The groundwater quality of the Upper Pearl River Watershed (UPRW) and surface water quality of the basin's outlet, Ross Barnett Reservoir (RBR), are critically important because of growing demands for drinking, agriculture, and industrial use in the region. To identify factors affecting water quality and characterize the surface water outlet and the watershed's groundwater, geochemical and statistical analyses were performed using results from various hydrogeochemical parameters. Based on surface geology, groundwater samples analyzed (n = 51) within the watershed were partitioned into three recharge zones: North, Mid, and South. Precipitation and rock-water interactions were identified to dominantly influence the groundwater chemistry in the region. The chemistry of the surface water samples (n = 9), on the other hand, was influenced more by precipitation with minor contribution from the proximal aquifer system. Principal component analysis (PCA) revealed that two groundwater recharge zones and RBR samples exhibited significant clustering. The groundwater had a complex array of parameters influencing its chemistry owing to diverse properties, including Na, Ca, Mg, alkalinity, and conductivity. Comparing land use at the sub-watershed level with the water quality parameters showed that agriculture and development could have contributed nitrate, especially to the groundwater in the south zone. However, a general lack of distinct relationship between land use and water quality, along with detection of excess nitrate in select wells suggested that the water in the region was likely affected by point sources, such as poultry farms. The research recommends evaluating point sources of pollution to cater to future water management in the region.
Keywords: Arsenic; Contamination; Hydrogeochemistry; Land use land cover; Multivariate statistics; Principal component analysis.