Research And Application Of HEC-HMS For : Flood Forecasting In Small Watershed

The establishment of flood warning system by small watershed hydrological model is of great significance for flood control and disaster reduction.Based on GIS platform,HEC-DSSvue calculation software and HEC-HMS model,the HEC-HMS flood prediction model of the research area was established in this paper,which was based on the watershed of wangjiahui hydrological station in Xinzhou city,Shanxi Province and the watershed of louchen hydrological station in Taiyuan city.The main research contents and results are as follows:(1)Collected the rainfall data of 8 rain stations in the Wangjiahui river watershed,the flow data of the Wangjiahui hydrological station from 1958 to2014,the rainfall data of 4 rain stations in the Loufan river watershed,the flow data of the Loufan hydrological station from 1995 to 2017,and the DEM(digital elevation model),land use and soil type data of the two watershed;Based on GIS platform,hydrologic analysis was carried out on DEM of two watershed,such as river network extraction and sub-watershed division,and the weight of sub-watershed was calculated by Tyson polygon method.SCS-CN method,SCS unit line method,Exponential recession method and Muskingum method provided by HEC-HMS model were used to calculate the runoff yield,direct runoff,base flow and river confluence,respectively,so as to construct the flood prediction model for the basins of Wangjiahui and Loufan hydrology stations.(2)According to the "Specification for hydrological information and forecast" the results of the flood simulation are compared and analyzed.The simulation results show that: Among the 25 floods in the watershed of Wangjiahui hydrothermal station,10 of the 13 floods were qualified regularly,and the qualified rate was 76.92%,in the calibration period;9 of the 12 floods were qualified regularly,and the qualified rate was 75.00%,in the validation period,all of which reached the accuracy of class B.Among the 25 floods in Loufan river watershed,10 of the 13 floods were qualified regularly,and the qualified rate was 76.92%,in the calibration period;10 of the 12 floods were qualified regularly,and the qualified rate was 83.33%,in the validation period,all of which reached the accuracy of class B.The results show that the applicability of HEC-HMS model in the two study areas is good and the applicability of small floods is better.(3)In the artificial method and the automatic optimization of HEC-HMS on seven parameters in the model to participate in the process of discovery: CN value,Lagtime,storage constant K and peak ratio R are the main parameters that affect the simulation results.CN value is the most sensitive parameters,and is positively related with flood peak discharge and runoff depth.The second sensitive parameters Lagtime and storage K are negatively related with flood peak discharge and runoff depth.