Assessment of borehole failure and drilling rationale using geospatial Technique in Unilorin, North-central, Nigeria

Abstract

Notwithstanding the pre-drilling geophysical surveys, the failure rates and suboptimal productivity of some boreholes within the University of Ilorin (UNILORIN) is calling for concern. On the background, this present study investigated the hydrogeological capability and potentiality of some borehole sites. To achieve this, an inventory of 47 boreholes with an existing lineament density map and Groundwater Potential Zonation (GWPZ) map of Ilorin South local government area were integrated. These boreholes were categorized based on the lineament density and groundwater potentiality. The results showed that 85% of the sampled boreholes were sited on zones of low groundwater potential (LGWP) while 15% were on zones of moderate groundwater potential (MGWP). Also, 4% of the boreholes coincided with zones of moderate lineament density and 96% of boreholes coincided with zones of low lineament density, and no borehole was found to coincide within areas of high lineament density. Conclusively, 83% of these boreholes (39 units) were drilled due to logistics motives (e.g., cost consideration, proximity to facilities, and/or as cosmetic projects) while only 17% of these boreholes (8 units) were drilled on account of scientific necessity or after the appropriate geoscientific evaluation was done. It is hoped that the findings in this study will benefit stakeholders and practitioners in water resource management.