ABSTRACT
ABSTRACT: This study presents an estimation of the vulnerability to pollution of the Mio-Pliocian and Quaternary aquifer in Porto-Novo region (South-East of Benin), part of the coastal sedimentary basin of Benin. The DRASTIC and GOD methods based on the characterisation of seven parameters for DRASTIC and three parameters for GOD were used in a GIS environment with ArcView software. The physico-chemical parameters of the groundwater have been evaluated in order to compare the results of the two methods and the derived pollution status. The results show that DRASTIC is the better method given the local conditions. The vulnerability map indicates that the coastal plain (South of Porto-Novo lagoon) has high and very high vulnerability. But, this zone is not more contaminated because there is little human activity. In the North of Porto-Novo lagoon, the aquifer vulnerability is medium and low, but the nitrate contents are highest, with concentrations reaching 334 mg/. The medium, high and very high degrees of vulnerability represent 80% of the mapped areas and 99.95% do not have a natural hydrogeological protection. Measures should be taken to protect the quality of the groundwater which is critical to the wellbeing of the people living in this rural zone.
