Evaluating the applicability of European karst vulnerability assessment methods to the Yucatan karst, Mexico

The development of vulnerability maps is considered to be the first step in promoting awareness, development of protection strategies and sustainable use of karst aquifers. Nevertheless, high subjectivity of current methodologies for groundwater vulnerability assessment leads to contradictory results when different models are applied over the same area. This makes it difficult for water institutions and decision makers to determine a method to be used on a specific karst area. Four European methods (EPIK, PI, COP and PaPRIKa) were applied for the Yucatan karst to estimate groundwater vulnerability and determine if any of these European methods display vulnerability outcomes in correspondence with regional characteristics such as sinkhole alignments and the shallow water table. Agreement between methodologies was evaluated according to the spatial match on vulnerability rates displayed by final maps; intrinsic features influencing such match and divergent factors were highlighted. Similar vulnerabilities, with more than 52% in average of spatial agreement, were found between COP, PI and EPIK maps. A considerable average up to 33% of match in moderate vulnerability between these three methods was analysed. However, despite the methods displaying similarities regarding moderate vulnerability, these methodologies show no congruence with regional characteristics. A result of a moderate vulnerability on Yucatan coastal and central areas, where the unsaturated zone reaches just a couple of metres, is not an accurate outcome for the shallow water table. Adaptations of these methods or a new integrated methodology would be necessary to estimate groundwater vulnerability in the Yucatan karst.