Abstract: The feasibility of extending the lead time with which small basin discharges can be forecasted is investigated through the combined use of the radar quantitative precipitation nowcast (QPN) and the semi distributed hydrologic modeling TOPMODEL (TOPography based hydrological MODEL). The study area includes the six small headwater basins (about 60-100 km2) subdivided from Foziling basin (1813 km2) in the upper reaches of the Pihe river located in Anhui Province (east China). Discharges for the events computed using radar estimates directly are assumed to be the references against which discharges driven by the nowcast precipitation fields are compared. It manifested that the accuracy of QPN is especially critical in extending the lead time for the prediction of small basin discharges; QPN of high accuracy can extend the lead time to about 0.7 hours for the cases chosen in this study, and the extended lead time varies with specific rainfall processes and the hydrological characteristics of each basin.