Hydrogeochemistry of Groundwater Supplied to the City of Monterrey, Mexico

The Monterrey Metropolitan Area (MMA) is the third greatest urban area of Mexico. Owing to the rapid industrialization and urbanization of this city, more water resources are necessary in this semi-arid region. Thus, the objectives of this work were to characterize the chemical properties of groundwater supplied to MMA and to assess inter-annual variations in the water chemistry. Three groups of water were identified: recharge waters from mountain belts dominated by marine sedimentary rocks (Ca-HCO₃ type), transition zone waters from alluvial sediments (Ca-HCO₃-SO₄ type) and waters flowing through conglomerates and alluvial sediments of the northeastern MMA (Ca-SO₄ type). The ionic composition and the salinity gradient of each water group were in agreement with the topographic flow paths of the study area. The non-parametric Mann-Whitney U-test indicated that there have been no significant changes on the groundwater quality supplied to the MMA between the years 2006 and 2012.