The amount and intensity of runoff at catchment scale are largely determined by the presence of impervious land cover types, which are predominant in an urbanized area. This paper examines the impact of different methods for estimating impervious surface cover on the prediction of peak discharges as determined by a fully distributed rainfall-runoff model (WetSpa). The study of River Yamuna and Hindon basin area shows detailed information on the spatial distribution of impervious surfaces, as obtained/calibrated from remotely sensed data.