Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 01 February 2011

By: Jeremy Westgarth-Taylor – Founder of Water Rhapsody and winner of a WWF Green Trust Award

There have been two conflicting reports about the predictions of weather patterns for the Western Cape winter of 2011. In the Cape Times last week Mmaphaka Tau – Senior Manager of National Disaster Management Centre – seems to be making a faux pas. He voiced criticism of the handling of the release of flood water saying that the sluice gates were opened too late. The chaps in charge of the dams, however, say that they operated the opening in compliance of best international practice.

Drought or flood?

It matters not whether the sluice gates were opened too early or too late.  The real reason why we have floods that do so much damage is the dams themselves.

Dam building

During years of lower than average and average rainfall, a period that lasts up to thirty years, a swollen river gives no warning not to build on a flood plain. Rainfall of perhaps a ten year flood may very well be handled by the flood control mechanisms of dams that are able to handle the rise, allowing water to be let out in a controlled way.

When one gets a flood that happens every 30 years, as has happened this year, the dam only makes things worse. In other words the dam makes no difference to the flood, and even makes it worse.

What has happened is that the ability of the dam to control small floods has drawn cash strapped municipalities to allow development and allow people to build on the flood plain.  The lesson of course is:  Don’t build on a flood plain.  The dam built to control floods will not work. Continue reading Drought or floods for the Western Cape?