David J Topping
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 decade has been on developing new methods for making continuous measurements of suspended-sediment transport and grain size in rivers.
Biography
I received my Bachelor's degree from the Massachusetts Institute of Technology in 1999, 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 80 peer-reviewed publications in the scientific literature that have received over 1500 citations I began my career with the USGS in 1993 in the National Research Program of the Water Mission Area and, in 2007, moved my research project to the Grand Canyon Monitoring and Research Center in the Southwest Biological Science Center.
Science and Products
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...
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...
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...
Rubin, David M.; Buscombe, Daniel; Wright, Scott A.; Topping, David; Grams, Paul; Schmidt, John C.; Hazel, J.E.; Kaplinski, Matthew A.; Tusso, Robert B. 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...
Dramais, Guillaume; Camenen, Benoit; Le Coz, Jerome; Topping, David; Peteuil, Christophe; Pierrefeu, Gilles Interpreting flux-based sediment budgets in a habitat context: Linking precise temporal-resolution measurements of sediment flux to spatially robust characterization of channel change
(Topping-Leonard) 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...
Leonard, Christina M.; Schmidt, John C.; Topping, David; Griffiths, Ronald 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...
Topping, David; Grams, Paul E.; Griffiths, Ronald; Hazel, Joseph E.; Kaplinski, Matthew; Dean, David; Voichick, Nicholas; Unema, Joel; Sabol, Thomas 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...
Grams, Paul; Buscombe, Daniel D.; Topping, David; Kaplinski, Matthew; Hazel, Joseph 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‐...
Topping, David; Mueller, Erich R.; Schmidt, John C.; Griffiths, Ronald; Dean, David; Grams, Paul E. 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...
Voichick, Nicholas; Topping, David; Griffiths, Ronald 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...
Grams, Paul E.; Buscombe, Daniel; Topping, David; Mueller, Erich R. 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...
Griffiths, Ronald; Topping, David Long-term continuous acoustical suspended-sediment measurements in rivers – Theory, evaluation, and results from 14 stations on five rivers
We have developed a physically based method for using two acoustic frequencies to measure suspended-silt-and-clay concentration, suspended-sand concentration, and suspended-sand median grain size in river cross sections at 15-minute intervals over decadal timescales. The method is strongly grounded in the extensive scientific literature on the...
Topping, David; Wright, Scott A.; Griffiths, Ronald; Dean, David
Water clarity of the Colorado River—Implications for food webs and fish communities
The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now...
Voichick, Nicholas; Kennedy, Theodore A.; Topping, David; Griffiths, Ronald; Fry, Kyrie Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads
The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We...
Dean, David; Topping, David; Schmidt, John C.; Griffiths, Ronald; Sabol, Thomas