05 March 2010

Cape of Storms to get stormier

Cape Town should brace itself for bigger storms dumping massive amounts of rain, as climate change takes hold, an environmental expert said on Tuesday.

Cape Town should brace itself for bigger storms dumping massive amounts of rain, as climate change takes hold, an environmental expert said on Tuesday.

Gregg Oelofse, the city's head of environmental policy, was speaking at the release of a report on his department's ongoing sea-level rise risk assessment project.

The report found that given the "weak" outcomes of last year's Copenhagen climate change summit, the world was assured of a minimum global temperature increase of two degrees Celsius and "more realistically", three.

"These temperature increases... place our coastal vulnerability as a very real concern that holds multiple implications for our city.

Problem has to be addressed now

"The risks associated with sea-level rise events can no longer be viewed as something to be addressed into the future, but must be considered as a priority in our immediate planning and management," it found.

Researchers said areas "highly vulnerable" to a rise in sea level included Blouberg, Camps Bay, Kommetjie, Glencairn and the entire Strand beachfront.

Oelofse said it was unlikely that the spectacular storm that hit the city's Atlantic seaboard and then battered False Bay in August 2008 was the result of climate change.

However, its impact was in line with what researchers were suggesting climate change would bring.

"What our model is suggesting is that what we have seen on our coastline, we're going to see more of into the future as a result of climate change," he said.

The best predictions for climate change were that the Western Cape was likely to be a drier area in the future.

Bigger storms

"But linked to that is that we're likely to see that our storms are going to be bigger when they do come.

"So instead of having the storms we're used to where we have drizzly rain for two weeks non-stop, we'll see these bigger storms that come and we have a massive amount of rainfall in a very short time."

The bigger the storm, the higher the wind velocity, and the higher the ocean swell that the wind pushed up against the coastline.

At the time of the 2008 storm, 18-metre swells were recorded off Scarborough on the Atlantic coastline, Oelofse said.

When that storm turned its attention to False Bay, the swells pushed salt water up eight city blocks into the stormwater drainage system at Strand.

Smart choices

He said that if the city and its people acted to make "smart choices" now, they could dramatically reduce the risks that came with rising sea levels.

This would mean that the phenomenon was not something that people needed to be "panicked or scared about", or see as a massive calamity.

Among exposed areas where decisions were needed in the next couple of years were the eroding Milnerton golf course, and the railway line at Glencairn beach.

Oelofse said that sometimes the most obvious solution was not the best one. "Particularly where coastlines are vulnerable, people immediately think that the best solution is to build a hard sea wall to protect that particular piece of property. 

"But... globally, a study was done that shows only around 605 of hard sea walls actually were effective and around 18% of them actually made the problem worse."

Capital cost

Mayoral committee member for the environment Marian Nieuwoudt said there were many solutions, but the city had to decide which ones it could afford. "Capital cost is a once off, but what can we maintain if we start with the process?" she asked.

A good example of this dilemma was Baden Powell drive, which runs along the False Bay dunes and is regularly blocked by blowing sand.

"We can choose to maintain that on a daily basis, or we can decide we cannot afford that, and retreat, and rebuild the road higher up beyond the dune system," she said. "The same in Strand... the idea is we reinstate the dune system there."

The Cape Town metro has 307km of coastline. - (Sapa, March 2010)


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