Evaluation of the Groundwater Vulnerability to Pollution Using an Intrinsic and a Specific Method in a GIS Environment: Application to the Plain of Sidi Bouzid (Central Tunisia)

The protection of groundwater is highly required in regions with arid and semi-arid climate like Sidi Bouzid Aquifer. Vulnerability mapping is considered as a fundamental aspect of sustainable groundwater management especially in overexploited and threatens aquifers. To evaluate the vulnerability to pollution of this aquifer, two intrinsic vulnerability methods were chosen: the generic DRASTIC and the pesticide DRASTIC methods, and a specific one which is the susceptibility index (SI) method. The results show a clear degradation of the water quality throughout the aquifer. The validity of these methods in the phreatic aquifer was tested by a comparison between nitrate concentration and distribution of the vulnerability classes in the study area. This comparison has proved that the SI method is the most valid method. This is due to the introduction of the land use parameter.