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ARS Home » Pacific West Area » Tucson, Arizona » SWRC » Research » Publications at this Location » Publication #76902
Title: A HYDROLOGIC METHOD FOR SEDIMENT TRANSPORT AND YIELD

Author
item Lane, Leonard
item Nichols, Mary

Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Proceedings
Publication Acceptance Date: 2/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Estimates of amounts of sediment transported are commonly used in engineering design and analysis. Equations have been developed to estimate sediment transport, however these equations are based on steady, uniform flow conditions (called normal flow). Typically, natural flow conditions do not meet these assumptions. A method has been developed to incorporate sediment transport equations with a runoff hydrograph approximation to estimate sediment transport and yield under non normal flow conditions. This method is called the hydrologic approach. The procedure was developed and calibrated using data from the Niobrara river in Nebraska and small watersheds in Arizona. Validation studies are conducted for steady and uniform flow conditions at Muddy Creek, Wyoming and the Rio Grande near Bernalillo, New Mexico. The sediment transport equations computed bed material sediment discharge rates comparable to those measured and to those ecomputed using several well accepted sediment transport formulae. The procedure is applied to unsteady, nonuniform flow events in ephemeral steam channels on the Walnut Gulch Watershed, Arizona.

Technical Abstract: Sediment transport equations are coupled with a runoff hydrograph approximation to produce a sediment transport and yield estimation procedure called the hydrologic method. The procedure was developed and calibrated using data from the Niobrara river in Nebraska and small watersheds in Arizona. Validation studies are conducted for steady and uniform flow conditions at Muddy Creek, Wyoming and the Rio Grande near Bernalillo, New Mexico. The sediment transport equations computed bed material sediment discharge rates comparable to those measured and to those computed using several well accepted sediment transport formulae. The procedure is applied to unsteady, nonuniform flow events in ephemeral steam channels on the Walnut Gulch Watershed, Arizona using a piecewise normal hydrograph approximation technique. Computed sediment yields explained about 99% of the variance in observed sediment yields. However, this good fit was obtained by the hydrologic method well representing the 10 runoff hydrographs and the mean suspended sediment concentration. When the 106 observed individual instantaneous sediment concentration values are compared with the corresponding computed values, it is found that the overall mean suspended sediment concentration for all 10 events and the means for each individual event are accurately predicted. However, temporal variations in observed suspended sediment concentration during the runoff event are not well represented by the hydrologic method.