Sensitive Region Recognition Of Nitrogen And Phosphorus Loss Of Water Source Area In Central Guizhou

Qianzhong water conservancy project is the largest long distance water diversion project in Guizhou province, the water quality of it would affect the safety of drinking water source in most areas in central Guizhou. At present, with the development of social economy,non-point source pollution problems have become increasingly prominent,and has become a major obstacle of the development of social economy.The research areas included the protection areas and quasi protection areas of Pingzhai reservoir,analysised region soil N, P element leaching characteristics by combining the Indoor simulation experiment; analysised and evaluated the current situation of non-point source pollution, and using GIS carried out space analysis,then we obtained the division of sensitivity area,and some conclusions as follows:(1)Non-point source pollution of complex composition in the study area,in order to analysis of non point source,we must understand the quality status of soil and water.The results showed that,59.62% soil quality of samples belongs to the class II standard;in the low water period, the quality standards for Grade I accounted for 59.62% of all water samples,Grade II-III accounted for 15.38%, Grade IVaccounted for 5.77%, Grade V accounted for9.62%. In the high water period, ratio of Grade IV water was as much as 72.92%, Grade I-III accounted for 22.91%, Grade V accounted for 4.17%. TN、NH3-N and TP in water most exceeded the national standard(GB3838-2002), its was the main index of non point source pollution.(2)The concentration of pollutant output of different land use types of soil is one of the key research on non-point source pollution.Study the leaching loss of three main land use types(farmland, woodland, wasteland) in study aeras,by means of indoor soil column continuous leaching simulation experiment.The results showed that,wasteland has the least leaching amount of total nitrogen, nitrate nitrogen and ammonia nitrogen,and the most leaching amount of total phosphorus and soluble phosphorus.Nitrate nitrogen was the main leaching form,the proportion of wasteland is 36.73%,farmland is 37.62%,woodland is 35.92%;particulate phosphorus was the main leaching forms of phosphorus.With the increase of leaching times,the change rules of total phosphorus and dissolved phosphoru sleaching losses is accorded with the power function equation,while the chang rules of total nitrogen is different land use typesdifferences.Nitrate nitrogen and ammonia nitrogen has the same change rules in woodland and farmland,but differnet with wasteland.(3)Selection principle of index parameters based on PNPI,the parameters were modified and optimized on the basis of evaluation.Using SCS curve estimation to generate runoff factor(Q);drawing on the experience of previous research results calculated land utilization factor(L);Calculate the distance factor(D) using kernel density method because it considering the density of river network,the loss risk of non-point source pollution decreased with increasing distance from the river,and increases with the river network density. While using the modified TOPSIS, the research areas was divided into 4 categories of sensitive control areas according to the assessment index.Highly sensitive area accounted for 2.34% of the total area of the study area,The moderately sensitive areas accounted for 12.79%,so we can implement highly individualized approach to management according to the sensitivity level.According to the present situation of water quality and soil quality and requirements of prevention and management,this study divides the sensitive region of loss of non-point source pollution.And put forward different management measures of the regions, provide reference of governance of non point source pollution in this area.