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(d) Waters of Group B are found in the fairly flat and bush-clad Lowveld areas,
extending far inland along the flats and up the main river valleys.
Group C: Slightly saline waters
(a) TDS values are usually less than 600 mg r', although there is little difference in
percentage composition between Group C, and Group A and B waters.
(b)· Group C waters are evident in three different localities, namely the coastal zone,
the Lebombo Mountains, and along the escarpment separating the Lowveld and
Middleveld.
(c) In the coastal zone most of the Group C waters (found in Tertiary and Recent
sands) overlie Group A waters present in the Cretaceous beds. Accordingly, in the
False Bay area (St Lucia) where the sand is thin, all shallow boreholes and wells
have Group C waters, while deep boreholes which penetrate the underlying
Cretaceous beds, yield Group A waters. Further south however, in the vicinity of
KwaMbonambi and Mposa the sand is more than 60 m deep and rests directly on
granite and Karoo rocks. No highly mineralized waters are found even in deeper
boreholes (at depths exceeding 90 m), which penetrate the underlying Cretaceous
rocks. Waters of the higher reaches of the Lebombo Mountains where springs are
plentiful, have a low percentage of (sea-derived) salts due to continual leaching.
The leachate is discharged from the lower-lying springs and little concentration of
salts can occur. By contrast, Group B waters are found in rhyolite in the flat, low­
lying areas in the vicinity of Hluhluwe station and Ingweni (where springs are
absent no leaching takes place). Van Wyk (1963) maintained that a similar process
of leaching by springs also operates along the escarpment stretching from Eshowe
through Melmoth, Mahlabatini, and Nongoma to Magudu in the north, with a low
percentage of salts apparent.
Group D: Temporary hard (carbonate) waters
(a) TDS values average 276 mg £"' (Bond, 1946: generally < 150 mg £"1)- equivalent
to Bond's Group E.