EFFECTS OF CLIMATE AND LITHOLOGY ON GROUNDWATER SALINITY IN CENTRAL MEXICO

Groundwater salinization is a common threat to coastal and arid areas, a threat worsened by increased groundwater withdrawals, which are expected to increase further due to global warming. Available water quality data for about 200 wells in central Mexico were used to map the spatial distribution of nitrate (NO₃-N), total dissolved solids (TDS), sodium (Na⁺), and sodium adsorption ratio (SAR). The study area was subdivided into three sections to estimate the impact of climate and lithologies on salinity. The results showed that lithology and climate are major factors contributing to the increase of these solutes. Spearman correlation showed a strong association of NO₃-N with TDS and Na but only in the two sections with arid/semiarid climates. Most wells had a SAR < 10, which corresponds to water fit for irrigation purposes and only 17 wells with water quality hazardous to soils. From a total of 54 aquifers, the results detected three severely impacted and four moderately impacted aquifers. Identifying the aquifers at risk of salinization is important to narrow down the possible causes of their high concentration and to develop strategies to manage aquifers more sustainably.