Research On Reservoir Group Real-time Operation And Multi-objective Scheme Evaluation In Xijiang River Basin Based On Repelling Saltwater Intrusion And Replenishing Fresh Water

With the social and economic development of the Pearl River basin,water demand in the Pearl River basin has gradually increased.Increasing water demand,uneven spatial and temporal distribution of water resources and low water supply during the dry season have led to the upsurge of salty tide in the lower reaches of the river basin in recent years,and the intrusion of salty tide has intensified.This seriously threatens water supply security in the lower reaches of the Pearl River.Reasonable reservoir group operation is an important way to ensure that there is sufficient water in the basin to repel saltwater intrusion and replenish fresh water,and ensure the safety of urban water supply.In this paper,the Xi jiang River.the main steam of the Pearl River,is taken as the research area.By considering factors such as resistance to saltwater intrusion,ecology,shipping,and power generation,an operational model is established to conduct research on real-time operation of reservoir group and scheme evaluation.The research results can provide reference for the realization of unified water management in the basin,the utilization of the comprehensive utilization benefit of the reservoir group,and actively respond to crises such as salty tides,and provide support for ensuring the safety of water supply in the basin.The main results obtained in this paper are as follows:(1)Based on Akaike information criterion and minimum sum of squares deviations criterion,the Frank copula function of the main and tributary where the Xijiang key reservoirs is located is constructed,and the probability of wetness-dryness encountering is calculated.The results show that the higher synchronization is reflected in the inflow of the main and tributaries of the Xijiang River basin,and extreme wetness-dryness encountering rarely occur in the basin.(2)The Xijiang reservoir group real-time simulation model is established.Based on the method of randomly generating outflow,the reservoir group operation schemes under different scenarios are obtained through simulation.Furthermore the range of the end water level of the key reservoir operation is obtained and the change law of the end water level of the reservoir group with total power generation is revealed.(3)Considering the water supply of reservoir group to repel saltwater intrusion,the Xijiang reservoir group real-time optimization operation model is established with the objective of maximizing the total power generation.The real-time optimization operation model is solved by flower pollination algorithm,and the operation scheme with the largest total power generation is obtained.According to the simulation results,the transmission law of the water shortage risk that repels saltwater intrusion is revealed,and the replenishment sequence and operation mode of reservoir groups are clarified.(4)The Xijiang reservoir group real-time multi-objective optimization operation model is established,and solved by improved NSGA-Ⅱ algorithm.Then,a multi-objective Pareto front curve and a set of feasible multi-objective optimized operation schemes are obtained,and the competitive relationship between the total power generation and the level of the basin to repel saltwater intrusion is clarified based on the results.(5)Based on the non-inferior solution set of the multi-objective optimization operation schemas,an evaluation index system of operation schemes is established,and the evaluation indexes are weighted with comprehensive weights.Evaluation models are established by grey comprehensive evaluation model,technique for order preference by similarity to ideal solution model,projection pursuit model and non-negative matrix factorization model.Finally,the optimal multi-objective optimization operation scheme is selected through the evaluation of the operation schemes.