Abstract:The PC versions of the Illinois Urban Drainage Area Simulator ILLUDAS (ILUDRAIN) and the Penn State Runoff Quality Model (PSRM-QUAL) are used to predict hydrographs from four relatively small urban sites (5Ð97 to 23Ð57 ha), each having a distinct land use designation (commercial, high density residential, low density residential, and highway), and all located in south Florida. The description of the sites and observed rainfall and runoff data were available from the US Geological Survey (USGS), and have been used in the past to validate their model (DR3M). The two models were calibrated and verified using measured rainfall-runoff data (72 storm events for calibration and 26 different events for verification) and measured hydrological characteristics of the four sites. The methodology and input parameters are presented. Predicted hydrographs from the two models are plotted against observed ones and show good agreement. Model performance is evaluated using the mean normalized error computation and scattergrams of predicted versus observed data. A comparison is also made with the results, using the same data and drainage areas, of the following three methods/models tested in previous studies: the runoff curve number (SCS) method combined with the Santa Barbara urban hydrograph method (SCS-SBUH); the Environmental Protection Agency (EPA) stormwater management model (SWMM); the USGS Distributed Routing Rainfall-Runoff Model (DR3M). The predictions from all models tested in this study showed good agreement with the observed data, with better predictions generally obtained for the more impervious sites.

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