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From improved knowledge to governance of transboundary groundwater

GEF-UNDP/UNEP Iullemeden-Taoudeni/Tanezrouft Aquifer System project

By IW:LEARN

March 21^st, 2022

GEF IW:LEARN World Water Day 2022 Special Bulletin

With the water resources of the Northern Sahara Aquifer System (NSSA) also known as SASS spread over 1 million km2 between Algeria, Libya, and Tunisia, the aquifer system in this region is poorly recharged and renewed. It is exposed to increasing exploitation, mainly for irrigated agriculture.

Under these conditions, it is necessary to formulate an "optimal" resource management scheme to ensure the necessary water withdrawals for the best development of the region without the risk of degrading the state of the resource.

Consequently, these three countries worked together to understand this resource by developing management tools such as a common database (more than 18,000 water points, mainly boreholes), a common GIS (to develop thematic maps), and a hydrogeological model (at the scale of the entire aquifer system and in sub-models). The hydrogeological model estimates an average recharge of one million m3 per year.

Additionally, one of the results of the investigations carried out on this model shows that there is a possibility to increase the exploitation by drilling the SASS, estimated at 2.2 billion m3 in 2000 [1], up to a level of 7.8 billion m3/year by 2030, while respecting all constraints related to the risks of degradation of the resource [2].

With the assumption of possibly tripling the current withdrawals to increase the exploitation regime of the SASS to a level representing eight times its renewable resources (estimated at 1 billion m3/year). Such an operation is obviously only feasible by drawing on the system's reserves.

Based on these results, the three countries decided to create and implement a management framework for this resource called the "Concertation Mechanism" to monitor and attempt to control overexploitation.

Traditional well, Niger. Photo credit: ITTAS project

This approach was developed and adapted in West Africa in the context of the transboundary water resources of the Iullemeden Aquifer System in 2004–2009 shared by Mali, Niger, and Nigeria. Unlike the SASS, this aquifer system is crossed by the Niger River over more than 600 km, with a total length of 4200 km.

The Transboundary Diagnostic Analysis (TDA) approach recommended by the GEF for International Waters and adapted to transboundary groundwater was applied to identify three major transboundary issues that threaten the water resources: namely (i) reduced water availability, (ii) degradation of water quality through pollution and contamination, and (iii) the negative impacts of climate change.

Subsequently, the appetite for concerted water management gradually built up between the national teams and the scientific and technical dialogue established between the countries encouraged the exchange of data and information to improve knowledge of the Iullemeden Aquifer System.

A climate of technical and scientific partnership progressively evolved between the national teams who recognized the need for a concertation mechanism for the efficient management of their common resource.

Indeed, to date, none of the three countries is able to control the identified transboundary risks in isolation. Moreover, there is no platform available to guide and advise them on the definition and monitoring of the implementation of a concerted management strategy for transboundary aquifers.

The other countries (Algeria, Benin, Burkina Faso, Mali, and Mauritania) sharing the water resources of the Taoudéni/Tanezrouft Aquifer System have joined those (Mali, Niger, and Nigeria) of the Iullemeden Aquifer System because the two aquifer systems constitute a single system (called "Iullemeden-Taoudeni/Tanezrouft Aquifer System SAIT" or in English "Iullemeden-Taoudeni/Tanezrouft Aquifer System ITTAS").

The countries are confronted with the same transboundary risks and are evolving in the same agro-climatic context. The GEF's TDA/SAP (Transboundary Diagnostic Analysis/) approach will soon be applied to the Senegal-Mauritania Aquifer System (Gambia, Guinea-Bissau, Mauritania, Senegal) drained by the flows of the two rivers, Senegal and Gambia.

This aquifer system will receive for the first time a regional study within its natural limits. Management tools (database, GIS, hydrogeological model), as well as a framework for concerted management of these water resources, have been planned.

The cooperation established over two decades ago between the OSS, UNEP and the GEF led progressively to applying its TDA/SAP approach to transboundary groundwater and setting up the Concertation Mechanism, a governance framework for these resources in the little-known aquifer systems of Africa.

[1] [1.33 in Algeria, 0.55 in Tunisia, 0.34 in Libya],

[2] By country, this exploitation is broken down as follows: 6.1 billion m3/year in Algeria, 0.72 billion m3/year in Tunisia, and 0.95 billion m3/year in Libya.

About the ITTAS project

The "Improving IWRM Knowledge based Management and Governance of the Niger Basin and the Iullemeden Taoudeni Tanezrouft Aquifer System (ITTAS)" project is funded by the GEF and implemented by UNDP and UNEP with the support of UNESCO, UNIDO, the OSS and the Niger Basin Authority (NBA). The objective of the project is to improve knowledge-based management, governance and resources conservation of the Niger Basin and the Iullemeden-Taoudeni/Tanezrouft Aquifer System (ITTAS) to support IWRM for the benefit of communities and the resilience of ecosystems.

For more information kindly contact the Project Manager, Allomasso Tchokponhoué (allomassot@yahoo.fr), visit the website and view the dedicated project page on iwlearn.net. For more information on the OSS, kindly contact the Manager, Dr. Abdelkader Dodo (abdelkader.dodo@oss.org.tn).