A groundwater potential zone mapping approach for semi-arid environments using remote sensing (RS), geographic information system (GIS), and analytical hierarchical process (AHP) techniques: a case study of Buffalo catchment, Eastern Cape, South Africa

Abstract

Abstract Theme unsuitability is noted to have inhibited the accuracy of groundwater potential zones (GWPZs) mapping approach, especially in a semi-arid environment where surface water supply is inadequate. This work, therefore presents a geoscience approach for mapping high-precision GWPZs peculiar to the semi-arid area, using Buffalo catchment, Eastern Cape, South Africa, as a case study. Maps of surficial-lithology, lineament-density, drainage-density, rainfall-distribution, normalized-difference-vegetation-index, topographic-wetness-index, land use/land cover, and land-surface-temperature were produced. These were overlaid based on analytical hierarchical process weightage prioritization at a constituency ratio of 0.087. The model categorizes GWPZs into the good (187 km 2 ), moderate (338 km 2 ), fair (406 km 2 ), poor (185 km 2 ), and very poor (121 km 2 ) zones. The model validation using borehole yield through on the coefficient of determination ( R 2 = 0.901) and correlation ( R = 0.949) indicates a significant replication of ground situation ( p value < 0.001). The analysis corroboration shows that the groundwater is mainly hosted by a fractured aquifer where the GWPZs is either good (9.3 l/s) or moderate (5.5 l/s). The overall result indicates that the model approach is reliable and can be adopted for a reliable characterization of GWPZs in any semi-arid/arid environment.