The aim of this paper is to develop a methodology for estimating flood risk, considering Noida as a case study. 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.