Fuzzy comprehensive evaluation with AHP and entropy methods and health risk assessment of groundwater in Yinchuan Basin, northwest China.

Water quality evaluation and health risk assessment are not only the basis of environmental protection work, but also of great significance to water environment supervision and management. In this paper, the fuzzy comprehensive evaluation for water quality was improved by using the analytic hierarchy process (AHP) and Entropy, and a health risk assessment model based on triangular fuzzy theory was developed. The evaluation results show 5 water categories: Class-1 (n = 1, 2%), Class-2 (n = 14, 32%), Class-3 (n = 15, 34%), Class-4 (n = 8, 18%) and Class-5 (n = 6, 14%), manifesting about 67% of the phreatic water can be used for drinking purposes in the research area. The Chadha diagram provides hydrochemical facies of the phreatic water are mainly NaCl type (n = 16, 36%) and Ca-Mg-Na type (n = 15, 34%). Fluorine as non-carcinogenic factor in health risk assessment, showing moderate correlation with SO42- (r = 0.54) and low correlation with Na+ (r = 0.38) in Pearson correlation analysis. The order of non-carcinogenic risk per year is as follow: Class-2, Class-3, All, Class-4 and Class-5 with the mean of 0.29, 0.51, 0.67, 0.86 and 1.55 × 10-8 for adults, 0.54, 0.95, 1.27, 1.58 and 2.89 × 10-8 for children. Compare with adults, children undertake higher health risk, in research area. Particularly, the region accepting Class-5 water supplement encounter high non-carcinogenic risk, where risk level is 2.24 and 2.28 times to the average risk level for adults and children, respectively. This paper provides insights into solving uncertainties in groundwater management and environmental protection, as well as into fuzzy logic techniques addressing pollution.