Mapping of Potential Groundwater Recharge Zones: A Case Study of Maputaland Coastal Plain, South Africa

Abstract

Abstract The potential groundwater zones of the Maputaland coastal plain of Kwazulu-Natal is identified by comparing the Analytic hierarchy process (AHP)-Multi criteria decision-making (MCDM)techniqueand Boolean logical approach. The map of groundwater potential zones was prepared by generation and integration of 8 thematic layers, i.e. geology, geomorphology, lineament density, soils, slope, rainfall and land use. Each thematic layer wereassigned with subjective relative weights under AHP-MCDM technique and Boolean logic and were overlaid in aGIS platform to identify the groundwater potential zones. The groundwater potential zones were delineated under two different GIS techniques to obtain confident results. Weights of thematic layers were allocated using AHP normalized eigen vector methodology and weighted linear combination method was employed to find the groundwater potential index.Whereas in a Boolean approach, AND operator was appliedin order to integrate thematic layers to delineate the groundwater potential zones. The delineated groundwater potential maps using AHP-MCDM technique indicates that 6.0% (310.5 km2) from total area falls under very good; 67% (3467 km2) good; 25% (1294 km2) poor and 2% (103.5 km2) under very poor, whereas in Boolean logic about 70 % of the area (i.e. 3623 km2) constitutes good and 30 % (1552 km2) of the areasconstitutes poor groundwater potential zone. Further, the obtained results indicate thatthe geology, geomorphology, landuse and slope playeda vital role in groundwater recharge. Thispioneer study in maputaland coastal plainexplores the baseline data of the potential groundwater zones. The resultsemanating from this study can be used in further understanding of the available groundwater resources and can be helpful in future to find the suitable groundwater exploration sites in the area.