Not enough rain yet to fill dams, says expert

Residents of Graaff-Reinet were overjoyed after recent rainfall in the town.
Residents of Graaff-Reinet were overjoyed after recent rainfall in the town.
Image: Mervin Mackelina

Despite heavy downpours across the country, not enough rainfall has been received to fill some dams.

Hydrologist, geologist and palaeontologist Dr Gideon Groenewald said the current rainfall received in drought-stricken areas across the country may appear to be sufficient, but it  was not.

Groenewald said in places like Makhanda, formerly known as Grahamstown, and Graaff-Reinet where over 40mm of rain was received, the dams were still empty.

On Thursday, social media users were astonished to see pictures of the empty Nqweba dam near Graaff-Reinet after good rainfall.

“I thought you will show us before and after the rain,” read one comment.

A second comment read: “So the dam is still 100% empty even after all this rain? Has there been no run-off?”

Groenewald, or Oom Gideon as he prefers to be called, has since explained the reasoning behind it.

He said over the past 20 years Graaff-Reinet had been in a downward cycle of rain.

“The rain was getting less and less as it went on.”

Groenewald drilled several boreholes in the drought-stricken town last year which yielded over 100,000 litres of water.

Groenewald emphasised the importance of drilling boreholes after rainfall and had also warned that waiting too long might cause bigger problems.

“The money to drill boreholes is now put on hold so now they waiting for more rain. The longer you wait the closer you get to the end of the cycle of the summer season and the dam won’t fill up again.

“Next year when the same cycle repeats, the dams dry up much quicker than this year.

“They will fix all the pumps and pump water and by the time the pumps are fixed the dams will be empty again,” he said.

He said the current rainfall only filled up shallow boreholes that were less than 36m deep.

“They hold water for another two or three months then they will be empty again.”

Boreholes deeper than 140m, drilled in Graaff-Reinet, would take years to fill.

“If you over-utilised the boreholes that I drilled and pump too fast and too quickly then you are going to damage the next generation.

“In terms of water, Graaff-Reinet has no choice but to drill boreholes. There is not rain in the clouds so the only source of water is groundwater.”