David J Topping, Ph.D.
My research is focused on sediment transport and sedimentology, and the physics linking sediment transport, sediment grain size, and channel morphology in rivers. Much of my work over the past two decades has been on developing new methods for making continuous measurements of suspended-sediment transport and grain size in rivers.
I received my Bachelor's degree from the Massachusetts Institute of Technology in 1988, my Master's degree from the University of Washington in 1991, and my doctorate from the University of Washington in 1997. I have authored or co-authored over 97 peer-reviewed publications in the scientific literature that have received over 2300 citations. I began my career with the USGS in 1993 in the National Research Program of the Water Resources Mission Area and, in 2007, moved my research project to the Southwest Biological Science Center's Grand Canyon Monitoring and Research Center.
Professional Experience
1993 - 2007: Water Resources Mission Area, National Research Program
2007 - present: Research Hydrologist, Southwest Biological Science Center's Grand Canyon Monitoring and Research Center
Education and Certifications
B.S., 1988: Massachusetts Institute of Technology
M.S., 1991: University of Washington
Ph.D., 1997: University of Washington
Science and Products
Filter Total Items: 80
Does channel narrowing by floodplain growth necessarily indicate sediment surplus? Lessons from sediment‐transport analyses in the Green and Colorado rivers, Canyonlands, Utah
Analyses of suspended sediment transport provide valuable insight into the role that sediment supply plays in causing geomorphic change. The sediment supply within a river system evolves depending on the discharge, flood frequency and duration, changes in sediment input, and ecohydraulic conditions that modify sediment transport processes. Changes in supply can be evaluated through analyses of cou
Authors
David Dean, David Topping, Paul Grams, Alexander E. Walker, John C. Schmidt
Causes of variability in suspended‐sand concentration evaluated using measurements in the Colorado River in Grand Canyon
Rivers commonly exhibit substantial variability in suspended‐sand concentration, even at constant water discharge. Here we derive an approach for evaluating how much of this variability arises from mean bed‐sand grain size. We apply this approach to the Colorado River in Grand Canyon, where discharge‐independent concentration of suspended sand varies by more than a factor of 23 (N = 1.4 × 106). Th
Authors
David M. Rubin, Daniel Buscombe, Scott A. Wright, David Topping, Paul Grams, John C. Schmidt, J.E. Hazel, Matthew A. Kaplinski, Robert B. Tusso
A physically based method of combining ADCP velocity data with point samples to compute suspended-sand discharge -- Application to the Rhone River, France
Measuring suspended-sand flux in rivers is a challenge since sand concentrations are highly variable in time and space throughout a river cross section. Most of the present methodologies rely on point or depth-integrated sampling (Nolan et al., 2005, Topping et al., 2016). The standard method estimates mean concentration and multiply it by discharge to compute the suspended-sand discharge. Here, w
Authors
Guillaume Dramais, Benoit Camenen, Jerome Le Coz, David Topping, Christophe Peteuil, Gilles Pierrefeu
Interpreting flux-based sediment budgets in a habitat context: Linking precise temporal-resolution measurements of sediment flux to spatially robust characterization of channel change
Continuous measurements of sediment transport at reach-bracketing gaging stations allow for the construction of continuous mass-balance sediment budgets for the intervening reach. Although these budgets identify periods of sediment surplus (net deposition) or sediment deficit (net erosion), such analyses cannot identify the locations within the reach where channel change occurs. Because channel ch
Authors
Christina Leonard, John C. Schmidt, David Topping, Ronald E. Griffiths
Geomorphic change and biogeomorphic feedbacks in a dryland river: The Little Colorado River, Arizona, USA
The Little Colorado River in Arizona, U.S.A. has undergone substantial geomorphic change since the early 1900s. We analyzed hydrologic and geomorphic data at different spatial and temporal scales to determine the type, magnitude, and rate of geomorphic change that has occurred since the early 20th century. Since the 1920s, there have been 4 alternating periods of high and low total-annual flow. Pe
Authors
David Dean, David Topping
Optimal timing of high-flow experiments for sandbar deposition
Sediment-transport theory and field measurements indicate that the greatest or most efficient deposition of sand in eddies occurs during controlled floods (a.k.a. High-Flow Experiments or HFEs) when the greatest amount of the finest sand is available on the bed of the Colorado River (Topping and others, 2010). Conducting HFEs when the sand on the bed of the Colorado River is depleted and coarse ca
Authors
David Topping, Paul E. Grams, Ronald E. Griffiths, Joseph E. Hazel, Matthew Kaplinski, David Dean, Nicholas Voichick, Joel Unema, Thomas A. Sabol
Long-term evolution of sand transport through a river network: Relative influences of a dam versus natural changes in grain size from sand waves
Temporal and spatial nonuniformity in supplies of water and sand in a river network leads to sand transport that is in local disequilibrium with the upstream sand supply. In such river networks, sand is transported downstream as elongating waves in which coupled changes in grain size and transport occur. Depending on the magnitude of each sand‐supplying event and the interval between such events,
Authors
David Topping, Erich R. Mueller, John C. Schmidt, Ronald E. Griffiths, David Dean, Paul E. Grams
How many measurements are required to construct an accurate sand budget in a large river? Insights from analyses of signal and noise
Morphological change in river channels is frequently evaluated in the context of mass balance sediment budgets. In a closed sediment budget, measurements of sediment influx and efflux are coupled with measured changes in channel topography to provide both spatial and temporal resolution, and independent estimates of the mass balance. For sediment budgets constructed over long river segments (~10 c
Authors
Paul Grams, Daniel D. Buscombe, David Topping, Matthew Kaplinski, Joseph Hazel
Technical note: False low turbidity readings from optical probes during high suspended-sediment concentrations
Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5
Authors
Nicholas Voichick, David Topping, Ronald E. Griffiths
Sand pulses and sand patches on the Colorado River in Grand Canyon
Alluvial sandbars occur in lateral recirculation zones (eddies) along the Colorado River in Grand Canyon National Park (Schmidt, 1990). Resource managers periodically release controlled floods from the upstream Glen Canyon Dam to rebuild these bars (Grams et al., 2015), which erode during fluctuating dam releases, and by hillslope runoff and wind deflation (Hazel et al., 2010). Because the dam blo
Authors
Paul E. Grams, Daniel Buscombe, David Topping, Erich R. Mueller
Importance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets
Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-b
Authors
Ronald E. Griffiths, David Topping
Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan
IntroductionThe purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen Canyon Dam Long-Term Experimental and Management Plan
Authors
Scott P. Vanderkooi, Theodore A. Kennedy, David J. Topping, Paul E. Grams, David L. Ward, Helen C. Fairley, Lucas S. Bair, Joel B. Sankey, Charles B. Yackulic, John C. Schmidt
Science and Products
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Filter Total Items: 80
Does channel narrowing by floodplain growth necessarily indicate sediment surplus? Lessons from sediment‐transport analyses in the Green and Colorado rivers, Canyonlands, Utah
Analyses of suspended sediment transport provide valuable insight into the role that sediment supply plays in causing geomorphic change. The sediment supply within a river system evolves depending on the discharge, flood frequency and duration, changes in sediment input, and ecohydraulic conditions that modify sediment transport processes. Changes in supply can be evaluated through analyses of couAuthorsDavid Dean, David Topping, Paul Grams, Alexander E. Walker, John C. SchmidtCauses of variability in suspended‐sand concentration evaluated using measurements in the Colorado River in Grand Canyon
Rivers commonly exhibit substantial variability in suspended‐sand concentration, even at constant water discharge. Here we derive an approach for evaluating how much of this variability arises from mean bed‐sand grain size. We apply this approach to the Colorado River in Grand Canyon, where discharge‐independent concentration of suspended sand varies by more than a factor of 23 (N = 1.4 × 106). ThAuthorsDavid M. Rubin, Daniel Buscombe, Scott A. Wright, David Topping, Paul Grams, John C. Schmidt, J.E. Hazel, Matthew A. Kaplinski, Robert B. TussoA physically based method of combining ADCP velocity data with point samples to compute suspended-sand discharge -- Application to the Rhone River, France
Measuring suspended-sand flux in rivers is a challenge since sand concentrations are highly variable in time and space throughout a river cross section. Most of the present methodologies rely on point or depth-integrated sampling (Nolan et al., 2005, Topping et al., 2016). The standard method estimates mean concentration and multiply it by discharge to compute the suspended-sand discharge. Here, wAuthorsGuillaume Dramais, Benoit Camenen, Jerome Le Coz, David Topping, Christophe Peteuil, Gilles PierrefeuInterpreting flux-based sediment budgets in a habitat context: Linking precise temporal-resolution measurements of sediment flux to spatially robust characterization of channel change
Continuous measurements of sediment transport at reach-bracketing gaging stations allow for the construction of continuous mass-balance sediment budgets for the intervening reach. Although these budgets identify periods of sediment surplus (net deposition) or sediment deficit (net erosion), such analyses cannot identify the locations within the reach where channel change occurs. Because channel chAuthorsChristina Leonard, John C. Schmidt, David Topping, Ronald E. GriffithsGeomorphic change and biogeomorphic feedbacks in a dryland river: The Little Colorado River, Arizona, USA
The Little Colorado River in Arizona, U.S.A. has undergone substantial geomorphic change since the early 1900s. We analyzed hydrologic and geomorphic data at different spatial and temporal scales to determine the type, magnitude, and rate of geomorphic change that has occurred since the early 20th century. Since the 1920s, there have been 4 alternating periods of high and low total-annual flow. PeAuthorsDavid Dean, David ToppingOptimal timing of high-flow experiments for sandbar deposition
Sediment-transport theory and field measurements indicate that the greatest or most efficient deposition of sand in eddies occurs during controlled floods (a.k.a. High-Flow Experiments or HFEs) when the greatest amount of the finest sand is available on the bed of the Colorado River (Topping and others, 2010). Conducting HFEs when the sand on the bed of the Colorado River is depleted and coarse caAuthorsDavid Topping, Paul E. Grams, Ronald E. Griffiths, Joseph E. Hazel, Matthew Kaplinski, David Dean, Nicholas Voichick, Joel Unema, Thomas A. SabolLong-term evolution of sand transport through a river network: Relative influences of a dam versus natural changes in grain size from sand waves
Temporal and spatial nonuniformity in supplies of water and sand in a river network leads to sand transport that is in local disequilibrium with the upstream sand supply. In such river networks, sand is transported downstream as elongating waves in which coupled changes in grain size and transport occur. Depending on the magnitude of each sand‐supplying event and the interval between such events,AuthorsDavid Topping, Erich R. Mueller, John C. Schmidt, Ronald E. Griffiths, David Dean, Paul E. GramsHow many measurements are required to construct an accurate sand budget in a large river? Insights from analyses of signal and noise
Morphological change in river channels is frequently evaluated in the context of mass balance sediment budgets. In a closed sediment budget, measurements of sediment influx and efflux are coupled with measured changes in channel topography to provide both spatial and temporal resolution, and independent estimates of the mass balance. For sediment budgets constructed over long river segments (~10 cAuthorsPaul Grams, Daniel D. Buscombe, David Topping, Matthew Kaplinski, Joseph HazelTechnical note: False low turbidity readings from optical probes during high suspended-sediment concentrations
Turbidity, a measure of water clarity, is monitored for a variety of purposes including (1) to help determine whether water is safe to drink, (2) to establish background conditions of lakes and rivers and detect pollution caused by construction projects and stormwater discharge, (3) to study sediment transport in rivers and erosion in catchments, (4) to manage siltation of water reservoirs, and (5AuthorsNicholas Voichick, David Topping, Ronald E. GriffithsSand pulses and sand patches on the Colorado River in Grand Canyon
Alluvial sandbars occur in lateral recirculation zones (eddies) along the Colorado River in Grand Canyon National Park (Schmidt, 1990). Resource managers periodically release controlled floods from the upstream Glen Canyon Dam to rebuild these bars (Grams et al., 2015), which erode during fluctuating dam releases, and by hillslope runoff and wind deflation (Hazel et al., 2010). Because the dam bloAuthorsPaul E. Grams, Daniel Buscombe, David Topping, Erich R. MuellerImportance of measuring discharge and sediment transport in lesser tributaries when closing sediment budgets
Sediment budgets are an important tool for understanding how riverine ecosystems respond to perturbations. Changes in the quantity and grain size distribution of sediment within river systems affect the channel morphology and related habitat resources. It is therefore important for resource managers to know if a river reach is in a state of sediment accumulation, deficit or stasis. Many sediment-bAuthorsRonald E. Griffiths, David ToppingScientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan
IntroductionThe purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen Canyon Dam Long-Term Experimental and Management PlanAuthorsScott P. Vanderkooi, Theodore A. Kennedy, David J. Topping, Paul E. Grams, David L. Ward, Helen C. Fairley, Lucas S. Bair, Joel B. Sankey, Charles B. Yackulic, John C. Schmidt - News