Abstract: Based on observed data from the experimental watersheds of Chengxi (a hilly area) and Huangshan (a mountainous area) both in Anhui Province in the eastern monsoon region of China, the characteristics of flood events in watersheds with different geomorphic types are analyzed. A topography-based hydrological model (Topmodel) has been used to simulate the floods events, and its applicability to different geomorphic areas is discussed. The results show the runoff coefficients of Huangshan watershed are larger than those of Chengxi watershed on both annual and event scales. For the same weather process, the start time of flood rising in Chengxi watershed lags behind in Huangshan watershed, while flood duration is uncertain due to its multiple influencing factors such as area, slope, land use, river network distribution, etc. The average values of Nash-Sutcliffe efficiency coefficients calculated for both watersheds reach 0.77, and the average relative error of different simulation periods can be controlled within 14%. The applicability of the Topmodel to mountainous areas is better than to hilly areas.

Key words: eastern monsoon region, experimental watersheds, runoff coefficient, Topmodel, flood simulation