The rainfallrunoff model TOPMODEL (TOPography based hydrological MODEL) is use d to simulate the hourly runoffs for Wenquan catchment (984km2) in Kaixian, Ch ongqing Municipality. The performance of TOPMODEL in the study area is addressed based on the rain gauge observations and 08:00 BST runoff data. It mani fests that the TOPMODEL performed well in the study catchment, and the Nash and Sucliffe efficiency criterion is 0.872 when calculated with 08:00 BST runoff dat a. Since the method is simple and the data are easily obtained, th is presentation is one of the foundational studies for the developments in the u se of rain gauge observations and radar rainfall estimates for flash flood analy sis and forecast.