Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 27 June 2010
By Bill Harding, a limnologist (aquatic sciences), who has been involved with issues to do with SA dams since the ’70s
South Africans will be aware that our country is not blessed with abundant rainfall, with an average of only 450mm a year, compared with the global average of 860mm a year.
Without substantial supplies of underground water, we rely heavily on water that is stored in dams. Our reliance on stored water is rendered critical by population growth and industrial expansion. Water resources per capita of population are dwindling.
At the same time, pressure on many dams is increasing, with a considerable portion of their inflows made up of waste-water effluents and urban runoff.
The Department of Water Affairs and Environment manages 574 dams, of which 320 are major dams, each holding more than a million cubic metres of water. From this storage, irrigation uses 62%; urban and domestic use equals 27%; and mining, industry and power generation absorb 8%. Commercial forestry utilises 3%.
Evidence suggests that the quality of about 35% of the storable volume is already severely impaired – and nearly all of this in the economic heartland of Gauteng. Water quality is in fact poorest in the areas with lowest runoff and highest contribution to GDP.
Insidious and sinister changes are appearing in some dams, completely unnoticed by routine monitoring programmes. From this it may be reasonably assumed that SA would possess a national programme for reservoir management.
In recent months there have been many reports referring to a water crisis, mentioning the extreme levels of pollution in most Gauteng dams. Continue reading