Analysis Of Dam Break Flood Evolution Based On GIS Technology

According to the files of "National medium and long term science and technology development plan (2006-2020) ", public safety is an important field of scientific research,attention to the handling of public emergencies and early warning work. Due to the improper design or construction of the dam, hidden danger in a certain extent will lead to the occurrence of dam break. In addition, as the deluge earthquakes, war, terrorist attacks and other force majeure and sabotage may also lead to the occurrence of dam break. When the dam break occurs, the flood evolution involves a wide range. Once the dam break occurs, it will cause huge losses to the agriculture, industry and construction of the downstream population protection area. Therefore, the simulation of dam break and the analysis of flood evolution play an important role in flood control and disaster reduction. This paper discusses key issues in simulation of dam break and basic methods, focuses on dealing with the 2-D flood breach formulation, the breach flow, flow rate, process validation, boundary conditions etc.One of the most important work is to determine the evolution of dam break flood breach flow process. however, the breach flow is unsteady process of graded flow, by the influence of many factors, such as breach shape, flood discharge process, the shape of the bottom of the river valley,slope,relative burst of upstream and downstream water level etc. Based on the summary of scholars’ formula,MIKE21 FM of the breach, flow process was simulated,and the results were compared with the empirical formula. The results that the flow calculation formula according to the weir dam breach flow process, is more safe and reliable.The flood evolution process is affected by the topography and buildings, there are some special characteristics of flood evolution in different regions. This paper will use the method of dam break flood and numerical simulation of flood routing to Shiquan Hydropower Station dam break analysis. According to the present situation of Shiquan dam, to draw up the break position,break shape, break timing and the bottom elevation, and determine the dam break working condition. The generalization of GIS (Arcgis and GPS) elevation of the proposed reservoir area river, the simulation area determination and correction by the measured terrain map and DEM map, create a MIKE21 two-dimensional model; using SMS hit the grid to the simulation area,inspection of sparse grids of the evolution of independence. Due to the design flood of different frequency calculates discharge of dam breach when the failure occurred. Draw the results of model flood calculation and analyze the process of simulating flood evolution, and the flood level, flood range, flood velocity distribution, flood velocity vector distribution and flood depth are analyzed. To analyze the characteristics of curve parts, Mountain streams rushing flood characteristics and location of severe breach not far downstream of Shiquan County area. The results show that the bending and cutting of the river channel in the mountainous area have a significant impact on the flood evolution process.