Research On Non-point Source Pollution Caused By Water Loss And Soil Erosion Of Dianchi Watershed Based On GIS

With the social and economic rapidly development and highly utilization of water resources,the pollution loading amount in Dianchi watershed is increasing day by day.The water pollution in Dianchi watershed is getting much more serious.Previous research on Dianchi watershed water resources conservation primarily focused on the point source pollution control.However,the research on the non-point source pollution formation caused by water loss and soil erosin and control cannot be ignored, as it is also an important aspect within bearing capacity of water resource.The research focused on the nonpoint source pollution caused by water loss and soil erosion in Dianchi Lake basin as well as 10 sub-basins during the rain spell.The main research contents are in the following:1.Through continuous monitoring pollutants concentration and pollution load and other contamination indexes and hydrology indexes of water in the sections of 10 sub-basins,then the research result shows that contamination indexes have significant correlation as well as pollutants load and between run-off and pollutions load;through the quantitative analysis of spatial variability of pollutant load and runoff,the result shows the spatial variability of the concentration of SS,TN,TP is much larger than other contaminations,also runoff is not the only factor determines sediment runoff,but also basin area;through applying the geostatistic theory ordinary kriging method,the paper has predicted pollutants concentration and built graphic models of the whole basin.2.Based on GIS,the paper applied a landscape pattern evaluation method by calculating location-weighted landscape contrast index(LCI) and landscape slope index(LSI).The result shows that LSI of farm land and forest land and LCI of the sub-basins responded statistically significantly to soil erosion modulus,erosion area and runoff only for farmland.3.Based on GIS,the paper also applied SCS model for predicting runoff and pollution load of Dianchi watershed and sub-basins,also built runoff and pollution load distribution map and the paper calculated the discharged amount and pollutants quantity affluxed Dianchi Lake.4.Based on GIS,the paper applied USLE model estimated total amount of soil erosion and soil erosion modulus,the result is dependable.Also,the estimated soil erosion intensity is classified by Soil Erosion Grading Standard,the result shows soil erosion levels above moderate levels took only 21.96% of Dianchi watershed area,but contributed 85.52%of the total soil erosion amount.Based on GIS,through the research on non-point source pollution caused by water loss and soil erosion in the Dianchi watershed,the author provided the estimating methods,technologies and measures to the quantity of contamination,further enriched the qualitative and quantitative research in this field.This research can provide some technical support to controlling non-point source pollution in Dianchi Lake basin,formulating and implementing the basin pollutant control plan,and protecting the Dianchi Lake basin water resources.