Abstract

Groundwater is the major water source for irrigation and domestic purposes in and around Beiluo River watershed, Guanzhong Basin of northwestern China. To provide a scientific basis for sustainable groundwater development, 25 groundwater samples in the lower Beiluo River watershed were collected and analyzed. The overall groundwater quality was assessed through entropy-weighted water quality index (EWQI) and US Salinity Laboratory (USSL) diagrams. The non-carcinogenic human health risks caused by fluoride through the oral and dermal pathways were also assessed. Then the influence of driving factors on groundwater quality was qualitatively discussed based on GIS technology, and the degree of influence of each factor on groundwater quality was calculated quantitatively through Geodetector. The results show that the hydrogeochemical type of groundwater in the lower Beiluo River watershed is dominated by SO₄·Cl-Na type, followed by HCO₃-Na type, HCO₃-Ca·Mg type, and SO₄·Cl-Ca·Mg type. Groundwater quality is good to very poor, which indicates the groundwater of some areas is unsuitable for drinking. In addition, groundwater in some parts of the study area is inappropriate for direct irrigation due to high salinity which can result in soil salinization. Residents of this area are facing health risks induced by drinking high-fluorine groundwater and children in study area are at higher health risk than adults. Geodetector calculation indicates that the explanatory power index q of major influencing factors is ranked as follows: population > soil types > land use types > elevation > topography, indicating that population is the main potential influencing factor on groundwater quality in this study.