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27 Jul 2012 12:14
A joint Namibian-German team of geohydrologists last week confirmed the existence of a massive aquifer with potentially up to 15-billion cubic metres of fresh water in Namibia. (M&G)
For most of the year, Namibia's populous central-northern regions of Ohangwena and Oshona have either too much water from seasonal floods or are limited to water supplied by an open canal and unreliable and often brackish boreholes. But that is set to change.
A joint Namibian-German team of geohydrologists last week confirmed the existence of a massive aquifer with potentially up to 15-billion cubic metres of fresh water beneath Ohangwena, enough to supply the area's current needs for four centuries.
"It was something of a side product of a technical training programme," said team leader Martin Quinger, of the German Federal Institute of Geo-Science and Natural Resources, of the events that led to the discovery of the pristine, 10000-year-old body of water beneath the flat sand plains of northern Ohangwena, Namibia's most densely populated region.
Situated in the Etosha-Cuvelai basin just south of the Angolan border, the Ohangwena II aquifer, as it has been named, lies at a depth of between 280m and 350m underneath a shallower, smaller aquifer that has been known of since the 1950s, but which was too saline for human use or conventional crop production.
As part of an ongoing programme to upgrade local government technicians' skills, Quinger and his team have been exploring the Etosha-Cuvelai since 2006.
In due course, they started detecting a larger mass below the upper aquifer that piqued their interest.
Using powerful transient electromagnetic imaging tools and drilling 17 test boreholes in the area, Quinger and his team had, over the past two years, "put together the pieces of a giant puzzle until we could see it's a massive thing", he said.
Measuring roughly 70km by 40km on the Namibian side of the border, the body of water appears to have accreted over millennia through an underground "wicking" effect through the deep sands of the central Cuvelai basin from rains draining from an Angolan mountain range about 350km away to the northeast.
Quinger said the rate at which it was replenished still had to be established by sampling on the Angolan side of the border, but the volume of water was enough to sustain the Ohangwena and Oshona regions, home to 40% of Namibia's population, with water for the next 400 years at current extraction rates.
"Because of the depth at which Ohangwena II is situated, the pressure pushes the water up to about 20m from the surface.
But exploiting the resource was not without its risks, he said. If the borehole is not properly sealed off from the body of salty water lying above it, it could leak into the borehole casing and contaminate the fresh water below. And if the deeper body of fresh water is pumped out faster than it can be replenished, there is a risk that the heavier salt water can leech into the fresh water below.
There are also other risks, including political ones: the day after the announcement was made, the ministry of agriculture, water and forestry's top officials excitedly announced a "water conference" to discuss the discovery's economic potential, prompting warnings about "water tenderpreneurs" from the local press.
Quinger said that the law preventing wildcat drilling was "somewhat on the shady side of things", because delays in the promulgation of the new Water Act means that colonial legislation dating back to 1956 is still in effect.
Under the new Act, Namibia will become a "declared area" and official permission will have to be sought before boreholes for water are sunk. But, as matters stand now, there is no law that prevents a farmer from sinking a borehole on his farm anywhere above Ohangwena II. "But we are sure common sense will prevail," Quinger said.
The authorities are tightening up licencing regulations for drilling permits and operators would have to prove conclusively that they have the capacity to seal off a borehole at depths considerably deeper than where water normally occurs in Namibia, Quinger said.
His team has also been raising awareness among the people in the area. "I've been going around telling people they have a resource more valuable than oil in the ground below them. Believe me, anyone who thinks he is going to just set up his drill up there is going to have someone looking over his shoulder very soon," he said.
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