ALTERNATIVE WATER SOURCES THE WAY TO GO
NEWS RELEASE
DATE: 9 JUNE 2010
ALTERNATIVE WATER SOURCES THE WAY TO GO
The combination of Mossel Bay’s expected future population growth, the probability of more droughts in future and the growing competition for available surface water will require a diversified approach to ensuring sustainable water sources for Mossel Bay in future, says Mr Johan du Preez, who is a member of the team overseeing the various water projects at the Municipality at present.
While the existing water sources, aided by ample rainfall over the last two decades, have been considered adequate for a number of years to come the area is now in the grip of the worst drought in 150 years since records are kept. This has necessitated a review of the Municipality’s longer term planning of its water sources.
Mr Du Preez says weather data for Mossel Bay that has been collected over nearly a century has shown that the area is prone to extreme weather conditions that includes drought spells as well as flood conditions.
The area’s population is expected to grow substantially in future, while there is the demand of the agriculture and forestry sectors as well as the impact of alien vegetation in rivers and catchment areas which has to be considered. The Municipalities in the region consume about fifteen percent of the available surface water in the catchment areas, while agriculture, forestry and alien vegetation account for the balance
More drought spells can be expected in the years to come and it has become clear that the Municipality will have to reduce its total dependence on surface water resources. All major dams are designed on the probability that they could run dry twice in a hundred-year period and this factor also has to be taken into account.
According to Mr Du Preez, alternative sources of potable water such as desalinated sea water will become very important in future, while the use of rainwater tanks to harvest rainwater at houses should be actively promoted.
Groundwater is another potentially valuable source of water and boreholes should be drilled to augment water supplies. Grey water can be used for various purposes at households, although this will reduce the quantity of waste water that will be available to the Municipality for re-use.
Mr Du Preez said that if the drought continues the Wolwedans Dam could run dry by October 2010.
Substantial quantities or prolonged rainfall conditions will be required for a substantial increase in dam levels to occur as the soil is very dry and soaks up much of the rain water before a flow off into dams and rivers occurs. During February 2010 78,5 mm of rain fell in the catchment area of the dam, of which an estimated nine per cent flowed into the dam. This extended water availability from the dam by 22 days.
The rainfall recorded at the Jonkersberg Bos weather station for the period January 2009 to April 2009 was less than fifty to sixty per cent of the long term average, and forecasts are than this trend will continue during June, July and August 2010.
The level of the Wolwedans Dam stood at 22,3 per cent on Tuesday, 8 June 2010.
Ends
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