| This research presents the temporal and spatial comparison of rainfall data obtained from rain gauges and radar at hourly, daily, event and subbasin scales. The HEC-HMS hydrologic model was used to investigate the impact of different rainfall inputs in the simulation of event based streamflow. In most cases, the radar was found to underestimate rainfall amount with respect to the rain gauges for the five-year study period. The investigation on daily and event basis showed that the rain gauge and radar rainfall have reasonably good correlation with each other, especially after the Mean Field Bias (MFB) correction were made to the radar rainfall data. The comparison of event based streamflow simulated using the two rainfall inputs indicated that significant differences in runoff amounts can result. More specifically, the runoff hydrographs estimated using rain gauge rainfall had better agreement with the observed hydrographs than those obtained using radar rainfall or merged rainfall (obtained from point rain gauge and spatially varying radar rainfall). It was found that the simulations of event hydrographs using merged rainfall showed significant improvements in runoff amount, peak flow, and time to peak for most of the runoff events when compared with radar rainfall simulations. |
