Numerical Simulation Of 2D Coupling Hydrodynamic Model Of River Channel-flood Plain Two-dimensional And Its Application In Flood Risk Analysis

Due to serious soil erosion and severe deposition of the channel, flood characteristics has getting to flood peak in advance and greater flood volume in a short time interval, so that floods occurred frequently and caused a great loss of lives and property. Now our country is during the transition from flood control to flood management. Diverse mix of engineering measures and non-engineering measures will be relied on to cope with floods, and it is an irresistible trend in flood control and disaster prevention career development. Hydrodynamic simulation model was built to simulate flood routing in flood submerged area, the flood risk information of inundated depths, flow velocity, submerge period and arrival time were obtained, and flood risk maps were drawn, which has become an important part of non-engineering measures development.In the background that building an all-round flood control and disaster prevention non-engineering measures, several conclusions were obtained as follows:(1) The problem that complicated fluid state and hydraulic elements near dyke breaches could not be simulated well by various models was focused on, so that river channel-flood plain two-dimensional dynamic coupling numerical simulation model theory was proposed and the model was built.(2) River channel-flood plain two-dimensional dynamic coupling numerical model was optimized by numerous technical measures. For example: coupling river and dyke was realized by dyke broadening, weir flow equations of overflow and levee-breach, hot start and changed dyke shape treatment technology; model stability and computational efficiency was enhanced by dry depth and wet depth theory; structures’ influence for water flow movement was simulated by roughness partition method and real terrain method; river channels topography was restored through these data sets of remote-sensing image, DEM and measured river profiles.(3) Flood risk analysis methods, flood risk analysis and model test technology, impact assessment and risk aversion transfer technology and the flood risk mapping technology was researched. And technical theory support for flood risk calculation would be provided by all these technologies.(4) To meet the flood risk analysis demand of overflow during ice frozen-up and thaw, and levee-breach during flood season of Mongolia section of Yellow River, two-dimensional dynamic coupling numerical model was built in river channel and both sides irrigation area. So that overflow and levee-breach flood’ routing in irrigation area was simulated simultaneously, and flood risk maps were drawn.(5) To meet the risk analysis demand of river floodplain and dyke of Ningxia section of Yellow River, two-dimensional dynamic coupling numerical model was built in river and Qingtongxia eastern protected region of preventing flood. So that river flood free routing, overbank movement and levee-breach flood was simulated simultaneously, and flood risk maps were drawn.Complicated fluid state near dyke breaches and overflow location was considered in river channel-flood plain two-dimensional dynamic coupling numerical model built in the paper, which cover the shortage existed in the coupled one-dimensional and two-dimensional model. And two-dimensional overbank movement of wide but shallow river, overflow flood, levee-breach flood, and arbitrary combination of these could be simulated simultaneously. The research achievement would provide technical support for developing a roadmap of risk aversion transfer, evaluating flood disaster loss, and Flood control management decisions.