| Dikes are traditional facilities for flood control and drainage in plain areas,with a long history and significant benefits.In the process of rapid urbanization,due to the lagging planning and management,the phenomenon of landfilling of rivers has been repeatedly forbidden.There are many broken rivers in the river system of the polder area,and the hydrodynamic conditions of the river network are poor,which has become an important reason for the poor water quality of the plain river network.Carrying out research on the improvement of hydropower in polder areas and implementing related projects is one of the key contents of comprehensive improvement of polder water environment.In this paper,the calculation method research and practical application of optimization design are carried out for the three river network hydrodynamic lifting schemes of gate-pump scheduling,river connection,and node optimization.Based on the digital processing of basic information such as channel length and crosssectional shape,the gate-pump opening rule is used as the boundary condition of the polder area,and the manning roughness coefficient of the channel is determined by manual trial and error method.At last,use the hydrodynamic module in Info Works ICM software to establish the hydrodynamic model of the river network.Using the average flow rate and effective flow length as indicators,through the sensitivity analysis of the model calculation results,determine the gate opening and closing scheme;establish a cost target optimization model,use the branch and bound method to solve,determine the pump opening and closing scheme;The ratio of the length of the backwater section(the flow section with a flow velocity lower than 0.005m/s)and the active water section(the flow section with a flow velocity greater than 0.1m/s)is the evaluation index.Through the calculation of the hydrodynamic model,the best gate-pump joint scheduling scheme is determined.According to three methods,the guillotine in the whole polder can be connected to the adjacent guillotine,to the adjacent river network nodes,and to the newly added nodes in the river channel.The proportion of the length of backwater and active water in the polder can be calculated and determined connectivity plan.Based on the condition that there are adjacent guillotines and the number of guillotines is large,the polder area is divided into several areas,the results of connectivity in each area are calculated first,and then the best solutions in each area are integrated to calculate the overall connectivity effect.According to the calculation results of the hydrodynamic model obtained by these two trial calculation methods,the best river connection scheme is determined.A method for calculating the hydrodynamic conditions of nodes in a complex river network system based on head loss.Through the calculation of the comprehensive water loss coefficient of the nodes,the nodes implementing the deep trough-shoal sequence are determined to improve the hydrodynamic conditions of these nodes.The research results of designing gate-pump scheduling and river connection scheme using hydrodynamic model and designing node optimization scheme using comprehensive water loss coefficient method will be implemented in the Wusongwei River Hydropower Project in Kunshan City.The best gate-pump scheduling scheme: the gate is opened for 2h every day,involving Mazhuanggang sluice,Qinglonggang sluice,Xijing flood control sluice and Youjing north sluice;the pump is opened 2.6h daily,involving Dayu South station and Gutang station,Jiuqugang station,Nanyu station,Xiyoujing station,Youjing south station;open the gate 0.5h after the pump is turned on.The best river connection plan: Yaojiagang area,Jiayulou area,Niuchebang area,Laoxiaoyuhe area,and Ganjinghe area are connected according to the local optimal plan,and the 8 guillotines outside the areas are connected to the adjacent newly added river nodes.19 nodes with large comprehensive water loss coefficient were selected to construct deep trough-shoal sequence. |
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