Predicting Sediment Yield in Storm‐Water Runoff from Urban Areas

Abstract

A mathematical model is presented for the purpose of representing the washoff of sediments from small urban watersheds during storm events. The model simulates the contribution of sediments from each of the different land surfaces present within an urban watershed. It has been determined that different land surfaces contribute sediments differently, and that a better estimate of the total sediment load could be determined by representing each of the major land surfaces independently. The model was developed and tested using water‐quality data from four small urban watersheds in Houston and Austin, Tex., and by using data from bare‐soil erosion plot studies. The performance of the model was determined by comparing the simulated results with the observed results during the storm events that were analyzed. Given the appropriate parameters, the model provides reasonable estimates of the observed sediment yield from each of the different land surfaces studied. The rate at which sediments are washed off the impervious area of a watershed is shown to correlate with the length of time since rainfall has last occurred.