Airborne and Ground Geophysics for Modelling a Karstic Conduit System: New Results from the 2007-2011 Campaigns in Tulum

Karst aquifers represent important sources for water supply to a significant part of the earth’s population. For sustainable use of these resources, development of management tools based on numerical groundwater models is required. A flow model of karst aquifers requires spatially distributed information on its characteristic flow domains. Methods determining the distribution of the electrical resistivity within the subsurface could provide such information. To explore the potential of airborne electromagnetic (AEM) mapping for providing such information to groundwater modelling of karst aquifers, the international project XPLORE was initiated. The project is carried out around the Sian Ka’an Biosphere Reserve, located near Tulum, Mexico. Airborne surveys were performed in 2007 and 2008 to prove the basic applicability of the AEM method. The results show that the signature of the cave system can be clearly detected by AEM mapping. Additionally, for better coverage of ground truth and calibration of the hydrological model, three extended ground geophysical campaigns have been conducted in 2009-2011 comprising geoelectrics, GPS-water level measurements, GPR, and borehole geophysics. The airborne data as well as mapped caves were used to generate a numerical ground water model of the karst system.