A homogeneous approach in modeling a coastal karst aquifer

Groundwater flow representation of a particular zone, from a given hydraulic conductivity and certain boundary conditions, commonly requires the use of numeric models. A groundwater flow model was implemented in the Puerto Morelos karst coastal aquifer, located in the Mayan Riviera of Quintana Roo, Mexico. To develop the model, data obtained from published literature as well as geologic, meteorological and hydrogeologic information were collected to build a conceptual model. Field work was also carried out to establish a monitoring network where observation wells were placed to measure water table depths. The equivalent porous medium (EPM) conceptualization was assumed; this assumption is reasonable because the numerical cell size is “large enough” to represent the combined hydrogeologic effect of matrix and conduits within the cell. Model calibration was achieved when minimum errors, between computed and measured groundwater heads as well as discharge to the model boundary, were obtained. The results show that the Puerto Morelos aquifer can be modeled as a homogeneous and isotropic medium; that is, with no consideration of heterogeneities implicit in karstic media. A groundwater mound was depicted in the Puerto Morelos urban area which affects the flow patterns of the system.