Abstract: In an attempt to overcome the difficulty of forecasting rainstorm flood in small watershed, the forecasting accuracy and applicability of FFMS model and HEC-HMS model were compared. FFMS stands for Flash Flood Module Simulation System, and HEC-HMS represents Hydrologic Engineering Center Hydrological Model System. The relative error of flood peak, the relative error of the peak time, and the Nash coefficient were selected as evaluation criteria for the comparison. Luanchuan and Hancheng watersheds in Henan Province as well as Haojiadian and Lipiyu watersheds in Liaoning Province were taken as case study. Verification results demonstrate that both models are applicable in forecasting storm floods in small watersheds; however, according to the results of the aforementioned three evaluation criteria, the prediction accuracy of FFMS model is better than that of HEC-HMS model. The research finding proves the validity and feasibility of FFMS model in rainstorm and flood forecasting in small watersheds of hilly areas, and can be popularized and applied in similar hilly areas.

Key words: flood forecasting, FFMS model, HEC-HMS model, small watershed in hilly area, forecasting accuracy