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
River Sediment Dynamics
River Geomorphology and Geomorphic Change
Sediment Storage in Grand Canyon
High-Flow Experiments on the Colorado River
Gross primary production estimates and associated light, sediment, and water quality data from the Colorado River below Glen Canyon Dam
Suspended-sediment, bedload, bed-sediment, and multibeam sonar data in the Chippewa River, WI
Surveyed peak-stage elevations, coordinates, and indicator data of strandlines from large floods on the Colorado River in Grand Canyon National Park, Arizona
Suspended-sediment, bed-sediment, and in-channel topographical data at the Green River at Mineral Bottom near Canyonlands National Park, and Colorado River at Potash, UT stream gages
Measurements of bed grain size on the Colorado River in Grand Canyon National Park, Arizona - 2000 to 2014
Topographic data, historical peak-stage data, and 2D flow models for the lowermost Little Colorado River, Arizona, USA, 2017
Geomorphic Change Data for the Little Colorado River, Arizona, USA
Geomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA
Geomorphic Change-Sediment Transport Data for Kanab Creek, Arizona USA
Mapping 2-D bedload rates throughout a sand-bed river reach from high-resolution acoustical surveys of migrating bedforms
Field investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements
Experimental reductions in sub-daily flow fluctuations increased gross primary productivity for 425 river kilometers downstream
The use of continuous sediment-transport measurements to improve sand-load estimates in a large sand-bedded river: The Lower Chippewa River, WI
The effects of requested flows for native fish on sediment dynamics, geomorphology, and riparian vegetation for the Green River in Canyonlands National Park, Utah
Historical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries
Strandlines from large floods on the Colorado River in Grand Canyon National Park, Arizona
Self-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size
Does channel narrowing by floodplain growth necessarily indicate sediment surplus? Lessons from sediment‐transport analyses in the Green and Colorado rivers, Canyonlands, Utah
Causes of variability in suspended‐sand concentration evaluated using measurements in the Colorado River in Grand Canyon
A physically based method of combining ADCP velocity data with point samples to compute suspended-sand discharge -- Application to the Rhone River, France
Interpreting flux-based sediment budgets in a habitat context: Linking precise temporal-resolution measurements of sediment flux to spatially robust characterization of channel change
Science and Products
- Science
River Sediment Dynamics
Sediment controls the physical habitat of river ecosystems. Changes in the amount and areal distribution of different sediment types cause changes in river-channel form and river habitat. The amount and type of sediment suspended in the water column determines water clarity. Understanding sediment transport and the conditions under which sediment is deposited or eroded from the various...River Geomorphology and Geomorphic Change
River channels and their adjacent floodplains are ever evolving in form and composition in response to changing patterns of streamflow, the quantity and size of supplied sediment, and feedbacks with the riparian and aquatic ecosystems. Changes in channel form affect aquatic and riparian habitats, which are important for plants, animals, and insects. Erosion and deposition of river channels and...Sediment Storage in Grand Canyon
The sandbars exposed along the shoreline of the Colorado River represent only a small fraction of the sand deposits in Grand Canyon, most of which are on the bed of the river in eddies and the channel. Current management practice includes efforts to maintain and build sandbars by releasing high flows from Glen Canyon Dam that are timed to coincide with periods of fine-sediment supply from...High-Flow Experiments on the Colorado River
Glen Canyon Dam has altered flow and fine sediment (sand, silt, and clay) dynamics of the Colorado River in Grand Canyon. Before the dam, the Colorado River experienced highly variable flows and carried a large amount of sediment through Grand Canyon, which maintained sandbars (highly valued camping areas in Grand Canyon) and provided sand that protected archeological and cultural sites from... - Data
Gross primary production estimates and associated light, sediment, and water quality data from the Colorado River below Glen Canyon Dam
These data were compiled to model the effects of flow regime and bed grain size distributions on rates of gross primary production (GPP) in the Colorado River below Glen Canyon Dam, AZ, USA. The objectives of our study were to quantify daily and weekly scale effects of an experimental flow regime on GPP in the Colorado River. The experimental flow was conducted at Glen Canyon Dam from May-August iSuspended-sediment, bedload, bed-sediment, and multibeam sonar data in the Chippewa River, WI
These data were compiled for analyses of sediment transport within the Chippewa River, WI. Objective(s) of our study were to determine sand loads contributed by the Chippewa River to the Mississippi River. These data include physical suspended-sediment samples, acoustical suspended-sediment measurements, acoustical suspended-sediment loads, quasi-continuous measurements of bed-elevation, multibeamSurveyed peak-stage elevations, coordinates, and indicator data of strandlines from large floods on the Colorado River in Grand Canyon National Park, Arizona
These data provide a comprehensive survey of peak-stage indicators along the Colorado River corridor between river mile (RM) 0 and RM 87 (see Figure 1 in the associated USGS-SIR). In 2008, the locations of peak-stage indicators in three short reaches downstream from RM 87 were measured using a handheld GPS unit (see Appendix 1 in the associated USGS-SIR). Total-station measurements were made usingSuspended-sediment, bed-sediment, and in-channel topographical data at the Green River at Mineral Bottom near Canyonlands National Park, and Colorado River at Potash, UT stream gages
Sediment Data: These data include (1) physical suspended-sediment sample data including suspended silt and clay concentration, suspended-sand concentration, and suspended-sand grain size distribution, (2) bed-sediment sample data with complete grain size analyses, and (3) 15-minute acoustical sediment data measured using a multifrequency array (1MHz and 2MHz) of sidelooking acoustic Doppler profilMeasurements of bed grain size on the Colorado River in Grand Canyon National Park, Arizona - 2000 to 2014
These data were compiled to better understand sedimentation patterns on the bed of the Colorado River in Grand Canyon National Park, and the way these patterns relate to suspended sediment grain size and concentration. These data were collected by the US Geological Survey Grand Canyon Monitoring and Research Center from 2000 to 2014, primarily using the "Flying Eyeball" underwater imaging system.Topographic data, historical peak-stage data, and 2D flow models for the lowermost Little Colorado River, Arizona, USA, 2017
These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include example models in FaSTMECH and SToRM solvers in the iRIC framework, topographic data collected by LiDAR and total station in June 2017, and high water marks from nine historic floods. Other data also include location and other information for control points and gGeomorphic Change Data for the Little Colorado River, Arizona, USA
These data include geospatial files (shapefiles and orthorectified raster images) and an input hydrograph (csv) for a 1-dimensional unsteady hydrologic model. Shapefiles consist of active channel boundarys and channel centerlines of six reaches of the LCR beginning ~4.5 km above Grand Falls, AZ, and ending ~12.8 km downstream from Cameron, AZ. These reaches are (1) the ~4.5 km above Grand Falls reGeomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA
These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include topographic data collected by LIDAR and total station in June 2017, high water marks from nine historic floods, and control points and gage structures. Topographic data include ground topography collected by LIDAR and channel bathymetry collected by total stationGeomorphic Change-Sediment Transport Data for Kanab Creek, Arizona USA
These data were compiled to accompany flow modeling work on Kanab Creek near the mouth (USGS gage 09403850). The data include topographic data collected by a remote sensing detection light detection and ranging (LIDAR) system and surveying total station in June 2017, high water marks from six floods from 2011 to 2013, and control points and gage structures. Topographic data include ground topograp - Publications
Filter Total Items: 76
Mapping 2-D bedload rates throughout a sand-bed river reach from high-resolution acoustical surveys of migrating bedforms
This paper introduces a method for determining spatially-distributed, 2-D bedload rates using repeat, high-resolution surveys of the bed topography. As opposed to existing methods, bedform parameters and bedload rates are computed from bed elevation profiles interpolated along the local bedform velocities. The bedform velocity fields are computed applying Large-Scale Particle Image Velocimetry, inAuthorsJérôme Le Coz, Emeline Perret, Benoît Camenen, David Topping, Daniel D. Buscombe, Kate C.P. Leary, Guillaume Dramais, Paul GramsField investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements
Collection of accurate suspended-sediment data using depth-integrating samplers requires that they operate isokinetically, that is, that they sample at the local stream velocity unaffected by the presence of the suspended-sediment sampler. Sub-isokinetic suspended-sediment sampling causes grain-size dependent positive biases in the suspended-sediment concentration measured by the suspended-sedimenAuthorsThomas A. Sabol, David J. Topping, Ronald E. Griffiths, Guillaume DramaisExperimental reductions in sub-daily flow fluctuations increased gross primary productivity for 425 river kilometers downstream
Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves sub-daily changes in water releases propAuthorsBridget Deemer, Charles Yackulic, Robert O Hall Jr., Michael Dodrill, Theodore Kennedy, Jeffrey Muehlbauer, David Topping, Nicholas Voichick, Mike YardThe use of continuous sediment-transport measurements to improve sand-load estimates in a large sand-bedded river: The Lower Chippewa River, WI
Accurately determining sediment loads is necessary for managing river environments but is difficult because multiple processes can lead to large discharge-independent changes in sediment transport. Thus, estimations of sediment load using discharge–sediment rating curves fit to sparse or historical sediment-transport measurements can be inaccurate, necessitating alternative approaches to reduce unAuthorsDavid Dean, David Topping, D. D. Buscombe, Joel T. Groten, Jeffrey R. Ziegeweid, Faith A. Fitzpatrick, John (William) Lund, Erin Nicole CoenenThe effects of requested flows for native fish on sediment dynamics, geomorphology, and riparian vegetation for the Green River in Canyonlands National Park, Utah
Releases of water from Flaming Gorge Dam together with climate-related variations in runoff determine the streamflow regime of the Green River, which affects the physical characteristics of the channel and riparian ecosystem of the Green River corridor in Canyonlands National Park. The dam has decreased peak streamflows and raised base streamflows, resulting in vegetation encroachment and channelAuthorsPaul E. Grams, Jonathan M. Friedman, David Dean, David J. ToppingHistorical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries
The Little Colorado River is a major tributary to the Colorado River with a confluence at the boundary between Marble and Grand Canyons within Grand Canyon National Park, Arizona. The bedrock gorge of the lower Little Colorado River is home to the largest known population of Gila cypha (humpback chub), an endangered fish endemic to the Colorado River Basin. Channel conditions might affect the spawAuthorsJoel A. Unema, David J. Topping, Keith Kohl, Michael J. Pillow, Joshua J. CasterStrandlines from large floods on the Colorado River in Grand Canyon National Park, Arizona
Strandlines of peak-stage indicators (such as driftwood logs, woody debris, and trash) provide valuable data for understanding the maximum stage and extent of inundation during floods. A series of seven strandlines have been preserved along the Colorado River in Grand Canyon National Park, Arizona, USA. A survey and analysis of these strandlines was completed from the Colorado River at Lees Ferry,AuthorsThomas A. Sabol, Ronald E. Griffiths, David J. Topping, Erich R. Mueller, Robert B. Tusso, Joseph E. HazelSelf-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size
Bedrock-canyon rivers tend to be supply limited because they are efficient transporters of sediment and not because the upstream supply of sediment is small. A byproduct of this supply limitation is that the finer alluvium stored in these rivers has shorter residence times and smaller volumes than in alluvial rivers. To improve our understanding of disequilibrium sediment transport and its effectAuthorsDavid Topping, Paul Grams, Ronald E. Griffiths, David Dean, Scott A. Wright, Joel A. UnemaDoes 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 M. Leonard, John C. Schmidt, David Topping, Ronald E. Griffiths