A linear reservoir simulation model of Wilson Creek Watershed

Abstract

This study has investigated whether a simple mathematical model could be used to produce useful results in flood event simulation. A simplified computer model of the Wilson Creek Watershed that simulates hourly streamflow due to rainfall has been developed. The sequential development of the model is discussed, along with the effect of the various model parameters. Physically, the model can be thought of as two stacked linear reservoirs with outflows corresponding to the hydrograph components direct runoff and spring flow. Input to the model consists of initial soil moisture content and hourly rainfall data. The model ignores the effects of evaporation, evapotranspiration and interception, assuming them to be negligible in the overall water balance during a rainstorm. The parameters that define the storage and outflow characteristics of each reservoir were determined by minimizing the least squares deviation of the percentage error between the recorded and simulated flood peaks and volumes. Five storms with peak discharges varying from 300 cfs to 1350 were selected for calibration of the model. To verify the model five additional storms were simulated. The model was found to be capable of a resonable reproduction of observed streamflow hydrographs. However, an anomaly was encountered in the reproduction of two of the storms. This anomaly requires further study.