The Assessment Of Flood Damage Loss Based On HEC-RAS And GIS

China is a country which has extremely serious flood disasters. For he high dam, once occurred across the dam flood, it will cause serious losses of lives and property of the downstream. Therefore, the simulation of the flood evolution has extremely important practical significance. Five aspect contents are included in this paper as following:First, it summarizes the development history of flood routing simulation system and introduces the methods of historical flood method, hydrological model method, hydraulic method and numerical simulation. And it compares and analyzes the advantages and disadvantages of these methods and then selects the method of hydraulic model which is combining with the GIS as the numerical simulation method.Second, HEC-RAS is widely applied in the flood calculation. This paper shows the principle of the steady flow and unsteady flow.Third, this paper introduces the technical route of the simulation of the flood evolution. The simulation of the flood evolution needs the topographic data, hydrologic data, channel roughness and so on. So, this paper firstly processes the DEM data of the study area using the Google Earth and HEC-GeoRAS and generates a file. Secondly, importing the file into the HEC-RAS, checking the section numbers and positions whether meets the requirement, if not satisfied, returning to former processing steps, importing the new file into the HEC-RAS again and completing the hydraulic structures geometric data such as bridges and wires. Thirdly, adding the boundary condition into the HEC-RAS and having numerical calculation, and generating the file which meets the HEC-GeoRAS. Lastly, importing the file into the HEC-GeoRAS to generate the flooding area map and flow velocity distribution map.Fourth, Changheba hydropower station is selected as a research object. The flooding area of Luding country caused by the overtopping floods of the Changheba hydropower station dam and its downstream Huangjiaping dam and Luding dam is analyzed in this paper. The analysis results can provide a technical support for the production of a flood risk chart and for flood control decision.Fifth, make the assessment of flood damage loss for Luding County.