Groundwater quality assessment using principal component analysis modified water quality index in the Huangbizhuang, Northern China Plain

This study was carried out to evaluate the groundwater quality in Huangbizhuang town, which is an important water source for Shijiazhuang and Beijing, China. Fifty-six geo-referenced water samples were collected from pumping and monitoring wells from July to September 2018. The study investigated the applicability of two weighting methods, the expert weighting method, and the principal component analysis weighting method, to water quality assessment and evaluated the water quality status and the leading causes of groundwater pollution by chemical analysis index and multivariate statistical methods. The results show that the overall quality is good, and shallow and deep groundwater in the study area is generally suitable for drinking and irrigation. The WQI of the expert weighting method reveals that 74.36% of the shallow groundwater and 58.82% of the deep groundwater is excellent. Shallow groundwater has a close hydraulic connection with surface water, and the water quality of shallow groundwater is superior to that of deep groundwater. Compared with the expert weighting method, the weight of natural factors is larger, and the WQI value is higher in PCA weighting. Since no subjective factor is involved, the PCA weighting method is more objective and more suitable for the study area. In addition, multivariate statistical calculation results show groundwater pollution is due to both point source pollution, industrial activities, and non-point source pollution, such as agricultural activities.