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11.6 A review of groundwater conditions in Natal/KwaZulu*
11.6.1 Types of aquifers
80th primary (porous flow) and secondary (fracture flow) aquifers are found. In the
former, the groundwater is contained in voids between the material particles, while in the
latter it is contained in discontinuities such as joints, fractures and bedding planes, within
and between various types of hard rock. Existing groundwater exploitation in
NatallKwaZulu, and its potential exploitation, mainly involves secondary aquifers. Primary
aquifers consisting of unconsolidated sediments are not common in the province. These
aquifers comprise sandy sediments in the "estuaries" of major rivers, the sandy beds of
rivers themselves in places, and sandy sediments of the Maputaland area of the Zululand
Coastal Plain where shallow perched water table conditions are evident (due to the
presence of underlying less permeable sediments) * * .
11.6.2 Factors affectinq groundwater availability
Apart from aquifer type, a number of other factors influence the availability and
characteristics of groundwater at any locality in NatallKwaZulu. The most important of
these are rainfall and topography and to a lesser extent, type of vegetation cover. Rainfall
over the region varies from about 1 400 - 2 000 mm annually in the elevated, and parts
of the coastal areas, to about 320 - 600 mm in the Dry Interior (River) Basins and in the
northern Lowveld areas. Most of the rain falls in the summer months when
evapotranspiration is high. There is no linear relationship between rainfall and the yield and
occurrence of groundwater in a given geological formation. However, the amount and
distribution of rainfall is very important in that the recharge of groundwater results
therefrom, and this has a marked effect on the sustainable exploitation of groundwater
(and the occurrence of springs). The recharge of groundwater results from percolation to
deeper levels both of rain falling on the soil surface, and percolation directly from the beds
*
**
Section written by Maud, R.R., 1993. Drennan Maud and Partners, Durban, with editorial
amendments by Alcock, P.G., 1994.
See Section 11.12.1.