Spatiotemporal analysis of land-use changes and water quality in an aquifer in a tropical agricultural region of northwestern Mexico: implications for sustainable groundwater management.

Abstract

This study presents a spatiotemporal assessment of groundwater quality and land use and land cover change in the Mocorito River Aquifer (MRA), a tropical agricultural system in northwestern Mexico, integrating hydrogeochemical data from seven monitoring wells sampled semiannually from 2012 to 2022 with LULC classification for the 2013-2022 period using Google Earth Engine. Groundwater quality was highly heterogeneous, with elevated total dissolved solids (TDS), electrical conductivity (EC), sodium (Na+), calcium (Ca2+), and episodically high fecal coliform (FC) concentrations. Comparison with Mexican drinking-water criteria identified TDS, total hardness (TH), nitrate (NO3-), sulfate (SO42-), and FC as management-relevant parameters. Gibbs diagrams indicated that water-rock interaction and evaporation/concentration contribute to groundwater mineralization. Land-use analysis showed expansion of permanent and rainfed agriculture and aquaculture, together with reductions in tropical forest, shrubland, grassland, and mangrove cover. Site-context comparison showed that monitoring wells located in agricultural and rural settings tended to exhibit greater mineralization, nutrient enrichment, or microbiological anomalies than less intensively cultivated settings. Hydrogeochemical interpretations were therefore constrained to evidence supported by the monitored dataset and by an independent process-based assessment of the same aquifer. The findings identify vulnerable monitored sectors and support targeted land-water management, improved sanitation, nutrient control, and long-term groundwater surveillance.