Sensitive Areas Recognition Of The Agricultural Non-point Source Pollution In Hongfeng Lake Water Source Protection Area Based On GIS

Hongfeng lake basin is an important drinking water source protection area in Guiyang,guaranteeing millions of people to drink.In recent years,the problem of the non-point source pollution is becoming more and more prominent.In order to reveal the non-point source pollution characteristics and identify the priority control areas,this paper selected the protection areas as the research areas.The GRA and Kriging analysis were used to analysis the water and soil testing data;The supervised classification method was used to interpret the land-use and the correlation analysis was selected with the water quality;Finally,based on above the results,the non-point source pollution sensitive areas about Hongfeng lake basin was identified by the APPI model.The results of the study have been concluded as follows:?1?The water quality of the main rivers in the high water period showed the level?,the average water period and the withered water period showed the level?during the research,it revealed the higher risk of non-point source pollution in the high water period.The soil with higher total nitrogen concentration was mainly distributed in the northern and northeastern regions,with the range of 0.263%-0.430%,and the soil with higher total phosphorus concentration was mainly distributed in the western and southwestern regions,with the range of 0.122%-0.203%.The pH is neutral and acidic and the soil nutrient quality mainly concentrated in level II and III,accounting for51.7%.?2?The results indicated that Hongfeng lake basin was dominated by woodland and farmland,accounting for more than 60%of the total area.From 2001 to 2016,the area of the woodland and farmland showed a downward trend.The area of construction land and grassland continued to increase.The growth area of construction land was 11.41 km²,up to 36.11%,the growth area of grassland was 9.65km²,up to14.62%.The increase of the two areas mainly came from the inflow of the farmland,woodland and unused land.?3?The construction land and farmland in the study areas showed a positive correlation with TP,NH₃-N and COD,and the significant negative correlation with DO,regarded as the"source".The woodland showed a significant negative correlation with TP,NH₃-N and COD,as the"sink".?4?The APPI model was used to evaluate the non-point source pollution through sediment,runoff,fertilizer,human and livestock emission indexes.The results showed the potential risks of agricultural non-point source pollution in Yangchang village,Yangtang Village,Luojia village,Pingzhai village and Pingba farm were higher,and the non-point source pollution potential index were 0.688,0.627,0.341,0.329 and1.335 respectively,which were considered as the sensitive control areas of the study areas by combining the distance factor.The more attention should be taken to prevent the risk of non-point source pollution during the high water period in the sensitive areas.In addition,the higher vegetation coverage should be improved to reduce the risk of non point source pollution.