Groundwater-flow modeling in the Yucatan karstic aquifer, Mexico

The current conceptual model of the unconfined karstic aquifer in the Yucatan Peninsula, Mexico, is that a fresh-water lens floats above denser saline water that penetrates more than 40km inland. The transmissivity of the aquifer is very high so the hydraulic gradient is very low, ranging from 7-10m...

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Veröffentlicht in:Hydrogeology journal 2002-10, Vol.10 (5), p.539-552
Hauptverfasser: Gonzalez-Herrera, Roger, Sanchez-y-Pinto, Ismael, Gamboa-Vargas, Jose
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Sprache:eng
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Zusammenfassung:The current conceptual model of the unconfined karstic aquifer in the Yucatan Peninsula, Mexico, is that a fresh-water lens floats above denser saline water that penetrates more than 40km inland. The transmissivity of the aquifer is very high so the hydraulic gradient is very low, ranging from 7-10mm/km through most of the northern part of the peninsula. The computer modeling program AQUIFER was used to investigate the regional groundwater flow in the aquifer. The karstified zone was modeled using the assumption that it acts hydraulically similar to a granular, porous medium. As part of the calibration, the following hypotheses were tested: (1) karstic features play an important role in the groundwater-flow system; (2) a ring or belt of sinkholes in the area is a manifestation of a zone of high transmissivity that facilitates the channeling of groundwater toward the Gulf of Mexico; and (3) the geologic features in the southern part of Yucatan influence the groundwater-flow system. The model shows that the Sierrita de Ticul fault, in the southwestern part of the study area, acts as a flow barrier and head values decline toward the northeast. The modeling also shows that the regional flow-system dynamics have not been altered despite the large number of pumping wells because the volume of water pumped is small compared with the volume of recharge, and the well-developed karst system of the region has a very high hydraulic conductivity.Original Abstract: Le modele conceptuel classique de l'aquifere karstique libre de la peninsule du Yucatan (Mexique) consiste en une lentille d'eau douce flottant sur une eau salee plus dense qui penetre a plus de 40km a l'interieur des terres. La transmissivite de l'aquifere est tres elevee, en sorte que le gradient hydraulique est tres faible, compris entre 7 et 10mm/km dans la plus grande partie du nord de la peninsule. Le modele AQUIFER a ete utilise pour explorer les ecoulements souterrains regionaux dans cet aquifere. La zone karstifiee a ete modelisee en posant l'hypothese qu'il fonctionne hydrauliquement comme un milieu poreux granulaire. Au cours de la calibration, les hypotheses suivantes ont ete testees: (1) les phenomenes karstiques jouent un role important dans le systeme aquifere, (2) un anneau ou une ceinture de depressions dans la region est la manifestation d'une zone a forte transmissivite qui permet l'ecoulement en conduits de l'eau souterraine en direction du Golfe du Mexique, et (3) la situation geologique
ISSN:1431-2174
1435-0157
DOI:10.1007/s10040-002-0216-6