chapter 1: WATER RESOURCES: DO WE HAVE ENOUGH?
WATER RESOURCES: DO WE HAVE ENOUGH?
D.B. Versfeld Natural Resources and Forestry Consultant
J.A van Rooyen Director: National Water Resource Planning Department of Water Affairs
INTRODUCTION
The South African National Water Resources Strategy of 2004 carries the sobriquet “our blue print for survival”. With an average rainfall of 450 mm/a, well below the world average of 860 mm/a, the country’s water resources are, in global terms, “scarce and extremely limited” (NWRS, 2004). How has South Africa responded to this, and how do we stand in 2012?
THE WATER BALANCE
The total available water yield for the country was estimated at 13 227 million m3, and total use at 12 871 million m3 in the NWRS (2004). The total national water requirement was therefore only marginally less than the total availability. In reality some water management areas, catchments, and metropolitan water supply systems were in deficit, whilst others had a small surplus. The challenge has always been always to balance the water requirement with supply everywhere – and to always remain one step ahead. Estimates in the NWRS were that ‘reliable local yield’ would be developed to between 14 166 and 14 940 million m3 by 2025, with a potential for further development of 5 410 million m3. This will be necessary to meet the anticipated growth in requirements - expected primarily in urban, rural, mining, and bulk industrial use as the population continues to grow, as past imbalances are redressed, and as the country seeks to expand its economic base. Irrigation use is being strictly managed, with expansion primarily achieved from water saved through efficiency measures. New afforestation will be limited to catchments where water cannot easily otherwise be put to use, or where forestry is clearly the most efficient user. Significant savings have already been achieved in forestry through environmental efficiency measures. New power stations are being constructed but these are drycooled, using only 10% of the water required by older wet-cooled stations. Phasing out of older power stations will, in the longer term, mean a lower demand on water for power generation. Water balance data is summarised in the tables below: Table 1.1: How much water do we have? (NWRS, 2004)
Resource
Volume (million m3)
Mean Annual Runoff: Storage capacity major dams: Available yield Surface water Groundwater Usable return flow Total available yield:
49 040 32 412 10 240 1 088 1 899 13 227
The Sustainable Water Resource Handbook
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