The health and life expectancy of populations in developing countries is
largely determined by the availability of good quality drinking water.
Boreholes and springs generally provide water of better microbiological and
physical quality than surface water sources, however, they may cause health
and aesthetic problems due to chemical constituents dissolved out of the host
rock.
As part of a pilot study to assess the health-related quality of community
water supplies, samples were taken from two Quaternary catchment areas in
KwaZulu-Natal. The Umkomazi catchment area is located inland from
Amanzimtoti, while the Umfolozi catchment area is located north-east of
Ulundi. The geology in these areas is significantly different. The Umkomazi
area is predominantly underlain by basement rocks of the Natal Structural
and Metamorphic Province, while the Umfolozi area is underlain by
sedimentary rocks of the Karoo Supergroup.
Geographical information systems (GIS) were used to examine the influence
of lithology, rainfall and landuse activities on groundwater quality. Major ion
analysis of groundwater samples from the Umkomazi area revealed a linear
relationship between borehole and spring concentrations. Dwyka Tillite was
found to produce water with the highest concentrations of major ions, while
Karoo dolerite produced water with the lowest concentrations of major ions.
Samples from basement rocks and Natal Group contained intermediate
concentrations of major ions. In the Umfolozi area Karoo dolerite samples
showed the lowest concentrations of major ions, while the Vryheid Formation
and Dwyka Tillite produced the highest borehole and spring concentrations,
respectively. High salinity levels in sedimentary rocks may be due to marine
influence during deposition. Piper diagrams show relative enrichment of
major cations and anions and Stiff diagrams showed characteristic patterns.
Fluoride is associated with siliceous basement rocks and related to calcium
concentrations through the solubility of calcium fluoride. The trace metals,
manganese, iron and zinc were found to cause significant aesthetic problems
and possibly health problems in sensitive individuals. These constituents are
derived from weathering of bedrock and possibly from the corrosion of metal
pipes.
There is an inverse relationship between mean annual rainfall (MAR) and
electrical conductivity (EC), except near the coast where windblown salinity
increases with rainfall. Nitrate, ammonium and E. Coli contamination are
linked to landuse activities such as occurrence of human and animal excreta
near the water source and the proximity of pit latrines. It is recommended
that rural communities be educated about the nature and importance of
groundwater quality. / Thesis (M.Sc.)-University of Natal, Durban, 1998.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/4655 |
| Date | January 1998 |
| Creators | Sherman, Heidi Michelle. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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