Remote Sensing and GIS Contribution for Groundwater Mapping Reservoirs in the Baya Watershed (Eastern Region of Côte d'Ivoire)

Abstract

This study is carried out in the Baya watershed in the eastern region of Côte d'Ivoire to highlight access to drinking water issue in the fratured areas of Côte d'Ivoire. It aims at mapping the groundwater reservoirs to optimize the future installment of new boreholes for a satisfactory success rate. For the methodological approach we use Landsat 7 satellite images to map fracture networks with the use of the directional filtering technique. The induced permeabilities from these fractures were calculated using Fanciss’s method. The multicriteria analysis and Hydrogeological Information System with Spatial Reference were adopted to map groundwater reservoirs. Structural mapping by remote sensing permitted the development of detailed fractures maps with more than 6,998 listed fractures responsible for the formation of fracture aquifers in the Baya watershed. The size of these fractures is spread over two orders of magnitude. The main orientations are NE-SO (N70-80), corresponding to the Eburnean orientations, E-O (N90-100) and NO-SE (N100-120), associated with the Liberian orientation. Induced permeabilities vary from 1.20.10-8 to 4.62.10-5 m/s with a regional average of about 5.32.10-6 m/s. The zones with strong induced permeabilities that coincide with those of high fracturing densities brought us to have five reservoirs in the basin, with two large reservoirs, two media and three small ones. This groundwater flows into the mainstream waters from two main directions.