On the Experience of Groundwater Vulnerability Assessment in Portugal

Abstract

During the 70 s and 80 s groundwater vulnerability mapping in Portugal was based mainly on the interpretation of the geological information in terms of vulnerability to groundwater pollution. In the 90 s a parametric method for the assessment vulnerability to pollution was introduced by the USEPA (the DRASTIC index). In 1993 Portugal (mainland) was the first European Union s Member-State to have its territory mapped using the DRASTIC index (1:500 000 scale). Since then several applications of the DRASTIC index, at different scales, and using different sources of base information has been made. The use of different sources of information, with different scales and sometimes with different approaches has lead to different final maps of the same area, as shown in this paper for Setúbal peninsula, just south of Lisbon. With the development of different methodologies for groundwater vulnerability assessment, based on the characterization of different parameters, a comparison of the results computed with these methodologies was justifiable. With this aim, a comparison between the computed results of the application of six vulnerability index methods (AVI, GOD, DRASTIC, SI, EPPNA and SINTACX) was carried out during 2002 for an aquifer system located near Évora (E from Lisbon). Conclusions for further research on vulnerability mapping are addressed at the end of this paper.