Karstic aquifer structure from geoelectrical modeling in the Ring of Sinkholes, Mexico

Groundwater models based on terrain resistivity can show the diverse properties and processes occurring between fractures, boreholes and conduits. Using electrical resistivity tomography, a conceptual model was created of the aquifer within the Ring of Cenotes, which surrounds the Chicxulub Crater on the Yucatan Peninsula, Mexico. Determining the hydrogeological parameters of an aquifer is vital since they determine flux and hydrodynamic patterns. In karstic environments, conventional techniques are not effective at recording heterogeneities such as fracture zones and conduits. Six transects were investigated among areas near cenotes (sinkholes) and aguadas (small surface-water bodies), as well as areas lacking these formations. The resulting profiles reached up to 30 m deep and showed an aquifer consisting of a fractured matrix saturated with freshwater. The matrix exhibiting resistivity values from 3 to 250 Ωm, lying under a vadose zone with values from 300 to 25,000 Ωm. Aguadas and cenotes are surface manifestations of the aquifer’s internal structure, which is a network of caves and conduits. In the Ring of Cenotes, the presence of these surface formations indicates increased hydraulic conductivity in their vicinity, with smaller conduits or fractures providing lesser conductivity in areas further away.