Research And Application On Joint Flood Control Operation Of Large-scale Reservoir Groups In The Middle And Upper Yangtze River

Since ancient times,flood disasters have been the natural disaster with the most frequents,the most severe losses,the largest number of people affected,and the widest impact in our country.The Yangtze River Basin has many main and tributary streams and complex relations between rivers and lakes.The special monsoon climate causes precipitation to be mainly concentrated in summer and heavy rains are frequent.The contradiction between huge inflow of water during flood season and limited river discharge capacity is very prominent,leading to flood disasters.Frequent occurrences have caused great harm to the safety of lives and property of people.With the continuous planning,construction and improvement of the river basin flood control system,the large-scale reservoir groups in the world has been built in the upper reaches of the Yangtze River.Its huge flood control storage capacity can effectively block floods,shift flood peaks,and greatly reduce the flood protection pressureof the urban agglomerations along the line and important flood control.However,due to the complex topological structure of the basin,the diverse flood encounter combinations,the close coupling of hydraulic relationships,the large scale of the reservoir group,the different ownership of the owners,the different operation objectives,the large number of flood control points,and the complex time and space high-dimensional characteristics,it has brought great challenges to the modeling and solution of the reservoir group.At present,a complete set of joint flood control operation rules and plans of the basin has not been established,which limits the full use of the flood control potential of the reservoir groups.Therefore,this article aims to reduce the overall flood control pressure,and focuses on the scientific problems and technical bottlenecks faced in the joint flood control operation under the new situation,and analyzes the characteristics of storm floods and flood control needs in the river basin.On this basis,the use of layered research strategies has carried out in depth research on watershed land-atmosphere coupled runoff forecasting,reservoir groups joint flood control optimal operation modeling and solution,conventional operation rules and risk management,and river basin flood control operation system integrated development.(1)The basic data of the main and tributary water systems of the upper reaches of the Yangtze River are collected,and the characteristics of rainstorms and floods in the basin are analyzed;secondly,the overall flood control system consisting of engineering measures and non-engineering measures is sorted out,and the flood control capabilities and flood control needs of each flood protection object The flood control situation,main contradictions and key challenges of the river basin have been analyzed level by level.With the Three Gorges Reservoir as the core and other main and tributary reservoirs as the core,the flood control regulation principles have been determined;In addition,the overall design flood controlled by Lizhuang,Zhutuo,Cuntan,Yichang and Luoshan was derived.The overall design flood controlled by Heluoshan is calculated,And as input data for reservoir group operation modeling and solving.The research work provides strong data support and decision-making basis for the joint flood control operation of large-scale reservoir groups in the upper reaches of the Yangtze River.(2)Aiming at the problem that runoff forecasting cannot meet the application requirements,the WRF model numerical precipitation forecasting system is introduced,and the multi-attribute decision-making method is used to screen out the optimal combination of models;on the other hand,the interval is constructed Short-term runoff forecast model library for key sections,and realized multi-objective calibration of model parameters and real-time correction of forecast errors;further,using forecast precipitation data to drive hydrological models,a set of adaptive land-atmosphere coupled runoff forecasting system was developed for Xiluodu?Yichang The interval provides high-precision and longforeseeing runoff forecasts.The results show that the WRF model can basically grasp the spatial distribution and rainfall level of the measured precipitation,and give precipitation forecast for the high-precision runoff forecast of the river basin;the multi-target parameter calibration and real-time correction method can more comprehensively describe the runoff characteristics of the river basin.Improve the accuracy of river basin runoff forecasting;compared to non-rainfall simulation forecasts,land-atmosphere coupled forecasting can better simulate the flood process trend and peak present time,especially for flood peak forecasting accuracy,which is important for flood control and dispatching of reservoir groups in the basin significance.(3)Focusing on the current large-scale reservoir group joint flood control optimization operation modeling and solving the many challenges facing,on the basis of considering the flood channel evolution,the reservoir groups joint flood control multi-objective optimization operation model was constructed.the advantages of each algorithm were combined,and the DP-POA-PSO hybrid optimization algorithm and improved strategy realizes the efficient solution of the operation model.In addition,a step-by-step research strategy was adopted to successively carry out joint flood control optimal operation with the largest remaining flood control storage capacity in the Chuanjiang section,the smallest sum of squares of the Three Gorges reservoir inflow,and the lowest flood level of the Three Gorges.The influence of different dispatching strategies on key flood control indicators is analyzed.The results show that the established operation model has strong flexibility and adaptability,and can fully reflect the real operation scenarios of the river basin.Compared with traditional optimization algorithms,the improved hybrid optimization algorithm has obvious advantages in key indicators such as convergence,calculation speed,and optimization effect;the use of the dispatch strategy of the highest flood level of the Three Gorges and the lowest flood control system can coordinate the flood control system of the upper reaches of the Yangtze River and give full play to the flood control and dispatch potential of the reservoirs.The highest flood level of the Three Gorges Reservoir has been reduced by an average of 13.56 m,and The flood control situation in the middle and lower reaches of the Yangtze River has been significantly improved.(4)Aiming at the problem that the optimal operation is difficult to be applied to the actual flood control of the project,the optimization extraction model of conventional operation rules with the result of the joint flood operation as input is constructed,the MOSCDE algorithm and the TOPSIS decision-making method are used to achieve model solution and scheme optimization,and are applied to the extraction of joint flood control rules for the upper reaches of the Yangtze River.The results show that compared with the current plan,the researched and formulated operation rule parameters have obvious advantages in various operation indicators;The eighth option,which is optimized through the optimal operation results of multiple typical design floods,can coordinate various incoming water conditions and achieve the overall optimal flood control operation effect;Risk control operation can effectively avoid the risk of flood control points breaking flood control standards,and improve the redundancy of flood control operate in the basin.The model method proposed in the study has significantly improved the joint flood control and operation level of the upper reaches of the Yangtze River,and has high engineering application value.(5)Focusing on the current hot issues of water conservancy informatization research and application,Exploring the technical means to realize the development and application of the information system of flood control operation in the river basin.The work flow of flood control operation was sorted out,the business requirements and related functions of the system were clarified,the professional model library for service-oriented packaging was developed,and the efficient decoupling of model services was realized,Reuse and interaction,the system software and hardware structure that meets the application requirements is designed,the appropriate front-end,back-end,and data development architecture are selected,and then the relevant research results of forecasting,operation and rules in this article are integrated,and a set of suitable river basin operation and management needs is developed.The integrated information system of the Three Gorges Project is deployed and operated in the cascade operation communication center of the Three Gorges Project.