Managing Hydrogeological Risk in the Iullemeden Aquifer System

The lullemeden sedimentary groundwater basin, composed only by the cretaceous calcareous sandstone Continental intercalaire and the tertiary sandstone Continental Terminal aquifers, is located in Mali, Niger and Nigeria with minor, non-connected sections in Algeria and Benin. One aquifer in Mali, tree in Niger and four in Nigeria compose the Continental Terminal. The Iullemeden Aquifer System (IAS), which covers an area of 525 000 km2 with 31 000 km2 in Mali, 434 000 km2 in Niger and 60 000 km2 in Nigeria, represents one of the major freshwater reservoirs of West Africa. It received significant seasonal water rainfall and is linked to many humid areas and ecosystems.

The following categories of environmental threats to the aquifer and the related ecosystems have been identified :

(a) land use change in recharge areas and humid zones of the IAS (i.e. because of 1-deforestation: in Niger : weak productivity of the forests (0,1 to 1,5 stere/ha/year) against 87% of the energizing needs between 1,5 and 2 millions tons of firewood per year. In Mali: 90% of the needs of firewood; 2- The silting of the rivers) ;
(b) climatic change : Sliding of isoyietes southwards of about 100 km: decrease of 20% to 30% of the rainfall
(c) The increase of the water demand because of the growth of the population: 15 millions in 2000, the double in 2025 ;
(d) The water quality degradation because of :

· The pollution of various origins: domestic, industrial, mining, artisanal, agricultural;
· The groundwater geochemistry of the Continental intercalaire : i.e, the attendance of Fluor-Apatite caused Bony Fluoroseses. In Niger, more than 300 victims mainly children are irreparably deformed.These threats/risks will be addressed by the project through the establishment of joint mechanism and cooperative frameworks for:

1. identification of transboundary risk and uncertainty issues;
2. formulation of joint risk mitigation and sharing policy; and
3. joint policy implementation through a joint IAS legal and institutional cooperative framework.

The scope for management of transboundary risk and conflict in the IAS is constrained by the scientific uncertainty on the aquifer system and by the impacts of climatic change. Further causes for indecision relate to social and policy uncertainty and sudden Basin unawareness.

To address these risk and uncertainty aspects the project will adopt a risk-based management approach. The emphasis can be expected to be on preparedness, responsibility, with monitoring and feedback to jointly address, mitigate and share risk and reduce uncertainty.

Finally, the MSP-GEF project is an opportunity for Mali, Niger and Nigeria to :
· A state of knowledge of water resources updated in the hole Basin;
· A Common Data base to the 3 countries;
· A Mathematical model for the evaluation of risks and the establishment of a hydrogeological risks map and for sustainable water resources management;
· An initiation to the formulation of Mechanism of Concertation for the joint groundwater resources management of resources and for the monitoring of the relevant indicators of hydrogeological risks.


Irhazer-Iullemeden Basin


Documents & Resources
General information
GEF ID 2041
Project type Medium-Size Project
Status closed (Project Closure)
Start Date 21 jun. 2004
End Date 31 mar. 2007
GEF characteristic:
Focal Area International Waters
GEF Allocation to project USD 958,000
Total Cost of the project: USD 1,738,000
YES - See results data (2041)
Mali , Niger , Nigeria , Regional

UN Environment (UNEP)

Project contacts
John Chabo Deputy Director
Abdel Kader Dodo Project Manager
Baba sy Lamine IT Officer