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Title: Investigation of potential high-yielding groundwater aquifer zones using remote sensing & GIS technology
Authors: Moodley, Tyrone 
Keywords: Groundwater;Aquifer zones;Remote sensing;GIS technology
Issue Date: 29-Sep-2022
Groundwater exploration has been critical in considering groundwater as an alternative
freshwater source in basin management. Groundwater exploration simulates the aquifer yield
capacity, which is helpful for planning purposes and water resource assessments. However,
understanding the dynamic flow conditions of groundwater affected by anthropogenic land
cover, water use changes, and uncertain climatic variability, especially in a semi-arid region
like South Africa (SA), has called for quantification and quality rating of the resource. The aim
of this study was to assess the groundwater potential (GWP) and identify high-yielding
groundwater aquifer zones in KwaZulu-Natal (KZN), South Africa. Groundwater potential
zones were spatially mapped using Geographic Information Systems (GIS) and remote sensingbased multi-criteria analysis. Spatial thematic layers viz. geology, lineament density, slope,
drainage density, rainfall, land use/land cover and evapotranspiration were processed and
developed using GIS and weighted using Saaty’s Analytical Hierarchy Process (AHP). The
thematic layers were subsequently aggregated using the GIS Weighted Overlay Method to
develop a groundwater potential index map. Indices from the map were correlated with data
from 113 boreholes using the Receiver Operating Characteristic Curve (ROC) and Area Under
the Curve (AUC) to validate the results. Due to the widespread domestic use of groundwater in
SA and the minimal available groundwater quality data in KZN, the groundwater quality data
for parts of SA were analysed regarding concentrations of pollutants, inorganic chemicals and
macropollutants. Groundwater quality data was obtained from available literature across SA
and was compared with the South African National Standards (SANS) and World Health
Organization’s (WHO) guidelines for drinking-water quality using the weighted arithmetic
Water Quality Index (WQI). A Piper Plot was then used to graphically analyse the chemistry
of the groundwater samples to compare their ionic compositions. The groundwater quality
results revealed that most parameters were below or slightly above the maximum permissible
limit, except fluoride, which exceeded the permissible limit in most studied locations and
drastically affected the WQI values. The computed WQI values ranged from 37.92 – 436.06.
Therefore, of the eleven groundwater data sets, four are classified as “good”, two as “poor”,
one as “very poor”, and four as “unfit for drinking”. The results highlight the need to treat
fluoride in South African groundwater, as it is a significant factor in categorising areas suitable
for groundwater consumption. From the groundwater quality results it was deduced that the
water quality data was either clustered as “magnesium-bicarbonate” or “sodium-chloride” type.
The results of the groundwater potential mapping revealed that the AHP-based GWP map exhibited a strong correlation with borehole data (r=0.726, n=113), indicating the accuracy of
the AHP as a rating method. The results computed that approximately 47.3 km2
(2%) of the
total area falls under Excellent GWP, 24405.4 km2
(27.45%) under good GWP, 50950.5 km2
(57.3%) under moderate GWP, and the poor and very poor GWP zones constitute around
13380.8 km2
(15.1%) and 135.6 km2
(1%) of KZN respectively.
Submitted in fulfilment of the academic requirements for the degree of Master of Engineering in the
Department of Civil Engineering and Geomatics, Durban University of Technology, 2022.
Appears in Collections:Theses and dissertations (Engineering and Built Environment)

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