Flood Evolution Numerical Simulation Research On Flood Hazard Mapping

Flood disaster is one of natural disaster frequently occurring in China. The human's life and safety are seriously threatened and its smooth will restrict social development of economy. In order to defend the flood and reduce flood disaster loss, we need take a series of measures for disaster reduction. Flood hazard map is an essential tool and basis for flood management. Flood hazard mapping should have reliably data, scientific method, establishing a reliable and high- efficient model. Through the research on numerical simulation techniques in flood hazard mapping in this paper, the key techniques in flood hazard mapping are presented. Advanced method and practice in flood risk analysis, flood risk assessment as well as flood hazard mapping adopted internationally are introduced.Researchers have been carried on the following aspects: 1) Flood risk calculation is the core content of flood hazard mapping, Flood risk analysis and calculation are researched by hydraulic method, establishing one-dimensional flood-routing model of the river channel is the basis of flood risk analysis and calculation, 2) Roughness is the most important parameter of the one-dimensional hydraulic model, to influencing factors of roughness is very complexity,and it's difficult to determined what the roughness is, according to the simulation results of the historical flood, determined the roughness on the different discharge levels, 3) To different frequency of flood have different degree of damage to the dike for flood hazard mapping, while the position and the range of the risk of the dike is difficult to confirm, establish one-dimensional flood-routing model of the river channel, According to simulation results, through comparing elevation of embankment top and water level of simulation, and divided the grade of the risk, prediction and analysis of risk on the left dike based on the results, 4) The design of the breach geometry changing with the time, is the most important factor to effect on the result of two-dimensional submerged simulation, the dike will break caused by earth dike overtopping, establishing dambreak model reasonably, will provide reliable data and upper boundary for two dimensions flood routing.