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residential, industrial and irrigation water on the Mfolozi, Mhlatuze, Mvoti, Mgeni and
Mpambanyoni rivers in the coastal zone.
(iil Berea Formation (Quaternary)
In the immediate coastal areas the base of the unconsolidated sandy Berea Formation of
Quaternary age, which is an in situ weathered coastal dune, can frequently be an aquifer
of considerable significance. Groundwater moves in a downslope or seaward direction in
the base of the formation (perched on the surface of the underlying impermeable bedrockl,
in a 1 - 2 m thick zone, the highly permeable overlying sandy material of considerable
thickness being dry. Where it emerges at the toe of the slope, the groundwater is often
under some slight artesian pressure - this being the origin of Currie's Fountain adjoining the
Botanical Gardens at the foot of the Berea in Durban*. Shallow screen wells of about
10 - 15 m depth installed in this sandy aquifer provide good yields of the order of 20 m 3
h- 1 from 200 mm diameter wells, the water quality being very good. The aquifer in the
same situation at the base of the Berea Formation, on the south bank of the Mhlatuze
River on the ridge opposite Felixton, is also being successfully exploited for domestic water
by means of a number of 20 - 25 m deep screen well boreholes. The groundwater quality
is very good in view of the exceptionally high mean annual rainfall of approximately
1 500 mm.
Interestingly in Durban, one deep screen well borehole of some 70 m depth located on the
highest part of the Bluff ridge of the Berea Formation, provides a good yield of high quality
groundwater on the basal contact of the formation with the underlying calcareous
sandstone (aeolianitel of the Bluff Formation. This groundwater constitutes seawards
seepage from the Happy Valley interdune swamp between the Bluff and Wentworth ridges,
to the west of the Bluff ridge proper.
*
Currie's Fountain was the second source of water for the growing infant city until about the 1870s.
The original water supply in Durban came from shallow wells dug in the alluvial sediments, as at the
Old Fort, and at the present location of Old Well Court between Smith and West streets - just west
of Field Street in the Central Business District.