| The scientific simulation of the formation and routing of flood is the basic work of planning construction and flood management of lake basin.Nansi lake is the largest freshwater lake of northern China with a surface area of 1266km2 and a catchment area of 31700 km2.Nansi lake consists of Nanyang lake,Dushan lake,Zhaoyang lake and Weishan lake.The lake is narrow and long,the terrain is complex,the inflows are numerous(as many as 53),flood of the lake rise up quickly and fall off difficultly,and local area of Nansi lake basin frequently appeared flood disaster.Threatened by climate change and human activities,extreme hydrological disasters have become more frequent and have changed the flood pattern and mechanism of disaster in the lake basin.Establishing a overall flood simulation model of Nansi lake basin of both sufficient precision and efficiency which considered complex changes in the external environment and then revealing the formation and routing process of flood is a key technology problem that needs to be solved in flood control planning in recent years.On the basis of previous studies,The paper puts forward "three-lake and two-river" flood routing model of Nansi lake based on fourth-order Runge-Kutta method,and then establishs a overall flood simulation model of Nansi lake basin by coupling the flood routing model with the distributed hydrological model of all river basins in Nansi lake basin based on ArcSWAT.Analyzing the influence of related engineering construction on peak value of water level and the influence of land use change on flood process of the basin and peak value of water level of Nansi lake based on established models.Finally,the paper proposes some suggestions for planning construction and flood management of Nansi lake basin.The main results of the paper are shown as follows:(1)Development of "three-lake and two-river" flood routing numerical model of Nansi lake.The paper uses fourth-order Runge-Kutta method to improve the model revolutionarily based on the idea that flood of Nansi lake were generalized to "three lakes" and "two rivers" in the 1960s and "three-lake and two-river" flood routing model with auxiliary curve method.The comparative results show that the improved flood routing model is superior to the traditional auxiliary curve method in calculating precision,flexibility and efficiency.(2)Study on the influence of the change of engineering construction on the peak value of water level of Nansi lake.Based on the results of "three-lake and two-river" flood routing numerical model of Nansi lake,the paper analyzes the influence of the change of some engineering construction such as drainage modulus and the stage-discharge relation of Hanzhuang sluice on peak value of water level of Nansi lake,and then puts forward some suggestions for the treatment of flood control of Nansi lake.(3)Establishment of the distributed hydrological model of all river basins in Nansi lake basin based on ArcSWAT.The paper selects Si river basin as the typical basin of east of Nansi lake basin and Zhuzhaoxin river basin as the typical basin of west of Nansi lake and then analyzes them comprehensively.The verification results show that both of them can meet the precision requirement of runoff simulation.The parameters of the typical river basin models after calibration and verification are extended to other river basins in Nansi lake basin,and the distributed hydrological model of all river basins in Nansi lake basin are established.(4)The paper establishs the overall flood simulation model of Nansi lake basin by coupling the "three-lake and two-river" flood routing numerical model with the distributed hydrological model of all river basins in Nansi lake basin and then analyzes the influence of land use change on flood process of the basin and peak value of water level of Nansi lake and finally puts forward some suggestions on the flood management in Nansi lake basin,such as controlling the development speed of urbanization and carrying out the return of farmland(mainly in east of Nansi lake basin). |
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