Evaluation Of Water Ecological Carrying Capacity Of Xiangjiang Changsha Comprehensive Hub Based On System Simulation Method

Chang sha Zhuzhou and Xiangtan river section of Xiangjiang river has changed from natural runoff to regulatory runoff after Xiangjiang changsha integrated hub operation which brings a lot of benefits for Changsha Zhuzhou and Xiangtan urban agglomeration.Its hydrological characteristics has changed,and the internal structure of water ecosystem changes accordingly.Xiangjiang Changsha comprehensive hinge reservoir area is an important economic development zone.Water resources supply contradiction and water environment pollution are increasingly prominent with the continuous development of economy and society.At present the research of water ecological carrying capacity has closely linked the human activity characteristics with the development of water ecosystem.It is helpful to study the carrying capacity and changing trend of water ecosystem in reservoir area for protecting the reservoir environment,promoting the healthy development of water ecosystem and promoting a sustainable lifestyle in society.This study is based on the Xiangjiang changsha comprehensive hub reservoir area and the SD model was built to simulate the operation of the water ecosystem in the reservoir area using the system dynamics method.The water ecological bearing capacity of reservoir area is evaluated using quantitative method.Then extract the reason for the key variables inVensim software and the decision variables and evaluation indexes are selected and different development schemes are established.Three typical years were selected,and the water ecological carrying capacity of different schemes was evaluated using Close-value method method.And explore ways to improve the ecological capacity of the reservoir area.The main conclusions are as follows:(1)The level of water ecological carrying capacity in the reservoir area is decreasing,the decline was evident from 2006 to 2013,and the level of water ecological carrying capacity in the reservoir area from is basically loadable from 2006 to 2009,and the level of water ecological carrying capacity in the reservoir area is weak after 2009.the level of water ecological carrying capacity in the reservoir area has decreased from 2014 to 2030,and the water ecological bearing capacity of the reservoir area is weak.(2)The key factors affecting water ecological carrying capacity in reservoir area are water supply and demand situation and water environment pollution.The main factors that cause the increase of water supply and demand pressure in the reservoir area are economic water consumption,and the main factors are industrial water consumption and agricultural irrigation water consumption.The leading factors that cause water environmental damage in the reservoir area are industrial COD and NH3-N emission.(3)The five development schemes of the status quo,economic development,environmental protection,resource conservation and comprehensive development are formed by changing the value of the decision variables.The close values of the five schemes in 2020 are 1.253,18.138,1.2,1.246 and 0,respectively.The close values of the five schemes in 2025 are 5.661,49.095,5.526,5.637 and 0.The close values of the five schemes in 2030 are 4.218,56.575,3.983,4.033 and 0,respectively.It is concluded that the comprehensive development scheme has the lowest close value and the optimal scheme(4)In the five schemes,the water ecological bearing capacity of the reservoir area shows different development trend,and the quantitative ranking from big to small is:Comprehensive development type>Environmental protection type>Resource saving type>Current status type>Economic development type.It shows that the comprehensive development plan can effectively improve the water ecological carrying capacity of the reservoir area.(5)Based on the current situation of water ecological carrying capacity and simulation scheme analysis in the reservoir area.It's suggested to relieve the pressure of water supply and demand in the reservoir area from adjusting economic structure,optimizing water supply structure,improving water efficiency and improving water-saving consciousness.To improve the water environment in the reservoir area from the two aspects of pollution prevention and control.