Ronald Griffiths
Science and Products
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...
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 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 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 Using 15-minute acoustic data to analyze suspended-sediment dynamics in the Rio Grande in the Big Bend Region
The Rio Grande in the Big Bend region is subject to rapid geomorphic change consisting of channel narrowing during years of low flow, and channel widening during rare, large, long duration floods. Since the 1940s, there have been large declines in mean and peak stream flow, and the channel has progressively narrowed. Large, channel widening floods...
Dean, David; Topping, David; Griffiths, Ronald; Sabol, Thomas; Schmidt, John C.; Bennett, Jeffery B. Inaccuracies in sediment budgets arising from estimations of tributary sediment inputs: an example from a monitoring network on the southern Colorado plateau
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 channel reach is in a state of...
Griffiths, Ronald; Topping, David Physically based method for measuring suspended-sediment concentration and grain size using multi-frequency arrays of acoustic-doppler profilers
As the result of a 12-year program of sediment-transport research and field testing on the Colorado River (6 stations in UT and AZ), Yampa River (2 stations in CO), Little Snake River (1 station in CO), Green River (1 station in CO and 2 stations in UT), and Rio Grande (2 stations in TX), we have developed a physically based method for measuring...
Topping, David J.; Wright, Scott A.; Griffiths, Ronald; Dean, David
Design of a sediment-monitoring gaging network on ephemeral tributaries of the Colorado River in Glen, Marble, and Grand Canyons, Arizona
Management of sediment in rivers downstream from dams requires knowledge of both the sediment supply and downstream sediment transport. In some dam-regulated rivers, the amount of sediment supplied by easily measured major tributaries may overwhelm the amount of sediment supplied by the more difficult to measure lesser tributaries. In this first...
Griffiths, Ronald E.; Topping, David J.; Anderson, Robert S.; Hancock, Gregory S.; Melis, Theodore S.