Analysis of hydrogeochemical processes regulating groundwater quality in a tropical agricultural landscape of northwestern Mexico
Abstract
This study assesses the hydrochemical and groundwater quality characteristics of the Mocorito River Aquifer (MRA), located in a tropical agricultural region of northwestern Mexico. A ten-year groundwater quality dataset (2012–2022) from seven monitoring sites was analyzed to evaluate seasonal and interannual hydrochemical variability, identify recent drought-related effects, and assess the influence of anthropogenic activities on groundwater quality. Hydrochemical parameters were evaluated using hydrogeochemical characterization, Water Quality Index (WQI), Piper and USSL diagrams, and multivariate statistical analyzes to identify spatial patterns and dominant controlling processes. The results revealed significant spatial heterogeneity in groundwater quality, with agricultural zones exhibiting the greatest deterioration due to intensive fertilization, excessive irrigation, and the leaching of dissolved salts and fertilizer-derived ions into the aquifer, while urban areas were mainly affected by microbiological contamination. Hydrogeochemical analyzes indicated that groundwater chemistry is controlled by the interaction of natural geogenic processes, including carbonate and silicate dissolution and ion exchange, together with anthropogenic pressures. The study demonstrates that agricultural practices intensify these natural hydrogeochemical processes, accelerating groundwater salinization and quality degradation in vulnerable areas of the aquifer. Although the MRA generally maintains good-to-moderate groundwater quality, localized zones present severe deterioration that limits its suitability for drinking and irrigation purposes. These findings highlight the importance of long-term groundwater monitoring and integrated management strategies to mitigate increasing agricultural impacts and improve the sustainability and resilience of aquifer systems under climatic and anthropogenic stress.