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Groundwater Hydrochemistry Of An Overexploited Aquifer: The Case Of The Toluca Valley, Mexico


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27 - 37




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M. C. Jiménez-Moleón, R. M. Fuentes, M. T. Mota-González & M. Islas-Espinoza


The demographic, industrial and agricultural growth of recent decades in the State of Mexico has caused a considerable increase in groundwater extraction and the overexploitation is mainly due to drinking water, because it is the supply source for the two densely populated zones in the country: the metropolitan areas of Toluca City and Mexico City and its conurbation. In this work, 49 groundwater sources of drinking water were analyzed in two sampling periods (dry and rainy seasons). According to the Electric Conductivity data, 67% of the samples in the dry and 63% in the rainy season presented weak mineralization and the rest of the samples showed medium mineralization. In addition, the values of hardness showed that the water had good quality, with the exception of 3% of the wells in the rainy season, which had medium quality. The corrosion coefficient showed that two samples in the dry season and four in the rainy season had aggressive characteristics that might damage the extraction and distribution networks. The concentrations of major ions (measured by ionic chromatography) in both sampling periods showed this relative abundance: Na+>Mg2+>Ca2+>K+=HCO3 ->>Cl->SO4 2-. It was found that the HCO3 - concentration increased with the groundwater flow in the area. Moreover, it was also possible to establish the principal species in solution and to corroborate the hydrochemical change in the area of study. Although there continues to be clear predominance of the Mg-Na-HCO3 type, the Na-HCO3 facies showed a progressive increase. Keywords: drinking water, hydrochemistry, major ions, groundwater quality, Toluca Valley, Mexico.


drinking water, hydrochemistry, major ions, groundwater quality, Toluca Valley, Mexico