Records of stream discharge and sediment concentration were used to compute sediment discharge on a daily basis (Porterfield, 1972). Continuous records of sediment concentration were drawn by interpolation between samples closely spaced in time and by extrapolation to estimated peaks of concentration. Sediment discharge was computed by equation 1, with appropriate coefficients for time intervals ranging from 15 minutes to several hours. The partial sediment discharges were summed for each day and entered into WATSTORE.
Sediment-transport curves were used judiciously to estimate sediment discharge for periods when samples were not sufficient to define concentration by time. With this method, a curvilinear relation between measurements of stream discharge and sediment discharge is derived on logarithmic paper. The relation then is applied to stream discharges for periods when sediment discharge cannot be computed directly.
Urgent requests for sediment-discharge data were received from the U.S. Army Corps of Engineers and other interested agencies following storm flows in 1980 and 1981. Procedures were devised for rapid computation of sediment discharge. These procedures involved immediate retrieval of stage records from gaging stations, immediate lab analysis of sediment samples, and extended working schedules to compute sediment-discharge records of storm flows. Retrieval of stream-discharge records and sediment samples was combined into a computer program to automate the computation of sediment discharge.