A sediment graph model based on an instantaneous unit sediment graph

A model was developed for predicting sediment graphs from agricultural watersheds. Storm sediment graphs are predicted by convolving source runoff with an instantaneous unit sediment graph (IUSG). The IUSG is the distribution of sediment from an instantaneous burst of rainfall producing one unit of runoff. The IUSG is the product of an instantaneous unit hydrograph and the sediment concentration distribution. Initial sediment concentration of the IUSG is assumed to vary linearly with source runoff volume. A sediment‐routing function, based on travel time and sediment particle size, is used to predict the sediment concentration distribution. Tests with 50 storms from five watersheds showed that the model is applicable to agricultural watersheds in the Texas blacklands. It should be useful in designing reservoirs or in waterquality‐modeling problems.