ORIGINAL ARTICLE A comparative study of four vulnerability mapping methods in a detritic aquifer under mediterranean climatic conditions M. Draoui Æ J. Vias Æ B. Andreo Æ K. Targuisti Æ J. Stitou El Messari Received: 10 November 2006 / Accepted: 1 May 2007 / Published online: 20 June 2007 Ó Springer-Verlag 2007 Abstract This paper presents the results of a comparative study relating to the application of four vulnerability mapping methods, GOD, AVI, DRASTIC and SINTACS, in a pilot detritic aquifer situated in NW Morocco, known as the Martil–Alila aquifer. The principal objective of this work is to determine the most suitable such methods for this aquifer type within a Mediterranean context, and to show the effect of the rainfall variations that are charac- teristic of the Mediterranean climate on the degree of vulnerability. The methods applied distinguish five classes of vulnerability, these being irregularly divided up in space, with the division varying according to the method in question. The vulnerability maps obtained by the different methods strongly suggest that the eastern half of the aquifer is more vulnerable to contamination than the western half, for all hydrological situations. The effect of climatic con- ditions on the degree of vulnerability is well represented by the DRASTIC, according to which the aquifer is moder- ately to strongly vulnerable during humid hydrological years and weakly to moderately vulnerable during dry ones. For the other methods, this climatic effect is limited to the area occupied by the two predominant classes (‘‘High’’ and ‘‘Low’’ for GOD and ‘‘High’’ and ‘‘Moderate’’ for SINTACS) while it is null for AVI. In conclusion, DRASTIC appears the most suitable for map- ping the vulnerability to contamination of Mediterranean coastal detritic aquifers such as the Martil–Alila aquifer. Keywords Detritic aquifer  GOD, AVI, DRASTIC and SINTACS methods  Vulnerability mapping  Mediterranean climate Introduction Coastal Mediterranean groundwater, considered a precious and limited resource, plays an important role in the supply of potable water. Demand for it increases particularly dur- ing the summer, the period associated with considerable tourist activity, but also the one that usually coincides with the lowest levels of water. Thus, there is a huge discrepancy between the availability of this resource and the demand for it. Furthermore, in terms of this quantitative imbalance, groundwater is subject to considerable harmful impacts of human activity taking place on land above the aquifers, which results in the deterioration of their quality. These conditions make it necessary to devise new strategies, such as the mapping of vulnerability to contamination, to achieve good management of this natural resource, protecting and preserving its quality and extending its usefulness. Interest in the protection of groundwater sources as an aspect of environmental management began after the introduction of the vulnerability concept by Albinet and Margat (1970). Since then, several studies on this issue have been published (Foster 1987; Adams and Foster 1992; Robins et al. 1994; Vrba and Zaporozec 1994; Ho ¨tzl 1996; M. Draoui (&)  K. Targuisti  J. Stitou El Messari Geology Department, Faculty of Science, University Abdelmalek Essaa ˆdi, P.O. Box 2121, 93002 Tetouan, Morocco e-mail: draoui9@caramail.com J. Vias Department of Geography, Faculty of Philosophy and Letters, University of Malaga, 29071 Malaga, Spain e-mail: jmvias@ma.es B. Andreo Department of Geology, Faculty of Science, University of Malaga, E 29071 Malaga, Spain e-mail: andreo@uma.es 123 Environ Geol (2008) 54:455–463 DOI 10.1007/s00254-007-0850-3