30 May 2012

West Africa: In Deep Water

Johannesburg — Right now, people in Niger, Mali and Nigeria could be sipping 50,000-year-old water from a two-aquifer system buried below their feet. But some of it may be contaminated.

A combination of soaring temperatures, declining rainfall and a booming population is putting a squeeze on the amount of surface water available for people living in one of the hottest parts of the world, so more and more boreholes are being drilled to tap the precious groundwater beneath the three countries.

But few realize that the water in the Iullemeden Aquifer System, which they see as their salvation, is connected to the surface water and under just as much pressure.

"Countries and people do not realize that groundwater and the surface water are all interconnected, and that there is a precarious balance between the two and we have to look at both in relation to each other," said Abdel Kader Dodo, the manager of a project by Sahara and Sahel Observatory (OSS), a regional intergovernmental body, to help Niger, Mali and Nigeria share the Iullemeden water carefully.

The Niger River and its tributary, the Rima, feed as well as draw water from Iullemeden, which comprises two major aquifers - the Intercalary Continental (IC) at the bottom, and the Terminal Continental (TC) at the top. Part of the TC is recharged by surface water, while the deep waters of the IC are not easily recharged, and are also being threatened by pollution caused by extensive mining in the region.

The OSS discovered that the Niger River receives 125 million cubic metres of water from the aquifer system every year, while the Rima provides it with 20 million cubic metres of water annually, and draws 12 million cubic metres from it.

The amount of water drawn from the Iullemeden has more than doubled over three decades, from 50 million cubic metres in 1970 to 180 million cubic metres in 2004, while the population that depends on water from the aquifer has shot up from six million in 1970 to 15 million in 2000. This might double by 2025, says the research team at OSS. The number of boreholes and wells drawing water has increased from a few hundred points in the 1940s to more than 17,000 in 2007.

Digging deep

Dodo of the OSS said the impression that the aquifer is under-exploited is not accurate. The government of Niger has said that just 20 percent of the country's renewable water resources are being tapped, and almost none of the non-renewable sources.

The warning has serious implications. In 1995, during a period when temperatures soared in Niger, the withdrawal of water exceeded the Iullemeden system's recharge rate. The OSS research team projects that there could be a drawdown of 10 metres of the deep waters of the IC by 2025.

But the moment people dip into these deep waters, the risk of being exposed to water with a high concentration of minerals increases. "There has been a surge in the number of children crippled by skeletal and dental fluorosis [a bone disease caused by too-high fluoride content in water, which often affects people in areas with deep boreholes]," said Dodo.

One of the best-known high fluoride belts extends along the East African Rift from Eritrea to Malawi, according tothe World Health Organization (WHO). Studies in early 2000 discovered high prevalence rates of the disease in parts of Niger and Nigeria. WHO reported that since then people in some of these areas have been provided with alternative water.

Few realize that the water in the Iullemeden Aquifer System, which they see as their salvation, is connected to the surface water and under just as much pressure

Mining and the use of chemicals is another common cause of water pollution in these areas.

What can be done?

"Mitigation measures and alternative sources of water can only work to a certain extent - we have to change our behaviour, and use and manage water responsibly," Dodo said. "The Iullemeden Aquifer System is located in one of the earth's regions most vulnerable to climate change, desertification and drought - two phenomena that threaten, among other things, the recharge of aquifers."

In 2008 the OSS project helped map the aquifer and develop an information base on it, such as the flow, discharge and recharge rates. These tools can help the countries concerned to set up a transboundary mechanism to manage Iullemeden, but not much has been done. "In 2009, Mali, Niger and Nigeria adopted an Agreement with road map (not yet signed) in order to establish this consultation mechanism for managing transboundary groundwater resources," said Dodo.

Until the government develops and implements a plan to manage the surface water, a lot of money and effort is being wasted on providing water in Niger, where people are dealing with yet another drought. Aquadev, a small Belgian NGO, has struck water four in out of 15 attempts in six years. Each attempt cost at least US$20,000. "There is a lack of knowledge and skills to this kind of work at the local level," said Stephanie van Steenberghe of Aquadev.

Dodo said the local authorities need good maps that show the aquifer at the village level. "The maps we have now produced should be downscaled, and the people involved in this job need a good understanding of the hydrology and the geology of the area."

Using Isotopes

Help could be at hand. The International Atomic Energy Agency (IAEA) uses isotopes (variants of a chemical element) for water analysis and has helped Chad, Egypt, Libya and Sudan tap into the Nubian aquifer.

The IAEA has used isotopes to test the quality of water for decades. It is a cheaper method, as it only takes a few samples to show what the quality of water is for hundreds of kilometres.

First, the age of the aquifer is determined by using the naturally occurring radioactive isotope, carbon-14, in the same way it is used to test ancient artefacts. The water in the Iullemeden's IC aquifer is more than 50,000 years old. The IAEA can also determine how much water remains the aquifer, and how long it could last. The IAEA in a collaborative project with other UN agencies discovered that the water in the Nubian aquifer would last several centuries, putting any concerns about possible conflicts in the future at rest.

Dodo said that if countries know how much water is available, and until when, the potential risk for conflict over water can be deflated. "When it is all transparent and out in the open, they should be able to manage it properly."

[ This report does not necessarily reflect the views of the United Nations ]

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