Ecology Health Assessment Of Nanxi River Basin Based On GIS And RS

Basin is important source of life for human,other animals and plants,in the process of social economy sustainable development of our country,the condition of basin ecosystem has become restriction factor that cannot be ignored.Through conduct assessment on ecosystem health of Nanxi River Basin,aims to provide scientific decision basis for economy development of Nanxi River Basin and coordinated and sustainable development of environment.Firstly,combined with RS and GIS technology,conduct analysis on ecosystem situation and the change of ecosystem structure of Nanxi River Basin,meanwhile consult Technical Guide for Basin Ecosystem Health Assessment of Ministry of Environmental Protection,construct assessment index system of land area and water area,among them,land area includes a total of three categories and nine indexes of land area ecological pattern,land area ecological function and land area ecological pressure,water area includes a total of three categories and seven indexes of water land habitat structure,hydrobios and water land ecological pressure,conduct ecosystem health assessment on 18 assessment units of Nanxi River Basin,meanwhile analyze existing major problems of the basin.Research conclusions include:? In 2014,the Nanxi River Basin ecosystem was dominated by forest,accounting for 82.99%.Then followed by farmland,urban and wetland which respectively was accounting for 7.96%,4.9%and 3.43%.? From 2000 to 2014,the main ecosystem type transformation in Nanxi River Basin occurred between farmland,forest and urban.The transfer area of farmland to forest and farmland to urban respectively was 59.35km~2 and 42.14km~2.The two together accounted for 56.29%of the total ecosystem conversion area.In 14 years,the expansion of urban in Nanxi River Basin mainly is farmland encroachment,followed by brush and grass encroachment.? The land area ecological health score of Nanxi River Basin is 75.82 points,at a good level.Among them,the excellent evaluation unit is 1,which is Yantan town,accounting for 21.67%of the valley area.The good evaluation unit is 15,accounting for 76.83%of the valley area.The general evaluation unit is 2,which are Dongou Street and Jiangbei Street accounting for the valley area of 1.50%.? In 9 indexes of land area ecology health situation assessment,the 7 indexes of forest coverage rate,landscape fragmentation degree,important habitat retention rate,water conservation retention function,soil retention function,reserve area ratio and construction area rate of Nanxi River Basin are both in good and above good level,land area ecology environment protection is better,the index of point source,non-point source pollution loading is common level.? The water area ecological health score of Nanxi River Basin is 60.51 points,at a good level.In the 7 indicators of ecological health assessment,the development and utilization strength of water source and runoff in dry season accounted for the same annual average runoff ratio are excellent.Compliance rate of water quality and fish species diversity are the 2 good evaluations.Disturbance index of aquatic habitat and retention rate of endemic species are the 2 general evaluations.The evaluation of channel connectivity index is terrible.? The ecological health comprehensive assessment score for Nanxi River Basin is 69.70 points,at a good level.Among them,the number of good evaluation unit is 16,accounting for 98.50%of the valley area.The general evaluation unit is 2,which are Dongou Street and Jiangbei Street.The limiting factors are forest coverage and impervious area proportion.? Main problems of basin include:rapid growth of urban and town land area,farmland,grassland,bush follow and other ecosystems continuously degrade,ecosystem stability reduces;The overall water quality condition is not optimistic;channel connectivity is terrible.