The Lvzhu River Floor Simulation Based On HEC-RAS And GIS

China is one of the countries that most threatened by flood disasters in the world,especially serious in bobai area of Guangxi zhuang autonomous region.Thus,flood disaster once occurred,it's gonna cause huge economic loss and casualtiesWe are able to designated the inundation area,expected flooding situation,estimates of possible economic losses and number of affected population.locate the possible severely afflicted area such as Industrial base,transportation hub,military area,etc by forecast flood Through the technical method before the it coming,so that can provide relevant basis for government for government decision-making.Lvzhu River is a first level tributary of Nanliu River,flows from north to south,join the Nanliu River in the middle of Bobai town.In the down stream area of Lvzhu River not only located many Industrial and agricultural production facilities but also gathered a large population.Bobai town is under serious flood threat.So that simulate the rare flood of Lvzhu River has a quite important significance and practical application value.The development of GIS technology provides the possibility to simulate the flood.Through literature reading and relevant research of data consulting,the current simulation research on flood lacks the prediction of flood and the accuracy is limited due to the fact that most of the models regard water as static.Therefore,this study formulated a digital terrain model to build a model that fits the real terrain,and then reflected the prediction according to the flood calculation method of hydrology and hydrology engineering.Coupled model that conforms to the principle of hydraulics ensures the simulation precision and combines with GIS technology to conduct the flood evolution simulation research.The research includes the following works:1.Sums up the principle of the flood evolution simulation.Choosed the numerical simulation method combined with the hydrological model and geographic information system technology method as the research technique.2.Description the principles of the steady flow model and the unsteady flow.3.In order to establish a reliable terrin model,choosed the ZY-3 stereopairs extracted the DEM of Lvzhu River drainage basin,and then combination with the AW3D30 DSM data extract the cross sections.4.Extracted the rivernets,drainage area via Arcgis hydrology tool.Created one key extract river slope tool to extract river slope of Lvzhu River.5.Design and calculation the flood of Lvzhu River via flow data and rainstorm data.6.Establish the one dimension steady flow and two dimensional unsteady flow flood model to simulate the flood,got the inundated area and velocity profile.7.Make the summary and prospect of the research.This paper combined GIS technology,HEC-RAS,HEC-geo RAS simulated recurrence the flood interval of ten thousand years,thousand years and hundred year.The model computation showed that in a thousand-year frequency flood,the maximum depth of the water is 24.18 meters,the maximum velocity is 7.74m/s.in a hundred-year frequency flood,the maximum depth of the water is 23.49 meters,the maximum velocity is 7.3m/s.in a fifty-year frequency flood,the maximum depth of the water is 23.23 meters,the maximum velocity is 7.1m/s.Three cases could cause different levels of flood threat to the coastal villages,especially in the middle and downstream basins of the river basin.The results of two-dimensional unsteady flow show that the flood process is slow at the first and fast in the end in a thousand-year frequency flood,the mainstream and tributaries flood confluence,spread gradually after the flood flow in the green pearl river to converge,the flow rate to the whole process of the flood peak,finally out of the sink,diffusion drowning coastal settlements and many villages in downstream,then began to fade after 17 hours.Through the work and research of this article.Show that it's feasible use GIS technology to combine HEC-RAS model to simulate flood process.the result can provide the reference for river management,the flood warning,damage assessment,targeted layout of flood control measures,personnel evacuation plan.