Ellen Bartlett
South Africa has long operated under the assumption that it is running out of water. The year 2020 is the oft-projected point at which the country will no longer have enough water to meet its needs.
In looking towards a future of high demand and dwindling supply, water resources planners have considered such schemes as diverting water from the Zambezi River and bringing it south by canal, towing icebergs from Antarctica and melting them, or even setting up huge ocean distilleries to turn salt water into fresh.
Basil Lund, a consulting engineer in Midrand, has what he says is a cost- effective engineering solution to the problem, an idea for saving water and pushing back the D-Day by at least three decades beyond 2020. The only drawback appears to be that it is too simple; it has yet to be taken seriously.
In a paper published in May in the South African Journal of Science, Lund proposed that South Africa take advantage of rainy years by diverting excess water into deep- storage dams where it could be saved for the inevitable dry years ahead.
He points out in the paper, entitled Water for All? that as the experts warned South Africa was running out of water, the amount of run-off from rain that fell on the Vaal Dam catchment area was enough to fill the dam at least four times.
But because there was nowhere for the water to go, it was lost. Had there been a deep- storage dam nearby, it would have been saved.
My idea is to catch all these very high floods and put them into storage. Thats the whole idea, to capture the water and to hold it so that it would be available when we need it in the years ahead …
Its a simple and an obvious idea … nothing very bright about it, he says. Though the engineering of it requires a little bit of planning.
Lund (76) is a specialist in the construction of earth dams. He has overseen the construction of water supply dams for Gaborone, the Orapa diamond mine in the middle of the Kalahari Desert in Botswana, and numerous others.
He points out that projections of future water availability are based on the assumption by the Ministry of Water Affairs and Forestry that only 60% of the mean annual runoff of all the rivers in the country will be used. The rest will be lost to the sea or to the air water stored in vast dams such as the Vaal evaporates at the rate of one to two metres a year.
Lund estimates that the addition of deep- storage dams would increase the yield to 90%.
Finding sites where evaporation would be at a minimum is also important. One solution not under consideration is the warren of mine shafts and tunnels under the Witwatersrand. Water from gold and coal mines is notoriously polluted; in fact, water pumped from the mines now must be treated before it can be returned to the river systems.
Lunds scheme has the praise of Graham Baker, editor of the South African Journal of Science, who calls it deceptively, brilliantly simple. But he has yet to get the water affairs department to take it seriously.
Water affairs ministry planners have told him that if results of ongoing studies of the countrys water resources indicate that deep storage is necessary, the ministry will pursue it. Ministry water specialists were unavailable for comment at the time of going to press. Lund argues that there is a need now.
He has identified a number of sites that would accommodate deep storage dams natural steep valleys where a large volume of water can be stored under a small surface area.
What Im asking for is for this to be made part of our future planning, he says. There is no doubt that we are ultimately going to be short of water. But you should take the long view and not the short view. Were going to need these deep storage sites in the future. Lets identify them and preserve the ground where theyre going to be located.