Study On Flood Routing Method Of Nierji-Dalai River

River flood forecasting is an important basis for decision-making of flood control,and plays a vital role in flood control and disaster reduction.However,due to the influence of human activities and the flooding of large floods,the runoff data and hydrological data of the river channel change,there is an inconsistency,which brings difficulties to the river flood forecast and reduces the river flood forecasting accuracy.Based on the analysis of river geography and flood data,this paper divides the study river into Nierji-Jiangqiao and Jiangqiao-Dalai two parts,and uses the segmented Muskingum flood algorithm and MIKE11 one-dimensional hydrodynamic model,and the river flood loss coefficient is introduced.The flooding model of Nenjiang River is studied by comparing the calculation process of historical flood with the measured process in order to improve the river flood forecasting accuracy in Nierji-Daji section of Nenjiang.Readers provide reference.The research contents and achievements of this thesis are as follows:(1)Through the study of regional geography and analysis of flood data from 1957 to 2013,it is found that there is water imbalance in the Jiangqiao-Dalai reach of the riverbank,so divide the Nierji-Dalai rive into Nierji-Jiangqiao and Jiangqiao-Dala two part,to study the characteristics of the two part of the river channel flood routing using hydrology method and hydraulic method.(2)Base on the piecewise Muskingum flood algorithm,the evolution of river flood in Nierji-Dalai reach.First of all,according to the the problem of water imbalance,establish the traditional segmented Muskingum flood routing model and the improved segmented Muskingum flood routing considering the imbalance of water;and then,set different parameters according to the level of the historical floods,using the particle swarm optimization algorithm combined with artificial experience to optimize the parameters of the routing models,and to study on the characteristics of river Flood in River and flood Loss of Jiangqiao-Daji river channel.The simulation results show that the simulated flood process is highly fitting with the measured flood process,and the applicability of the model is strong;at the same time,the parameter rate results of the improved segmented Muskingum flood routing model show that the characteristics of river flood Propagation in the Jiangqiao-Dalai river change after 1998,and with the increase of flood level,the proportion of river flood loss is reduced.(3)Based on MIKE11 one-dimensional hydrodynamic model,the evolution of river flood in Nierji-Dalaihe reach.Firstly,the one-dimensional hydrodynamic model of the Nierji-Jiangqiao reach and the Jiangqiao-Dalai reach is established by combining the DEM data,section data and tributary characteristics of the river basin;then,according to simulate the historical flood of 1957 to 2013,study the change of the riverbed roughness by comparing the results of the model parameters.The simulation results show that the floods in 1998 are seriously affected the Nierji-Dalai River,and the river bed roughness values in 1998 are no longer applicable to the river after 1998,and according to the results of the model parameters,it can be seen that after 1998,the river bed roughness becomes smaller and the river flood propagation speed is accelerated.(4)Comparative analysis of the results of the two models and case application analysis.First of all,according to the model principle,establishment and the data required of segmented Muskingum flood routing model and MIKE11 model,analysis the applicability of the two models;then,analysis and compare the simulate results of two models,which show that for the big flood two models have high and strong applicability,but for the small flood,because of considering the terrain characteristics,the simulation results of MIKE11 onedimensional hydrodynamic model is better.Finally,apply two models to the flood in 2013,and verify the applicability of the two models.Based on the above research,this paper not only make up the original river basin flood forecasting project,considering the characteristics of flood evolution process,but also studies the river terrain changes after 1998,and the influence of river topography change on river flood routing,provides an important reference for the Nenjiang River flood control.