Groundwater Potential Zones in the Koulikoro District, Mali: Delineation Using GIS, Remote Sensing and Multi-Criteria Analysis

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.