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Left: During heavy rains a spruit becomes
a torrent carrying valuable topsoil with it.

Last month, the estates north of
Johannesburg and south of Pretoria
received between 100mm and 130mm
of rain in 24 hours. Being of a certain
age, I automatically translate 100mm
as ‘four inches’ a figure that sticks in
my mind, because I recall ‘four inches’
falling where I was living in Bryanston in
1970 and being told it was a record.
That much rain (100mm) falling on a
square kilometre, which is about the
size of the estate in which I nowadays
live, would weigh 100 000 tons.
Despite appearances South Africa is, and
always will be, short of water. A neighbour
has just sunk a borehole in her driveway
which yields 1 000 litres of groundwater a
day - plenty, as a supplement, for most
people’s purposes. Ground water will
save Gauteng one day.

For a book I wrote for the World
Summit in 2002 (Coming Back to
Earth), I ascertained that the reserves
of groundwater in the PWV region
(Pretoria, Witwatersrand, Vereeniging)
were estimated at 10 000 million cubic
metres. Compare that with the Gariep
Dam’s 6 000 million. Groundwater can
be stored for as long as we like – and,
while it is underground, it’s evaporation-
free.

The impact of floods on our

vulnerable ecosystem.

A flooded wetland -
note the sacred ibises
gorging on creatures
rising from the ground.

15
DPL