This paper is the result of hydrogeological survey engineering.
[Objective] The Xin'anjiang River Basin is an important ecological security barrier in East China, and its governance is long-term, arduous, complex, and repetitive. Scientifically evaluating the water environment quality of the basin and identifying the key polluted areas and major pollution factors could provide an important basis for promoting the improvement of the ecological environment of the river basin.
[Methods] Based on the water quality data of 88 monitoring points of Xin'anjiang River basin, the principal component analysis method was used to optimize the evaluation index system of water quality, and then the entropy weight method was adopted to calculate the weight of each index and the comprehensive water quality index of each monitoring point. Moreover, the comprehensive index map of water quality was drawn by the spatial analysis function of GIS.
[Results] The results show that the comprehensive index of 88 monitoring points ranged from 0.02-1.313, and the environmental quality of surface water in the basin was generally good, mainly for class III. The water quality of Zhejiang section was better than that of the Anhui section. The key pollution area was distributed in the Xiuning-Shexian-Huizhou district, forming two pollution centers in Qiankou Town, Yansi Town-Sancun Town. Moreover, TN, TP and NH₃-N were the main pollution indicators of the basin, where TN was a global pollutant, TP and NH₃-N were regional pollutants.
[Conclusions] The water quality evaluation model composed of principal component analysis and entropy weighting method avoids the repeated selection and the subjectivity of weight assignment for evaluation index, which could efficiently evaluate the complex index system of water environment and better reflect the actual spatial distribution of water quality. It is feasible and practical in water quality evaluation.