Application of set pair analysis based on the improved five-element connectivity in the evaluation of groundwater quality in XuChang, Henan Province, China
The evaluation of groundwater quality plays an important part in the evaluation of groundwater resources. It analyses the temporal and spatial distributions and utilisation of underground water according to the main components and corresponding water quality standards for underground water. Thereby, it can provide a scientific basis for the development, utilisation, planning, and management of groundwater resources. Set pair analysis (SPA), based on the improved five-element connectivity degree, was used in this research to establish a comprehensive evaluation model of water quality, so as to evaluate the groundwater quality in XuChang, Henan Province, China. Meanwhile, fuzzy evaluation was also used to measure groundwater quality. As demonstrated in the research results, SPA is proven to be convenient and useful with objective and stable results, it therefore is an effective approach with which to evaluate groundwater quality. In addition, the results obtained using SPA matched those from fuzzy comprehensive evaluation; it was concluded, based on the analysis, that the groundwater in XuChang was severely polluted. The groundwater quality at the observation points located in the lower reaches is poorer than that of the upper reaches; hazardous substances permeate underground to pollute shallow groundwater through decomposition and loss due to weathering and rainfall.