Qingshan Basin Water Environment Assessment Study

The South Tiaoxi River, is the headwater of Tai Lake, its health status affect people’sproduction and life in Hang-Jia-Hu area. Currently, people’s concerns are not only limited to thewater quality, but also extends to the state of health of the entire river ecosystem. This studyselected South Tiaoxi River Qingshan lake basin, couple the weight of fuzzy of analytic hierarchyprocess by information entropy to assess water quality; select two main tributaries, processeutrophication evaluation under the premise of analysis of chlorophyll a; then with acomprehensive evaluation for Qingshan Lake basin river health. The main conclusions are asfollows:1) Fuzzy Analytic Hierarchy Process has great significance in the process of comprehensiveevaluation of water quality, but the method to determine the weights coefficient of evaluationindexes with a certain degree of subjectivity. Therefore, this paper presents the right to re-amendthe weight of Fuzzy Analytic Hierarchy Process based on entropy coefficient of Shannon entropytheory, to obtain comprehensive weight. On the basis, using the improved fuzzy AHP method cancomprehensively evaluate the water quality. This paper took the basin of Qingshan Lake as anexample, selected five indicators to assess water quality, the results showed that by using theweight of information entropy theory fuzzy AHP, considering not only the objective informationof data, but also the decision-maker’s subjective intention, has a good reasonableness. Taking theweight which had coupled to evaluate the basin water quality by Fuzzy AHP evaluation, cancomprehensively reflect the actual condition of the basin’s water quality.2) Chlorophyll a is an important indicator to evaluate eutrophication degree. Through thecorrelation analysis of chlorophyll a and other physical and chemical indicators of water quality inQingShan basin, this paper studied the variation trend of chlorophyll a and the influence of thefactors such as nutrient salt, CODMn, pH and DO. With chlorophyll a as the basic parameter, toevaluate water eutrophication by the method of integrated nutrition state index in QingShan basin.Combined with the factor analysis, the results showed that upstream areas in QingShan basin areclose to the water eutrophication; in the middle and lower reaches, is of the serious eutrophicationdegree, integrated nutrition state index is close to severe eutrophication level. Eutrophication ofriver basin as a whole index was53.15, belongs to the mild eutrophic water quality.3) Based on the domestic and foreign research and field survey of watershed, according toprinciples of scientific, systematic, and operability to build a river health evaluation index system.The index system is composed of5sub-indices which include river habitat conditions, hydrology,water quality conditions, aquatic organisms and social conditions and20secondary indicators ofQingshan Lake basin. Determine five evaluation levels of the evaluation criteria; use the expert scoring method to determine the weight of various indicators, and then use fuzzy hierarchycomprehensive evaluation to assess river health. The results show that the degree of membershipbelongs to the sub-health state is0.3733, which is greater than the other at all levels. According tothe maximum membership principle to determine the results of the evaluation, the Qingshan Lakebasin river health is in a sub-health condition.