Spatial Analysis and GIS Mapping of Regional Hydrochemistry, Groundwater Quality, and Probabilistic Health Risk in Western Sichuan Basin, Southwestern China

Nitrate contamination in groundwater is widespread, and studying the extent of contamination and its health risk effects on the population is beneficial for groundwater protection. In this study, 130 groundwater samples collected from the western Sichuan Basin were analyzed for hydrochemical spatial distribution, groundwater quality, and probabilistic health risk. Piper diagram showed that the hydrochemical type of groundwater samples was Ca-HCO3. The hydrochemical components were mainly controlled by carbonate dissolution, silicate weathering and cation exchange based on ion ratios and saturation index. The statistical and spatial analysis showed that the concentration of NO3− exceeded the permission limit for drinking purpose in the central and eastern parts of the study area. The EWQI results showed that about 90.84