Identification of natural water sources and anthropogenic contamination applying the VISHMOD methodology in a volcano-sedimentary aquifer

This study employs hydrogeochemical modeling as a tool for the hydrogeological investigation of the Puebla Valley aquifer (PV). The aim is to gain insights into the origin, distribution, and circulation of groundwater. The objective is to identify the water-rock interaction processes that govern the composition of groundwater, contributing to a comprehensive understanding of the PV aquifer’s chemical variations in the study area. The VISHMOD methodology is implemented to identify and simulate water-rock mixing and interaction processes in the study aquifer. Three end-members were identified: one associated with local flow, intermediate flow in a volcanic environment and regional flow in a carbonate environment. The results suggest that the groundwater chemistry has been affected due to anthropogenic contamination associated with the influence of the Atoyac River, the return of irrigation water, and wastewater from the metropolitan area of the city of Puebla. Ternary mixing processes define the flows, where the local extreme member contributes 74%, indicating the dominance of recharge zones. On the other hand, the regional members (located in carbonate rocks) contributes 9%, and the intermediate member (located in volcanic rocks) contributes the remaining 17%.