Comparison Study of Two Methods Used to Estimate Surface Runoff Hydrograph for Small Basins

Abstract

In this study Rainstorm hydrograph peak discharge and unit-hydrograph peak discharge in small basins were calculated and evaluated using various methods for peak discharge assessment applying 6-hour storm rainfall duration. Rainfall-runoff models: HEC-1 option of the WMS software based on the American Soil Conservation Service (SCS) Curve Number (CN) Method and Mockus Method were used to compute runoff hydrograph peak discharge, and time to peak discharge in the Khazir river basin near the Mosul city North Iraq for dry, normal and wet soil cases. The aim of this study was to assess the ability of these two methods to predict design peak discharge in comparison with the observed data obtained. The results demonstrate that the peak discharges computed by HEC-1 in the WMS software method are mostly closest to the data observed. And the dry state of soil at CN=66 showed the best agreement with the observed data.