Groundwater Potential Mapping using Geospatial and AHP Techniques in Eastern Province of Rwanda

Abstract

The article presents an analysis of the potential groundwater recharge zones in the Eastern Province of Rwanda using Geographic Information System  (GIS) technology. The groundwater potential zones (GWPZs) in the area are influenced by several factors. To conduct the spatial analysis, seven theme  layers were created and integrated, including geology, drainage density, rainfall, slope, soil, land use and land cover (LULC), and normalized difference  vegetation index (NDVI). The Analytical Hierarchy Process (AHP), based on multiple criteria, was utilized to assign weights to each layer. By overlaying the  theme layers with the prescribed weights, a map of potential groundwater recharge zones was generated. These zones were classified into five  categories: poor, fair, medium, good, and excellent, representing 173 km² (1.9 %), 1002 km² (11.3%), 5976 km² (67.2%), 1732 km² (19.5%), and 12 km²  (0.1%), respectively. The findings revealed that a significant portion of the study area exhibited good to moderate potential zones for groundwater. Among the seven districts in the Eastern Province, Rwamagana district had the highest coverage of good and excellent groundwater potential zones,  accounting for 59% and 1% of the area, respectively. The accuracy of the GWPZ map was assessed by comparing it with borehole yield data, demonstrating the reliability of the chosen methodology. These validated results provide valuable support for the sustainable management and strategic  utilization of groundwater resources in the study area. The study outcomes can guide decision-makers in making informed choices regarding  the conservation of groundwater resources in the research area.