HEC-HMS Building And Application In Flood Forecasting Of Gongcheng River Basin

Guangxi is located in south China where is low latitudes area. It has complex geological structure and rich annual rainfall, that cause the mountain torrent disaster occurred frequently. Guangxi is the province which torrent disaster is serious in China. Therefore, to establish perfect mechanism of mountain torrent disaster early warning and forecast is the key and difficult point for mountain torrent disaster prevention.This study chose Gongcheng River basin as the research object and collected five precipitation stations’data of rainfall and runoff data of Gongcheng station. This study also analyzed the rainfall and runoff characteristics of Gongcheng River basin and collect the storm characteristic value in each period of mountain torrent disaster events and analyzed the causes and the characteristics of mountain flood disasters in the basin and calculated single critical rainfall and regional critical rainfall. The critical rainfall can be the warning index when the forecasting model has not been established. Also, this paper comparing and analysing the advantages and disadvantages of two calculation methods.Based on digital elevation model of Gongcheng River basin and GIS platform, this study built mountain torrent disaster flood forecasting model and extracted the river network and sub basin and other digital watershed information of Gongcheng River basin. Collecting the basin’s information such as the landuse type and soil type and using HEC-HMS hydrological model to build basin model. Respectively, used first scheme:initial and constant loss, Snyder unit hydrograph, recession, Muskingum and second scheme:SCS curver number, SCS unit hydrograph, recession, Muskingum to simulate rainfall-funoff process of Gongcheng River basin. The simulation results show that in both method the accuracy of peak flow, runoff depth, lag time and DC number, the first scheme is slightly higher than the second. Both schemes meet the requirements of the forecasting rules. The results also show that HEC-HMS hydrological model is suitable for forecasting mountain torrent disaster of Gongcheng River basin, it can be applied in practical work. Finally, this study summaried and analyzed the influence factors of mountain flood forecasting accuracy and put forword further research train of thought and ideas in the future.