Evolución química del agua subterránea a través del acuífero del Valle de Mexicali

The water quality of the Mexicali Valley aquifer was evaluated in order to estimate the geochemical processes involved with the increase of its salinity and the subsequent subsoil mineralization. The study area is located in the municipality of Mexicali, Baja California, Mexico in a section where the riparian corridor of the Colorado River converges with an agricultural area. The water of this river contains less than 1000 ppm of dissolved solids on average, but as the water is channeled and used in the crop’s irrigation, it undergoes a solute enrichment process until 2400 ppm in the upper aquifer. According to chemical analyzes the water salinization is mainly caused by sodium, sulfate and chlorine ions, while the geochemical modeling carried out with the PHREEQC program indicates that the processes related to calcite precipitation, dolomite and gypsum dissolution and water evaporation are primarily responsible for the water chemical evolution in the area.