A project has mapped groundwater in Africa’s vast Sahel region, showing notable reserves

A report compiled on the 4-year-long project the International Atomic Energy Agency (IAEA) conducted in Africa’s Sahel region – an area spanning seven million square kilometres and 13 nations home to 135 million people across West, Central, and North Africa that has also been prone to drought. The project, using isotopic techniques to assess groundwater quality and origin in five shared aquifers and basins, showed the first broad overview of the region’s groundwater supply.

The IAEA trained the scientists from participating countries – Algeria, Ghana, Mali, and Senegal among many others – to carry out a detailed examination of the groundwater with the use of nuclear-based techniques. The project explored the aquifers and basins that are the region’s main source of groundwater: The Iullemeden Aquifer System, the Liptako-Gourma-Upper Volta System, and the Lake Chad, Senegalo-Mauritanian, and Taoudeni basins.

As the Sahel region has been stricken with extreme drought in recent decades, agriculture has been badly affected, causing widespread hunger. On top of that, as there are not many rivers where water can be drawn from, the groundwater systems are effectively the region’s main source of fresh water.

“This project is a significant achievement given the vast area studied,” IAEA project leader, Neil Jarvis, said. “Inadequate water management practices can increase water scarcity. If countries are to manage growing demands for fresh water, they need to have the tools to understand and map the water resources at their disposal.”

Throughout the duration of the project, the IAEA tirelessly promoted collaboration among national experts and provided equipment and training for the technical staff to collect water samples and investigate their origin and composition through the use of hydrochemical analyses and mapping techniques.

Partner organisations included the United Nations Educational, Scientific and Cultural Organisation (UNESCO), the Liptako-Gourma Integrated Development Authority, and the Niger Basin Authority, among many others.

Through its Technical Cooperation Fund and contributions from Japan, New Zealand, the Republic of Korea, Sweden, and the United States (U.S.) and Australia through the Peaces Uses Initiatives, the IAEA ensured the effective implementation of the project.

Thus far, the data that has been gathered has offered valuable information for the participating nations, including the origins and flow patterns between the various aquifers and levels of contamination and pollution in the basins.

As water molecules contain what can described as unique “fingerprints” based on their varying proportions of isotopes – variations of an element with varying amounts of neutrons – scientists are able to examine the proportion of isotopes in water samples to figure out its age, source, and quality. These include interactions between water bodies, rainfall conditions of the past and present, replenishment rates of aquifers, and the path and fate of contaminants in the water.

The isotope studies have substantiated the existence of large quantities of good quality groundwater in numerous parts of the project area, suited for human consumption. In other areas the sources of replenishment for various aquifers, much like the Lake Chad Basin, was determined for the very first time. Analyses of other areas, such as the Liptako-Gourma region, have shown that the groundwater exists in small, independent pockets – a factor that may have implications in managing this precious, finite resource.

Presently, the areas where the groundwater has been contaminated – usually through human activity – seem to be isolated.

“This is good news, but it is important that governments take prompt measures to protect this vulnerable resource against pollution, as the situation can change very quickly,” IAEA isotope hydrologist, Luis Araguás Araguás.

Additionally, the project has helped to bring about a far better understanding of the relationship between surface and shallow groundwater in multiple areas, along with the age of the groundwater studied.

“This information can offer valuable clues as to how long it would take for the water to be –if at all – replenished,” Araguás Araguás explained.

 

Source: UN-Water