Applicability analysis of different evaluation methods in groundwater quality evaluation: A case of Xi’an city

Abstract

In order to find a suitable method for the evaluation of groundwater quality in Xi’an, the principles of single factor evaluation method, fuzzy comprehensive evaluation method and modified fuzzy comprehensive evaluation method are briefly described. Three methods are applied to the comparative analysis of water quality evaluation of 34 phreatic water samples in Xi’an. The results show that: (1) The results of fuzzy comprehensive evaluation method are more optimistic than those of single factor evaluation method. (2) The single factor evaluation method is simple in calculation and can directly reflect the degree of pollutants exceeding the standard in water, but the evaluation results are too one-sided to reflect the actual situation of water quality; The fuzzy comprehensive evaluation method and the modified fuzzy comprehensive evaluation method more comprehensively consider the comprehensive impact of evaluation factors on water quality, and their results are more objective than the single factor evaluation method. (3) The modified fuzzy comprehensive evaluation method improves the accuracy of the membership matrix by changing the critical value of Class V water. The weighted average calculation method avoids the error caused by the square term of concentration, so that the evaluation results will not be distorted. It is a very effective evaluation method, which should be promoted.