Analysis of Spatial Relationship Between Groundwater Potential Zones and Borehole Yields in Adamawa Sub-Catchment of the Upper Benue River Basin, Northeastern Nigeria

Abstract

The sustainable provision of water resources is a critical challenge in many parts of Nigeria, particularly in semi-arid and rapidly developing regions like the Adamawa sub-catchment of the Upper Benue River Basin. Consequently, the accurate delineation of Groundwater Potential Zones (GWPZ) is paramount for effective water resource management and the sustainable siting of boreholes to prevent failures, which are a common issue in areas with poor groundwater prospects. This research, therefore, focuses on the Adamawa sub-catchment to establish the spatial relationship between predicted Groundwater Potential Zones and the actual yields obtained from existing boreholes. In this study stratified and purposive sampling techniques were employed for sampling boreholes. Representative spread of 414 borehole data cutting across the entire sub-catchment were selected and used for validation. For the production of groundwater potential zones map various thematic maps of individual criterion were integrated through overlay analysis. The yields of existing boreholes and the values produced from the groundwater potential zone map were correlated using Pearson correlation analysis.  The overlay analysis shows that 78.20% of the boreholes fall within groundwater potential zones that correspond to their observed yields, indicating a high level of spatial agreement between predicted potential and actual performance. This suggests that the geospatial modeling approach used to delineate groundwater potential zones is largely effective in capturing the dominant controls on groundwater occurrence within the Adamawa sub-catchment. In practical terms, most high-yield boreholes are located in high-potential zones, while low-yield boreholes tend to fall within low-potential areas. Such a level of agreement is generally considered satisfactory in groundwater studies, given the inherent heterogeneity of subsurface conditions. However, despite the overall strong relationship, 21.8% of boreholes did not correspond to their mapped groundwater potential zones, which is not unusual in groundwater studies. In addition, the result of Pearson moment correlation analysis revealed R is positive 0.782. It is imperative to note that the value of R is meant to show the direction and strength of the relationship between the yields of existing boreholes in the sub-catchment and the groundwater potential map produced. The relationship is a positive, meaning that as groundwater potential increases borehole yield increases correspondingly. The strength of the relation is strong (R = 0.782). The study concluded that there is strong positive relationship between groundwater potential and the existing borehole yields in Adamawa sub-catchment. Some recommendations were also proposed for both practitioners and researchers.