Groundwater vulnerability mapping for a sub-catchment of the Rio La Venta watershed, Chiapas, Mexico

Karst systems are particularly vulnerable to overexploitation and pollution due to their high hydraulic conductivity and points of rapid infiltration that allow quick influx of runoff and pollutants into the aquifer. The sustainability of non-contaminated groundwater in these systems is imperative for both humans and groundwater-dependent ecosystems. An important practice in managing groundwater sustainability involves assessing aquifer vulnerability. This study created the first groundwater vulnerability map (GVM) for a sub-catchment of the Rio La Venta watershed in Chiapas, Mexico, using an adaptation of the hazard–pathway–target method. This project also conducted the first tracer study in the Rio la Venta watershed to establish connectivity between the catchment and the Rio La Venta Canyon. Finally, this study evaluated the results of the GVM through a sensitivity analysis. Results of the GVM clearly demarcate areas of very high, high, moderate, and low vulnerability within the study area most of which being classified as low vulnerability. The zones of high vulnerability were successfully validated through two dye tracer tests that measured rapid groundwater flow velocities. With the limited resources available to land managers in this area, a problem common in many developing countries, tools that quickly and inexpensively highlight areas that require special protection to help maintain or improve water quality in their watersheds have great utility. Conveying this information to land managers and policymakers can lead to potential changes in current land use practices and allow for the reallocation of resources in support of reducing future negative human–landscape interactions.