Integrated Assessment of Groundwater Potential Using Geospatial Techniques in Southern Africa: A Case Study in the Zambezi River Basin

Abstract

Groundwater resources are largely used in rural communities of river basins due to their acceptable water quality and reliability for domestic purposes where little or no treatment is required. However, groundwater resources have been affected by changes in land use, mining activities, agricultural practices, industrial effluent, and urbanisation among anthropogenic influences while climate change impacts and volcanic eruptions have affected its involvement among the natural phenomena. The purpose of the study was to assess groundwater potential in the basin with the use of Analytical Hierarchy Process (AHP), remote sensing, GIS techniques, and groundwater occurrence and movement influencing factors. These factors were used to produce seven thematic maps, which were then assigned weights and scale using an AHP tool, based on their degree of influence on groundwater occurrence and movement. A weighted groundwater potential map was produced with four zones denoted as 0.4% (317 km2) for very good potential; 27% (19,170 km2) for good potential; 61% (43,961 km2) for moderate potential and 12% (8639 km2) for poor potential. Validation, using existing boreholes, showed that 89% were overlain on moderate to very good potential zones and henceforth considered to be a novel approach which is useful for groundwater resources assessment and integrated water management in the basin.

Assessment of groundwater potential zones using an integration of Remote Sensing, GIS and 2D Electrical Resistivity imaging in the Echway watershed, Baro River Basin, Southwest Ethiopia

“…Infiltration amount decreases when the terrain is steeper, and infiltration ratios are raised when the topography is plain. The amount of precipitation that percolates and reaches the aquifer highly depends on the slope's nature [22]. Most of the study area comprised plain to moderate slopes, with steep slopes representing only a small portion of the region.…”

An Integration of Geospatial Modelling and Machine Learning Techniques for Mapping Groundwater Potential Zones in Nelson Mandela Bay, South Africa

“…Groundwater recharge and drainage density (DD) are complexly related and affected by various lithological structural factors [4,17]. Prior research has indicated that areas characterized by low drainage density are more prone to groundwater recharge [8,17], whereas other studies suggest that high drainage density constitutes a high potential for recharge [5].…”

“…Groundwater recharge and drainage density (DD) are complexly related and affected by various lithological structural factors [4,17]. Prior research has indicated that areas characterized by low drainage density are more prone to groundwater recharge [8,17], whereas other studies suggest that high drainage density constitutes a high potential for recharge [5]. In this study, the inverse connection between drainage density and groundwater was employed, where regions exhibiting very high DD imply rapid runoff and drainage from the area [17].…”

“…Rather, they assist in explaining features that could be associated with the availability of groundwater [16]. The GIS approach has been integrated with various techniques, such as multicriteria decision-making methods including analytical hierarchical process (AHP) which is widely used for groundwater mapping [2,5,8,17], and fuzzy-AHP [18,19], multi-influencing factor (MIF), fuzzy logic (FL), certainty factor (CF) [20], weight of evidence (WOE) [21], evidence belief function (EBF) [22] for landslide mapping, and index models (IMs) [17,23]. Other researchers, such as Mogaji et al [24], have also attempted to delineate GWPZs based on techniques such as the Dempster-Shafer theory of evidence (DS-EBF) model, which revealed great accuracy.…”

“…The AHP technique, as explained by Abrar et al [8], enables researchers to define groundwater potential zones (GWPZs) by evaluating the importance of hierarchically non-saturated criteria concerning those positioned at a high level. Based on the AHP and GIS approach, Ndhlovu et al [17] evaluated GWPZs in the Zambezi by assessing the effect of various factors, such as lineament density, lithology, land use and land cover (LULC), soil properties, slope degrees, rainfall, and drainage density, and argued that these factors have the potential in determining groundwater potential. Owolabi [25] attempted to develop feasible research to demonstrate a GWPZ with a high accuracy in the Eastern Cape, and claimed that the AHP model is vital to delineating GWPZs in semiarid regions.…”