Effect of impervious surface on peak discharge and runoff volume

Abstract

Urbanization processes increase the area of impervious surface in a catchment due to alteration of pervious surface. As a result, the urbanization processes will affect the rainfall-runoff process as higher surface runoff volume will be generated. Therefore, this study was carried in order to determine peak discharge and runoff volume for Golok River Basin. In this study HEC-HMS hydrological engineering modelling was used to simulate the rainfall-runoff process of Golok River basin. In order to compute peak discharge and runoff volume, the initial and constant rate, Snyder’s Synthetic unit hydrograph, constant monthly base flow and Muskingum routing were chosen. The model parameters were calibrated using 1981 historical major events observed streamflow data. Calibrated model parameters was validated by using 1982 historical major events observed streamflow data. A statistical test for hydrological model efficiency, Nash and Sutcliffe (NSE) was employed to check the efficiency of calibration and validation process. The results found that values of NSE of 0.681 and 0.643 for calibration and validation respectively. The model calibration was found to be good and meanwhile it was satisfactory for validation. Calibrated and validate parameters then were used to determine the peak discharge and runoff volume for 5, 10, 50 and 100 years Average Recurrence Interval (ARI) for different percentage of impervious surface. The simulation results were then compared to the 2003 peak discharge and runoff volume. The result of this study proved that peak discharge and runoff volume of Golok River basin were increased as the impervious surface increased.