Flood Simulation And Risk Analysis In The Main Urban Area Of Shangli County Based On MIKE

Shangli County is located in the west of Jiangxi Province and has a mid-subtropical monsoon climate.Affected by the monsoon,heavy rains frequently occur in summer,and the territory is dominated by hills and mountains,and the terrain is low.Once floods occur,they will pose a serious threat to the lives of people in the main urban area.The current response to flood threats mainly relies on engineering measures and non-engineering measures.However,engineering measures are expensive and pollute the environment,which are not conducive to large-scale use,which makes it necessary to adopt non-engineering measures.As one of the non-engineering measures,the flood risk map can provide timely and effective information such as risk avoidance transfer and disaster estimation when Shangli County is facing floods,and can provide direct help for the flood prevention and mitigation work in Shangli County.In this paper,combined with the hydrological characteristics of Shangli County,a numerical simulation of the flood evolution of Lishui River is carried out to show the changes of floods in time and space.Analyze the results of flood simulation,and obtain information such as flood inundation range and water depth.The specific method is:use the MIKE11 hydrodynamic model to establish a one-dimensional model of the Lishui main channel,use the flow,water level,and flood mark data measured in 2019 to calibrate the model,and simulate the evolution of the river in 5,10,and 20 years,respectively Process;use the MIKE21 model to establish a two-dimensional model of the watershed;use the MIKE FLOOD model to laterally couple the one-dimensional and two-dimensional models to simulate the evolution process of floods of different frequencies from overflowing the river to the shore;use the ARCMAP software to compare the simulation results with Integrate geographic information to obtain flood disaster information and draw flood risk maps and transfer maps.The conclusions are as follows:(1)The river course of the one-dimensional model is generalized to 9500km,and the one-dimensional river model is continuously debugged,and the roughness of the river course is obtained as follows:Fuling Village-Caichang Village’s roughness is 0.04-0.041;Caichang Village-The roughness of the entrance of the room is 0.038-0.04;the roughness of the entrance of the room-Shuangbanzhou is 0.038-0.04;the roughness of the entrance of Shuangbanzhou-Shuiyuan is 0.03-0.04.(2)Using the model calibrated with the data of 2019,the simulation results are compared with the actual survey of inundation in2019,which shows that the simulation results are in line with reality.For example,the maximum water level of the Lishui River is simulated from upstream and downstream.It is 90.4m in Foling Village,87.1m in Caichang Village,86.24m in Xinmin Village,84.18m in Shuangbanzhou Water,and the actual measured water level difference is-011m,-0.13m,+0.04m,+0.07m,less than 0.2 m is in line with the basic laws of the river course,and as the magnitude of the flood continues to increase,the simulated maximum water level and flood peak of the corresponding river section also become higher(larger)in turn.(3)Generalize the research area of 14.1km~2,and use the tool of MIKE21 to divide the model range,which is divided into 12945 irregular triangles.The area of each triangle is between 30km~2 and 5967km~2.The maximum area of the triangle in the unencrypted area shall not exceed 5000m2.(4)The Mike Flood model is simulated,and the inundation areas of the once-in-five,once-in-ten,and once-in-20-year floods are 3.7km~2,4.94km~2,and 5.53km~2,respectively,of which Li Town and Jinshan Town are the main flood disaster areas.;The simulation shows that the maximum flow at the outlet is 497.57m~3/s,803.67m~3/s,and 982.77m~3/s;the simulation shows that the maximum flooding depth is 4.26m,5.77m,and 5.93m.