Numerical Simulation Of Small Watershed Floods In Island Areas Based On MIKE FLOOD

In recent years,with the global climate change and the rapid development of China’s urbanization,the frequency and intensity of flood disasters in China’s cities and the resulting national economic losses have been increasing.Compared with the relatively complete flood control planning and construction of big river watersheds,those of the small and medium-sized river watersheds are relatively weak,as it may cause more severe flooding disasters with common floods.In order to investigate the current situation of flood control in Zhujiajian Island,the one-dimensional river network model of MIKE 11,the two-dimensional hydrodynamic model MIKE 21 and the MIKE FLOOD coupling model are used to simulate the flood in small watersheds in the island area.The research results can provide technical support for flood control and land use planning.The main research contents and conclusions are shown as follows.(1)The characteristics of runoff yield and concentration of the small watershed in the island area are analyzed.The properties of flood disasters in the island areas are discussed and analyzed from the aspects of rainstorm characteristics,runoff yield and concentration characteristics,tidal effects and flood and waterlogging characteristics.(2)According to the basic data of the research area,the MIKE 11,MIKE 21 and MIKE FLOOD coupling models of the small island watershed are established and verified.(3)The flood disaster of Zhujiajian Island under different boundary conditions is simulated.According to the design rainfall,the design and check of the tide level,the gate dispatching scheme at the river estuary,and the initial river water level conditions,ten schemes are designed.The change of water level of the representativeriver cross-sections with time,the inundated water area and the inundated water depth at the time with relative high water level and the flood evolution process in key areas were simulated and analyzed.According to the simulation results,the disaster situation in the study area under different schemes was comprehensively evaluated.Among the ten schemes,the total inundated water area is above 19%,and the maximum inundated water depth in the key areas is above 0.6m.(4)Under certain conditions of precipitation,the nearshore tide level,the gate dispatching rules and the initial river water level affect the flood discharge of one-dimensional river channel and the overflow of two-dimensional flood plain,among which the tide level and the dispatching rules of the gate have outstanding influence.