Study On The Optimization Of The Connectivity Scheme Of Jinhu Lake And Yangtze River And Its Water Environment Effect On Jinhu Lake In Zhijiang

In the context of global climate change and the increasingly severe situation of water resources,in order to improve the overall allocation of water resources,improve the health of rivers and lakes and enhance the ability to resist floods and droughts,the river and lake water system connectivity is put forward as a water control strategy in the new period of the country.The study means to develop a scientific and effective water system connectivity proposal to alleviate the contradiction between regional economic development and the uneven distribution of water resources and between the insufficient water supply and deterioration of water quality,improve the water ecological environment and the carrying capacity of water resources and water environment,and maintain the sustainable development of society,economy and ecology.In recent years,governments have provided a pioneer and practical reference for the ecological restoration of rivers and lakes in the vast area of the country.The inconsistency of water resources,insufficient water supply and deterioration of water quality,improving water ecological environment,improving the carrying capacity of water resources and water environment,maintaining social,economic and ecological sustainable development have important supporting role.Jinhu Lake is the largest landscape lake in Zhijiang and the existing water liquidity.The water environment problems such as poor,insufficient water and serious water quality are urgent to be solved.According to the current development situation,it is difficult to quickly realize the recovery and improvement of water quality by relying solely on the water purification capacity of Jinhu Lake itself.Therefore,a two-dimensional hydrodynamic water model is established for its own characteristics and current water diversion strips.The process of water replenishment is simulated to develop a comprehensive technology that integrates lake eutrophication treatment,water allocation and pollution prevention.Through the establishment of MIKE-21 hydrodynamic water quality model,the dynamic simulation of different diversion routes is carried out,the effect of water diversion in various dispatching modes is analyzed and compared,and the water supplement project of Jinhu Lake water environment is improved.The implementation of the project provides scientific basis for decision-making,and all kinds of thinking and exploration in the process of the project study will provide technical and theoretical reference for other similar water system connected engineering research,design and engineering implementation.In this paper,based on the data collected from the field of Jinhu Lake in the process of flood discharge(including topographic elevation,water level,flow field,water quality and hydrometeorology),based on the MIKE21 model system of the Danish hydrodynamic Research Institute(DHI),the water quality model board conforming to the characteristics of the ecological water supplement in Jinhu Lake is compiled and combined with the hydrodynamic module to construct the two-dimensional hydrodynamic in Jinhu Lake.The force water model is used to determine the parameters of the model and the simulation results by comparing the measured data with the verifying point.On this basis,4 kinds of feasible ecological water supplement schemes are set up,and the water dynamic water quality model has been built and simulated by the comprehensive analysis of the Jinhu Lake habitat improvement requirements and environmental laws and regulations.By contrast and analysis of different schemes to improve the water environment in Jinhu Lake area,a better scheme is screened out,so as to provide reference for efficient utilization and management of water resources in Jinhu Lake basin.Through the analysis of the current status and functional planning requirements of water resources in Jinhu Lake,Jinhu Lake is a landscape lake,under the premise of ensuring the safety of flood discharge,as far as possible to ensure that the lake has more water in the lake to meet the good landscape function.The flood control standard of Jinhu Lake is 50 years’ flood,and the highest water level can be 41.2 m in the lake in low water period.And the corresponding water supplement is 4.3 million m~3.The highest water level can be stored before flood season,that is,the flood limit water level is 40.5 m.The distribution of water resources in Jinhu Lake is not equal during the year.The water quality is poor and the water quality is not up to the standard in the whole year.The main excess factor is total nitrogen and total phosphorus.The main pollution comes from the use of chemical fertilizer in the surrounding farmland,the discharge of domestic sewage,the feeding of fish feed,the emission of industrial production,and the release of the pollutants in the sediment.By setting and simulating 4 kinds of ecological water supplement schemes,we can see that different ecological water supplement schemes have great difference in water quality improvement in different lake areas.Under the circumstances of objective conditions,it is suggested to adopt scheme three,that is,from the high irrigation canal of the Yangtze River to the West Drainage channel,and the average concentration of TP and TN in water body can reach type IV water standard when continue to supply water for 14 days at a flow rate of 5m~3/s.