摘要
The lack of knowledge about fracture systems in Tanda region has led to an approximative establishment of drilling and so a difficult access to groundwater. Thus, a multidisciplinary approach including satellite imagery and electrical resistivity method was conducted with the main objective to locate productive fractures of water in the study area. Indeed, 195-54, 195-55, 196-54, and 196-55 scenes of Landsat 7 ETM+ satellite images were used. Also, sixty-two (62) vertical electrical soundings (VES) of the Schlumberger configuration and hundred twenty-nine (129) electrical trailing (ET) were performed with a resistivity-meter SYSCAL Pro. Thanks to different treatments applied to satellite images, structural lineaments have been extracted whose main directions are N00-10 (N-S), N90-100 (E-W), N70-80 and N100-110. The interpretation of electrical trailing data made it possible to validate the lineament map by the determination of the fracturing directions. Those are NW-SE, N-S, NE-SW and to some extent E-W. The result of the electrical sounding data showed the presence of three geoelectric layers comprising firstly cuirass and lateritic clays and possibly topsoil, secondly sands and/or clay sandstone and firdly either granites or sandstones or schists. The second geoelectrical layer corresponds to the potential aquifer because of its relatively low electrical resistivity values (13 Ω·m to 180 or 240 Ω·m). In addition, drillings established at the right of these geological structures provided an average water yield of 4.22 m3·h-1, sufficient for rural hydraulic. Moreover, these results made it possible to obtain a correlation between drilling productivity and the major directions of fracturing. This indicates that the most productive directions are in order of importance NE-SW, NW-SE, E-W and finally N-S. They also correspond to the major fracturing directions of Tanda region. These results are encouraging and contribute to a better implementation of future drilling in this region.
The lack of knowledge about fracture systems in Tanda region has led to an approximative establishment of drilling and so a difficult access to groundwater. Thus, a multidisciplinary approach including satellite imagery and electrical resistivity method was conducted with the main objective to locate productive fractures of water in the study area. Indeed, 195-54, 195-55, 196-54, and 196-55 scenes of Landsat 7 ETM+ satellite images were used. Also, sixty-two (62) vertical electrical soundings (VES) of the Schlumberger configuration and hundred twenty-nine (129) electrical trailing (ET) were performed with a resistivity-meter SYSCAL Pro. Thanks to different treatments applied to satellite images, structural lineaments have been extracted whose main directions are N00-10 (N-S), N90-100 (E-W), N70-80 and N100-110. The interpretation of electrical trailing data made it possible to validate the lineament map by the determination of the fracturing directions. Those are NW-SE, N-S, NE-SW and to some extent E-W. The result of the electrical sounding data showed the presence of three geoelectric layers comprising firstly cuirass and lateritic clays and possibly topsoil, secondly sands and/or clay sandstone and firdly either granites or sandstones or schists. The second geoelectrical layer corresponds to the potential aquifer because of its relatively low electrical resistivity values (13 Ω·m to 180 or 240 Ω·m). In addition, drillings established at the right of these geological structures provided an average water yield of 4.22 m3·h-1, sufficient for rural hydraulic. Moreover, these results made it possible to obtain a correlation between drilling productivity and the major directions of fracturing. This indicates that the most productive directions are in order of importance NE-SW, NW-SE, E-W and finally N-S. They also correspond to the major fracturing directions of Tanda region. These results are encouraging and contribute to a better implementation of future drilling in this region.
