Groundwater Potential Zones in the Koulikoro District, Mali: Delineation Using GIS, Remote Sensing and Multi-Criteria Analysis
Emmanuel Sagara *
Department of Geography, Faculty of History and Geography (FHG), University of Social Sciences and Management of Bamako (USSGB), Mali.
Souleymane Bengaly
Faculty of History and Geography (FHG), University of Social Sciences and Management of Bamako (USSGB), Mali.
Adama Youssouf Kone
Laboratory of Geodynamics and Cartography (LGC), Faculty of Science and Technology (FST), University of Science, Technology, and Engineering of Bamako (USTTB), Mali.
Moussa Aliou Keita
Faculty of History and Geography (FHG), University of Social Sciences and Management of Bamako (USSGB), Mali.
*Author to whom correspondence should be addressed.
Abstract
Background: Groundwater development in Precambrian basement terrains is constrained by the discontinuous and heterogeneous distribution of productive aquifers.
Aim: This study aimed to map potential groundwater zones in the Koulikoro district (Mali) by integrating Geographic Information Systems (GIS), remote sensing, and Multi-Criteria Analysis (MCA), and to validate the resulting map using borehole production data.
Study Design: A spatial analysis using a weighted multi-criteria overlay combined with validation against field borehole data.
Place and Duration of Study: Koulikoro district, Koulikoro Region, Mali. The data covered the period 1992–2022.
Methodology: Seven hydrogeological criteria—slope, geology, fracture density, drainage density, weathering thickness, rainfall, and land use—were derived from Sentinel-2 imagery (10 m), a Digital Elevation Model (30 m, SRTM/NASA), geological maps, and the national borehole database (SIGMA). Each criterion was reclassified into five suitability levels and weighted using Saaty's Analytic Hierarchy Process (AHP). A weighted overlay in ArcGIS produced the groundwater potential map.
Results: About 68% of the study area (3,769 km² of 5,510 km²) shows high or moderate potential, with 30% classified as 'high' and 38% as 'moderate'. The remaining area is classified as 'low' (4%) or 'very low' (28%). Validation against the yields of 214 boreholes shows an overall agreement of 71%, with 89% of boreholes in the 'very good' yield class occurring within 'high' potential zones and 56% of boreholes in the 'low' yield class occurring within 'very low' zones. The association is highly significant (chi-square = 289.4, df = 9, p < 0.001; Cohen's kappa = 0.58). The AHP consistency ratio (CR = 0.082 < 0.10) indicates acceptable consistency among the pairwise judgements. The map expresses relative groundwater prospectivity rather than groundwater volume or sustainable yield.
Conclusion: The integrated GIS, remote sensing, and MCA approach identifies priority zones for further groundwater investigation in the Koulikoro district and provides a cost-effective screening framework for sustainable groundwater resource management in similar Precambrian basement settings.
Keywords: Groundwater potential, geographic information systems, remote sensing, multi-criteria analysis, analytic hierarchy process, Borehole