecography",
    abstract = "The present two‐part review aims to put the different phenomena that have been called “beta diversity” over the years into a common conceptual framework and to explain what each of them measures. The first part (Tuomisto 2010) discussed basic definitions of “beta diversity”. Each arises from a different way of combining a definition of “diversity” with a definition of its alpha component and with a mathematical relationship between the alpha and gamma components. This second part assumes that an appropriate basic definition of a beta component (which may or may not be true beta diversity) has been chosen, and the focus here will be on how to quantify it for a given dataset. About twenty different approaches have been used for this purpose. It turns out that only two of these approaches accurately quantify the selected beta component: one does so for the entire dataset, and the other for two sampling units at a time. The other approaches actually quantify other phenomena, such as mean species turnover between sampling units, compositional gradient length (with or without reference to an external gradient), distinctness of a focal sampling unit, rate of species accumulation with increasing sampling effort, rate of compositional turnover along an external gradient, or the rate of decay in compositional similarity with increasing geographical distance. Although most of these phenomena can be expressed as a function of a beta component of diversity, they do not equal a beta component of diversity. Many of these derived variables are not even numerically correlated with the beta component on which they are based, which needs to be taken into account when interpreting the results. The effects of sampling decisions when results are extrapolated beyond the available data will also be discussed.",
    url = "https://doi.org/10.1111/j.1600-0587.2009.06148.x",
    doi = "10.1111/j.1600-0587.2009.06148.x",
    openalex = "W2037339961",
    references = "doi101038nature06813, doi102475ajs24111"
}

@article{doi101002rra1503,
    author = "Melis, Theodore S. and Korman, Josh and Kennedy, Theodore A.",
    title = "ABIOTIC \& BIOTIC RESPONSES OF THE COLORADO RIVER TO CONTROLLED FLOODS AT GLEN CANYON DAM, ARIZONA, USA",
    year = "2011",
    journal = "River Research and Applications",
    url = "https://doi.org/10.1002/rra.1503",
    doi = "10.1002/rra.1503",
    openalex = "W2065800011",
    references = "doi103133pp1677"
}

Abstract Climate change is expected to accelerate the hydrologic cycle, increase the fraction of precipitation that is rain, and enhance snowpack melting. The enhanced hydrological cycle is also expected to increase snowfall amounts due to increased moisture availability. These processes are examined in this paper in the Colorado Headwaters region through the use of a coupled high-resolution climate–runoff model. Four high-resolution simulations of annual snowfall over Colorado are conducted. The simulations are verified using Snowpack Telemetry (SNOTEL) data. Results are then presented regarding the grid spacing needed for appropriate simulation of snowfall. Finally, climate sensitivity is explored using a pseudo–global warming approach. The results show that the proper spatial and temporal depiction of snowfall adequate for water resource and climate change purposes can be achieved with the appropriate choice of model grid spacing and parameterizations. The pseudo–global warming simulations indicate enhanced snowfall on the order of 10%–25% over the Colorado Headwaters region, with the enhancement being less in the core headwaters region due to the topographic reduction of precipitation upstream of the region (rain-shadow effect). The main climate change impacts are in the enhanced melting at the lower-elevation bound of the snowpack and the increased snowfall at higher elevations. The changes in peak snow mass are generally near zero due to these two compensating effects, and simulated wintertime total runoff is above current levels. The 1 April snow water equivalent (SWE) is reduced by 25% in the warmer climate, and the date of maximum SWE occurs 2–17 days prior to current climate results, consistent with previous studies.

@article{doi1011752010jcli39851,
    author = "Rasmussen, Roy and Liu, Changhai and Ikeda, Kyoko and Gochis, David and Yates, David and Chen, Fei and Tewari, Mukul and Barlage, Michael and Dudhia, Jimy and Yu, Wei and Miller, Kathleen A. and Arsenault, Kristi R. and Grubı̆sı́c, Vanda and Thompson, Greg and Gutmann, E. D.",
    title = "High-Resolution Coupled Climate Runoff Simulations of Seasonal Snowfall over Colorado: A Process Study of Current and Warmer Climate",
    year = "2011",
    journal = "Journal of Climate",
    abstract = "Abstract Climate change is expected to accelerate the hydrologic cycle, increase the fraction of precipitation that is rain, and enhance snowpack melting. The enhanced hydrological cycle is also expected to increase snowfall amounts due to increased moisture availability. These processes are examined in this paper in the Colorado Headwaters region through the use of a coupled high-resolution climate–runoff model. Four high-resolution simulations of annual snowfall over Colorado are conducted. The simulations are verified using Snowpack Telemetry (SNOTEL) data. Results are then presented regarding the grid spacing needed for appropriate simulation of snowfall. Finally, climate sensitivity is explored using a pseudo–global warming approach. The results show that the proper spatial and temporal depiction of snowfall adequate for water resource and climate change purposes can be achieved with the appropriate choice of model grid spacing and parameterizations. The pseudo–global warming simulations indicate enhanced snowfall on the order of 10\%–25\% over the Colorado Headwaters region, with the enhancement being less in the core headwaters region due to the topographic reduction of precipitation upstream of the region (rain-shadow effect). The main climate change impacts are in the enhanced melting at the lower-elevation bound of the snowpack and the increased snowfall at higher elevations. The changes in peak snow mass are generally near zero due to these two compensating effects, and simulated wintertime total runoff is above current levels. The 1 April snow water equivalent (SWE) is reduced by 25\% in the warmer climate, and the date of maximum SWE occurs 2–17 days prior to current climate results, consistent with previous studies.",
    url = "https://doi.org/10.1175/2010jcli3985.1",
    doi = "10.1175/2010jcli3985.1",
    openalex = "W2081918746",
    references = "doi105194hess1114172007"
}

The Mekong River Basin, site of the biggest inland fishery in the world, is undergoing massive hydropower development. Planned dams will block critical fish migration routes between the river's downstream floodplains and upstream tributaries. Here we estimate fish biomass and biodiversity losses in numerous damming scenarios using a simple ecological model of fish migration. Our framework allows detailing trade-offs between dam locations, power production, and impacts on fish resources. We find that the completion of 78 dams on tributaries, which have not previously been subject to strategic analysis, would have catastrophic impacts on fish productivity and biodiversity. Our results argue for reassessment of several dams planned, and call for a new regional agreement on tributary development of the Mekong River Basin.

@article{doi101073pnas1201423109,
    author = "Ziv, Guy and Baran, Eric and Nam, So and Rodriguez‐Iturbe, I. and Levin, Simon A.",
    title = "Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin",
    year = "2012",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "The Mekong River Basin, site of the biggest inland fishery in the world, is undergoing massive hydropower development. Planned dams will block critical fish migration routes between the river's downstream floodplains and upstream tributaries. Here we estimate fish biomass and biodiversity losses in numerous damming scenarios using a simple ecological model of fish migration. Our framework allows detailing trade-offs between dam locations, power production, and impacts on fish resources. We find that the completion of 78 dams on tributaries, which have not previously been subject to strategic analysis, would have catastrophic impacts on fish productivity and biodiversity. Our results argue for reassessment of several dams planned, and call for a new regional agreement on tributary development of the Mekong River Basin.",
    url = "https://doi.org/10.1073/pnas.1201423109",
    doi = "10.1073/pnas.1201423109",
    openalex = "W2000337799",
    references = "doi101038nature06813"
}

[1] Support for low-carbon energy and opposition to new large dams encourages global development of small hydropower facilities. This support is manifested in national and international energy and development policies designed to incentivize growth in the small hydropower sector while curtailing large dam construction. However, the preference of small to large dams assumes, without justification, that small hydropower dams entail fewer and less severe environmental and social externalities than large hydropower dams. With the objective to evaluate the validity of this assumption, we investigate cumulative biophysical effects of small (<50 MW) and large hydropower dams in China's Nu River basin, and compare effects normalized per megawatt of power produced. Results reveal that biophysical impacts of small hydropower may exceed those of large hydropower, particularly with regard to habitat and hydrologic change. These results indicate that more comprehensive standards for impact assessment and governance of small hydropower projects may be necessary to encourage low-impact energy development.

@article{doi101002wrcr20243,
    author = "Kibler, Kelly M. and Tullos, Desirèe",
    title = "Cumulative biophysical impact of small and large hydropower development in Nu River, China",
    year = "2013",
    journal = "Water Resources Research",
    abstract = "[1] Support for low-carbon energy and opposition to new large dams encourages global development of small hydropower facilities. This support is manifested in national and international energy and development policies designed to incentivize growth in the small hydropower sector while curtailing large dam construction. However, the preference of small to large dams assumes, without justification, that small hydropower dams entail fewer and less severe environmental and social externalities than large hydropower dams. With the objective to evaluate the validity of this assumption, we investigate cumulative biophysical effects of small (<50 MW) and large hydropower dams in China's Nu River basin, and compare effects normalized per megawatt of power produced. Results reveal that biophysical impacts of small hydropower may exceed those of large hydropower, particularly with regard to habitat and hydrologic change. These results indicate that more comprehensive standards for impact assessment and governance of small hydropower projects may be necessary to encourage low-impact energy development.",
    url = "https://doi.org/10.1002/wrcr.20243",
    doi = "10.1002/wrcr.20243",
    openalex = "W1844132276",
    references = "doi1010292006wr005092"
}

Summary Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (# m −3), but the factors that govern invertebrate drift in larger rivers remain poorly understood. For example, while large increases or decreases in discharge can lead to large increases in invertebrate drift, the role of smaller, incremental changes in discharge is poorly described. In addition, while we might expect invertebrate drift concentrations to be proportional to benthic densities (# m −2), the benthic–drift relation has not been rigorously evaluated. Here, we develop a framework for modelling invertebrate drift that is derived from sediment transport studies. We use this framework to guide the analysis of high‐resolution data sets of benthic density and drift concentration for four important invertebrate taxa from the C olorado R iver downstream of G len C anyon D am (mean daily discharge 325 m 3 s −1) that were collected over 18 months and include multiple observations within days. Ramping of regulated flows on this river segment provides an experimental treatment that is repeated daily and allowed us to describe the functional relations between invertebrate drift and two primary controls, discharge and benthic densities. Twofold daily variation in discharge resulted in a >10‐fold increase in drift concentrations of benthic invertebrates associated with pools and detritus (i.e. G ammarus lacustris and P otamopyrgus antipodarum). In contrast, drift concentrations of sessile blackfly larvae (S imuliium arcticum), which are associated with high‐velocity cobble microhabitats, decreased by over 80% as discharge doubled. Drift concentrations of C hironomidae increased proportional to discharge. Drift of all four taxa was positively related to benthic density. Drift concentrations of G ammarus, P otamopyrgus and C hironomidae were proportional to benthic density. Drift concentrations of S imulium were positively related to benthic density, but the benthic–drift relation was less than proportional (i.e. a doubling of benthic density only led to a 40% increase in drift concentrations). Our study demonstrates that invertebrate drift concentrations in the C olorado R iver are jointly controlled by discharge and benthic densities, but these controls operate at different timescales. Twofold daily variation in discharge associated with hydropeaking was the primary control on within‐day variation in invertebrate drift concentrations. In contrast, benthic density, which varied 10‐ to 1000‐fold among sampling dates, depending on the taxa, was the primary control on invertebrate drift concentrations over longer timescales (weeks to months).

@article{doi101111fwb12285,
    author = "Kennedy, Theodore A. and Yackulic, Charles B. and Cross, Wyatt F. and Grams, Paul E. and Yard, Michael D. and Copp, Adam J.",
    title = "The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river",
    year = "2013",
    journal = "Freshwater Biology",
    abstract = "Summary Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (\# m −3), but the factors that govern invertebrate drift in larger rivers remain poorly understood. For example, while large increases or decreases in discharge can lead to large increases in invertebrate drift, the role of smaller, incremental changes in discharge is poorly described. In addition, while we might expect invertebrate drift concentrations to be proportional to benthic densities (\# m −2), the benthic–drift relation has not been rigorously evaluated. Here, we develop a framework for modelling invertebrate drift that is derived from sediment transport studies. We use this framework to guide the analysis of high‐resolution data sets of benthic density and drift concentration for four important invertebrate taxa from the C olorado R iver downstream of G len C anyon D am (mean daily discharge 325 m 3 s −1) that were collected over 18 months and include multiple observations within days. Ramping of regulated flows on this river segment provides an experimental treatment that is repeated daily and allowed us to describe the functional relations between invertebrate drift and two primary controls, discharge and benthic densities. Twofold daily variation in discharge resulted in a >10‐fold increase in drift concentrations of benthic invertebrates associated with pools and detritus (i.e. G ammarus lacustris and P otamopyrgus antipodarum). In contrast, drift concentrations of sessile blackfly larvae (S imuliium arcticum), which are associated with high‐velocity cobble microhabitats, decreased by over 80\% as discharge doubled. Drift concentrations of C hironomidae increased proportional to discharge. Drift of all four taxa was positively related to benthic density. Drift concentrations of G ammarus, P otamopyrgus and C hironomidae were proportional to benthic density. Drift concentrations of S imulium were positively related to benthic density, but the benthic–drift relation was less than proportional (i.e. a doubling of benthic density only led to a 40\% increase in drift concentrations). Our study demonstrates that invertebrate drift concentrations in the C olorado R iver are jointly controlled by discharge and benthic densities, but these controls operate at different timescales. Twofold daily variation in discharge associated with hydropeaking was the primary control on within‐day variation in invertebrate drift concentrations. In contrast, benthic density, which varied 10‐ to 1000‐fold among sampling dates, depending on the taxa, was the primary control on invertebrate drift concentrations over longer timescales (weeks to months).",
    url = "https://doi.org/10.1111/fwb.12285",
    doi = "10.1111/fwb.12285",
    openalex = "W2026747350",
    references = "doi103133pp1677"
}

Comparative phylogeography can elucidate the influence of historical events on current patterns of biodiversity and can identify patterns of co-vicariance among unrelated taxa that span the same geographic areas. Here we analyze temporal and spatial divergence patterns of cloud forest plant and animal species and relate them to the evolutionary history of naturally fragmented cloud forests--among the most threatened vegetation types in northern Mesoamerica. We used comparative phylogeographic analyses to identify patterns of co-vicariance in taxa that share geographic ranges across cloud forest habitats and to elucidate the influence of historical events on current patterns of biodiversity. We document temporal and spatial genetic divergence of 15 species (including seed plants, birds and rodents), and relate them to the evolutionary history of the naturally fragmented cloud forests. We used fossil-calibrated genealogies, coalescent-based divergence time inference, and estimates of gene flow to assess the permeability of putative barriers to gene flow. We also used the hierarchical Approximate Bayesian Computation (HABC) method implemented in the program msBayes to test simultaneous versus non-simultaneous divergence of the cloud forest lineages. Our results show shared phylogeographic breaks that correspond to the Isthmus of Tehuantepec, Los Tuxtlas, and the Chiapas Central Depression, with the Isthmus representing the most frequently shared break among taxa. However, dating analyses suggest that the phylogeographic breaks corresponding to the Isthmus occurred at different times in different taxa. Current divergence patterns are therefore consistent with the hypothesis of broad vicariance across the Isthmus of Tehuantepec derived from different mechanisms operating at different times. This study, coupled with existing data on divergence cloud forest species, indicates that the evolutionary history of contemporary cloud forest lineages is complex and often lineage-specific, and thus difficult to capture in a simple conservation strategy.

@article{doi101371journalpone0056283,
    author = "Ornelas, Juan Francisco and Sosa, Victoria and Soltis, Pamela S. and Daza, Juan M. and González, Clementina and Soltis, Pamela S. and Gutiérrez‐Rodríguez, Carla and de los Monteros, Alejandro Espinosa and Castoe, Todd A. and Bell, Charles D. and Ruíz-Sánchez, Eduardo",
    title = "Comparative Phylogeographic Analyses Illustrate the Complex Evolutionary History of Threatened Cloud Forests of Northern Mesoamerica",
    year = "2013",
    journal = "PLoS ONE",
    abstract = "Comparative phylogeography can elucidate the influence of historical events on current patterns of biodiversity and can identify patterns of co-vicariance among unrelated taxa that span the same geographic areas. Here we analyze temporal and spatial divergence patterns of cloud forest plant and animal species and relate them to the evolutionary history of naturally fragmented cloud forests--among the most threatened vegetation types in northern Mesoamerica. We used comparative phylogeographic analyses to identify patterns of co-vicariance in taxa that share geographic ranges across cloud forest habitats and to elucidate the influence of historical events on current patterns of biodiversity. We document temporal and spatial genetic divergence of 15 species (including seed plants, birds and rodents), and relate them to the evolutionary history of the naturally fragmented cloud forests. We used fossil-calibrated genealogies, coalescent-based divergence time inference, and estimates of gene flow to assess the permeability of putative barriers to gene flow. We also used the hierarchical Approximate Bayesian Computation (HABC) method implemented in the program msBayes to test simultaneous versus non-simultaneous divergence of the cloud forest lineages. Our results show shared phylogeographic breaks that correspond to the Isthmus of Tehuantepec, Los Tuxtlas, and the Chiapas Central Depression, with the Isthmus representing the most frequently shared break among taxa. However, dating analyses suggest that the phylogeographic breaks corresponding to the Isthmus occurred at different times in different taxa. Current divergence patterns are therefore consistent with the hypothesis of broad vicariance across the Isthmus of Tehuantepec derived from different mechanisms operating at different times. This study, coupled with existing data on divergence cloud forest species, indicates that the evolutionary history of contemporary cloud forest lineages is complex and often lineage-specific, and thus difficult to capture in a simple conservation strategy.",
    url = "https://doi.org/10.1371/journal.pone.0056283",
    doi = "10.1371/journal.pone.0056283",
    openalex = "W2054874978",
    references = "doi1011300091761320020301031euaads20co2, openalexw2311147777"
}

Nearly all ecosystems have been altered by human activities, and most communities are now composed of interacting species that have not co‐evolved. These changes may modify species interactions, energy and material flows, and food‐web stability. Although structural changes to ecosystems have been widely reported, few studies have linked such changes to dynamic food‐web attributes and patterns of energy flow. Moreover, there have been few tests of food‐web stability theory in highly disturbed and intensely managed freshwater ecosystems. Such synthetic approaches are needed for predicting the future trajectory of ecosystems, including how they may respond to natural or anthropogenic perturbations. We constructed flow food webs at six locations along a 386‐km segment of the Colorado River in Grand Canyon (Arizona, USA) for three years. We characterized food‐web structure and production, trophic basis of production, energy efficiencies, and interaction‐strength distributions across a spatial gradient of perturbation (i.e., distance from Glen Canyon Dam), as well as before and after an experimental flood. We found strong longitudinal patterns in food‐web characteristics that strongly correlated with the spatial position of large tributaries. Above tributaries, food webs were dominated by nonnative New Zealand mudsnails (62% of production) and nonnative rainbow trout (100% of fish production). The simple structure of these food webs led to few dominant energy pathways (diatoms to few invertebrate taxa to rainbow trout), large energy inefficiencies (i.e., <20% of invertebrate production consumed by fishes), and right‐skewed interaction‐strength distributions, consistent with theoretical instability. Below large tributaries, invertebrate production declined ∼18‐fold, while fish production remained similar to upstream sites and comprised predominately native taxa (80–100% of production). Sites below large tributaries had increasingly reticulate and detritus‐based food webs with a higher prevalence of omnivory, as well as interaction strength distributions more typical of theoretically stable food webs (i.e., nearly twofold higher proportion of weak interactions). Consistent with theory, downstream food webs were less responsive to the experimental flood than sites closest to the dam. We show how human‐induced shifts to food‐web structure can affect energy flow and interaction strengths, and we show that these changes have consequences for food‐web function and response to perturbations.

@article{doi1018901217271,
    author = "Cross, Wyatt F. and Baxter, Colden V. and Rosi, Emma J. and Hall, Robert O. and Kennedy, Theodore A. and Donner, Kevin C. and Kelly, Holly A. Wellard and Seegert, Sarah E. Z. and Behn, Kathrine E. and Yard, Michael D.",
    title = "Food‐web dynamics in a large river discontinuum",
    year = "2013",
    journal = "Ecological Monographs",
    abstract = "Nearly all ecosystems have been altered by human activities, and most communities are now composed of interacting species that have not co‐evolved. These changes may modify species interactions, energy and material flows, and food‐web stability. Although structural changes to ecosystems have been widely reported, few studies have linked such changes to dynamic food‐web attributes and patterns of energy flow. Moreover, there have been few tests of food‐web stability theory in highly disturbed and intensely managed freshwater ecosystems. Such synthetic approaches are needed for predicting the future trajectory of ecosystems, including how they may respond to natural or anthropogenic perturbations. We constructed flow food webs at six locations along a 386‐km segment of the Colorado River in Grand Canyon (Arizona, USA) for three years. We characterized food‐web structure and production, trophic basis of production, energy efficiencies, and interaction‐strength distributions across a spatial gradient of perturbation (i.e., distance from Glen Canyon Dam), as well as before and after an experimental flood. We found strong longitudinal patterns in food‐web characteristics that strongly correlated with the spatial position of large tributaries. Above tributaries, food webs were dominated by nonnative New Zealand mudsnails (62\% of production) and nonnative rainbow trout (100\% of fish production). The simple structure of these food webs led to few dominant energy pathways (diatoms to few invertebrate taxa to rainbow trout), large energy inefficiencies (i.e., <20\% of invertebrate production consumed by fishes), and right‐skewed interaction‐strength distributions, consistent with theoretical instability. Below large tributaries, invertebrate production declined ∼18‐fold, while fish production remained similar to upstream sites and comprised predominately native taxa (80–100\% of production). Sites below large tributaries had increasingly reticulate and detritus‐based food webs with a higher prevalence of omnivory, as well as interaction strength distributions more typical of theoretically stable food webs (i.e., nearly twofold higher proportion of weak interactions). Consistent with theory, downstream food webs were less responsive to the experimental flood than sites closest to the dam. We show how human‐induced shifts to food‐web structure can affect energy flow and interaction strengths, and we show that these changes have consequences for food‐web function and response to perturbations.",
    url = "https://doi.org/10.1890/12-1727.1",
    doi = "10.1890/12-1727.1",
    openalex = "W2130555990",
    references = "doi101007s0026700227370, doi101017s1464793105006950, doi10103835012241, doi101038nature09440, doi101038nature11148, doi101126science1107887, doi101126science2775325494, doi101139f80017, doi1012019781315273075, doi1023072531565, doi103133pp1677"
}

Abstract By trapping sediment in reservoirs, dams interrupt the continuity of sediment transport through rivers, resulting in loss of reservoir storage and reduced usable life, and depriving downstream reaches of sediments essential for channel form and aquatic habitats. With the acceleration of new dam construction globally, these impacts are increasingly widespread. There are proven techniques to pass sediment through or around reservoirs, to preserve reservoir capacity and to minimize downstream impacts, but they are not applied in many situations where they would be effective. This paper summarizes collective experience from five continents in managing reservoir sediments and mitigating downstream sediment starvation. Where geometry is favorable it is often possible to bypass sediment around the reservoir, which avoids reservoir sedimentation and supplies sediment to downstream reaches with rates and timing similar to pre‐dam conditions. Sluicing (or drawdown routing) permits sediment to be transported through the reservoir rapidly to avoid sedimentation during high flows; it requires relatively large capacity outlets. Drawdown flushing involves scouring and re‐suspending sediment deposited in the reservoir and transporting it downstream through low‐level gates in the dam; it works best in narrow reservoirs with steep longitudinal gradients and with flow velocities maintained above the threshold to transport sediment. Turbidity currents can often be vented through the dam, with the advantage that the reservoir need not be drawn down to pass sediment. In planning dams, we recommend that these sediment management approaches be utilized where possible to sustain reservoir capacity and minimize environmental impacts of dams.

@article{doi1010022013ef000184,
    author = "Kondolf, G. Mathias and Gao, Yongxuan and Annandale, George W. and Morris, Gregory L. and Jiang, Enhui and Zhang, Junhua and Cao, Yongtao and Carling, Paul A. and Fu, Kaidao and Guo, Qingchao and Hotchkiss, Rollin H. and Peteuil, C. and Sumi, Tetsuya and Wang, Hsiao‐Wen and Wang, Zhongmei and Wei, Zhilin and Wu, Baosheng and Wu, Caiping and Yang, Chih Ted",
    title = "Sustainable sediment management in reservoirs and regulated rivers: Experiences from five continents",
    year = "2014",
    journal = "Earth s Future",
    abstract = "Abstract By trapping sediment in reservoirs, dams interrupt the continuity of sediment transport through rivers, resulting in loss of reservoir storage and reduced usable life, and depriving downstream reaches of sediments essential for channel form and aquatic habitats. With the acceleration of new dam construction globally, these impacts are increasingly widespread. There are proven techniques to pass sediment through or around reservoirs, to preserve reservoir capacity and to minimize downstream impacts, but they are not applied in many situations where they would be effective. This paper summarizes collective experience from five continents in managing reservoir sediments and mitigating downstream sediment starvation. Where geometry is favorable it is often possible to bypass sediment around the reservoir, which avoids reservoir sedimentation and supplies sediment to downstream reaches with rates and timing similar to pre‐dam conditions. Sluicing (or drawdown routing) permits sediment to be transported through the reservoir rapidly to avoid sedimentation during high flows; it requires relatively large capacity outlets. Drawdown flushing involves scouring and re‐suspending sediment deposited in the reservoir and transporting it downstream through low‐level gates in the dam; it works best in narrow reservoirs with steep longitudinal gradients and with flow velocities maintained above the threshold to transport sediment. Turbidity currents can often be vented through the dam, with the advantage that the reservoir need not be drawn down to pass sediment. In planning dams, we recommend that these sediment management approaches be utilized where possible to sustain reservoir capacity and minimize environmental impacts of dams.",
    url = "https://doi.org/10.1002/2013ef000184",
    doi = "10.1002/2013ef000184",
    openalex = "W1969483029",
    references = "doi1010292006wr005092"
}

River networks evolve as migrating drainage divides reshape river basins and change network topology by capture of river channels. We demonstrate that a characteristic metric of river network geometry gauges the horizontal motion of drainage divides. Assessing this metric throughout a landscape maps the dynamic states of entire river networks, revealing diverse conditions: Drainage divides in the Loess Plateau of China appear stationary; the young topography of Taiwan has migrating divides driving adjustment of major basins; and rivers draining the ancient landscape of the southeastern United States are reorganizing in response to escarpment retreat and coastal advance. The ability to measure the dynamic reorganization of river basins presents opportunities to examine landscape-scale interactions among tectonics, erosion, and ecology.

@article{doi101126science1248765,
    author = "Willett, Sean D. and McCoy, Scott and Perron, J. Taylor and Goren, Liran and Chen, Chia‐Yu",
    title = "Dynamic Reorganization of River Basins",
    year = "2014",
    journal = "Science",
    abstract = "River networks evolve as migrating drainage divides reshape river basins and change network topology by capture of river channels. We demonstrate that a characteristic metric of river network geometry gauges the horizontal motion of drainage divides. Assessing this metric throughout a landscape maps the dynamic states of entire river networks, revealing diverse conditions: Drainage divides in the Loess Plateau of China appear stationary; the young topography of Taiwan has migrating divides driving adjustment of major basins; and rivers draining the ancient landscape of the southeastern United States are reorganizing in response to escarpment retreat and coastal advance. The ability to measure the dynamic reorganization of river basins presents opportunities to examine landscape-scale interactions among tectonics, erosion, and ecology.",
    url = "https://doi.org/10.1126/science.1248765",
    doi = "10.1126/science.1248765",
    openalex = "W1975052733",
    references = "doi102475ajs30145313"
}

Abstract River restoration is one of the most prominent areas of applied water‐resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human‐altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process‐based restoration; growing recognition of the importance of biological‐physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.

@article{doi1010022014wr016874,
    author = "Wohl, Ellen and Lane, Stuart N. and Wilcox, Andrew C.",
    title = "The science and practice of river restoration",
    year = "2015",
    journal = "Water Resources Research",
    abstract = "Abstract River restoration is one of the most prominent areas of applied water‐resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human‐altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process‐based restoration; growing recognition of the importance of biological‐physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.",
    url = "https://doi.org/10.1002/2014wr016874",
    doi = "10.1002/2014wr016874",
    openalex = "W1874839958",
    references = "doi101016b9780123747396002645, doi101111j13652427200601708x"
}

Abstract Documentation of the interacting effects of river regulation and climate on riparian vegetation has typically been limited to small segments of rivers or focused on individual plant species. We examine spatiotemporal variability in riparian vegetation for the Colorado River in Grand Canyon relative to river regulation and climate, over the five decades since completion of the upstream Glen Canyon Dam in 1963. Long‐term changes along this highly modified, large segment of the river provide insights for management of similar riparian ecosystems around the world. We analyze vegetation extent based on maps and imagery from eight dates between 1965 and 2009, coupled with the instantaneous hydrograph for the entire period. Analysis confirms a net increase in vegetated area since completion of the dam. Magnitude and timing of such vegetation changes are river stage‐dependent. Vegetation expansion is coincident with inundation frequency changes and is unlikely to occur for time periods when inundation frequency exceeds approximately 5%. Vegetation expansion at lower zones of the riparian area is greater during the periods with lower peak and higher base flows, while vegetation at higher zones couples with precipitation patterns and decreases during drought. Short pulses of high flow, such as the controlled floods of the Colorado River in 1996, 2004, and 2008, do not keep vegetation from expanding onto bare sand habitat. Management intended to promote resilience of riparian vegetation must contend with communities that are sensitive to the interacting effects of altered flood regimes and water availability from river and precipitation.

@article{doi1010022015jg002991,
    author = "Sankey, Joel B. and Ralston, Barbara E. and Grams, Paul E. and Schmidt, John C. and Cagney, Laura E.",
    title = "Riparian vegetation, Colorado River, and climate: Five decades of spatiotemporal dynamics in the Grand Canyon with river regulation",
    year = "2015",
    journal = "Journal of Geophysical Research Biogeosciences",
    abstract = "Abstract Documentation of the interacting effects of river regulation and climate on riparian vegetation has typically been limited to small segments of rivers or focused on individual plant species. We examine spatiotemporal variability in riparian vegetation for the Colorado River in Grand Canyon relative to river regulation and climate, over the five decades since completion of the upstream Glen Canyon Dam in 1963. Long‐term changes along this highly modified, large segment of the river provide insights for management of similar riparian ecosystems around the world. We analyze vegetation extent based on maps and imagery from eight dates between 1965 and 2009, coupled with the instantaneous hydrograph for the entire period. Analysis confirms a net increase in vegetated area since completion of the dam. Magnitude and timing of such vegetation changes are river stage‐dependent. Vegetation expansion is coincident with inundation frequency changes and is unlikely to occur for time periods when inundation frequency exceeds approximately 5\%. Vegetation expansion at lower zones of the riparian area is greater during the periods with lower peak and higher base flows, while vegetation at higher zones couples with precipitation patterns and decreases during drought. Short pulses of high flow, such as the controlled floods of the Colorado River in 1996, 2004, and 2008, do not keep vegetation from expanding onto bare sand habitat. Management intended to promote resilience of riparian vegetation must contend with communities that are sensitive to the interacting effects of altered flood regimes and water availability from river and precipitation.",
    url = "https://doi.org/10.1002/2015jg002991",
    doi = "10.1002/2015jg002991",
    openalex = "W2104122334",
    references = "doi103133pp1677"
}

Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algal biomass. In one location, we used a 738 days time series of GPP to identify the relative contribution of different physical controls of GPP. We developed both linear and semimechanistic time series models that account for unmeasured temporal covariance due to factors such as algal biomass dynamics. GPP varied from 0 g O2 m−2 d−1 to 3.0 g O2 m−2 d−1 with a relatively low annual average of 0.8 g O2 m−2 d−1. Semimechanistic models fit the data better than linear models and demonstrated that variation in turbidity primarily controlled GPP. Lower solar insolation during winter and from cloud cover lowered GPP much further. Hydropeaking lowered GPP but only during turbid conditions. Using the best model and parameter values, the model accurately predicted seasonal estimates of GPP at 3 of 4 upriver sites and outperformed the linear model at all sites; discrepancies were likely from higher algal biomass at upstream sites. This modeling approach can predict how changes in physical controls will affect relative rates of GPP throughout the 385 km segment of the Colorado River in Grand Canyon and can be easily applied to other streams and rivers.

@article{doi101002lno10031,
    author = "Hall, Robert O. and Yackulic, Charles B. and Kennedy, Theodore A. and Yard, Michael D. and Rosi, Emma J. and Voichick, Nicholas and Behn, Kathrine E.",
    title = "Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon",
    year = "2015",
    journal = "Limnology and Oceanography",
    abstract = "Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algal biomass. In one location, we used a 738 days time series of GPP to identify the relative contribution of different physical controls of GPP. We developed both linear and semimechanistic time series models that account for unmeasured temporal covariance due to factors such as algal biomass dynamics. GPP varied from 0 g O2 m−2 d−1 to 3.0 g O2 m−2 d−1 with a relatively low annual average of 0.8 g O2 m−2 d−1. Semimechanistic models fit the data better than linear models and demonstrated that variation in turbidity primarily controlled GPP. Lower solar insolation during winter and from cloud cover lowered GPP much further. Hydropeaking lowered GPP but only during turbid conditions. Using the best model and parameter values, the model accurately predicted seasonal estimates of GPP at 3 of 4 upriver sites and outperformed the linear model at all sites; discrepancies were likely from higher algal biomass at upstream sites. This modeling approach can predict how changes in physical controls will affect relative rates of GPP throughout the 385 km segment of the Colorado River in Grand Canyon and can be easily applied to other streams and rivers.",
    url = "https://doi.org/10.1002/lno.10031",
    doi = "10.1002/lno.10031",
    openalex = "W2154166486",
    references = "doi1018901217271"
}

Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.

@article{doi101093bioscibiv002,
    author = "Wohl, Ellen and Bledsoe, Brian P. and Jacobson, Robert B. and Poff, N. LeRoy and Rathburn, Sara L. and Walters, David and Wilcox, Andrew C.",
    title = "The Natural Sediment Regime in Rivers: Broadening the Foundation for Ecosystem Management",
    year = "2015",
    journal = "BioScience",
    abstract = "Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.",
    url = "https://doi.org/10.1093/biosci/biv002",
    doi = "10.1093/biosci/biv002",
    openalex = "W2113580194",
    references = "doi1010292006wr005092"
}

Increases in river fragmentation globally threaten freshwater biodiversity. Rivers are fragmented by many agents, both natural and anthropogenic. We review the distribution and frequency of these major agents, along with their effects on connectivity and habitat quality. Most fragmentation research has focused on terrestrial habitats, but theories and generalizations developed in terrestrial habitats do not always apply well to river networks. For example, terrestrial habitats are usually conceptualized as two-dimensional, whereas rivers often are conceptualized as one-dimensional or dendritic. In addition, river flow often leads to highly asymmetric effects of barriers on habitat and permeability. New approaches tailored to river networks can be applied to describe the network-wide effects of multiple barriers on both connectivity and habitat quality. The net effects of anthropogenic fragmentation on freshwater biodiversity are likely underestimated, because of time lags in effects and the difficulty of generating a single, simple signal of fragmentation that applies to all aquatic species. We conclude by presenting a decision tree for managing freshwater fragmentation, as well as some research horizons for evaluating fragmented riverscapes.

@article{doi101111nyas12853,
    author = "Fuller, Matthew R. and Doyle, Martin W. and Strayer, David L.",
    title = "Causes and consequences of habitat fragmentation in river networks",
    year = "2015",
    journal = "Annals of the New York Academy of Sciences",
    abstract = "Increases in river fragmentation globally threaten freshwater biodiversity. Rivers are fragmented by many agents, both natural and anthropogenic. We review the distribution and frequency of these major agents, along with their effects on connectivity and habitat quality. Most fragmentation research has focused on terrestrial habitats, but theories and generalizations developed in terrestrial habitats do not always apply well to river networks. For example, terrestrial habitats are usually conceptualized as two-dimensional, whereas rivers often are conceptualized as one-dimensional or dendritic. In addition, river flow often leads to highly asymmetric effects of barriers on habitat and permeability. New approaches tailored to river networks can be applied to describe the network-wide effects of multiple barriers on both connectivity and habitat quality. The net effects of anthropogenic fragmentation on freshwater biodiversity are likely underestimated, because of time lags in effects and the difficulty of generating a single, simple signal of fragmentation that applies to all aquatic species. We conclude by presenting a decision tree for managing freshwater fragmentation, as well as some research horizons for evaluating fragmented riverscapes.",
    url = "https://doi.org/10.1111/nyas.12853",
    doi = "10.1111/nyas.12853",
    openalex = "W1844988729",
    references = "doi101007s109800089283y, doi1010292006wr005092"
}

Dams impound the majority of rivers and provide important societal benefits, especially daily water releases that enable on-peak hydroelectricity generation. Such "hydropeaking" is common worldwide, but its downstream impacts remain unclear. We evaluated the response of aquatic insects, a cornerstone of river food webs, to hydropeaking using a life history-hydrodynamic model. Our model predicts that aquatic-insect abundance will depend on a basic life-history trait-adult egg-laying behavior-such that open-water layers will be unaffected by hydropeaking, whereas ecologically important and widespread river-edge layers, such as mayflies, will be extirpated. These predictions are supported by a morethan-2500-sample, citizen-science data set of aquatic insects from the Colorado River in the Grand Canyon and by a survey of insect diversity and hydropeaking intensity across dammed rivers of the Western United States. Our study reveals a hydropeaking-related life history bottleneck that precludes viable populations of many aquatic insects from inhabiting regulated rivers.

@article{doi101093bioscibiw059,
    author = "Kennedy, Theodore A. and Muehlbauer, Jeffrey D. and Yackulic, Charles B. and Lytle, David A. and Miller, Scott W. and Dibble, Kimberly L. and Kortenhoeven, Eric W. and Metcalfe, Anya N. and Baxter, Colden V.",
    title = "Flow Management for Hydropower Extirpates Aquatic Insects, Undermining River Food Webs",
    year = "2016",
    journal = "BioScience",
    abstract = {Dams impound the majority of rivers and provide important societal benefits, especially daily water releases that enable on-peak hydroelectricity generation. Such "hydropeaking" is common worldwide, but its downstream impacts remain unclear. We evaluated the response of aquatic insects, a cornerstone of river food webs, to hydropeaking using a life history-hydrodynamic model. Our model predicts that aquatic-insect abundance will depend on a basic life-history trait-adult egg-laying behavior-such that open-water layers will be unaffected by hydropeaking, whereas ecologically important and widespread river-edge layers, such as mayflies, will be extirpated. These predictions are supported by a morethan-2500-sample, citizen-science data set of aquatic insects from the Colorado River in the Grand Canyon and by a survey of insect diversity and hydropeaking intensity across dammed rivers of the Western United States. Our study reveals a hydropeaking-related life history bottleneck that precludes viable populations of many aquatic insects from inhabiting regulated rivers.},
    url = "https://doi.org/10.1093/biosci/biw059",
    doi = "10.1093/biosci/biw059",
    openalex = "W2344907110",
    references = "doi101007s0002701403770, doi101007s0026700227370, doi1010292006wr005092, doi101038nature09440, doi101073pnas0609812104, doi101111j13652427200902272x, doi101126science1107887, doi1018901217271, doi1023071467300, doi1023071468026, doi1023073802723, doi103133pp1677, doi105860choice453789"
}

Abstract Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (average at one‐third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model‐based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model‐based temperature projections indicate that continued business‐as‐usual warming will drive temperature‐induced declines in river flow, conservatively −20% by midcentury and −35% by end‐century, with support for losses exceeding −30% at midcentury and −55% at end‐century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.

@article{doi1010022016wr019638,
    author = "Udall, B. and Overpeck, Jonathan T.",
    title = "The twenty‐first century Colorado River hot drought and implications for the future",
    year = "2017",
    journal = "Water Resources Research",
    abstract = "Abstract Between 2000 and 2014, annual Colorado River flows averaged 19\% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (average at one‐third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model‐based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model‐based temperature projections indicate that continued business‐as‐usual warming will drive temperature‐induced declines in river flow, conservatively −20\% by midcentury and −35\% by end‐century, with support for losses exceeding −30\% at midcentury and −55\% at end‐century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.",
    url = "https://doi.org/10.1002/2016wr019638",
    doi = "10.1002/2016wr019638",
    openalex = "W2598538582",
    references = "doi101016jearscirev201002004, doi101016jforeco200909001, doi1010292005wr004455, doi1010292007gl029988, doi101038nature08823, doi101038nclimate1633, doi101073pnas0812721106, doi101073pnas0913139107, doi101126science1177303, doi1011751520045019940330140astmfm20co2, doi101175bams8891383, doi101175bamsd11000941, doi101890es15002031, doi105194hess1114172007"
}

@article{doi101016jsedgeo201711007,
    author = "Mueller, Erich R. and Grams, Paul E. and Hazel, Joseph E. and Schmidt, John C.",
    title = "Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon",
    year = "2017",
    journal = "Sedimentary Geology",
    url = "https://doi.org/10.1016/j.sedgeo.2017.11.007",
    doi = "10.1016/j.sedgeo.2017.11.007",
    openalex = "W2768034872",
    references = "doi103133pp1677"
}

Across the entire mantle we interpret 94 positive seismic wave-speed anomalies as subducted lithosphere and associate these slabs with their geological record. We document this as the Atlas of the Underworld, also accessible online at www.atlas-of-the-underworld.org, a compilation comprising subduction systems active in the past ~ 300 Myr. Deeper slabs are correlated to older geological records, assuming no relative horizontal motions between adjacent slabs following break-off, using knowledge of global plate circuits, but without assuming a mantle reference frame. The longest actively subducting slabs identified reach the depth of ~ 2500 km and some slabs have impinged on Large Low Shear Velocity Provinces in the deepest mantle. Anomously fast sinking of some slabs occurs in regions affected by long-term plume rising. We conclude that slab remnants eventually sink from the upper mantle to the core-mantle boundary. The range in subduction-age versus – depth in the lower mantle is largely inherited from the upper mantle history of subduction. We find a significant depth variation in average sinking speed of slabs. At the top of the lower mantle average slab sinking speeds are between 10 and 40 mm/yr, followed by a deceleration to 10–15 mm/yr down to depths around 1600–1700 km. In this interval, in situ time-stationary sinking rates suggest deceleration from 20 to 30 mm/yr to 4–8 mm/yr, increasing to 12–15 mm/yr below 2000 km. This corroborates the existence of a slab deceleration zone but we do not observe long-term (> 60 My) slab stagnation, excluding long-term stagnation due to compositional effects. Conversion of slab sinking profiles to viscosity profiles shows the general trend that mantle viscosity increases in the slab deceleration zone below which viscosity slowly decreases in the deep mantle. This is at variance with most published viscosity profiles that are derived from different observations, but agrees qualitatively with recent viscosity profiles suggested from material experiments.

@article{doi101016jtecto201710004,
    author = "van der Meer, Douwe G. and van Hinsbergen, Douwe J.J. and Spakman, Wim",
    title = "Atlas of the underworld: Slab remnants in the mantle, their sinking history, and a new outlook on lower mantle viscosity",
    year = "2017",
    journal = "Tectonophysics",
    abstract = "Across the entire mantle we interpret 94 positive seismic wave-speed anomalies as subducted lithosphere and associate these slabs with their geological record. We document this as the Atlas of the Underworld, also accessible online at www.atlas-of-the-underworld.org, a compilation comprising subduction systems active in the past \textasciitilde\ 300 Myr. Deeper slabs are correlated to older geological records, assuming no relative horizontal motions between adjacent slabs following break-off, using knowledge of global plate circuits, but without assuming a mantle reference frame. The longest actively subducting slabs identified reach the depth of \textasciitilde\ 2500 km and some slabs have impinged on Large Low Shear Velocity Provinces in the deepest mantle. Anomously fast sinking of some slabs occurs in regions affected by long-term plume rising. We conclude that slab remnants eventually sink from the upper mantle to the core-mantle boundary. The range in subduction-age versus – depth in the lower mantle is largely inherited from the upper mantle history of subduction. We find a significant depth variation in average sinking speed of slabs. At the top of the lower mantle average slab sinking speeds are between 10 and 40 mm/yr, followed by a deceleration to 10–15 mm/yr down to depths around 1600–1700 km. In this interval, in situ time-stationary sinking rates suggest deceleration from 20 to 30 mm/yr to 4–8 mm/yr, increasing to 12–15 mm/yr below 2000 km. This corroborates the existence of a slab deceleration zone but we do not observe long-term (> 60 My) slab stagnation, excluding long-term stagnation due to compositional effects. Conversion of slab sinking profiles to viscosity profiles shows the general trend that mantle viscosity increases in the slab deceleration zone below which viscosity slowly decreases in the deep mantle. This is at variance with most published viscosity profiles that are derived from different observations, but agrees qualitatively with recent viscosity profiles suggested from material experiments.",
    url = "https://doi.org/10.1016/j.tecto.2017.10.004",
    doi = "10.1016/j.tecto.2017.10.004",
    openalex = "W2766661285",
    references = "doi1010022013rg000444, doi1010022013tc003349, doi101007s0053101410603, doi1010160025322771900533, doi1010160040195181902754, doi101016jearscirev201006002, doi101016jearscirev201101007, doi101016jearscirev201203002, doi101016jearscirev201403008, doi101016jjsames200806002, doi101016jpalaeo200402033, doi101016s0012821x0100588x, doi101016s1367912001000694, doi1010292005jb004035, doi1010292007gc001743, doi101029tc001i003p00251, doi101073pnas1411762111, doi101093gjiggt095, doi101126science29054981910, doi1011300091761320020301031euaads20co2, doi101130b257081, doi101130g23193a1, doi101130ges000541, doi101146annurevearth281211"
}

Abstract The geomorphic evolution of the upper Indus River that traverses across the southwest (SW) edge of Tibet, and the Ladakh and Zanskar ranges, was examined along a ~350-km-long stretch of its reaches. Based on the longitudinal river profile, stream length gradient index, and river/strath terraces, this stretch of the river is divided into four segments. Valley fill river terraces are ubiquitous, and strath terraces occur in the lower reaches where the Indus River cuts through deformed Indus Molasse. Optically stimulated luminescence ages of river/strath terraces suggest that valley aggradation occurred in three pulses, at ~52, ~28, and ~16 ka, and that these broadly coincide with periods of stronger SW Indian summer monsoon. Reconstructed longitudinal river profiles using strath terraces provide an upper limit on the bedrock and provide incision rates ranging from 1.0±0.3 to 2.2±0.9 mm/a. These results suggested that rapid uplift of the western syntaxes aided by uplift along the local faults led to the formation of strath terraces and increased fluvial incision rates along this stretch of the river.

@article{doi101017qua201719,
    author = "Kumar, Anil and Srivastava, Pradeep",
    title = "The role of climate and tectonics in aggradation and incision of the Indus River in the Ladakh Himalaya during the late Quaternary",
    year = "2017",
    journal = "Quaternary Research",
    abstract = "Abstract The geomorphic evolution of the upper Indus River that traverses across the southwest (SW) edge of Tibet, and the Ladakh and Zanskar ranges, was examined along a \textasciitilde 350-km-long stretch of its reaches. Based on the longitudinal river profile, stream length gradient index, and river/strath terraces, this stretch of the river is divided into four segments. Valley fill river terraces are ubiquitous, and strath terraces occur in the lower reaches where the Indus River cuts through deformed Indus Molasse. Optically stimulated luminescence ages of river/strath terraces suggest that valley aggradation occurred in three pulses, at \textasciitilde 52, \textasciitilde 28, and \textasciitilde 16 ka, and that these broadly coincide with periods of stronger SW Indian summer monsoon. Reconstructed longitudinal river profiles using strath terraces provide an upper limit on the bedrock and provide incision rates ranging from 1.0±0.3 to 2.2±0.9 mm/a. These results suggested that rapid uplift of the western syntaxes aided by uplift along the local faults led to the formation of strath terraces and increased fluvial incision rates along this stretch of the river.",
    url = "https://doi.org/10.1017/qua.2017.19",
    doi = "10.1017/qua.2017.19",
    openalex = "W2617029399",
    references = "doi1010079783662032374, doi1010161350448794900868, doi101016s135044879900253x, doi1010291999jb900120, doi1010292009jf001426, doi101038379505a0, doi101046j13653091200000008x, doi101093oso97801985409220010001, doi101111j147547541999tb00987x, doi101126science27653201821, openalexw2270285851"
}

) through the Serengeti Mara Ecosystem is the largest remaining overland migration in the world. One of the most iconic portions of their migration is crossing of the Mara River, during which thousands drown annually. These mass drownings have been noted, but their frequency, size, and impact on aquatic ecosystems have not been quantified. Here, we estimate the frequency and size of mass drownings in the Mara River and model the fate of carcass nutrients through the river ecosystem. Mass drownings (>100 individuals) occurred in at least 13 of the past 15 y; on average, 6,250 carcasses and 1,100 tons of biomass enter the river each year. Half of a wildebeest carcass dry mass is bone, which takes 7 y to decompose, thus acting as a long-term source of nutrients to the Mara River. Carcass soft tissue decomposes in 2-10 wk, and these nutrients are mineralized by consumers, assimilated by biofilms, transported downstream, or moved back into the terrestrial ecosystem by scavengers. These inputs comprise 34-50% of the assimilated diet of fish when carcasses are present and 7-24% via biofilm on bones after soft tissue decomposition. Our results show a terrestrial animal migration can have large impacts on a river ecosystem, which may influence nutrient cycling and river food webs at decadal time scales. Similar mass drownings may have played an important role in rivers throughout the world when large migratory herds were more common features of the landscape.

@article{doi101073pnas1614778114,
    author = "Subalusky, Amanda L. and Dutton, Christopher L. and Rosi, Emma J. and Post, David M.",
    title = "Annual mass drownings of the Serengeti wildebeest migration influence nutrient cycling and storage in the Mara River",
    year = "2017",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = ") through the Serengeti Mara Ecosystem is the largest remaining overland migration in the world. One of the most iconic portions of their migration is crossing of the Mara River, during which thousands drown annually. These mass drownings have been noted, but their frequency, size, and impact on aquatic ecosystems have not been quantified. Here, we estimate the frequency and size of mass drownings in the Mara River and model the fate of carcass nutrients through the river ecosystem. Mass drownings (>100 individuals) occurred in at least 13 of the past 15 y; on average, 6,250 carcasses and 1,100 tons of biomass enter the river each year. Half of a wildebeest carcass dry mass is bone, which takes 7 y to decompose, thus acting as a long-term source of nutrients to the Mara River. Carcass soft tissue decomposes in 2-10 wk, and these nutrients are mineralized by consumers, assimilated by biofilms, transported downstream, or moved back into the terrestrial ecosystem by scavengers. These inputs comprise 34-50\% of the assimilated diet of fish when carcasses are present and 7-24\% via biofilm on bones after soft tissue decomposition. Our results show a terrestrial animal migration can have large impacts on a river ecosystem, which may influence nutrient cycling and river food webs at decadal time scales. Similar mass drownings may have played an important role in rivers throughout the world when large migratory herds were more common features of the landscape.",
    url = "https://doi.org/10.1073/pnas.1614778114",
    doi = "10.1073/pnas.1614778114",
    openalex = "W2629471082",
    references = "doi101098rstb20031359, doi101111j146979981961tb06080x, doi1018901217271"
}

Abstract River networks are hierarchical dendritic habitats embedded within the terrestrial landscape, with varying connectivity between sites depending on their positions along the network. This physical organisation influences the dispersal of organisms, which ultimately affects metacommunity dynamics and biodiversity patterns. We provide a conceptual synthesis of the role of river networks in structuring metacommunities in relation to dispersal processes in riverine ecosystems. We explore where the river network best explains observed metacommunity structure compared to other measurements of physical connectivity. We mostly focus on invertebrates, but also consider other taxonomic groups, including microbes, fishes, plants, and amphibians. Synthesising studies that compared multiple spatial distance metrics, we found that the importance of the river network itself in explaining metacommunity patterns depended on a variety of factors, including dispersal mode (aquatic versus aerial versus terrestrial) and landscape type (arid versus mesic), as well as location‐specific factors, such as network connectivity, land use, topographic heterogeneity, and biotic interactions. The river network appears to be less important for strong aerial dispersers and insects in arid systems than for other groups and biomes, but there is considerable variability. Borrowing from other literature, particularly landscape genetics, we developed a conceptual model that predicts that the explanatory power of the river network peaks in mesic systems for obligate aquatic dispersers. We propose directions of future avenues of research, including the use of manipulative field and laboratory experiments that test metacommunity theory in river networks. While field and laboratory experiments have their own benefits and drawbacks (e.g. reality, control, cost), both are powerful approaches for understanding the mechanisms structuring metacommunities, by teasing apart dispersal and niche‐related factors. Finally, improving our knowledge of dispersal in river networks will benefit from expanding the breadth of cost‐distance modelling to better infer dispersal from observational data; an improved understanding of life‐history strategies rather than relying on independent traits; exploring individual‐level variation in dispersal through detailed genetic studies; detailed studies on fine‐scale environmental (e.g. daily hydrology) and organismal spatiotemporal variability; and synthesising comparative, experimental, and theoretical work. Expanding in these areas will help to push the current state of the science from a largely pattern‐detection mode into a new phase of more mechanistically driven research.

@article{doi101111fwb13037,
    author = "Tonkin, Jonathan D. and Altermatt, Florian and Finn, Debra S. and Heino, Jani and Olden, Julian D. and Pauls, Steffen U. and Lytle, David A.",
    title = "The role of dispersal in river network metacommunities: Patterns, processes, and pathways",
    year = "2017",
    journal = "Freshwater Biology",
    abstract = "Abstract River networks are hierarchical dendritic habitats embedded within the terrestrial landscape, with varying connectivity between sites depending on their positions along the network. This physical organisation influences the dispersal of organisms, which ultimately affects metacommunity dynamics and biodiversity patterns. We provide a conceptual synthesis of the role of river networks in structuring metacommunities in relation to dispersal processes in riverine ecosystems. We explore where the river network best explains observed metacommunity structure compared to other measurements of physical connectivity. We mostly focus on invertebrates, but also consider other taxonomic groups, including microbes, fishes, plants, and amphibians. Synthesising studies that compared multiple spatial distance metrics, we found that the importance of the river network itself in explaining metacommunity patterns depended on a variety of factors, including dispersal mode (aquatic versus aerial versus terrestrial) and landscape type (arid versus mesic), as well as location‐specific factors, such as network connectivity, land use, topographic heterogeneity, and biotic interactions. The river network appears to be less important for strong aerial dispersers and insects in arid systems than for other groups and biomes, but there is considerable variability. Borrowing from other literature, particularly landscape genetics, we developed a conceptual model that predicts that the explanatory power of the river network peaks in mesic systems for obligate aquatic dispersers. We propose directions of future avenues of research, including the use of manipulative field and laboratory experiments that test metacommunity theory in river networks. While field and laboratory experiments have their own benefits and drawbacks (e.g. reality, control, cost), both are powerful approaches for understanding the mechanisms structuring metacommunities, by teasing apart dispersal and niche‐related factors. Finally, improving our knowledge of dispersal in river networks will benefit from expanding the breadth of cost‐distance modelling to better infer dispersal from observational data; an improved understanding of life‐history strategies rather than relying on independent traits; exploring individual‐level variation in dispersal through detailed genetic studies; detailed studies on fine‐scale environmental (e.g. daily hydrology) and organismal spatiotemporal variability; and synthesising comparative, experimental, and theoretical work. Expanding in these areas will help to push the current state of the science from a largely pattern‐detection mode into a new phase of more mechanistically driven research.",
    url = "https://doi.org/10.1111/fwb.13037",
    doi = "10.1111/fwb.13037",
    openalex = "W2762841489",
    references = "doi101038nature06813, doi101111fwb12533"
}

The most recent IPCC assessment has shown an important role for negative emissions technologies (NETs) in limiting global warming to 2 °C cost-effectively. However, a bottom-up, systematic, reproducible, and transparent literature assessment of the different options to remove CO2 from the atmosphere is currently missing. In part 1 of this three-part review on NETs, we assemble a comprehensive set of the relevant literature so far published, focusing on seven technologies: bioenergy with carbon capture and storage (BECCS), afforestation and reforestation, direct air carbon capture and storage (DACCS), enhanced weathering, ocean fertilisation, biochar, and soil carbon sequestration. In this part, part 2 of the review, we present estimates of costs, potentials, and side-effects for these technologies, and qualify them with the authors' assessment. Part 3 reviews the innovation and scaling challenges that must be addressed to realise NETs deployment as a viable climate mitigation strategy. Based on a systematic review of the literature, our best estimates for sustainable global NET potentials in 2050 are 0.5–3.6 GtCO2 yr−1 for afforestation and reforestation, 0.5–5 GtCO2 yr−1 for BECCS, 0.5–2 GtCO2 yr−1 for biochar, 2–4 GtCO2 yr−1 for enhanced weathering, 0.5–5 GtCO2 yr−1 for DACCS, and up to 5 GtCO2 yr−1 for soil carbon sequestration. Costs vary widely across the technologies, as do their permanency and cumulative potentials beyond 2050. It is unlikely that a single NET will be able to sustainably meet the rates of carbon uptake described in integrated assessment pathways consistent with 1.5 °C of global warming.

@article{doi10108817489326aabf9f,
    author = "Fuss, Sabine and Lamb, William F. and Callaghan, Max and Hilaire, Jérôme and Creutzig, Felix and Amann, Thorben and Beringer, Tim and de Oliveira Garcia, Wagner and Hartmann, Jens and Khanna, Tarun and Luderer, Gunnar and Nemet, Gregory F. and Rogelj, Joeri and Smith, Pete and Vicente‐Vicente, José Luis and Wilcox, Jennifer and del Mar Zamora Dominguez, Maria and Minx, Jan C.",
    title = "Negative emissions—Part 2: Costs, potentials and side effects",
    year = "2018",
    journal = "Environmental Research Letters",
    abstract = "The most recent IPCC assessment has shown an important role for negative emissions technologies (NETs) in limiting global warming to 2 °C cost-effectively. However, a bottom-up, systematic, reproducible, and transparent literature assessment of the different options to remove CO2 from the atmosphere is currently missing. In part 1 of this three-part review on NETs, we assemble a comprehensive set of the relevant literature so far published, focusing on seven technologies: bioenergy with carbon capture and storage (BECCS), afforestation and reforestation, direct air carbon capture and storage (DACCS), enhanced weathering, ocean fertilisation, biochar, and soil carbon sequestration. In this part, part 2 of the review, we present estimates of costs, potentials, and side-effects for these technologies, and qualify them with the authors' assessment. Part 3 reviews the innovation and scaling challenges that must be addressed to realise NETs deployment as a viable climate mitigation strategy. Based on a systematic review of the literature, our best estimates for sustainable global NET potentials in 2050 are 0.5–3.6 GtCO2 yr−1 for afforestation and reforestation, 0.5–5 GtCO2 yr−1 for BECCS, 0.5–2 GtCO2 yr−1 for biochar, 2–4 GtCO2 yr−1 for enhanced weathering, 0.5–5 GtCO2 yr−1 for DACCS, and up to 5 GtCO2 yr−1 for soil carbon sequestration. Costs vary widely across the technologies, as do their permanency and cumulative potentials beyond 2050. It is unlikely that a single NET will be able to sustainably meet the rates of carbon uptake described in integrated assessment pathways consistent with 1.5 °C of global warming.",
    url = "https://doi.org/10.1088/1748-9326/aabf9f",
    doi = "10.1088/1748-9326/aabf9f",
    openalex = "W2804406438",
    references = "doi101016jgloenvcha201605009, doi101016jrser200910009, doi101073pnas0812721106"
}

Abstract Invasive species can produce complex and unpredictable effects across multiple trophic levels through a combination of direct and indirect pathways. Invasive silver carp (Hypophthalmichthys molitrix) exert substantial pressure on the link between primary production and intermediate trophic levels in large rivers of the Midwestern USA. The goal of our manuscript was to describe the silver carp population invasion in the Illinois River (Illinois, USA) and explore the potential effects of silver carp on the native biota. We obtained 22 years of data from three long‐term monitoring programmes for phytoplankton, zooplankton, and age‐0 and adult native fishes. To determine when silver carp started affecting native biota, we used nonlinear regression to estimate the change point in silver carp biomass. We then used piecewise linear regression to separately model the response of phytoplankton and age‐0 and adult native fishes, using the model‐estimated change point in silver carp biomass. We tested for differences in taxon‐specific zooplankton density and biomass between pre‐ and post‐establishment periods using generalised linear models. To explore associations between native biota, silver carp and other potential drivers, we used single‐factor linear‐regression models in an information theoretic‐based approach. Our analysis showed individual silver carp condition decreased while their population numbers and biomass increased during their establishment in the Illinois River. Concurrently, analysis of 22 years of producer and consumer abundance and biomass data shows phytoplankton density and macrozooplankton density and biomass decreased—zooplankton by over 90%—during the same period, though the responses of age‐0 native fish biomass and adult native fish biomass were more nuanced. Our study provides compelling evidence of multiple trophic‐level effects from the silver carp invasion in North America and highlights the importance of long‐term data collection and monitoring. Our research shows managers that zooplankton and perhaps phytoplankton are quickly and negatively affected by silver carp, which may eventually cascade into higher trophic levels over longer timescales.

@article{doi101111fwb13097,
    author = "DeBoer, Jason A. and Anderson, Alison and Casper, Andrew F.",
    title = "Multi‐trophic response to invasive silver carp (Hypophthalmichthys molitrix) in a large floodplain river",
    year = "2018",
    journal = "Freshwater Biology",
    abstract = "Abstract Invasive species can produce complex and unpredictable effects across multiple trophic levels through a combination of direct and indirect pathways. Invasive silver carp (Hypophthalmichthys molitrix) exert substantial pressure on the link between primary production and intermediate trophic levels in large rivers of the Midwestern USA. The goal of our manuscript was to describe the silver carp population invasion in the Illinois River (Illinois, USA) and explore the potential effects of silver carp on the native biota. We obtained 22 years of data from three long‐term monitoring programmes for phytoplankton, zooplankton, and age‐0 and adult native fishes. To determine when silver carp started affecting native biota, we used nonlinear regression to estimate the change point in silver carp biomass. We then used piecewise linear regression to separately model the response of phytoplankton and age‐0 and adult native fishes, using the model‐estimated change point in silver carp biomass. We tested for differences in taxon‐specific zooplankton density and biomass between pre‐ and post‐establishment periods using generalised linear models. To explore associations between native biota, silver carp and other potential drivers, we used single‐factor linear‐regression models in an information theoretic‐based approach. Our analysis showed individual silver carp condition decreased while their population numbers and biomass increased during their establishment in the Illinois River. Concurrently, analysis of 22 years of producer and consumer abundance and biomass data shows phytoplankton density and macrozooplankton density and biomass decreased—zooplankton by over 90\%—during the same period, though the responses of age‐0 native fish biomass and adult native fish biomass were more nuanced. Our study provides compelling evidence of multiple trophic‐level effects from the silver carp invasion in North America and highlights the importance of long‐term data collection and monitoring. Our research shows managers that zooplankton and perhaps phytoplankton are quickly and negatively affected by silver carp, which may eventually cascade into higher trophic levels over longer timescales.",
    url = "https://doi.org/10.1111/fwb.13097",
    doi = "10.1111/fwb.13097",
    openalex = "W2793985206",
    references = "doi1018901217271"
}

ABSTRACT We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets.

@article{doi1015901982022420180033,
    author = "Albert, James S. and Val, Pedro and Hoorn, Carina",
    title = "The changing course of the Amazon River in the Neogene: center stage for Neotropical diversification",
    year = "2018",
    journal = "Neotropical Ichthyology",
    abstract = "ABSTRACT We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10\% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets.",
    url = "https://doi.org/10.1590/1982-0224-20180033",
    doi = "10.1590/1982-0224-20180033",
    openalex = "W2897400636",
    references = "doi101002ece32704, doi101016jgr201704001, doi101016jmarpetgeo201602027, doi1010292018gl078129, doi101130ges006471"
}

@article{doi101016jgloplacha201904015,
    author = "Chahal, Poonam and Kumar, Anil and Sharma, Choudhurimayum Pankaj and Singhal, Saurabh and Sundriyal, Yaspal and Srivastava, Pradeep",
    title = "Late Pleistocene history of aggradation and incision, provenance and channel connectivity of the Zanskar River, NW Himalaya",
    year = "2019",
    journal = "Global and Planetary Change",
    url = "https://doi.org/10.1016/j.gloplacha.2019.04.015",
    doi = "10.1016/j.gloplacha.2019.04.015",
    openalex = "W2942176975",
    references = "doi101017qua201719"
}

River ecosystems are highly biodiverse, influence global biogeochemical cycles, and provide valued services. However, humans are increasingly degrading fluvial ecosystems by altering their streamflows. Effective river restoration requires advancing our mechanistic understanding of how flow regimes affect biota and ecosystem processes. Here, we review emerging advances in hydroecology relevant to this goal. Spatiotemporal variation in flow exerts direct and indirect control on the composition, structure, and dynamics of communities at local to regional scales. Streamflows also influence ecosystem processes, such as nutrient uptake and transformation, organic matter processing, and ecosystem metabolism. We are deepening our understanding of how biological processes, not just static patterns, affect and are affected by stream ecosystem processes. However, research on this nexus of flow-biota-ecosystem processes is at an early stage. We illustrate this frontier with evidence from highly altered regulated rivers and urban streams. We also identify research challenges that should be prioritized to advance process-based river restoration.

@article{doi101126scienceaaw2087,
    author = "Palmer, Margaret A. and Ruhí, Albert",
    title = "Linkages between flow regime, biota, and ecosystem processes: Implications for river restoration",
    year = "2019",
    journal = "Science",
    abstract = "River ecosystems are highly biodiverse, influence global biogeochemical cycles, and provide valued services. However, humans are increasingly degrading fluvial ecosystems by altering their streamflows. Effective river restoration requires advancing our mechanistic understanding of how flow regimes affect biota and ecosystem processes. Here, we review emerging advances in hydroecology relevant to this goal. Spatiotemporal variation in flow exerts direct and indirect control on the composition, structure, and dynamics of communities at local to regional scales. Streamflows also influence ecosystem processes, such as nutrient uptake and transformation, organic matter processing, and ecosystem metabolism. We are deepening our understanding of how biological processes, not just static patterns, affect and are affected by stream ecosystem processes. However, research on this nexus of flow-biota-ecosystem processes is at an early stage. We illustrate this frontier with evidence from highly altered regulated rivers and urban streams. We also identify research challenges that should be prioritized to advance process-based river restoration.",
    url = "https://doi.org/10.1126/science.aaw2087",
    doi = "10.1126/science.aaw2087",
    openalex = "W2973781695",
    references = "doi101093bioscibiw059, doi1018901217271"
}

Abstract This study explores paleoflood deposits of the Siang River, known as the Tsangpo in Tibet. The river that often experiences large floods brings down huge amount of sediment and water that adversely affect the downstream regions with large human populations in the states of northeast Himalaya and its foreland. Along it's ~300 km mountainous stretch we collected samples for sedimentological, petrographic and Sr–Nd isotopic study to explore sediment provenance and dated the paleofloods (via optically stimulated luminescence, OSL). Geomorphic indices including precipitation and a geomorphic swath profile across the Brahmaputra catchment were studied to understand the interplay of mountain relief and rainfall that determine potential zones of high erosion and sediment supply. The OSL technique indicated the Siang River experienced at least eight large floods between 7 and 1 ka, possibly under the influence of warm and wet climatic conditions. The petrographic and isotopic data suggests that the eastern Himalayan syntaxis, which has the highest uplift and exhumation rate in the area, is not always the highest sediment producing zone. In some instances, the Tibetan plateau produces higher fluxes of sediments via glacial and landslide lake outburst floods (GLOFs and LLOFs). © 2020 John Wiley & Sons, Ltd.

@article{doi101002esp4893,
    author = "Panda, Sandeep and Kumar, Anil and Das, Satyabrata and Devrani, Rahul and Rai, Santosh and Prakash, Kuldeep and Srivastava, Pradeep",
    title = "Chronology and sediment provenance of extreme floods of Siang River (Tsangpo‐Brahmaputra River valley), northeast Himalaya",
    year = "2020",
    journal = "Earth Surface Processes and Landforms",
    abstract = "Abstract This study explores paleoflood deposits of the Siang River, known as the Tsangpo in Tibet. The river that often experiences large floods brings down huge amount of sediment and water that adversely affect the downstream regions with large human populations in the states of northeast Himalaya and its foreland. Along it's \textasciitilde 300 km mountainous stretch we collected samples for sedimentological, petrographic and Sr–Nd isotopic study to explore sediment provenance and dated the paleofloods (via optically stimulated luminescence, OSL). Geomorphic indices including precipitation and a geomorphic swath profile across the Brahmaputra catchment were studied to understand the interplay of mountain relief and rainfall that determine potential zones of high erosion and sediment supply. The OSL technique indicated the Siang River experienced at least eight large floods between 7 and 1 ka, possibly under the influence of warm and wet climatic conditions. The petrographic and isotopic data suggests that the eastern Himalayan syntaxis, which has the highest uplift and exhumation rate in the area, is not always the highest sediment producing zone. In some instances, the Tibetan plateau produces higher fluxes of sediments via glacial and landslide lake outburst floods (GLOFs and LLOFs). © 2020 John Wiley \& Sons, Ltd.",
    url = "https://doi.org/10.1002/esp.4893",
    doi = "10.1002/esp.4893",
    openalex = "W3025898191",
    references = "doi101017qua201719"
}

How diversity is structured has been a central goal of microbial ecology. In freshwater ecosystems, selection has been found to be the main driver shaping bacterial communities. However, its relative importance compared with other processes (dispersal, drift, diversification) may depend on spatial heterogeneity and the dispersal rates within a metacommunity. Still, a decrease in the role of selection is expected with increasing dispersal homogenization. Here, we investigate the main ecological processes modulating bacterial assembly in contrasting scenarios of environmental heterogeneity. We carried out a spatiotemporal survey in the floodplain system of the Paraná River. The bacterioplankton metacommunity was studied using both statistical inferences based on phylogenetic and taxa turnover as well as co-occurrence networks. We found that selection was the main process determining community assembly even at both extremes of environmental heterogeneity and homogeneity, challenging the general view that the strength of selection is weakened due to dispersal homogenization. The ecological processes acting on the community also determined the connectedness of bacterial networks associations. Heterogeneous selection promoted more interconnected networks increasing β-diversity. Finally, spatiotemporal heterogeneity was an important factor determining the number and identity of the most highly connected taxa in the system. Integrating all these empirical evidences, we propose a new conceptual model that elucidates how the environmental heterogeneity determines the action of the ecological processes shaping the bacterial metacommunity.

@article{doi101038s4139602007232,
    author = "Huber, Paula and Metz, Sebastián and Unrein, Fernando and Mayora, Gisela and Sarmento, Hugo and Devercelli, Melina",
    title = "Environmental heterogeneity determines the ecological processes that govern bacterial metacommunity assembly in a floodplain river system",
    year = "2020",
    journal = "The ISME Journal",
    abstract = "How diversity is structured has been a central goal of microbial ecology. In freshwater ecosystems, selection has been found to be the main driver shaping bacterial communities. However, its relative importance compared with other processes (dispersal, drift, diversification) may depend on spatial heterogeneity and the dispersal rates within a metacommunity. Still, a decrease in the role of selection is expected with increasing dispersal homogenization. Here, we investigate the main ecological processes modulating bacterial assembly in contrasting scenarios of environmental heterogeneity. We carried out a spatiotemporal survey in the floodplain system of the Paraná River. The bacterioplankton metacommunity was studied using both statistical inferences based on phylogenetic and taxa turnover as well as co-occurrence networks. We found that selection was the main process determining community assembly even at both extremes of environmental heterogeneity and homogeneity, challenging the general view that the strength of selection is weakened due to dispersal homogenization. The ecological processes acting on the community also determined the connectedness of bacterial networks associations. Heterogeneous selection promoted more interconnected networks increasing β-diversity. Finally, spatiotemporal heterogeneity was an important factor determining the number and identity of the most highly connected taxa in the system. Integrating all these empirical evidences, we propose a new conceptual model that elucidates how the environmental heterogeneity determines the action of the ecological processes shaping the bacterial metacommunity.",
    url = "https://doi.org/10.1038/s41396-020-0723-2",
    doi = "10.1038/s41396-020-0723-2",
    openalex = "W3043996931",
    references = "doi101111fwb12533"
}

Abstract Human‐induced global change dramatically alters individual aspects of river biodiversity, such as taxonomic, phylogenetic or functional diversity, and is predicted to lead to losses of associated ecosystem functions. Understanding these losses and dependencies are critical to human well‐being. Until now, however, most studies have only looked either at individual organismal groups or single functions, and little is known on the effect of human activities on multitrophic biodiversity and on ecosystem multifunctionality in riverine ecosystem. Here we profiled biodiversity from bacteria to invertebrates based on environmental DNA (hereafter, ‘eDNA’) samples across a major river catchment in China, and analysed their dependencies with multiple ecosystem functions, especially linked to C/N/P‐cycling. Firstly, we found a spatial cross‐taxon congruence pattern of communities' structure in the network of the Shaying river, which was related to strong environmental filtering due to human land use. Secondly, human land use explained the decline of multitrophic and multifaceted biodiversity and ecosystem functions, but increased functional redundancy in the riverine ecosystem. Thirdly, biodiversity and ecosystem function relationships at an integrative level showed a concave‐up (non‐saturating) shape. Finally, structural equation modeling suggested that land use affects ecosystem functions through biodiversity‐mediated pathways, including biodiversity loss and altered community interdependence in multitrophic groups. Our study highlights the value of a complete and inclusive assessment of biodiversity and ecosystem functions for an integrated land‐use management of riverine ecosystems.

@article{doi101111gcb15357,
    author = "Li, Feilong and Altermatt, Florian and Yang, Jianghua and An, Shuqing and Li, Aimin and Zhang, Xiaowei",
    title = "Human activities' fingerprint on multitrophic biodiversity and ecosystem functions across a major river catchment in China",
    year = "2020",
    journal = "Global Change Biology",
    abstract = "Abstract Human‐induced global change dramatically alters individual aspects of river biodiversity, such as taxonomic, phylogenetic or functional diversity, and is predicted to lead to losses of associated ecosystem functions. Understanding these losses and dependencies are critical to human well‐being. Until now, however, most studies have only looked either at individual organismal groups or single functions, and little is known on the effect of human activities on multitrophic biodiversity and on ecosystem multifunctionality in riverine ecosystem. Here we profiled biodiversity from bacteria to invertebrates based on environmental DNA (hereafter, ‘eDNA’) samples across a major river catchment in China, and analysed their dependencies with multiple ecosystem functions, especially linked to C/N/P‐cycling. Firstly, we found a spatial cross‐taxon congruence pattern of communities' structure in the network of the Shaying river, which was related to strong environmental filtering due to human land use. Secondly, human land use explained the decline of multitrophic and multifaceted biodiversity and ecosystem functions, but increased functional redundancy in the riverine ecosystem. Thirdly, biodiversity and ecosystem function relationships at an integrative level showed a concave‐up (non‐saturating) shape. Finally, structural equation modeling suggested that land use affects ecosystem functions through biodiversity‐mediated pathways, including biodiversity loss and altered community interdependence in multitrophic groups. Our study highlights the value of a complete and inclusive assessment of biodiversity and ecosystem functions for an integrated land‐use management of riverine ecosystems.",
    url = "https://doi.org/10.1111/gcb.15357",
    doi = "10.1111/gcb.15357",
    openalex = "W3086590667",
    references = "doi101016jscitotenv201906340"
}

The sensitivity of river discharge to climate-system warming is highly uncertain, and the processes that govern river discharge are poorly understood, which impedes climate-change adaptation. A prominent exemplar is the Colorado River, where meteorological drought and warming are shrinking a water resource that supports more than 1 trillion dollars of economic activity per year. A Monte Carlo simulation with a radiation-aware hydrologic model resolves the longstanding, wide disparity in sensitivity estimates and reveals the controlling physical processes. We estimate that annual mean discharge has been decreasing by 9.3% per degree Celsius of warming because of increased evapotranspiration, mainly driven by snow loss and a consequent decrease in reflection of solar radiation. Projected precipitation increases likely will not suffice to fully counter the robust, thermodynamically induced drying. Thus, an increasing risk of severe water shortages is expected.

@article{doi101126scienceaay9187,
    author = "Milly, P. C. D. and Dunne, K. A.",
    title = "Colorado River flow dwindles as warming-driven loss of reflective snow energizes evaporation",
    year = "2020",
    journal = "Science",
    abstract = "The sensitivity of river discharge to climate-system warming is highly uncertain, and the processes that govern river discharge are poorly understood, which impedes climate-change adaptation. A prominent exemplar is the Colorado River, where meteorological drought and warming are shrinking a water resource that supports more than 1 trillion dollars of economic activity per year. A Monte Carlo simulation with a radiation-aware hydrologic model resolves the longstanding, wide disparity in sensitivity estimates and reveals the controlling physical processes. We estimate that annual mean discharge has been decreasing by 9.3\% per degree Celsius of warming because of increased evapotranspiration, mainly driven by snow loss and a consequent decrease in reflection of solar radiation. Projected precipitation increases likely will not suffice to fully counter the robust, thermodynamically induced drying. Thus, an increasing risk of severe water shortages is expected.",
    url = "https://doi.org/10.1126/science.aay9187",
    doi = "10.1126/science.aay9187",
    openalex = "W3008579903",
    references = "doi1010022016wr019638, doi101023bclim000001370222656e8, doi1010292007gl031166, doi101038nature04141, doi101038nclimate2246, doi101038nclimate3046, doi101126science1151915, doi1011751520049319721000081otaosh23co2, doi101175jclid1705231, doi102307210739"
}

Abstract The Indus River, originating from Manasarovar Lake in Tibet, runs along the Indus Tsangpo suture zone in Ladakh which separates the Tethyan Himalaya in the south from the Karakoram zone to the north. Due to the barriers created by the Pir-Panjal ranges and the High Himalaya, Ladakh is located in a rain shadow zone of the Indian summer monsoon (ISM) making it a high-altitude desert. Occasional catastrophic hydrological events are known to endanger lives and properties of people residing there. Evidence of such events in the recent geologic past that are larger in magnitude than modern occurrences is preserved along the channels. Detailed investigation of these archives is imperative to expand our knowledge of extreme floods that rarely occur on the human timescale. Understanding the frequency, distribution, and forcing mechanisms of past extreme floods of this region is crucial to examine whether the causal agents are regional, global, or both on long timescales. We studied the Holocene extreme flood history of the Upper Indus catchment in Ladakh using slackwater deposits (SWDs) preserved along the Indus and Zanskar Rivers. SWDs here are composed of stacks of sand-silt couplets deposited rapidly during large flooding events in areas where a sharp reduction of flow velocity is caused by local geomorphic conditions. Each couplet represents a flood, the age of which is constrained using optically stimulated luminescence for sand and accelerator mass spectrometry and liquid scintillation counter 14C for charcoal specks from hearths. The study suggests occurrence of large floods during phases of strengthened ISM when the monsoon penetrated into arid Ladakh. Comparison with flood records of rivers draining other regions of the Himalaya and those influenced by the East Asian summer monsoon (EASM) indicates asynchronicity with the Western Himalaya that confirms the existing anti-phase relationship of the ISM-EASM that occurred in the Holocene. Detrital zircon provenance analysis indicates that sediment transportation along the Zanskar River is more efficient than the main Indus channel during extreme floods. Post–Last Glacial Maximum human migration, during warm and wet climatic conditions, into the arid upper Indus catchment is revealed from hearths found within the SWDs.

@article{doi101130b359761,
    author = "Sharma, Choudhurimayum Pankaj and Chahal, Poonam and Kumar, Anil and Singhal, Saurabh and Sundriyal, YP and Ziegler, Alan D. and Agnihotri, Rajesh and Wasson, Robert and Shukla, Uma Kant and Srivastava, Pradeep",
    title = "Late Pleistocene–Holocene flood history, flood-sediment provenance and human imprints from the upper Indus River catchment, Ladakh Himalaya",
    year = "2021",
    journal = "Geological Society of America Bulletin",
    abstract = "Abstract The Indus River, originating from Manasarovar Lake in Tibet, runs along the Indus Tsangpo suture zone in Ladakh which separates the Tethyan Himalaya in the south from the Karakoram zone to the north. Due to the barriers created by the Pir-Panjal ranges and the High Himalaya, Ladakh is located in a rain shadow zone of the Indian summer monsoon (ISM) making it a high-altitude desert. Occasional catastrophic hydrological events are known to endanger lives and properties of people residing there. Evidence of such events in the recent geologic past that are larger in magnitude than modern occurrences is preserved along the channels. Detailed investigation of these archives is imperative to expand our knowledge of extreme floods that rarely occur on the human timescale. Understanding the frequency, distribution, and forcing mechanisms of past extreme floods of this region is crucial to examine whether the causal agents are regional, global, or both on long timescales. We studied the Holocene extreme flood history of the Upper Indus catchment in Ladakh using slackwater deposits (SWDs) preserved along the Indus and Zanskar Rivers. SWDs here are composed of stacks of sand-silt couplets deposited rapidly during large flooding events in areas where a sharp reduction of flow velocity is caused by local geomorphic conditions. Each couplet represents a flood, the age of which is constrained using optically stimulated luminescence for sand and accelerator mass spectrometry and liquid scintillation counter 14C for charcoal specks from hearths. The study suggests occurrence of large floods during phases of strengthened ISM when the monsoon penetrated into arid Ladakh. Comparison with flood records of rivers draining other regions of the Himalaya and those influenced by the East Asian summer monsoon (EASM) indicates asynchronicity with the Western Himalaya that confirms the existing anti-phase relationship of the ISM-EASM that occurred in the Holocene. Detrital zircon provenance analysis indicates that sediment transportation along the Zanskar River is more efficient than the main Indus channel during extreme floods. Post–Last Glacial Maximum human migration, during warm and wet climatic conditions, into the arid upper Indus catchment is revealed from hearths found within the SWDs.",
    url = "https://doi.org/10.1130/b35976.1",
    doi = "10.1130/b35976.1",
    openalex = "W3160626787",
    references = "doi101017qua201719"
}

The deterioration of river water quality in urbanized areas is getting more serious, and affects the regional ecology and development of social economy; however, its mechanisms of dynamic variation is still an open question. In this study, we detected the dynamics of water quality and its driven mechanisms in the Yangtze River Delta plain, one of the most developed areas in China. The results showed that the spatial agglomerations of dissolved oxygen (DO), ammonia nitrogen (NH3-N), and total phosphorus (TP) presented seasonal differences, which exhibited a trend of shifting from west to east and then to west from spring to winter. Further, the relative contribution rates of the river network characteristics affecting water quality were quantified on the basis of backpropagation artificial neural networks. We found that the average contribution rates of river structure (more than 60%) were higher than that of river connectivity, and the dominant factors influencing water quality were water surface ratio (WP) and multifractal indices (Δa, Δf). Specifically, the average relative contribution rates of WP, Δa and Δf were 18.72%, 15.03%, and 14.52% during the flood season, respectively, and 15.83%, 16.58%, and 14.54% during the non-flood season. The functional connectivity influenced by obstruction of sluices also influences water quality, which accounting for 11.15% and 12.85% in the flood and non-flood seasons, respectively.

@article{doi101016jecolind2022108582,
    author = "Yu, Zhihui and Wang, Qiang and Xu, Youpeng and Lu, Miao and Lin, Zhixin and Gao, Bin",
    title = "Dynamic impacts of changes in river structure and connectivity on water quality under urbanization in the Yangtze River Delta plain",
    year = "2022",
    journal = "Ecological Indicators",
    abstract = "The deterioration of river water quality in urbanized areas is getting more serious, and affects the regional ecology and development of social economy; however, its mechanisms of dynamic variation is still an open question. In this study, we detected the dynamics of water quality and its driven mechanisms in the Yangtze River Delta plain, one of the most developed areas in China. The results showed that the spatial agglomerations of dissolved oxygen (DO), ammonia nitrogen (NH3-N), and total phosphorus (TP) presented seasonal differences, which exhibited a trend of shifting from west to east and then to west from spring to winter. Further, the relative contribution rates of the river network characteristics affecting water quality were quantified on the basis of backpropagation artificial neural networks. We found that the average contribution rates of river structure (more than 60\%) were higher than that of river connectivity, and the dominant factors influencing water quality were water surface ratio (WP) and multifractal indices (Δa, Δf). Specifically, the average relative contribution rates of WP, Δa and Δf were 18.72\%, 15.03\%, and 14.52\% during the flood season, respectively, and 15.83\%, 16.58\%, and 14.54\% during the non-flood season. The functional connectivity influenced by obstruction of sluices also influences water quality, which accounting for 11.15\% and 12.85\% in the flood and non-flood seasons, respectively.",
    url = "https://doi.org/10.1016/j.ecolind.2022.108582",
    doi = "10.1016/j.ecolind.2022.108582",
    openalex = "W4210363605",
    references = "doi101016jscitotenv201906340"
}

Abstract Understanding the mechanisms controlling downstream water‐level variations after the operation of the Three Gorges Dam is important for riverine flood and drought management. However, our quantitative understanding of the multiple controls of river morphology, vegetation, and floodplain resistance on water levels in the Middle Yangtze River (MYR) remains limited. Here, we analyze changes in river channels and floodplain resistance in the MYR using 450 cross‐sectional profiles as well as data on discharge, water levels, sediment, and satellite images from 2003 to 2015. Results show an overall decline in low‐flow water‐levels (at a given small discharge) due to severe incisions of low‐flow channels caused by a sharp reduction of ∼90% in sediment loads from 1950–2002 to 2003–2020. In contrast, high‐flow water‐levels (at a given large discharge) display minor changes. Our analysis shows that the notably increased floodplain resistance due to vegetation growth is likely the dominant factor elevating flood water‐levels, followed by riverbed coarsening and greater fluctuations in the river longitudinal profiles. Our findings further the understanding of downstream geomorphic response to dam operation and their impacts on water levels and have important implications for riverine flood management in dammed river systems.

@article{doi1010292022wr032338,
    author = "Hu, Yong and Li, Dongfeng and Deng, Jinyun and Yue, Yao and Zhou, Junxiong and Chai, Yuanfang and Li, Yitian",
    title = "Mechanisms Controlling Water‐Level Variations in the Middle Yangtze River Following the Operation of the Three Gorges Dam",
    year = "2022",
    journal = "Water Resources Research",
    abstract = "Abstract Understanding the mechanisms controlling downstream water‐level variations after the operation of the Three Gorges Dam is important for riverine flood and drought management. However, our quantitative understanding of the multiple controls of river morphology, vegetation, and floodplain resistance on water levels in the Middle Yangtze River (MYR) remains limited. Here, we analyze changes in river channels and floodplain resistance in the MYR using 450 cross‐sectional profiles as well as data on discharge, water levels, sediment, and satellite images from 2003 to 2015. Results show an overall decline in low‐flow water‐levels (at a given small discharge) due to severe incisions of low‐flow channels caused by a sharp reduction of ∼90\% in sediment loads from 1950–2002 to 2003–2020. In contrast, high‐flow water‐levels (at a given large discharge) display minor changes. Our analysis shows that the notably increased floodplain resistance due to vegetation growth is likely the dominant factor elevating flood water‐levels, followed by riverbed coarsening and greater fluctuations in the river longitudinal profiles. Our findings further the understanding of downstream geomorphic response to dam operation and their impacts on water levels and have important implications for riverine flood management in dammed river systems.",
    url = "https://doi.org/10.1029/2022wr032338",
    doi = "10.1029/2022wr032338",
    openalex = "W4296906579",
    references = "doi103133pp1677"
}

Our research introduces the river regulation effects on three sections of the upper and middle Odra River (south-western Poland), with differently channelized parts. In the upper and lower reaches, the river was straightened, narrowed, and trained with groins, whereas in the middle section, it was also impounded by numerous barrages. The discharge duration (DD) and water stage duration (WSD) curves for water-gauge stations from these river sections were analyzed to recognize changes in river flows and channel morphology since the mid-20th century. This analysis is supplemented by an examination of repeated surveys of the gauge cross sections of the river, annual precipitation totals in its catchment, and their relationship to the variation of the North Atlantic Oscillation (NAO) index. Our findings provide new hydrological insights for the region. The three river sections exhibited different patterns of the adjustment of the channel morphology to the river channelization: upper section was typified by channel incision, middle section by channel stability, and lower section by channel incision in its upper part and vertical stability of the channel bed in the lower part. Barrages in the middle section stabilized water stages in a wide range of hydrological conditions. Annual precipitation totals and river run-off did not change systematically over the study period. The variation in precipitation totals was inversely related to annual values of the NAO index. The study confirms the usefulness of DD/WSD curves to analyze changes in river run-off and the vertical position of the channel bed.

@article{doi103390w15020370,
    author = "Nádudvari, Ádám and Czajka, Agnieszka and Wyżga‬‬, Bartłomiej and Zygmunt, Marcin and Wdowikowski, Marcin",
    title = "Patterns of Recent Changes in Channel Morphology and Flows in the Upper and Middle Odra River",
    year = "2023",
    journal = "Water",
    abstract = "Our research introduces the river regulation effects on three sections of the upper and middle Odra River (south-western Poland), with differently channelized parts. In the upper and lower reaches, the river was straightened, narrowed, and trained with groins, whereas in the middle section, it was also impounded by numerous barrages. The discharge duration (DD) and water stage duration (WSD) curves for water-gauge stations from these river sections were analyzed to recognize changes in river flows and channel morphology since the mid-20th century. This analysis is supplemented by an examination of repeated surveys of the gauge cross sections of the river, annual precipitation totals in its catchment, and their relationship to the variation of the North Atlantic Oscillation (NAO) index. Our findings provide new hydrological insights for the region. The three river sections exhibited different patterns of the adjustment of the channel morphology to the river channelization: upper section was typified by channel incision, middle section by channel stability, and lower section by channel incision in its upper part and vertical stability of the channel bed in the lower part. Barrages in the middle section stabilized water stages in a wide range of hydrological conditions. Annual precipitation totals and river run-off did not change systematically over the study period. The variation in precipitation totals was inversely related to annual values of the NAO index. The study confirms the usefulness of DD/WSD curves to analyze changes in river run-off and the vertical position of the channel bed.",
    url = "https://doi.org/10.3390/w15020370",
    doi = "10.3390/w15020370",
    openalex = "W4316664079",
    references = "doi101002esp5085"
}

Abstract River meanders entrenched into bedrock are found worldwide, and they are famously well represented in the Colorado Plateau of the southwestern U.S. Meandering of bedrock streams can eventually lead to cutting off canyon loops, and these abandoned “rincons” are locations with high preservation of fluvial deposits and landforms. We document and luminescence date the fluvial terraces in and around the Jackson Hole rincon along the Colorado River downstream of Moab, Utah. Results indicate cutoff and abandonment of the rincon at ~200 ka and also record the rapid and unsteady incision in this region over the past 300 ky. A convergence of conditions contributed to the cutoff of the rincon, including alluvial‐channel conditions at the onset of MIS 6 glacial‐climate, which provided channel‐bed cover and enhanced lateral erosion of weak strata. Also, a contemporaneous rock‐avalanche partially obstructed the paleochannel just downstream of the breach, potentially creating a backwater that further enabled a flood to avulse across the neck. Although other studies show that bedrock‐channel meandering and cutoff can generate unpaired strath terraces and short‐term increases in incision rates, these are not evident in the record at the Jackson Hole rincon. This novel case study leverages the high preservation potential within abandoned bedrock meanders to illuminate the processes and controls of rincon formation during landscape evolution.

@article{doi101002esp5886,
    author = "Pederson, Joel L. and Young, S. and Turley, Mike and Tanski, Natalie and Rittenour, Tammy M. and Harris, Ron",
    title = "The how, when, and why of an abandoned bedrock meander of the Colorado River, Utah (U.S.)",
    year = "2024",
    journal = "Earth Surface Processes and Landforms",
    abstract = "Abstract River meanders entrenched into bedrock are found worldwide, and they are famously well represented in the Colorado Plateau of the southwestern U.S. Meandering of bedrock streams can eventually lead to cutting off canyon loops, and these abandoned “rincons” are locations with high preservation of fluvial deposits and landforms. We document and luminescence date the fluvial terraces in and around the Jackson Hole rincon along the Colorado River downstream of Moab, Utah. Results indicate cutoff and abandonment of the rincon at \textasciitilde 200 ka and also record the rapid and unsteady incision in this region over the past 300 ky. A convergence of conditions contributed to the cutoff of the rincon, including alluvial‐channel conditions at the onset of MIS 6 glacial‐climate, which provided channel‐bed cover and enhanced lateral erosion of weak strata. Also, a contemporaneous rock‐avalanche partially obstructed the paleochannel just downstream of the breach, potentially creating a backwater that further enabled a flood to avulse across the neck. Although other studies show that bedrock‐channel meandering and cutoff can generate unpaired strath terraces and short‐term increases in incision rates, these are not evident in the record at the Jackson Hole rincon. This novel case study leverages the high preservation potential within abandoned bedrock meanders to illuminate the processes and controls of rincon formation during landscape evolution.",
    url = "https://doi.org/10.1002/esp.5886",
    doi = "10.1002/esp.5886",
    openalex = "W4399011140",
    references = "doi101002sici10969837199807237651aidesp89130co2v, doi101016jquageo201503012, doi101016jradmeas200806002, doi101016s1350448700000913, doi101016s1350448703000167, doi101016s135044879900253x, doi101029gm107p0237, doi101038313105a0, doi101111j15023885201200248x, doi1026034laatl2011443, openalexw2270285851"
}

Abstract River terraces are commonly used to infer climate and tectonic histories. Yet, it is increasingly recognised that other processes, such as river capture, can affect river terrace genesis and incision rates and patterns. In this study, we conduct a field‐based investigation of river terrace sequences along the Kolokithas and Varitis Rivers in central Crete, Greece, that share a confluence and preserve geomorphic evidence for the recent capture of the Kolokithas headwaters by the Varitis. We use digital topographic analysis, mapping, and optically stimulated luminescence (OSL) geochronology to quantify the river terrace and bedrock incision response to river capture. Topographic analysis indicates the Varitis captured ~30 km 2 of drainage area from the Kolokithas. We find differences in terrace characteristics, number of terraces, and incision rates and patterns on the adjacent valleys. The Kolokithas has four terrace levels, and the Varitis has five. All terraces are strath terraces, except for the oldest on the Kolokithas, a ~8 m thick fill terrace that starkly contrasts the time‐equivalent ~1–2 m thick strath terrace on the Varitis. Relative and absolute age control suggests three Pleistocene terraces were emplaced during cooler climate intervals, and two Holocene terraces are perhaps because of anthropogenic disturbances. The incision patterns differ on each valley, with generally more incision upstream on the Varitis relative to the Kolokithas. Incision rates on the Varitis are roughly twice as high as on the Kolokithas, but the average incision rate of both valleys combined is comparable to coastal rock uplift rates derived from marine terraces. Collectively, our results suggest that fluvial systems are sensitive to climate and tectonic processes even when affected by geomorphic disturbances, like river capture and beheading. However, care must be taken when interpreting river terraces as direct records of climate and tectonic processes, particularly when working on a single river valley.

@article{doi101002esp70035,
    author = "Gallen, Sean F. and Wegmann, Karl W.",
    title = "The impact of river capture on fluvial terraces and bedrock incision",
    year = "2025",
    journal = "Earth Surface Processes and Landforms",
    abstract = "Abstract River terraces are commonly used to infer climate and tectonic histories. Yet, it is increasingly recognised that other processes, such as river capture, can affect river terrace genesis and incision rates and patterns. In this study, we conduct a field‐based investigation of river terrace sequences along the Kolokithas and Varitis Rivers in central Crete, Greece, that share a confluence and preserve geomorphic evidence for the recent capture of the Kolokithas headwaters by the Varitis. We use digital topographic analysis, mapping, and optically stimulated luminescence (OSL) geochronology to quantify the river terrace and bedrock incision response to river capture. Topographic analysis indicates the Varitis captured \textasciitilde 30 km 2 of drainage area from the Kolokithas. We find differences in terrace characteristics, number of terraces, and incision rates and patterns on the adjacent valleys. The Kolokithas has four terrace levels, and the Varitis has five. All terraces are strath terraces, except for the oldest on the Kolokithas, a \textasciitilde 8 m thick fill terrace that starkly contrasts the time‐equivalent \textasciitilde 1–2 m thick strath terrace on the Varitis. Relative and absolute age control suggests three Pleistocene terraces were emplaced during cooler climate intervals, and two Holocene terraces are perhaps because of anthropogenic disturbances. The incision patterns differ on each valley, with generally more incision upstream on the Varitis relative to the Kolokithas. Incision rates on the Varitis are roughly twice as high as on the Kolokithas, but the average incision rate of both valleys combined is comparable to coastal rock uplift rates derived from marine terraces. Collectively, our results suggest that fluvial systems are sensitive to climate and tectonic processes even when affected by geomorphic disturbances, like river capture and beheading. However, care must be taken when interpreting river terraces as direct records of climate and tectonic processes, particularly when working on a single river valley.",
    url = "https://doi.org/10.1002/esp.70035",
    doi = "10.1002/esp.70035",
    openalex = "W4408328012",
    references = "doi101002esp5886"
}

Abstract Erosion can remain active and changing in landscapes long after tectonic drivers have ceased, potentially due to local‐geologic controls, climate changes, or geodynamics. We present new fluvial incision‐rate histories and terrain analyses of the Colorado River system through the central Colorado Plateau to understand what has caused the variable erosion across this post‐orogenic landscape. Results from new cosmogenic and luminescence dating of fluvial terrace and upland gravel deposits in Glen and Meander Canyons establish incision‐rate histories that are marked by an Early‐Middle Pleistocene erosion hiatus, followed by ∼200 m of rapid incision over the last ∼350 kyr. Projection of fluvial topography from above knickzones of the Colorado River drainage system roughly agree with the observed magnitude of recent incision and reflect a common baselevel fall from Pliocene river integration through Grand Canyon, which is still propagating through the drainage. A response‐time model indicates that baselevel fall from integration likely took 2–4 Myr to reach the central Colorado Plateau and 100s kyr to travel across the study area, potentially accounting for incision rate changes in the fluvial terrace records of Meander and Glen Canyons. The upstream‐migrating incision has likely been partitioned into multiple waves across the landscape due to the local geologic controls of lava damming, salt tectonics, and heterogenous bedrock. As baselevel fall from Pliocene Colorado River integration diffuses upstream, it can only account for perhaps a quarter of the total ∼2 km of exhumation in the central Colorado Plateau, demanding an unknown driver for significant erosion in the Pliocene.

@article{doi1010292024av001359,
    author = "Tanski, Natalie and Pederson, Joel L. and Hidy, Alan J. and Rittenour, Tammy M. and Mauch, James",
    title = "The Mystery of Baselevel Controls in the Incision History of the Central Colorado Plateau",
    year = "2025",
    journal = "AGU Advances",
    abstract = "Abstract Erosion can remain active and changing in landscapes long after tectonic drivers have ceased, potentially due to local‐geologic controls, climate changes, or geodynamics. We present new fluvial incision‐rate histories and terrain analyses of the Colorado River system through the central Colorado Plateau to understand what has caused the variable erosion across this post‐orogenic landscape. Results from new cosmogenic and luminescence dating of fluvial terrace and upland gravel deposits in Glen and Meander Canyons establish incision‐rate histories that are marked by an Early‐Middle Pleistocene erosion hiatus, followed by ∼200 m of rapid incision over the last ∼350 kyr. Projection of fluvial topography from above knickzones of the Colorado River drainage system roughly agree with the observed magnitude of recent incision and reflect a common baselevel fall from Pliocene river integration through Grand Canyon, which is still propagating through the drainage. A response‐time model indicates that baselevel fall from integration likely took 2–4 Myr to reach the central Colorado Plateau and 100s kyr to travel across the study area, potentially accounting for incision rate changes in the fluvial terrace records of Meander and Glen Canyons. The upstream‐migrating incision has likely been partitioned into multiple waves across the landscape due to the local geologic controls of lava damming, salt tectonics, and heterogenous bedrock. As baselevel fall from Pliocene Colorado River integration diffuses upstream, it can only account for perhaps a quarter of the total ∼2 km of exhumation in the central Colorado Plateau, demanding an unknown driver for significant erosion in the Pliocene.",
    url = "https://doi.org/10.1029/2024av001359",
    doi = "10.1029/2024av001359",
    openalex = "W4407750894",
    references = "doi101002esp5886"
}

Barrier displacement by river capture is an important mechanism for the assembly of freshwater fish faunas. The production of increasingly comprehensive and rigorously dated phylogentic trees for major clades of fishes, along with improved resolution in historical geomorphology, provide an unprecedented opportunity to develop thorough biogeographical scenarios of faunal assembly that synthesise existing knowledge and provide detailed context for future study. The Pecos River of southwestern North America is a textbook example of drainage formation by river capture and provides a straightforward case of freshwater fish faunal assembly by river capture. Fishes ultimately confined to the middle section of the Pecos River (Capitan area of endemism) have their closest relatives in the Brazos, Colorado (Texas), and Red rivers, which served as ancient dispersal corridors from the Mississippi River drainage. The Capitan area of endemism developed in association with two dissolution basins that, in the Late Miocene, captured headwaters of these rivers. In the Late Pliocene or Early Pleistocene, the endorheic middle Pecos River (Capitan area of endemism) was captured by or overflowed into a tributary to the Río Grande, which became the lower Pecos River. The nascent lower Pecos River also harboured an endemic-fish assemblage as part of a nexus of springfed rivers (ancestral Río Grande, Devils River, lower Pecos River) that comprised the Devils area of endemism. Even after a through-flowing Pecos River linked the Capitan and Devils areas of endemism, many endemic species remained only within their original area of endemism, giving the Pecos River a composite fish fauna. The Río Grande connection later allowed fishes dispersing along the Gulf of Mexico coast, aided by Late Pleistocene sea-level falls and glacial outbursts, not only to populate the Río Grande, but also to disperse up the Pecos River. Incision of the lower Río Grande valley and uplift in the Sangre de Cristo Mountains empowered the Pecos River to capture headwater streams from the adjacent South Canadian River and middle Río Grande, bringing in additional fishes. More recently, humans introduced at least 50 species to the drainage, while human impacts fragmented the native fauna. Non-native versus native status remains uncertain for several species (e.g. Miniellus stramineus) and multiple lineages of diverse origin may exist for some widespread, polytypic species like Cyprinella lutrensis and Pimephales promelas. The composite fish fauna of the Pecos River is a biogeographical anomaly explainable by the complex geomorphological history that produced it. As such, it provides a unique opportunity for studies of fish-assemblage evolutionary ecology. Also, its historical association with neighbouring drainages helps clarify their biogeography (as detailed here). Further broadening of this synthesis could support biogeographical scenarios at large spatial scales, illustrating the potential that now exists for reconstructing regional river-drainage faunas.

@article{doi101111brv70012,
    author = "Hoagstrom, Christopher W and Davenport, Stephen R and Osborne, Megan J",
    title = "Assembling the Pecos River fish fauna: barrier displacement on the Southern Great Plains, North America.",
    year = "2025",
    journal = "Biological reviews of the Cambridge Philosophical Society",
    abstract = "Barrier displacement by river capture is an important mechanism for the assembly of freshwater fish faunas. The production of increasingly comprehensive and rigorously dated phylogentic trees for major clades of fishes, along with improved resolution in historical geomorphology, provide an unprecedented opportunity to develop thorough biogeographical scenarios of faunal assembly that synthesise existing knowledge and provide detailed context for future study. The Pecos River of southwestern North America is a textbook example of drainage formation by river capture and provides a straightforward case of freshwater fish faunal assembly by river capture. Fishes ultimately confined to the middle section of the Pecos River (Capitan area of endemism) have their closest relatives in the Brazos, Colorado (Texas), and Red rivers, which served as ancient dispersal corridors from the Mississippi River drainage. The Capitan area of endemism developed in association with two dissolution basins that, in the Late Miocene, captured headwaters of these rivers. In the Late Pliocene or Early Pleistocene, the endorheic middle Pecos River (Capitan area of endemism) was captured by or overflowed into a tributary to the Río Grande, which became the lower Pecos River. The nascent lower Pecos River also harboured an endemic-fish assemblage as part of a nexus of springfed rivers (ancestral Río Grande, Devils River, lower Pecos River) that comprised the Devils area of endemism. Even after a through-flowing Pecos River linked the Capitan and Devils areas of endemism, many endemic species remained only within their original area of endemism, giving the Pecos River a composite fish fauna. The Río Grande connection later allowed fishes dispersing along the Gulf of Mexico coast, aided by Late Pleistocene sea-level falls and glacial outbursts, not only to populate the Río Grande, but also to disperse up the Pecos River. Incision of the lower Río Grande valley and uplift in the Sangre de Cristo Mountains empowered the Pecos River to capture headwater streams from the adjacent South Canadian River and middle Río Grande, bringing in additional fishes. More recently, humans introduced at least 50 species to the drainage, while human impacts fragmented the native fauna. Non-native versus native status remains uncertain for several species (e.g. Miniellus stramineus) and multiple lineages of diverse origin may exist for some widespread, polytypic species like Cyprinella lutrensis and Pimephales promelas. The composite fish fauna of the Pecos River is a biogeographical anomaly explainable by the complex geomorphological history that produced it. As such, it provides a unique opportunity for studies of fish-assemblage evolutionary ecology. Also, its historical association with neighbouring drainages helps clarify their biogeography (as detailed here). Further broadening of this synthesis could support biogeographical scenarios at large spatial scales, illustrating the potential that now exists for reconstructing regional river-drainage faunas.",
    url = "https://pubmed.ncbi.nlm.nih.gov/40113332/",
    doi = "10.1111/brv.70012",
    openalex = "W4408724939",
    pmid = "40113332",
    references = "doi1010160044848687903218, doi101016jscitotenv201906340, doi101038nature06813, doi101038ngeo2813, doi101111fwb12533, doi101111j13652427200601708x, doi101126science2885467854, doi101130g331471, doi101130ges006471, doi101641b580507"
}

Abstract Although rates of fluvial incision across the Colorado Plateau are known reasonably well, rate variability through time and its controlling processes are still poorly understood. We used boulder armored benches from the Teasdale-Torrey lowlands reach of the Fremont River in the northwestern Colorado Plateau (Utah, USA) as temporal markers to determine regional incision rates and explore controls on rate variability. Bench gravels are sourced from Tertiary volcanic rocks capping nearby Boulder and Thousand Lakes Mountains. The sedimentology of bench deposits suggests that most form from mass movement with later fluvial reworking. Volcanic boulders are tougher than the local sedimentary bedrock, which promotes boulder armoring and topographic inversion. Thirty-seven boulder cosmogenic 3He exposure ages from 11 different benches range from &gt;600 ka to ca. 100 ka. Soil carbonate stages from two benches are in good agreement with surface exposure ages. Averaged Fremont River and tributary incision rates determined from bench exposure ages are 32% faster for tributaries off of Thousand Lakes Mountain (0.41 m/k.y.) than tributaries off of Boulder Mountain (0.28 m/k.y.). This difference in incision rate may be due to Laramideage structures limiting incision for the tributaries that drain Boulder Mountain and extensive Pleistocene ice caps on Boulder Mountain creating a wider and thicker boulder armor slowing incision.

@article{doi101130ges028431,
    author = "Marchetti, David W. and Ellwein, Amy L. and Huth, Tyler E. and Cerling, Thure E. and Anderson, Leif and Passey, Benjamin H. and Hynek, Scott A.",
    title = "Ages of boulder armored benches document varying Fremont River tributary incision rates, Teasdale-Torrey lowlands, Utah, USA",
    year = "2025",
    journal = "Geosphere",
    abstract = "Abstract Although rates of fluvial incision across the Colorado Plateau are known reasonably well, rate variability through time and its controlling processes are still poorly understood. We used boulder armored benches from the Teasdale-Torrey lowlands reach of the Fremont River in the northwestern Colorado Plateau (Utah, USA) as temporal markers to determine regional incision rates and explore controls on rate variability. Bench gravels are sourced from Tertiary volcanic rocks capping nearby Boulder and Thousand Lakes Mountains. The sedimentology of bench deposits suggests that most form from mass movement with later fluvial reworking. Volcanic boulders are tougher than the local sedimentary bedrock, which promotes boulder armoring and topographic inversion. Thirty-seven boulder cosmogenic 3He exposure ages from 11 different benches range from \>600 ka to ca. 100 ka. Soil carbonate stages from two benches are in good agreement with surface exposure ages. Averaged Fremont River and tributary incision rates determined from bench exposure ages are 32\% faster for tributaries off of Thousand Lakes Mountain (0.41 m/k.y.) than tributaries off of Boulder Mountain (0.28 m/k.y.). This difference in incision rate may be due to Laramideage structures limiting incision for the tributaries that drain Boulder Mountain and extensive Pleistocene ice caps on Boulder Mountain creating a wider and thicker boulder armor slowing incision.",
    url = "https://doi.org/10.1130/ges02843.1",
    doi = "10.1130/ges02843.1",
    openalex = "W4414011467",
    references = "doi101002esp5886"
}