No abstract

Stratiform fissured layer within basement aquifers has increasingly been tapped because of its good transmissivity and groundwater storage capacity. This study aims to determine the hydrodynamic properties and thickness of the fissured layer of granitoids in the Tchologo region where access to drinking water has deteriorated over the years. Statistical analysis of the vertical distribution of the linear discharge from 148 boreholes measured from the length below the base of the saprolites has made it possible to characterize the geometry of fissured layer. The useful thickness of the fissured layer was determined from the 80% percentile method. Linear discharge range from 0.0087 to 0.678 m 3 h −1 .m −1 . The thickness of the most transmissive part of the fissured layer is between 20 and 40 m. The 40 m depth is the useful thickness of the hard-rock aquifer. The mean linear discharge and mean discharge for this useful thickness are 0.129 m 3 h −1 .m −1 and 5.21 m 3 .h-1, respectively. These results will improve the success rate of drilling in the region because it will be possible to define the average useful depth of the boreholes to be drilled.