Abstract |
A simulation model describes the quantitative and qualitative regimes of storm water runoff from urban watersheds. The urban runoff system consists of three basic subsystems: Precipitation, runoff, and quality. Each of the three subsystems is mathematically modeled using probability and statistical techniques. Major flooding in the High Plains of Texas is associated with short-duration high-intensity convective storms. The model assumes these short-duration precipitation events are random and governed by a stationary probability distribution function. A bivariate log-normal distribution function fits the observed rainfall depths and durations for Lubbock, Texas. The runoff process is modeled by using the British Road Research Laboratory method, which assumes that all runoff is derived from interconnected impervious areas. Rainfall inputs are simulated by the Monte Carlo method. The outflow hydrograph is generated by single-step reservoir routing. The total pollutant load is predicted by a multiple regression involving the storm characteristics and the antecedent conditions. (Author) |