IAEA project maps shows significant reserves in groundwater in Sahel region

Sahel forest near Kayes MaliThe Sahel forest in Mali. (Image source: NOAA, US Gov, Unidentified/Commons)Scientists from participating countries – Algeria, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Ghana, Mali, Mauritania, Niger, Nigeria, Senegal, and Togo – were trained by the Agency to carry out a detailed examination of groundwater using nuclear-based techniques 

An IAEA project shows that significant reserves of good quality water are available in Africa’s drought-prone Sahel region. Pollution is still limited and has not yet become a serious threat to these vital resources. The findings, compiled in five reports are the result of a four-year Agency effort to help 13 countries use isotopic techniques to assess groundwater origin and quality in five shared aquifers and basins, providing the first broad overview of the region’s groundwater supplies.

The project looked at the aquifers and basins that provide the main source of groundwater to the region’s population: the Iullemeden Aquifer System, the Liptako-Gourma-Upper Volta System, and the Senegalo-Mauritanian, Lake Chad and Taoudeni basins.

“This project is a significant achievement given the vast area studied,” said IAEA project leader Neil Jarvis. “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.”  

The Agency promoted collaboration among national experts and provided equipment and training for technical staff to collect water samples and investigate their origin and composition, using hydrochemical analyses and mapping techniques. 

Partner organizations included the United Nations Educational, Scientific and Cultural Organization (UNESCO), the Niger Basin Authority, the Lake Chad Basin Commission, the Volta Basin Authority, the Liptako-Gourma Integrated Development Authority, the Organization for the Development of the Senegal River and the German Federal Institute for Geosciences and Natural Resources. 

Spreading over a 7-mn sq km area, the Sahel is home to 135 million people across West, Central, and North Africa. The area has suffered from extreme drought in recent decades, affecting agriculture and causing widespread hunger.The data gathered has provided valuable information for the participating countries, including origin and flow patterns between the different aquifers and contamination levels in the basins.

The isotope studies confirmed the existence of large quantities of good quality groundwater suitable for human consumption, in several parts of the project area. In some areas, such as the Lake Chad Basin, the sources of recharge for various aquifers were established for the first time. 

Areas where groundwater has become contaminated, usually through human activity, appear to be isolated at present. “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,” said Luis Araguás Araguás, an IAEA isotope hydrologist.

The project also helped to generate a better understanding of the relationship between surface and shallow groundwater in many areas, as well as the age of groundwater. “This information can offer valuable clues as to how long it would take for the water to be – if at all – replenished,” Araguás Araguás said. In various areas, such as the Liptako-Gourma region, the analyses show that groundwater exists in small independent pockets, which could have implications for managing this finite resource.

Water molecules carry unique “fingerprints” based on their different proportions of isotopes – variations of an element with a different number of neutrons. Scientists study changes in the proportion of isotopes in water samples to determine its source, age, and quality. 

The project is being showcased at the first International Conference on the IAEA Technical Cooperation Programme: Sixty Years and Beyond – Contributing to Development, taking place 30 May – 1 June in Vienna, Austria. 

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