DRISTPI, a new groundwater vulnerability mapping method for use in karstic and non-karstic aquifers

This paper proposes a new method, called DRISTPI, to evaluate the intrinsic vulnerability to contamination of different types of aquifers. Taking the DRASTIC method as a starting point, we highlight the need to define two scenarios to differentiate karst materials from the rest of the study area. The changes made in DRISTPI, with respect to DRASTIC, include the elimination of factors that are mainly related to the movement of water through the saturated zone of the aquifer (the original A and C factors) because the aim of this new method is to protect the groundwater (the resource) rather than the water supply (the source). Furthermore, the DRISTPI method incorporates a new factor called PI to characterize areas of preferential infiltration. Specifically, the vulnerability of two European aquifers with different geological, hydrogeological and climatic characteristics was evaluated using the DRISTPI method, and the results were compared with those obtained using DRASTIC, PI, COP, the Slovene Approach and PaPRIKa methods. These results were statistically analysed by confronting spatial autocorrelation coefficients to measure the cross-correlation between pairs of vulnerability maps.