Abstract: Study on flood characteristics and hydrological simulations are of great significance to flood control and disaster mitigation. According to the measured data of five experimental watersheds in Anhui Province, we analyze the characteristics of the floods in each watershed, and then simulate the floods in each watershed by using TOPMODEL to examine its applicability in flood forecasting in the monsoon region of east China. Our results reveal that the rainfall-runoff scatter points of floods in each experimental watershed all present a good positive correlation. The rainfall amount increases with the rising of elevation, and the runoff coefficients in mountainous area are greater than those in the plain and hilly area. The Wawuliu watershed which has the smallest area is the most sensitive to storms; the Suncun watershed features the smallest difference in the modulus of flood peak and the longest flood rising time; while the Huangshan watershed has the longest flood duration. The average value of watershed's topographic index gradually increases with the rising of altitude, while the value corresponding to the largest proportion drops. And the larger the standard deviation of the topographic index is, the more diversified land use types the watershed has. The TOPMODEL can generally reproduce the flood processes of each experimental watershed, and the captured results of large flows are better than those of small ones. The simulation of natural watersheds is better than that of human-disturbed watersheds.

Key words: flood characteristics, topographic index, experimental watersheds, TOPMODEL, flood simulations