Study On Ecological Water Vulnerability Of Jinning Jiangchuan Crossing Section In Central Yunnan Diversion Project

Among the basic resources of nature,water is the most scarce and the most basic resource for mankind,and the pollution of this irreplaceable resource has been aggravated in recent years.Ecological water plays a decisive role in the vegetation and other ecological environment.There are plenty of water resources in the southwest region,but the ecological damage is becoming more and more serious because of the influence of climate,rainfall and human activities.The vulnerability of ecological water has become the key problem that restricts the sustainable development of social and economic development in Southwest China.Jinning Jiangchuan is located in the central Yunnan area,which belongs to the typical southwest region.The research area has already carried on the research of water resources and ecology,but the research on ecological water is still in the blank stage.The particularity of the ecological environment in Central Yunnan and the development of the water diversion project in Central Yunnan will inevitably cause further damage to the ecology in Central Yunnan.In order to protect the ecological environment of the study area and prevent the damage of the ecological water in the late construction of the Middle Yunnan water diversion project,the vulnerability of the ecological water in the central Yunnan area is bound to be studied.By analyzing the typical characteristics of the high water vulnerability area,suggestions are provided for the protection of ecological water in the future.First of all,on the basis of field investigation,based on the results of previous studies,the ecological changes of Jinning Jiangchuan section of the diversion project of central Yunnan are analyzed by using 3S technology.According to the hydrogeological conditions of the study area,the factors that may affect the ecological water vulnerability of the study area are screened out,and SPSS software is used to verify the correlation degree of the influencing factors by stepwise regression,and the evaluation factors of the vulnerability of ecological water are determined.Based on the analysis of each evaluation factor,the index system of ecological water vulnerability is established.After calculating the regression coefficient of each evaluation factor,logistic regression model is established.After the model is established,the model is tested by the admissibility(TOLERANCE)and the variance expansion factor(VIF),and then the fitting degree of the model is evaluated using the Wald test.Finally,the accuracy of the model is evaluated by the ROC characteristic curve to evaluate the AUC index of the model.Under the premise of accurate and reliable model,the correlation assignment of the evaluation factors of the model is carried out,and the ecological water vulnerability zoning map of the study area is obtained by grid superposition.By analyzing the typical characteristics of ecological water high vulnerability area,the protection suggestions for ecological water in the process of engineering development are obtained.Through the research and analysis,the following achievements are made as follows:(1)the influence factors of the ecological water in the study area are analyzed with the data of the field survey,and the SPSS software is verified by the stepwise regression method,and the water rich,groundwater type,terrain humidity index,surface water system and road are determined.5 factors are used to evaluate the vulnerability of ecological water.(2)the Logistic regression model is established and the feasibility and accuracy of the model are evaluated using admissibility and variance expansion,Wald test,and ROC characteristic curve,and the conclusion that the model is consistent with the actual situation has a high precision;(3)The study area was divided into three grades of high fragile area(I),medium fragile area(II),and relatively stable zone(III).(4)according to the model,the fragile area of the ecological water is analyzed in this area,where the fragile area of the water rich in the rock stratum is mainly located in the area of the fractured water area of the bedrock and the karst development along the line of the engineering line.There are more fragile areas in the surface water system 400 m,and the surface water system is more vulnerable to the vulnerability of the ecological water.The impact of the road distribution on the vulnerability of ecological water is less,but the influence of the terrain humidity is greater;the fragile areas of the ecological water are mainly distributed in the areas under the moderate humidity.Through the analysis of the typical characteristics of the high vulnerability area of ecological water,it is suggested that the dredging of bedrock fissure water and the blocking of groundwater in the karst area near the engineering line should be paid attention to in the process of water diversion project,and the stability of the groundwater environment should be kept.In the development of the project,it is necessary to pay attention to the change of the ecological water in the vicinity of the water source area,so as to prevent the further damage of the ecological water from the construction of the project.