ADDIS ABABA (Thomson Reuters Foundation) – Famous as the source of the Blue Nile, which flows from Lake Tana in the Ethiopian highlands, this East African country is far less well-known for its promising groundwater potential.
But the Ethiopian government is now planning to tap into its largely unexploited groundwater resources, both to sustain a population of over 90 million – many of whom suffer from water shortages - and to alleviate the impacts of climate stresses.
The Ministry of Water and Energy (MoWE) hopes to increase potable water coverage to 98.5 percent of households nationwide by the end of next year, from 68.5 percent in 2013. And for that it will need new water supplies.
Scientists from the British Geological Survey and University College London estimated in a 2012 study on Africa’s underground water reserves that Ethiopia has groundwater storage of 12,700 km³, much less than some of its northern neighbours.
Large sedimentary aquifers in North Africa contain a considerable proportion of Africa’s groundwater, with Libya, Algeria, Sudan, Egypt and Chad having the biggest reserves, the researchers noted. But many of these Saharan aquifers are not actively recharged, having been filled more than 5,000 years ago when the climate of the area was wetter, they added.
According to Zebene Lakewe, a hydrologist at Ethiopia’s MoWE, studies show the country’s groundwater is recharged by 36 billion m3 per year thanks to precipitation and other surface water – a substantial amount compared with other less rainy countries in the region, such as Sudan and Egypt.
Pastoralists are among Ethiopia’s main users of groundwater, mainly in lowland areas where there is a scarcity of surface water. They sink small boreholes for subsistence herding and agriculture.
But the government still doesn’t know much about this natural resource. It is currently undertaking a survey of groundwater, hoping to cover 22.7 percent of the total area thought to have underground reserves by 2015, up from just 3 percent surveyed in 2010.
While the ministry has yet to fully assess Ethiopia’s groundwater potential, Seifu Kebede, head of the School of Earth Sciences at Addis Ababa University, believes the benefits are already clear.
“If there were no rainwater in Ethiopia for eight consecutive years, we have the potential of our groundwater to sustain us through that period, and this can act as a climate buffer,” Kebede said.
Groundwater can be depleted through overuse, but it has the potential to outlast surface water sources for some time, as aquifers are less exposed - and thus more resilient - to extreme weather like drought.
They can also be faster to exploit. Kebede said a conventional water dam takes five to six years to construct on average, including finding the right location and financing. Accessing ground water through drilling is much quicker, although it has a high initial cost.
“We live in an age of ever-expanding cities and population centres, and the use of centralised water systems is becoming obsolete, leading to the need for decentralised ones, which groundwater provides,” Kebede said.
His university, which houses about 50,000 students, could be supplied by piping groundwater to its premises, he added.
Groundwater still needs a water treatment plant, like the water coming from the mains supply, but locally installed systems could be more versatile.
Some groundwater, especially in eastern Ethiopia, does have high levels of salinity, which could be tackled with desalination schemes or by using saltier water for non-drinking purposes such as agriculture or industry, Kebede added.
NILE WATER WOES
Groundwater could also be used to ease the perennial water tensions between Ethiopia and the two upper Nile riparian countries, Egypt and Sudan, Kebede said.
“So far (the argument) has been framed as a dispute over who gets to use the 85 billion m3 of water the river discharges, of which Ethiopia contributes 86 percent,” Kebede said.
Although Egypt and Sudan receive very little rainfall, they are part of a much bigger fossil water aquifer system called the Nubian Sandstone Aquifer System, which stretches across four countries and contains an estimated 150,000 km3 of groundwater. Experts say this could be used to offset any reductions in Nile water levels.
“The Egyptians argue that if they pump the (ground) water, it’s going to be depleted because it has so little rainwater recharging it,” Kebede said. “Our argument is to use the water under a managed depletion approach, taking note of the fact that some of it is lost every year to the sea anyway.”
Both Kebede and Lakewe welcomed the potential of groundwater to boost resilience to climate change, but warned against treating it as separate from surface water, as both impact on the other.
“The drying up of Haramaya Lake in eastern Ethiopia was related to the pumping of groundwater for agriculture and household use,” said Kebede. Recent reports indicate the lake is again being replenished thanks to a government rehabilitation project.
Lakewe said the use of groundwater has another advantage in that it is less prone to pollution and less contaminated by waterborne diseases, making it an ideal choice for industry and household use.
Although the government has said it plans to provide almost every household in the country with access to clean water by the end of 2015, some aren’t convinced.
Eyasu Alemayehu, who lives in one of the smart suburbs of the capital Addis Ababa, said that even though his neighbourhood has water coverage in theory, the supply is patchy.
“I have to wake up in the middle of the night every fortnight to see if the water has returned, and wait for my water tank to fill up,” Alemayehu said, adding that water flows in the pipes to his house on average just three times a week.
The problems are so widespread that Prime Minister Hailemariam Desalegn has been forced to admit that at least 25 percent of the capital’s 3 million-plus population has an unreliable water supply.
For Lakewe, however, the solution to the water headache in Addis and the rest of the country lies in tapping more groundwater resources.
“So far only a third of Addis’s water coverage comes from groundwater, with the rest coming from two rainwater-fed dams,” Lakewe said.
E.G. Woldegebriel is a journalist based in Addis Ababa with an interest in environmental issues.