Study of the Vulnerability of Fractured Aquifers in the Context of an Implementation of a Modern Landfill: Application of Remote Sensing and the Geotechnical Method on the Site of Kossihouen (Côte d'Ivoire, West Africa)
Résumé
The workshop of the interdepartmental committee responsible for managing household waste in Abidjan (Ivory Coast) in 2007 showed that the landfill site should be chosen out of the coastal sedimentary basin to protect the groundwater of the Continental Terminal aquifer against pollution. Indeed, this aquifer provides the potable water to Abidjan populations and also assures uniformity of the price of water by the water company of the Ivory Coast. But, given the groundwater flow and the possibility of transfer of fluid between the discontinuous and continuous aquifers, is it possible that an activity taking place outside the coastal sedimentary basin of Côte d'Ivoire (such as a landfill site) contributes to the pollution of the groundwater in Abidjan. To resolve this problem, the geotechnical surveys, the laboratory tests and in-situ tests were conducted to determine the types of the soil across the study site. The Landsat TM scenes 196-56 of 12/30/1990 were processed to study the fracturation of the site. The geotechnical tests carried out in situ on the study area and the laboratory test allowed knowing the nature of the formations and their differents permeabilities. Indeed, the formations are generally complex and formed of sandy clay of low to very low permeability ranging from 9.8. 10-7 to 1.1. 10-5 m/s in situ and 1.68.10-6 to 1.76. 10-5 m / s in the laboratory. Regarding remote sensing, the Landsat image processing revealed mega-fractures (NE-SW) on the site of the modern landfill of Kossihouen.