7 March 2006
Due to the wide-spread rains over the past two months, major dams in South
Africa currently contain 85% of their overall full supply capacity, compared to
64% at the same time last year. Only three provinces, namely the Eastern Cape,
Limpopo and the Western Cape, have less stored water than at the same time last
year. This contrast of overflowing dams in some river systems, with relatively
empty dams in other river systems, is a long-term indication of South African
climate variability.
In our biggest river system, the Vaal-Orange, the water is currently
adequate to fill up all its major dams. In the Vaal River the Grootdraai Dam is
overflowing at present while the Vaal Dam is approaching 110% of its full
supply capacity with seven sluice gates open at the moment, releasing around
1000 cubic meters per second into the Vaal River. Downstream of the Vaal Dam,
the Bloemhof Dam is currently also overflowing at a rate of 1000 cubic meters
per second. In the Orange River the Gariep Dam is overflowing at about the same
rate. This water feeds into the Van der Kloof Dam, which is currently 86% full.
At Van der Kloof Dam 400 cubic meters per second are currently being released
into the Orange River via Eskomâs hydropower turbines, to generate electricity.
Based on the water currently in the Vaal-Orange System, a peak river flow of
around 1600 cubic meters per second is expected at Upington by 8 March 2006.
For comparison, the peak flow during the 1988 floods was in the order of 8000
cubic meters per second.
In stark contrast with these dams overflowing in the Vaal-Orange System are
the Allemanskraal and Kalkfontein Dams in the Free State currently containing
around 20% of their full supply capacities. The rivers upon which these dams
are situated also form part of the catchment areas of the Vaal and Orange
Rivers.
In Mpumalanga rivers are flowing strongly and the situation calls for
caution. The flow rate in the Sabie River at the Kruger Gate of the Kruger
National Park is around 1000 cubic meters per second and the river threatened
to burst its banks few days ago. The Olifants River currently carries around
600 cubic meters per second, which does not represent a problem at this stage,
seeing that the flow in the Upper Olifants River is steady with the inflow into
the Witbank Dam at around 50 cubic meters per second.
After a very dry span of four years the Bronkhorstspruit Dam is nearly full
and is expected to start overflowing within a few days. All water shortage
problems in Mpumalanga have not been solved as yet by these welcome rains over
the past few weeks, however. The Kwena Dam in the Crocodile River catchment,
inter alia providing water to the town of Nelspruit, is still only around 32%
full, while the Driekoppies Dam in the Komati River, providing water for
irrigation farming and to communities, is only 43% full. In the upper reaches
of the Olifants River Catchment, the Rhenosterkop Dam is still less than 30%
full.
While catchments in Limpopo province are currently generally not as wet as
those in Mpumalanga, many rivers in Limpopo are flowing strongly. Strong flows
have been recorded in the upper reaches of the Limpopo and flow rates of just
below 600 cubic meters per second are being recorded at Beit Bridge. South
Africa has an understanding with water managers in Mozambique to let them know
if flow rates in the Limpopo River at Beit Bridge start to exceed 1000 cubic
meters per second. Although many dams in the Limpopo Province are full, other
dams still require substantial inflows during the remainder of the summer
rainfall season. The Tzaneen Dam in the Great Letaba River is currently less
than 40% full, while the Middle Letaba Dam in the Middle Letaba River is 44%
full. The Ebenezer Dam also in the Great Letaba River, inter alia supplying
water to Polokwane, is also only around 40% full.
In general the public should be careful in all their dealings around rivers
at this stage. Most catchments are wet and any further rain is likely to
rapidly generate run-off and thus rising water levels in rivers.
Enquiries:
Mr Amelius Muller
Chief Director: Regional Co-ordination and Support
Tel: (012) 336 8746
Cell: 082 807 4341
Issued by: Department of Water Affairs and Forestry
7 March 2006
