A Multi-criteria Decision using the Analytical Hierarchy Process (AHP) for Delineation of Groundwater Potential Zones in Part of the Obudu-Massif, Nigeria

Groundwater occurrence incrystalline basement terrains is stronglycontrolled by lithology, structural features,topography, and climatic conditions. Thisstudy evaluated groundwater potential zones(GWPZ) in parts of the Obudu Massif,Southeastern Nigeria, Using an integratedGeographic Information System (GIS) andAnalytical Hierarchy Process (AHP)approach. Eight groundwater conditioningfactors, namely lithology, lineament density,drainage density, precipitation, elevation,slope, aspect, and curvature, were analyzedand weighted through pairwise comparisonwith the AHP framework. The resultingconsistency ratio (CR) of 0.071 indicatedacceptable consistency in the weightingprocess. The analysis revealed thatgeology/lithology (42.6%) and lineamentdensity (18.6%) exert the greatest influence ongroundwater occurrence, followed by drainagedensity (12.5%) and slope (10.5%). Thegroundwater potential map produced,delineated the study area into three classes:low high and very high GWPZs. Raster pixelinterpretation showed that high GWPZ coverapproximately 119 km2(49.3%) of the studyarea, while very high GWPZ occupy about30km2(12.3%). Low GWPZ account for 92 km2(38.4%). Areas with very high groundwaterpotential are mainly concentrated within thecentral-southern and southeastern portions ofthe study area, where favorable lithologic andstructural conditions enhance groundwaterrecharge and storage. A strong positiveagreement between intermediate-to-hightransmissivity values obtained from pumpingtest data and the mapped high-to-very-highgroundwater potential zones confirmed thereliability of the model. The high to very highGWPZs were considered indicative of themodel accuracy. The study demonstrates thatthe integration of GIS, remote sensing, andAHP provides a reliable and cost-effectiveapproach for groundwater exploration,borehole siting, and sustainable groundwaterresource management in crystalline basementterrains.