Hydraulic Forecasting Of Flash Floods In The Earthquake-Afflicted Area

Flash flood disaster is one of the most serious and the most frequent naturaldisasters in the mountain.area in our country. It is a serious threat to the safety of lifeand property of the people. It affects the healthy and stable development of thenational economy and people’s lives. At the same time, there are other secondarymountain disasters along with the earthquake of flood disasters, further exacerbatingthe degree of hazards. It is a serious impediment to the effective implementation ofdisaster recovery and reconstruction work. So flash flood disaster is the bottleneckof sustainable mountain development.The flash flood disasters hydraulic forecasting technology research canestablish a scientific and effective forecasting system. It can improve forecastingaccuracy, and the timely warning information issue, provided measures in preventionand reduction of disasters, select the withdrawal and significance avoidance routesand safe resettlement sites scientifically, develop disaster prevention and mitigationplan for government departments. It plays an active role in promoting localeconomic and social development.In this paper, Hydrologic model are constructed, different rate(P=20%,10%,5%,3.3%,2%,1%,0.5%,0.2%) storm-rain and corresponding floodmodel are designed. Using HEC-HMS to analogue flow rate, and using hydrologicmanual of SiChuan province to verify the discharge. Then using HEC-GeoRAS,HEC-RAS model to simulate the different rate of and design evolution of floodsituation(P=20%、10%、5%、3.3%、2%、1%、0.5%、0.2%).Through the analysis and discuss, the conclusions of this paper are as follows:1. To get the first hand data by the way of field observation and investigation,and it can get the results by data processing and analyzing by using3S technology.The relative height difference reach1833m in study area, and it is a typical alpineravines and area rich in precipitation. It average annual monsoon rainfall reached565m, and geotechnical structure broken. It offers topography、rainfall and materialconditions for debris flow hazards in the mountain area and get high occur for it.2. It realizes the simulation of rainfall runoff process in study area byHEC-HMS model, and using different method to simulate the basin precipitation、overland runoff and river confluence process. And formed with different rainstorm frequency(P=20%、10%、5%、3.3%、2%、1%、0.5%、0.2%) under the process ofrunoff and flood process simulation. And through the Sichuan hydrologic handbookverification, that using HEC-HMS model can relatively accurately simulated rainfallrunoff process, overcome the small watershed within data, such as lack ofdifficulties.3:Realizing the flood evolution process of study area by HEC-RAS model, andget different frequency (P=20%、10%、5%、3.3%、2%、1%、0.5%、0.2%). Designingthe parameter of floods in the trip.(1) the maximum elevation of each section of thewater line in the design frequency (2) the water line within the channel (3) thehydrological parameters of each channel section (4) the flooding of the scope andresults, and all the results accords with the situation.Through using HEC-HMS and HEC-RAS model, realize the simulation of floodevolution under different rainfall frequency and flood forecasting, and prove thepracticality of earthquake flood hydrologic forecast technology based on HECmodel.This study provides a useful exploration for the study of flash flood disastershydraulic forecasting technology in earthquake area, the study results iscomparatively reasonable which can offer some reference for the early informationissue of disaster prevention,formulate personnel evacuation plan and flash flood riskassessment...