DEVELOPMENT priorities may have to be re-evaluated after a new study revealed that SA had 4% less water than previously believed .
The latest national study, released last week, conducted on behalf of the Water Research Commission , tried to quantify the natural state of water resources in SA and found this was 4% less than estimated in 1995.
The study was commissioned by the commission , a government body that directs and funds research on critical water issues.
Future developments might have to be scaled back in order for water needs to be met, the study’s project director, Brian Middleton, said .
Several sectors, including agriculture, forestry, electricity generation, industry, groundwater developers and municipalities, may need to revisit water use strategies in the light of these findings.
Middleton said new mines and power stations might have to be put on hold as water would either not be available or would be too costly.
“We’ve behaved like a water-rich country when we’re not. We’re actually a semi-arid country and our mean annual rainfall is below the world average,” Middleton said.
The findings also have serious implications for water tariffs, adding to the woes of ratepayers recently slapped with huge increases to fund new electricity generation projects.
“We’ve probably underpriced water. I think we’re like all humans: if you get something for free, you waste it,” he said.
The study, Water Resources of SA 2005, carried out an integrated assessment of surface water and underground water resources, as well as water quality countrywide.
National water studies have been done since the 1950s, and with each study, estimates of total natural water resources have declined.
As research techniques and technologies were improving all the time, the most recent findings tended to be regarded as the most accurate, said Middleton. Regular updating of statistics relating to water was vital to the country’s water security.
According to the study, SA’s mean annual runoff was just more than 49000-million cubic metres ; usable groundwater exploitation potential was estimated at about 10000-million cubic metres — 25% less during drought s.
The study covered SA, Lesotho and Swaziland, and included information on rainfall, stream flow, irrigation, groundwater, alien vegetation, afforestation and water quality.
The report, carried out by a consortium of consulting engineering firms, was breaking new ground by delivering an integrated assessment of surface water and underground water resources.
Middleton said that groundwater was used in probably 75% of the country’s area — mainly in small towns — while larger urban areas used mostly surface water.
“The study’s results suggest that there is merit in considering the conjunctive use of both sources . When surface water is available, we need to consider drawing on this more efficiently , allowing our groundwater reserves to build up for droughts.”
newmarchj@bdfm.co.za