Tapping Ground Water as Climate Defences:Ethiopian Experiences

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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. Read on...