Fuzzy Comprehensive Evaluation of Water Quality of the DayutangRiver Watershedin Yuanyang Terrace Area

The DayutangRivere watershed was selected as target,and the survey on agricultural production and the environmental status of the terraced area was conducted. Water samples were collected scientifically. According to“Surface Water Quality Standards” (GB3838-2002),and based on the actual situation of local agricultural production and laboratory conditions,total nitrogen and total phosphorus were chosen. The experimental determination was done strictly according to the national standards. Fuzzy Comprehensive Evaluationwas used to evaluate the water quality of the nine selected sampling sites,which were above the forest G01,forest exports G03、H05、J02,Dayutang G09,terrace junction J05,and river inlet H03、H01. The results showed that the overall water quality of the Dayutang watershed is good,except that the water quality of G09 met the water quality of Class V,the water quality indicators of G01 and J05 reached the water quality of Class IV,and the water quality of other sections met the water quality of class I ～ III. Some smaller basins need to pay more attention. The pollutants from the upper reaches of the village distributed a significant degradation effect when they enter the mountainous channels in the terraced canals. It had a positive impact on the water quality in the watershed.