Ecological Risk Study Of ChangSha Multipurpose Hydraulic Project Reservoir Area In Xiang River

The Changsha Multipurpose Hydraulict Project in Xiang river,changing the river hydrological situation.on the one hand,that project ensures the security of urban water,improves the ability of the Xiang river navigation,and promotes the economic development of Changsha-Zhuzhou-Xiangtan urban agglomeration.On the other hand,it affects the ecological environment of the Changsha Multipurpose Hydraulict hub area in Xiang river,result in the change of ecological risk in the reservoir area.In this paper,the Changsha comprehensive hub area as the research object.based on regional ecological risk mechanism and risk assessment theory,with thinking about the ecological environment of Changsha comprehensive hub.choosing the ecological risk evaluation index.Using the analytic hierarchy process to measure the weights assignment,and the quantitative method to measure the risk level before and after the hydrologica project running,and put forward corresponding risk management measures,which to maintaining the ecological security of the reservoir area.The main research contents of this study are as follows.(1)The ecological risk of the reservoir area is small with the Changsha Multipurpose Hydraulict Project in Xiang river running,the integrated ecological risk value are 0.348,0.322,0.285,0.458 in 2006;2007,2014,2015.the risk level before running of the project is medium risk,reduced to low risk level after operation of the project.To be specific,the ecological risk source integrated risk changes before and after the operation,that reduced only 0.017 before operation,in which the risk of the reservoir dyke break flood risk,soil erosion and hydrological situation is increased.the intensity of pollutant discharge and social system pressure lower risk.The comprehensive loss degree decreased by 3.29%and 7.17%,change is significant,the aquatic biodiversity index rose slightly,the water environment quality and the ecosystem service value was improved,firstly the ecological risk of land use is higher than that of the hub project,and later gradually decline.(2)The ecological risk in the reservoir area is mainly affected by three factors:engineering operation,mode of economic development and environmental protection and management.From the perspective of ecological risk source,the ecological risks of flood,soil erosion and hydrological situation were increased after the operation of the project.However,with the improvement of social and economic development and the increase of environmental protection input,the risk of pollutant emission intensity and social system pressure is decreasing.From the ecologic risk receptor,the ecological risk of land use rises after the project operation.with the increase of river water level and the decrease of pollutant discharge,the loss of biodiversity loss,water environment quality and loss of ecosystem services are all declining.(3)According to the ecological risk factors in the reservoir area,the countermeasures of ecological risk management were put forward.In terms of soil and water conservation,we will strengthen supervision and control over water and soil management in the reservoir area and reduce man-made damage.From the joint dispatching mode,reasonable selection of traffic events,maintaining the ecological functions of the reservoir area and the downstream,and the habitats of aquatic organisms is not destroyed to carry out hydrological regulation of reservoir area.We will promote biodiversity conservation in the reservoir area from the implementation of policies and regulations and strengthening supervision.We will strengthen the monitoring of land use,transform the land use strictly,and optimize the land use structure in the reservoir area on land conservation.In addition,we will strengthen environmental protection in the reservoir area by implementing the "river chiefs system",controlling environmental pollution according to law and raising public awareness of environmental protection.