Assessment of groundwater vulnerability in coastal zone using SI method and GIS: case study of Bouficha aquifer (northeast Tunisia).

Nowadays, groundwater is under stress due to contamination, over-exploitation, seawater intrusion, climate change, etc. The groundwater contamination is the major problem which can engender the total deterioration of the aquifer. The groundwater vulnerability assessment may contribute to predicate and to delimitate the areas affected by contamination or any future pollution. This research aims to zoning the potential pollution of the Bouficha shallow aquifer, located in the northeast Tunisia, using the SI model and GIS. Five parameters are presented in the SI model: depth to groundwater (D), recharge (R), aquifer media (A), topography (T), and land use (LU). The different parameters were collected from diverse sources for assess groundwater vulnerability. The net recharge map was generated using GIS-based multi-criteria analysis method based on different parameters (slope, lithology, LU, soil, and drainage density). The generated vulnerability map shows three vulnerability classes: low vulnerability (< 45), moderate vulnerability (45-64), and high vulnerability (64-84) which represent 3.14%, 76.8%, and 20.06% of the total area, respectively. The SI vulnerability represent a moderate positive correlation with the measured nitrate concentrations (R = 0.76). The sensitivity analysis shows that the land use parameter is the most influential parameter for groundwater vulnerability in BFC.