RESOURCES in AFRICA

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MANAGING SHARED AQUIFER

RESOURCES in AFRICA

THIRD INTERNATIONAL CONFERENCE Tripoli 25– 27 May 2008

[Pro ceedings]

International Hydrological Programme

Division of Water Sciences

IHP-VII Series on Groundwater No. 1

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status of any country, territory, city or area or of its authorities, or the delineation of its frontiers or boundaries.

Published in 2010 by the United Nations

Educational, Scientific and Cultural Organization 7, place de Fontenoy, 75352 Paris 07 SP

Printed by UNESCO

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In Tripoli, in 1999 and 2002, the General Water Authority of Libya and UNESCO, in cooperation with the Sahara and Sahel Observatory (OSS), convened two major conferences devoted to the identification of shared aquifer resources in Africa. The first marked a milestone in the discussion of the emerging concept of regional aquifers and was instrumental in launching the UNESCO International Shared Aquifer Resources Management Initiative (ISARM^*).

The second Tripoli conference focused more specifically on the features of those African aquifers that are shared between several states.

The outcomes of these two conferences not only provided sound scientific data but also cre- ated networks of experts who, over the last years, have continued to work on the issue of national sustainable development and the sound management of shared water resources.

For the third time, African and international experts on groundwater resources management convened in Tripoli from 25–27 May 2008 on the occasion of the Third International Conference on ‘Managing Shared Aquifer Resources in Africa’.Hosted by the General Water Authority of the Libyan Arab Jamahiriya and jointly convened by UNESCO’s International Hydrological Programme and Sahara and Sahel Observatory (OSS), the Tripoli III Conference was attended by more than local, regional and international 150 experts of different disciplines. The Con- ference was co-sponsored and attended by the

representatives of international, regional and national organizations and institutions, including AMCOW, AWF, BGR, BRGM/FFEM, CEN-SAD, FAO, IAEA, IAH, IGRAC, SIWI, and UNECA.

Revealing updates on latest activities and developments in the field of transboundary aquifer management in Africa, in terms of hydrogeological as well as socio-economic studies, legal instruments and management techniques, the Tripoli III conference was instrumental in taking the ISARM initiative in Africa one stage further.

During the Conference the Regional Centre for Shared Aquifer Resources Management (RCSARM), hosted by the Libyan Arab Jamahiriya, was officially launched. RCSARM had been established as a centre under the auspices of UNESCO at the Thirty-fourth General Conference in October 2007. The Centre will have a guiding role in Africa and in the Arab States for the dissemination of data and technology and for capacity building and awareness-raising on transboundary aquifers resources studies, with projects on shared aquifer management and sub-regional capacity building programmes.

The International Conference gave further recognition to the importance of shared groundwater resources in Africa, in supporting livelihoods and thus providing a basis for human welfare. Nevertheless, the conference also emphasized the lack of data, knowledge and capacity that is hindering sustainable management of the shared resources in many places. This is reflected in the joint Conference Statement prepared by the participants from more than 20 African States and national, regional and international organizations and associations.

Furthermore, the outcomes of the conference will provide beneficial information for groundwater resources related activities to be organized by international organizations during the next years.

* ISARM is an inter-agency initiative launched by the Intergovernmental Council of the International Hydrological Programme of UNESCO at its Four- teenth Session (June 2000) The Council, having recognized that transboundary aquifer systems are important sources of fresh water in some regions of the world, particularly under arid and semi-arid climatic conditions adopted Resolution No. XIV-12.

UNESCO has therefore undertaken the inventory of the main transboundary aquifers in different regions of the world and published the Atlas of Trans boundary Aquifers.

J. Alberto Tejada-Guibert Director, a.i., UNESCO Division of Water Sciences

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Groundwater is gaining greater importance by time in many parts of Africa, particularly in the arid and semi-arid zones of the continent where it is often the only source of water available.

Moreover, groundwater is generally preferred for domestic uses due to its relative purity and the absence of contaminants that are found typically in surface waters and known to cause several serious water borne diseases.

Groundwater occurs in large sandstone and carbonate aquifers that may extend beyond the boundaries of any single state thus forming

‘transboundary or shared’ aquifers. Sustain- able development of such aquifers requires collective efforts by concerned institutions in the riparian states to integrate hydrogeological studies, build regional data bases, draw well defined programmes for monitoring aquifer behavior and plan for their joint management, which is highly dependent on the state of knowledge and the degree of cooperation among riparian states.

Libya’s major groundwater basins are shared with all six neighboring countries. This unique situation has allowed the country to gain wide experience in the field and helped create coordination bodies such as the Joint Authority for the Study and Management of the Nubian Sandstone Aquifer shared by Libya, Egypt, Sudan and Chad; and the Consultation Mecha- nism Unit for the North Sahara Aquifer System shared by Libya, Algeria, and Tunisia.

UNESCO played a major role in organizing three international conferences in Tripoli since 1999. The last two conferences – convened in the years 2002 and 2008 – were dedicated for the management of shared aquifer resources

in Africa. Both conferences attracted a large number of scientists from nearly all African states and international organizations as well as key experts from all over the world. Pro- ceedings of these conferences will definitely contribute to the state of knowledge on groundwater in Africa and will greatly assist in the development of common understanding of water management issues and help reduce tension between states sharing these aquifers.

In December 2007, Libya and UNESCO signed an agreement for the establishment and oper- ation of a Regional Centre for Shared Aquifer Resources Management (RCSARM) in Tripoli.

The mission of the Centre is to contribute to the strengthening of the capacity in groundwater resources management in the region and in particular on regional shared groundwater management issues, with emphasis on Arab states and Africa.

Libya has also been recently selected by the African Ministerial Council on Water (AMCOW) to host the African Groundwater Commission.

This will add a new dimension to Libya’s responsibility and that of UNESCO towards the region and will necessitate making these scientific gatherings in Tripoli on African shared aquifers a regular event.

It is indeed a great honor for the General Water Authority of Libya to take part of this international effort aimed at laying the foundation for a sound and sustainable management of shared aquifers worldwide. The conference and the proceedings would not have been realized without the dedication of the UNESCO team and all those who participated in the event.

Omar M. Salem Director, General Water Authority Tripoli, Libya

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These proceedings were prepared within the framework of the UNESCO-IHP/ISARM Pro- gramme.

The proceedings were compiled by Holger Trei- del, UNESCO Division of Water Sciences, with the support of Aude Vincent. Marina Rubio provided the editing coordination.

The conference was co-organized with the generous support of the Authorities of the Libyan Arab Jamahiriya and various co- convenors.

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Conference Summary Report

Tripoli III Conference Statement

Opening Ceremony

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Opening message ...18 H.E. Dr A. Al-Mansuri

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Opening message...20 Charles Ngangoue

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Opening message...22 Tefera Woudeneh

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Opening message...24 Johnson A. Oguntola

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Ressources et utilisations des eaux

souterraines en Afrique...26 Jean Margat

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Codification of the Law on

Transboundary Aquifers...35 Amb. Chusei Yamada

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Transboundary aquifer resources management - General overview

and objectives of the Conference...40 Omar Salem

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Importance des aquifères

transfrontaliers en Afrique...45 Youba Sokona

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The road to Tripoli III:

What was discovered on the way,

and where to next?...49 Shammy Puri

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Management of Transboundary

Aquifer Systems: a worldwide challenge, a need for increased concertation and political support ...50 Didier Pennequin

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New Dimensions in Studying

Shared Aquifers in Africa ...59 Samir Anwar Al-Gamal

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Impacts of climate change on transboundary aquifers

and adaptation measures ...68 Richard Taylor and Alice Aureli

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Challenges to transboundary aquifer management in the SADC region ...70 Philip Beetlestone

Session 1: What do we know about transboundary aquifers in Africa?

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Main achievements in the management of transboundary aquifers in Africa and relevance for national policy...80 Bo Appelgren

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Transboundary groundwater management in the River Basin

Organisations of SADC...87 Greg Christelis, Piet Heyns, Jürgen Kirchner, Alexandros Makarigakis, Yongxin Xu

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Les aquifères transfrontaliers du circum-Sahara et les changements climatiques : améliorer la compréhension des enjeux...94 C. Baubion et A. Mamou

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Groundwater resources evaluation of Agades Province, Niger (Iglalen-

Tegeden-Igorar) ...99 Salem M. Rashrash, Nabila A. Altwibi

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Rim Zairi, Jean-Luc Seidel, Guillaume Favreau, Aws Alouini, Ibrahim Baba Goni, Christian Leduc

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Transboundary aquifer management and climate change programmes:

the experiences of the Nile Basin

Programme...102 Callist Tindimugaya

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The state of understanding on groundwater flow and solute transport between Ethio-Djibouti and Ethio-Kenyan boundaries

along the East African Rift ...103 Seifu Kebede

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Delineation of the shared Groundwater Bodies in Egypt using the European WFD Approach - A step toward

formulating the African WFD...105 Taher M. Hassan

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The hydrogeochemical characteristics of coastal aquifers in the West Coast of Africa: A review ...107 Aniekan Edet

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Assessment of renewal rate

in the shared Djeffara coastal aquifer by isotopic investigation...113 K. Zouari, M. Megribi, N. Chkir, R. Trabelsi, B. Ben Baccar and P. Aggarwal

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Étude du système aquifère

de la Djeffara tuniso-libyenne...123 Ahmed Mamou et Mohamedou Ould Baba Sy

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Groundwater losses by evaporation in the Nubian Sandstone and the Paleozoic aquifers in Libya and Egypt: Earth

observation, field experiments

and numerical modelling ...130 M. Menenti and W.G.M. Bastiaanssen

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La stratégie de développement rural et de gestion des ressources naturelles : un cadre de gestion durable des

ressources en eau dans une perspective d'intégration économique...134 Wafa Essahli and Gilbert Zongo

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Water Geochemistry for the management of urban-coastal aquifers: the case of Dakar (Senegal)...139 V. Re, S. Cissé Faye, E. Sacchi, G.M. Zuppi

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Apport de la modélisation dans la gestion concertée des aquifères transfrontaliers : cas du SASS et du SAI ...146 Mohamedou Ould Baba Sy

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Gestion conjointe des systèmes aquifère côtier partagé du Golfe de Guinée : point des activités et perspectives dans la mise en œuvre du projet MSP/FEM...150 P. Jourda, M. Boukari, B. Banoeng-Yakubo, C.N. Ajandu, K. Gnandi et E. Naah

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Metadata catalogues as a base of the Shared Water Information Systems for shared water resources management ...161 Paul Haener

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Gestion intégrée des ressources en eau dans les bassins transfrontaliers – Bassin côtier sénégalo-mauritanien – Comportement du champ captant d’Idini pour l’alimentation en eau potable de la ville de Nouakchott, Mauritanie....163 Bassirou Diagana et Samba Thieye

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Gestion des eaux souterraines dans une région sous contraintes naturelles et anthropiques sévères : le bassin

du lac Tchad...180 Benjamin Ngounou Ngatcha, Benoît Laignel, Jacques Mudry et PierreGenthon

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West African Sahel zone ...186 R. Leiterer, J. Reiche, C. Thiel, C. Schmullius and A.K. Dodo

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Transboundary aquifers

management/modelling as management tool ...194 Mohammed El-Fleet

Session 3: Looking into the future:

What options do we have?

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Trends and developments in the legal and institutional dimension of shared

groundwater management...196 Stefano Burchi

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Facing the challenge of launching joint initiatives to manage Africa’s

transboundary aquifer systems...197 Waltina Scheumann and Mathias Polak

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Transboundary aquifer management is about people...203 Frank van Weert and Jac van der Gun

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Main achievements in the management of transboundary aquifers in Africa

and relevance for national policy ...213 Anders Jägerskog

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Legal framework for sharing

transboundary groundwater resources in regions of Africa ...214 Tushar Kanti Saha

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Further developments of ISARM in Africa:

the legal and institutional focus area.

Example from the Americas ...217 Raya M. Stephan

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Developing common web-based databases for monitoring of shared aquifers: application in the Mediterranean region ...223 Jacques Ganoulis

Ofelia C. Tujchneider, Marta del C. Paris, Marcela A. Pérez and Mónica P. D´Elia

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Benefit Sharing Framework in Transboundary River Basins:

The Case of the Nile...241 Tesfaye Tafesse

Groundwater issues of Libya and

surrounding countries ...250 Avdhesh K. Tyagi and Abdelfatah Ali

Session 4: GEF-IW LEARN

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Testing regional dialogue and twinning processes in Africa for adaptive learning in transboundary water resources

governance ...252 Janot Mendler de Suarez

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Groundwater priorities in Africa –

Five years of GEF experience...255 Andrea Merla

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Nubian Sand Stone Aquifer System from Science to Practices:

Causal Chain Analysis ...257 Ahmed R. Allam, Ahmed R. Khater, Lotfi Madi and Abdula Kair

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La gestion concertée des ressources en eau partagées du Système Aquifère saharo-sahélien d’Iullemeden

(Afrique de l’Ouest)...266 Abdel Kader Dodo, Mohamedou Ould Baba Sy et Ahmed Mamou

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Le système aquifère du Sahara septentrional: exemple d’une gestion concertée d’une ressource partagée...273 Djamel Latrech

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Shared Aquifer Resources...276 Jac van der Gun

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Quo Vadis Aquifer? A joint programme addressing the links between

groundwater and human security...281 Fabrice Renaud, José Luis Martin-Bordes and Brigitte Schuster

Poster Presentations

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Levels of Cadmium, Chromium and Lead detected in a groundwater source in Zaria, Northern Nigeria...288 S.J. Oniye, A.M. Chia, D.A. Adebote,

S.P. Bako and I.G. Ojo

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Évaluation des ressources en eau dans la région de Yaoundé (centre-Cameroun) : influence des fluctuations climatiques sur leur évolution...293 Dorice Kuitcha, Gaston Lienou, Véronique Kamgang Kabeyene Beyala, Luc Sigha Nkamjou and Georges Emmanuel Ekodeck

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Isotopic composition of groundwater and palaeoclimatic condition of North Western Sahara Aquifer System

(NWSAS), Africa...301 Samir Al-Gamal, Youba Sokona, Djamel Latrech, Abdel Kader Dodo, Lamine Babasy

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Groundwater flow system definition and its potential in transboundary

and climate change issues ...304 J.J. Carrillo-Rivera, A. Cardona

and L. Padilla Sanchez

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Remote Sensing applications for the exploration of the Ntane Sandstone Transboundary Aquifer in Eastern

Botswana and Zimbabwe ...306 Max Karen

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Development of digital water well licensing system using new technologies for governance in El Kharga Oases - New Valley, Egypt ...307 Taher M. Hassan and Nahed E. El Arabi

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Les prémisses d’une vision communautaire de la gestion

des cours d’eau internationaux ...309 Naoual Bennaçar

Appendices

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Acronyms...312

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List of authors ...319

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Scope and Objectives of the Conference

The Third International Conference on Manag- ing Shared Aquifer Resources in Africa was held in Tripoli, Libya, from 25-27 May 2008, and jointly organized by the General Water Author- ity (GWA) of the Libyan Arab Jamahiriya, the Sahara and Sahel Observatory (OSS) and UNESCO’s International Hydrological Pro- gramme (IHP).

The Conference brought together more than 150 experts from 20 African countries, international institutions, universities and UN organizations, revealing the latest activities and developments in the field of transboundary aquifer management, with a particular focus on Africa. Besides the latest findings on the hydrogeological characteristics of transboundary aquifers socio-economic studies, legal instruments and management techniques were presented and discussed.

The conference contributed directly to the objectives of the seventh phase of UNESCO’s International Hydrological Programme (IHP-VII) and to the current debate on transboundary aquifers management. The outcomes and recommendations of the conference were compiled in the ‘Tripoli III Statement’ and provided valuable input for some of the related activities and events organized by international organizations subsequent to the conference.

These included the debates on transboundary aquifers in Africa that took place at the Stock- holm World Water Week in August 2008, the 5th World Water Forum sessions on Trans- boundary Waters in March 2009 in Istanbul and the UN World Water Day on 22 March 2009, the theme of which was ‘Transboundary Waters’.

Opening Ceremony

Representatives from the host country, the Libyan Arab Jamahiriya, as well the co-organizers UNESCO-IHP and OSS, welcomed the

participants and provided an overview on the scope and expected outcomes of the conference. This was followed by welcome addresses given by representatives of AMCOW, AfDB/AWF, UNECA, UNDP-GEF, FAO and IAEA, stressing the importance of the conference in taking the Internationally Shared Aquifer Resources Management (ISARM) Initiative in Africa one stage further. A speech delivered by the Special Rapporteur of the UN International Law Commission on the set of draft articles on the Law of Transboundary Aquifers informed the participants about this new instrument of international law and its relevance for the African continent.

Session 1: What do we know about transboundary aquifers in Africa?

The first session provided an overview about the current state of knowledge on Trans- boundary Aquifer Systems in Africa. Many African countries are dependant to a greater extent on the groundwater resources contained in large transboundary aquifer systems. These resources often represent the only source of water supply for those countries located in the arid zones of the continent.

The UNESCO-led Internationally Shared Aquifer Resources Management (ISARM) Ini- tiative was instrumental in collecting and col- lating the information that is currently available about the 38 Transboundary Aquifers Systems that have been identified in Africa to date.The inventory shows that one aquifer system is often shared by three or more countries at a time. While water scarcity in most African countries implies a serious threat to socio-economic development, at the same time many aquifer systems are under-utilized. The limited financial resources and inad equate appreciation of aquifer systems, add to the current limitations of the sustainable management of transboundary groundwater resources in Africa.

While emphasising the need for sound scien-

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pay due attention to socio-economic conditions, institutional and legal frameworks and ecological requirements. Based on the understanding that none of these key factors may be left aside in view of a holistic management approach, the different facets of managing shared groundwater resources were discussed during the session.

A presentation on the ISARM Americas revealed achievements and lessons learnt from this comprehensive inventory of transboundary aquifers in North, Central and SouthAmerica rounded up the picture of the state of knowledge on transboundary aquifers on a global scale.

Session 2: Management of

Transboundary Aquifers in Africa:

‘How have we been doing?

The second session focused on reviewing the strengths and weaknesses of current transboundary aquifer management approaches and explored the underlying causes and exam- ples of the successful application of sustainable management approaches were presented.

However, a number of limitations were identified, including lack of coordination and cooperation between institutions at national as well as at regional level, insufficient professional and institutional capacities, restricted knowledge on hydrogeological characteristics, fragmented monitoring of groundwater quantity and quality and lack of adequate funding.

The African Development Bank - African Water Facility (AWF) focused on the financing aspects of transboundary aquifer management.

Regional water security and the importance of improved water governance were underlined, pointing towards the lack of available info r - mation in the field of political, socio-economic, environmental and cultural development. The support provided by AWF considers the estab-

eration and the promotion of collaboration and partnerships including, those with national governments, communities and NGOs as well as the private sector and commercial banks.

The objective is to incorporate groundwater management into established RBOs and to raise the level of recognition of the need for transboundary aquifer frameworks beyond the RBO frameworks, especially in North Africa.

A presentation given by the representative of the German Federal Institute for Geosciences and Natural Resources (BGR) focused on initiatives related to the management and protection of groundwater resources supported by BGR and the German Federal Ministry for Economic Cooperation and Development (BMZ). These included seminars organised at Stockholm World Water Week, policy advice assistance with a regional focus on Africa and the Middle East and in particular supporting the establishment of the African Groundwater Commission (AGWC) under the auspices of AMCOW.

The representative of CEN-SAD highlighted the Community’s main concerns and areas of inter- vention: food security, water resources management and desertification, and then elabo- rated on the scope for partnerships and funding support in the sub-region.

An applied research case on the urban-coastal aquifers at Dakar, Senegal was presented. The case study included geochemical and isotope analysis and correlations to trace saline intrusion and anthropogenic groundwater pollution, and proposed the scope for interventions to control water quality in the coastal wells which are used for urban drinking supplies. The case study underlined the risks of saline intrusion from over-abstraction and the risk of pollution from inappropriate sanitation and wastewater management.

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The session focused on evaluating options for the future of Transboundary Aquifer Mana- gement, taking into consideration Institutional and Legal Aspects, Governance and Policy Guidance as well as Economic Aspects and Financial Instruments. It was generally agreed that there is an urgent need to move forward from the current situation where proper management of groundwater resources is an excep- tion rather than common standard. The African Groundwater Commission (AGWC) has been commissioned by AMCOW to provide strategic support throughout this process. The AGWC will act as a sounding board for strategic advice on groundwater in Africa; it will operate at the regional economic communities and river/lake basin organizations; and promote the integration of groundwater in IWRM and national and regional frameworks.

Recent efforts to integrate groundwater into international legal instruments were highlighted, drawing attention to the Berlin Rules (2004) which complement and extend the UN (1997) Convention on Non-navigational Uses of International Waters. Reference was made to the 5^th Report of the United Nations Inter- national Law Commission (ILC) and the draft articles on the Law of Transboundary Aquifers that consider the sustainable utilization of shared groundwater resources, activities that impact transboundary aquifer systems, and made considerable progress on the definition of key policy terms. However, several key parameters we found to remain poorly defined.

These include the definition of the terms ‘equi- table use’, ‘significant harm’, the definition of

‘land-based activities’, the consideration of longer time scales upon which groundwater systems operate relative to surface water bodies, specific obligations related to data exchange and prior notification, and the definition of recharge and discharge areas.

A desk study on Conceptualizing Cooperation for Africa‘s TBA Systems undertaken by BGR analysed the nature of impacts, patterns, cooperation and joint activities associated with Transboundary Aquifer Systems (TBAS) in

user boundaries, and, uncertainties in cause and effect relationships. In terms of drivers of cooperation, the study considers the cost of non-cooperation, knowledge and third-party support as important. It was concluded that (1) awareness, (2) motivation, (3) institutional frameworks, and (4) an enabling environment are required to trigger broad involvement in transboundary aquifer management.

A review of three key political paradigms surrounding transboundary aquifer management - epistemic community approach, hegemony, and discourse theory – emphasised the importance of politics in transboundary aquifer management and suggested that increasing technical and institutional capacities may help reduce inequalities in power between a weaker nation and aquifer’s hegemony.

Session 4: GEF – IW:LEARN

This session focused on the Global Environ- ment Facility’s International Waters Learning Exchange and Resource Network (GEF – IW:LEARN) and presented several case studies.

The Transboundary Diagnostic Analysis (TDA) methodology and possibilities how it could be adopted to groundwater resources were presented and discussed.

In response to a crisis of governance, the IW:LEARN project addresses the challenges which are common to GEF-funded projects in the area of shared water resources: moving the legal aspects high on the agenda, integrating groundwater and climate change in transboundary surface water projects, and supporting investment through benefit-sharing, also by sensitizing Finance Ministers. The project’s recent focus on Africa has won the endorse- ment of AMCOW’s. It was recommended that conjunctive management of surface and groundwater be pursued, and that the oil and gas industry be engaged in order to benefit from their data and resources. The countries sharing the Nubian Sandstone Aquifer System

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plicated both by the uneven capacity in the four NSAS countries and by the difficulties involved of canvassing all the stakeholders. The countries sharing the North-Western Sahara Aquifer System (NWSAS) have made significant strides in data collection and joint aquifer modelling, and a joint arrangement for permanent aquifer-level cooperation has been established and has begun functioning in 2007. The countries sharing the Iullemeden Aquifer Sys- tem (IAS) are set on a similar path, including joint data collection and modelling, and an institutional arrangement for permanent cooperation. The sensitization of Ministers of Parli- ment and journalists to water governance issues, successfully conducted by the Global Water Partnership in the Mediterranean region, has provided the inspiration necessary to mount a comparable initiative underway in Northern Africa, with potential for replication elsewhere in Africa.

Round Table Discussion: Role

of the UNESCO Category 2 Regional Centre on Shared Aquifer Resources Management in Africa (RCSARM)

The Regional Centre on Transboundary Aquifer Resources Management in Africa (RCSARM) and the Arab States was launched during the Conference. The Centre was established as a Category 2 Centre under the auspices of UNESCO and is hosted by the General Water Authorities of the Libyan Arab Jamahiriya in Tripoli.

The objectives of the Centre are to:

(i) generate and provide scientific and technical information and support exchange of information on regional shared groundwater management issues, with the emphasis on Africa and Arab States;

(ii) promote cooperation on multidisciplinary

Meteorological Organization (WMO);

(iii) undertake capacity-building on integrated water and agriculture management within the African region at institutional, professional and educational level including awareness-raising activities to the general public and to specific targeted audiences;

(iv) seek and respond to invitations for cooperation with international institutions and centres and to advance methodology in the field of shared groundwater management, support and cooperation with the IHP ISARM Project.

During the round table discussion, the conference participants debated on the role of the newly established Center for Africa and the Arab States and future cooperation opportuni- ties with existing institutions. The importance of including socio-economic and legal aspects in the scope of research activities of the Centre was stressed. The use of existing tools to quan- tify the economic benefits of the appropriate management of shared aquifer resources was promoted in order to make aware of the cost of mismanagement. The need for training and capacity development measures in these fields was also highlighted.

Representatives of international organizations, centres and research institutes expressed their will to closely cooperate with the newly established RCSARM Centre.

The participants requested that UNESCO continue its support to African countries in the study and management of Transboundary Aquifers and requested that the outcomes and recommendations of the conference, ‘Tripoli III Statement’, be presented for the consideration of decision makers at the Stockholm World Water Week in August 2008, the 5^th World Water Forum 2009 in Istanbul and the UN World Water Day on 22 March 2009.

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More than 150 participants from more than 20 countries and national, regional and international organizations and Associations attended the International Conference on

Third International Conference on managing shared aquifer resources in Africa Tripoli, 25-27 May 2008, and formulated the following Conference Statement.

We the participants,

Thanking the authorities of the Great Socialist People’s Libyan Arab Jamahiriya in arranging the series of African ‘Tripoli Meetings’¹which have led to better understanding and strength- ened networks, and in hosting the Regional Centre on Shared Aquifer Resource Mana- gement for Africa,

Considering the challenges of the UN MDG’s, and with concern that they may not be met in Africa by 2015,

We the participants, addressing the topic of shared aquifer resources of Africa,

Having recognised the strategic nature of groundwater in Africa,

Having reviewed the significant achievements

since ‘Tripoli I 1999’, through the identification of 38 continent wide, shared aquifer systems, Responding to the African Union and AMCOW priorities,

Being aware of the important role of the regional, subregional, and non governmental organisations contributions to the implemen - tation of developmental policies, for the sound and sustainable development of groundwater,

Noting that sustainable use of groundwater could contribute significantly towards achieving water security for poverty alleviation, as well as mitigation and adaptation to the impacts of climate change and its variability across the Continent,

Taking note of the need for regulatory instruments and appropriate financial mechanisms for sustainable use which support investment in infrastructure for shared aquifer management,

We, the participants,

Welcome the establishment of the African Groundwater Commission by AMCOW, Welcome the opportunity provided by the First African Water Week and World Water Week in

‘Third International Conference on Managing Shared Aquifer Resources in Africa’

Conference Statement

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of Libya,

Take note of the text, and the need for action, on the Draft Articles on the Law on the Use of Transboundary Aquifers prepared by the UN International Law Commission,

Considering the above, we have formulated the following ‘Message from Tripoli III’:

We call for further actions that encourage the joint, sustainable management of aquifers shared by countries in Africa, and,

Call on national governments to facilitate transboundary aquifer management through appropriate regulatory and administrative arrangements at domestic level;

Call on bilateral, multilateral financial institutions to reinforce their long term support to Countries and regional organisations in their development of groundwater for their national economic development, including providing the necessary funds for resource exploration, evaluation and sound data collection to fill in data gaps leading to knowledge based sound management practices;

Call for partnerships with industry, especially the mineral development, oil & gas sectors, to participate in identification and use of productive aquifers that could contribute to poverty alleviation, human development and environmental sustainability;

Call upon UNESCO (ISARM-Africa) and GEF International Waters to continue and reinforce their programme, and deploy a long term effort in support of the sustainable management of shared aquifer resources of Africa.

We commend this Statement for the attention of AU, AMCOW and their constituent bodies for consideration and pursuit as appropriate, and,

We address the Tripoli III Statement for the attention of the political process of the 5th World Water Forum.

Tripoli, May 2008

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In Name of God the Most Merciful, Misses and Misters the Representatives of the participating Arab and African countries,

Misses and Misters Guests,

I’m glad to welcome you all and I appreciate your care to attend the activities of the Third International Conference on Managing Shared Aquifer Resources in Africa, which we are glad to host it in the Great Jamahiriya during the period from May 25^thto 27^th2008 and I express our most sincere wishes that this conference succeeds.

This Conference is held under certain international circumstances witnessing an increase in aridity and desertification intensity along with climatic changes and increase of water demand, which makes the aquifer management an issue that requires more attention.

It is also held under circumstances witnessing a water crisis at local and international levels, with an increase in water demand, especially groundwater which is the main source of the water supply in many countries, among them is the Great Jamahiriya. Considering the importance and sensitivity of the shared aquifers, regarding their management and development, and in line with the policy of the Great Jamahiriya, whom since a long time took the initiative to set up a continuous consultation mechanism with the countries sharing aquifers with it, aiming to coordinate the exploitation forms and undertake joint studies to protect such aquifers from depletion and contamination. Among these projects is the study of Nubian Sandstone Aquifer System, taking the initiative to establish the Joint Commission

between Libya, Egypt, Chad and Sudan, which Libya is honored to host its headquarters since its establishment in 1989, also studying the North Sahara Aquifer System between the Great Jamahiriya, Tunisia and Algeria, which was crowned by establishing a consultation mechanism and forming a coordination unit hosted by the Sahel and Sahara Observatory in its headquarters in neighboring Tunisia.

I’m also glad to praise the continuous cooperation with UNESCO in the various fields of Water, especially the shared ones and to declare the establishment of the Regional Centre for the Management of the Shared Aquifers in Africa and the Arab region, in the Great Jamahiriya, which I had the honor to sign the agreement of its establishment with the Director-General of UNESCO in Tripoli on 27/12/2007, whose most important targets is the consolidation of joint studies, capacity building and exchange of information on shared aquifers, and strengthening their management for a sustainable development.

The water is the control element for sustainable development, therefore the balance between the demand on water and the available resources, deserves our attention, for the benefit of the present and future generations.

The increasing demand on water is a result of many factors, especially the demographic increase, as the international statistics indicate that the world population will increase by 50%, from 6.1 billion in the mid 2001 to 9.3 billions by 2050, leading to increasing the intensity of the food crisis.

In addition, the desertification phenomena is a result of long dry periods and lack of develop-

Opening message

H.E. Dr. A. Al-Mansuri

Secretary of General People's Committee for Agriculture, Livestock and Marine Wealth

(19)

ment in several regions of the world, starting from the African Continent, in addition to the mismanagement of natural resources and in particular the over-exploitation of aquifers.

Therese reasons together formed large pres- sure areas worldwide, especially the Sahara countries in Africa, leading to the emigration of thousands of people searching for survival and running away from the specter of poverty, hunger and death.

Comprehending such dangers and in application of the United Nations Agreement, Libya prepared a national work plan to combat desertification, which included several strategies and projects to combat desertification and rehabili- tate affected lands.

Undoubtedly, you realize the extreme signifi- cance which the Alfatah Revolution and its leader Colonel Muammar Al-Quaddafi, give to the water issue and the huge investments provided to overcome the water shortage problem and combating desertification. Such efforts included the conveyance of potable water along thousands of kilometers of large dia - meter pipes, deep from the Sahara desert to the coastal cities and valleys, in the largest project of its kind, the Great Man Made River, which came to multiply the production, to secure a certain level of food security, to fulfill the potable water needs of costal towns, that until recently witnessed severe shortage, notwith- standing the establishment of many desalin- ization plants and well fields. This huge civil project will provide a transitory solution to the water shortage problem in the coastal areas of the North Jamahiriya, and as the Leader of the revolution noted, this solution is not final, but rather a final attempt to safeguard life in North Africa, therefore it is necessary to join efforts and intensify research to locate economically feasible alternatives for a sustainable and continuous supply of water.

You might comprehend the urgent need in the Arab region and Africa to develop our water legislations, which is an extension of our great cultural heritage that paved the way for the birth of the most ancient legislations since thousands of years and which was contempo- rary to the birth and rise of the great civili - zations in the Arab region and Africa.

The distinguished nature of the occurrence and distribution of surface and groundwater resources, either quantity or source, and the continuous decrease of the per capita share of it make the issue of sound management of such resources in a sustainable manner in quantity and quality, among the prior interests of the water institutions, therefore its elemen- tary that the international legislations attract a special interest to secure the rights of the countries and regions, and to achieve sustainable development under water shortage con - ditions.

Water legislation, like other legislations related to human life, develops with time to cope with social, economic and political growth. In the Great Jamahiriya we issued the first modern water law since 1965 which was later replaced with the law n°3 of 1982, which is among the modern laws dealing with all aspects of regu- lating the exploitation and management of water resources, and protecting it from depletion and contamination.

In this pleasant occasion, I am glad to express my gratitude and acknowledgment to the UNESCO, to the Sahel and Sahara Observatory and to all International and Regional Organi- zations present in this Conference for their effective participation in the preparation stages.

We also express our gratitude to the local exter- nal preparatory committees for their great effort to realize this event wishing you a com- fortable stay and a successful conference.

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Mesdames et Messieurs, Distingués invités.

Au moment où s’ouvre cette troisième confé- rence internationale sur les aquifères transfrontaliers, ici dans cette belle ville de Tripoli, je voudrais en ma qualité de Président du Comité technique consultatif des Experts du Conseil des Ministres Africains de l'eau (AMCOW) et en mon nom propre, remercier le Gouvernement de la République Arabe Jamahiriya Libyenne et son Chef pour l’attention toute particulière qu’ils accordent aux questions de la gestion des aquifères transfrontaliers et également au peuple de Libye pour l’accueil chaleureux dont nous sommes l’objet depuis notre arrivée dans cette belle ville de Tripoli.

Je remercie aussi les co-organisateurs de cette conférence à savoir, l’Observatoire du Sahel et du Sahara et surtout l’UNESCO pour l’aimable invitation qu’il a bien voulu nous adresser afin de prendre part à cette importante conférence.

Je remercie aussi le Gouvernement de l’Alle- magne à travers son Ministère Fédéral de la Coopération Economique et du Développement (BMZ) et tous les sponsors des présentes assises.

Je remercie également le personnel de l’Am- bassade de la République du Congo en Libye, pour leur attention et l’intérêt accordé à cette conférence dont l’impact pour notre pays et pour le continent n’est plus à démonter.

Les Ministres Africains de l'eau, soucieux de promouvoir la coopération régionale, le déve- loppement économique et social, l’éradication de la pauvreté en Afrique grâce à la gestion des

ressources en eau et la fourniture des services liés à l'eau, ont créé en avril 2002, à Abuja au Nigéria, le Conseil des Ministres Africains de l’Eau (AMCOW) dans l’esprit de la Vision africaine de l’eau à l’horizon 2025.

C’est ainsi, que lors de sa sixième session ordi- naire tenue en mai 2007 à Brazzaville au Congo, le Conseil des Ministres a décidé d’institution- naliser la gestion des eaux souterraines en Afrique. En agissant ainsi, il donne l’occasion à toutes les parties prenantes de cette branche du secteur de l’eau, de mettre en valeur toutes leurs capacités.

En effet, beaucoup de pays africains ont re - cours à de l’eau souterraine pour approvision- ner leurs localités (urbaines et rurales), mais les informations et les connaissances dans ce domaine restent encore faibles. Dans mon pays le Congo, la ville de Pointe Noire, deuxième ville du pays, située sur l’océan atlantique, approvisionne environ 800 000 personnes par jour à partir des forages industriels et forages domestiques. L’hydraulique rurale est en grande partie assurée également par les eaux souterraines. L’information et les connaissances sur les paramètres de ces aquifères restent très faibles, ce qui rend l’exploitation difficile.

Au niveau de la sous-région Afrique centrale, l’harmonisation des politiques en matière des ressources en eau est en cours, avec l’appui de la Communauté Economique des États de l’Afrique Centrale (CEEAC). La présente Confé- rence vient à point nommé pour nous permettre de bénéficier des expériences des autres sous-régions et assurer une meilleure intégra- tion régionale.

En décidant de mettre en place une commission africaine sur les eaux souterraines lors de

Opening message

Charles Ngangoue

Président du Conseil Des Ministres Africains de l’eau (African Ministers’ Council on Water, AMCOW)

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sa réunion de novembre 2007 à Nairobi, le Comité Exécutif de l’AMCOW a voulu donner à l’Afrique un instrument de gestion de ses eaux souterraines de façon durable et aborder la question des aquifères transfrontaliers à l’instar des eaux de surface transfrontaliers.

A travers ses activités, la commission africaine sur les eaux souterraines doit permettre à l’AMCOW de disposer des outils de prise en compte et de mise en œuvre de ses décisions en la matière. L’eau étant également un facteur de paix, des conflits seraient évités, la crois- sance économique garantie, l’intégration régionale assurée et ainsi que d’autres actions positives de développement.

Tout cela n’est possible qu’avec l’effort de tous.

C’est pour cela que l’AMCOW a engagé et encourage le partenariat stratégique avec les pays et les institutions telles que le NEPAD, la Banque Africaine de Développement, l’Union Européenne, le G8, les Organisations des Na - tions Unies à travers le Groupe eau-Afrique des Nations Unies (PNUE, UN-Habitat, UNESCO, UNICEF), les différents Gouvernements et les Agences de coopération et de Développement à l’instar de la GTZ, l’AFD, DANIDA, le Groupe Eau Afrique de l’Initiative eau et assainissement de l’Union européenne ainsi que le Programme Eau et l’assainissement (WSP) de la Banque Mondiale.

Ces partenaires stratégiques et bien d’autres que je n’ai pas pu citer, se sont constamment sentis solidaires de l’AMCOW et ont toujours apporté un appui conséquent à ses activités.

L’agenda africain de l’eau 2008, a permis à l’AMCOW de tenir :

• la Conférence régionale sur l’assainissement et l’hygiène en février 2008 à Etheik- wini en Afrique du Sud ;

• La Première Semaine Africaine de l’eau en mars 2008 à Tunis ;

• et bientôt le Sommet de l’Union Africaine sur l’eau et l’assainissement en juillet 2008 à Sharm El Sheikh en Égypte.

Tous ces évènements importants pour le secteur de l’eau et de l’assainissement en Afrique se sont tenus avec l’appui considérable des partenaires précités. C’est ici une fois de plus, l’occasion de les remercier et de les encourager à s’engager d’avantage dans la mise en œuvre des décisions, des déclarations et des plans d’actions de ces différents évènements de haut niveau dont nous devons dès à présent capita- liser, valoriser les résultats en vue d’un déve- loppement harmonieux, intégré et durable du secteur de l’eau et de l’assainissement au pro- fit de l’ensemble des populations africaines.

Je voudrais pour terminer, renouveler ma profonde gratitude à l’endroit de tous ceux qui ont rendu possible, la tenue de cette Troisième Conférence Internationale sur les aquifères transfrontaliers.

Je souhaite par la même occasion plein succès à ses travaux et vous remercie mesdames et messieurs de votre aimable attention.

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Your Excellency Dr. Mansuri, Secretary of People’s Committee for Agriculture, Livestock and Marine Wealth of the Government of Libyan Arab Jamahiriya;

Mr. Omar Salem, Director of the General Water Authority of the Libyan Arab Jamahiriya;

Distinguished Representatives of AMCOW, TAC and Governments;

Distinguished Representatives of UNESCO, IHP, OSS, UN Water Africa, Donors, NGOs and other Stakeholders;

Ladies and Gentlemen.

It is in deeded my pleasure to make this brief statement on behalf of the African Develop- ment Bank and the African Water Facility on this International Conference on transboundary aquifer resources management in Africa. I would like to take the opportunity to thank the Government of Libya particularly the General Water Authority for organizing this important Conference on transboundary aquifers with the Observatoire du Sahara et du Sahel (OSS) and UNESCO-IHP.

I hope over the coming three days we will deliberate on the key challenges and issues of transboundary aquifers and come-up with specific recommendations of concerted actions on the sustainable use of these unique water resources of Africa. From this perspective, the Conference will provide us with an opportunity for interaction, networking and design of col- laborative efforts and identify specific actions that we can jointly work on in this area.

It is important to note that Africa is endowed with groundwater resources in shallow and deep aquifers stored in over 40 transboundary aquifer systems and that proper management is of critical importance to ensure the sustainable use to provide for the lively hood needs of millions of our people and contribute to the socioeconomic development of the continent.

I would like to note that our engagement at the regional level has gained momentum under the leadership of AMCOW and has allowed us to articulate the African water challenges and design concrete strategies and actions to enable us achieve better provision of water and sanitation service and meet the socio-economy demands of our people. I would like to indicate that in this respect the African Water Vision and Frame Work for Action has indeed provided us with the appropriate framework to guide the regional efforts of sustainable water resources development in Africa.

The steps taken by AMCOW to consider transboundary river basin management to include groundwater resources management as well as the actions taken to establish an African Groundwater Commission are laudable.

Nevertheless, while we now have better understanding of the water challenges of Africa including groundwater, we have yet to translate our visions and strategies into action on the ground to make a difference on the lively hood of millions of African. Indeed this is now the greatest challenges that require our commitment, energy and collective actions.

As Africa’s premier financial institutions, the African Development Bank seeks to help African countries deal with the threats of poverty, growing populations needs for liveli- hood, ensure water security for economic and social development, adaptation to climate

Opening message

Tefera Woudeneh

Chief Water Operations Officer, African Water Facility, African Development Bank

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change impact and associated risks. The key issue here is the development of the necessary water infrastructure including storage facilities to significantly increase the availability of adequate quality and quantity of water to meet the socio-economic and environmental needs and manage risks.

In this respect, the Bank’s water and sanitation sector investment has grown five fold since 2002, from less than US$ 70 million per annum to over US$ 350 million per year. This is expected to further increases to reach US$ 600 million per year by 2010. The support is targeted to contribute to the efforts of sustainable water security to meet the water supply and sanitation needs, food and energy security and risk management.

Let me take the opportunity to highlight some of the important initiatives and actions that has important bearing on groundwater resources management.

The Bank with other partners and stakeholders has been supporting the effort of AMCOW to articulate and promote the African water policy challenges at the regional and international forums. The Bank has consistency promoted and advocated for international awareness and support to address the key water challenges of Africa through the World Water Forum process.

The African Water Vision launched at the Second WWF and the discussion on groundwater issues as specific theme on the Fourth World Forum are significant steps in this direc- tion. I would like to inform you that the Bank has been requested to lead the Africa’s participation in the Fifth World Water Forum and I hope that the outcome from this Conference will forum part of the regional documentation for submission at the Forum.

More recently the groundwater resources management was one of the main themes of the first African Water Week in the framework of achieving water Security. This aspect was concisely capture in the Ministerial Declaration where the Minister called on governments and partners to ‘harness local groundwater resources to improve livelihoods and manage risks associated with climate change and insti- tutionalize dialogue on groundwater mana-

gement in Africa and implement the Roadmap for the African Groundwater Commission’.

The Bank is supporting NEPAD and is moving ahead with the development of the Medium to Long-term Strategic Framework for the NEPAD Water and Sanitation Programme as well as the preparation of water infrastructure financing under the Infrastructure Consortium for Africa initiative. The NEPAD Water and Sanitation Pro- gramme is mainly focused on transboundary water resources management including groundwater in transboundary aquifers. In this respect support to the North African transboundary aquifers systems has been identified as an important area of focus.

The implementation of the Rural Water Supply and Sanitation Initiative is moving forward with programmes implantation in 21 countries by end of 2008 which brings coverage to an addi- tional population of about 32 million for water supply and 29 million people for sanitation with an investment of about US$ 1,024 billion.

Groundwater provides significant portions of the water resources to meet the basic needs of rural communities.

The implementation of the African Water Facil- ity has moved forward successfully with the approval of 34 projects amounting to about Euro 30 million. The Facility is planning to mobilize Euro 236 million over the coming years to provide support in strengthening water governance at national and transboundary level; investments to meet water needs; strengthening the financial base and improving knowledge and water wisdom. We are currently closely working with OSS in supporting activities related to transboundary aquifers in North Africa and the IGAD sub region. The effort will continue to expand and in this respect I would like to assure you of our desire to closely work with our partners on the management of transboundary aquifers in Africa.

In conclusion, I would like to reiterate that the Bank and the African Water Facility will work with you in moving this important agenda of the continent forward. I wish you a successful meeting and look forward to actionable outcome over the next three days.

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His Excellency, Dr A. Mansuri,

Secretary General of Agriculture, Libya, Dr Omar Salem, General Director of General Water Authority of Libya,

His Excellency, Ambassador Chusei Yamada, Dr Youba Sokona, Executive Secretary of OSS, Madame Alice Aureli,

UNESCO Representative,

Distinguished representatives of international and multilateral institutions,

Eminent experts and participants at this international conference, Ladies and Gentlemen,

Permit me to join the previous speakers in wel- coming you all, on behalf of the United Nations Economic Commission for Africa (UNECA) and on behalf of the organizers of the 3rd Inter- national Conference on Managing Shared Aquifer Resources in Africa, taking place here in Tripoli, Libya.

I will like to express our profound appreciation to the government of Libya, for hosting the International Conference on Managing Shared Aquifer Resources in Africa for the third con- secutive time, and for the generous hospitality extended to all participants at this conference.

This to us is a clear indication of the unwaver- ing commitment of the Libyan government to the improvement of groundwater resources management policies in Africa through better assessment of the groundwater resource situa-

tion, identification of critical problems and their causes, improving reporting on monitoring of progress against set targets, and improved evaluation of water policy, strategy and actions.

Furthermore, since the management of transboundary aquifers is premised on the cooperation among the riparian countries, it needs be acknowledged the very important contribution of Libya to forging regional cooperation and integration in Africa through supporting this initiative.

Let me also take this opportunity to thank the United Nations Educational, Scientific and Cultural Organization (UNESCO), and the Observatoire du Sahara et du Sahel (OSS) for providing valuable technical and leadership input to the organization of this International Conference, without which this conference would not have been possible. The UN- Water/Africa grouping, secretariat of which is hosted at UNECA, could not have designated any other better agency to lead other UN agencies in this particular thematic area of groundwater management.

We at UNECA view shared aquifer management from the point of view of their contributions to the continent’s socio-economic development, through groundwater contributions to environmental sustainability and ecosystem integrity, provision of water access to farmers through the use of small-scale water technology, and the role of groundwater as a reliable source of safe water and sanitation.

The importance of this International Confer- ence to the African countries where the poverty challenge, coupled with inadequate population access to water and sanitation is still very acute, cannot be over-emphasized. In order to meet the MDG drinking water target in Africa, about 300 million people still need to gain

Opening message

Johnson A. Oguntola

Representative of United Nations Economic Commission for Africa (UNECA), Senior Regional Advisor (IWRM)

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access to an improved drinking water source.

Groundwater represents a cheap source for attaining this objective.

From irrigation point of view, groundwater con- stitutes the main source of water either in its occurrence as independent hydraulic entities like is commonly the case in the northern parts of Africa, or as tributary aquifers recharged by surface water sources. In either of these cases, good management is needed to prevent anar- chy in the use of the resource and to prevent externality on other users in the system.

We are gratified to note that this International Conference has been designed to address pertinent issues on Transboundary Aquifer Management, including institutional and legal aspects, governance and policy guidance, econ omic aspects and financial issues. We have no doubt that the next three days of dis- cussions on these issues will provide us with a better management of Transboundary Aquifer Resources in Africa.

I wish the conference very successful delibera- tions, and thank you for your attention.

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Une vision générale sur les eaux souterraines de l’ensemble du continent africain, les ressources qu’elles offrent et leurs utilisations, nécessairement panoramique et macrosco- pique, s’attachera surtout aux contrastes essen- tiels et aux comparaisons entre les situations de chaque pays, illustrées par des images car- tographiques et des chiffres-clés. Elle peut s’or- ganiser en six constats majeurs.

Une géographie des eaux souterraines très contrastée

La répartition et l’abondance relative des eaux souterraines sont commandées par la double diversité géologique et climatique, qui se tra- duit pas deux contrastes majeurs et indépen- dants :

•

au plan géologique :

Contraste entre bassins sédimentaires et socle ancien ou formations volcaniques plus localisées, qui détermine la variété des conditions hydrogéologiques,

•

au plan climatique :

Contraste entre zone aride et semi-aride et zone humide, qui détermine l’extrême variété des apports météoriques et des évaporations potentielles génératrices de l’alimentation et parfois de la décharge des aquifères.

Le croisement de ces deux contrastes géogra- phiques fonde la typologie des ressources en eau souterraine du continent africain, basée à la fois sur le structure des réservoirs aquifères et la dynamique de leur renouvellement, repré- sentée par exemple par la carte à légende

matricielle illustrant la monographie des eaux souterraines de l’Afrique publiée par les Nations Unies en 1987.

Les ressources en eau souterraine renouvelables les plus abondantes et mobilisables sont à l’évidence situées dans les régions à la fois à aquifère étendu et productif, et en zone humide.

Cette géographie contrastée détermine aussi la diversité des demandes en eau qui sollicitent les eaux souterraines, plus particulièrement les demandes en eau d’irrigation en zones pauvres en « eau verte », en fonction à la fois des poten- tialités en sols et en eau.

Une typologie hydrogéologique très différenciée

Les conditions hydrogéologiques régionales de l’Afrique sont schématisables par quatre types majeurs de formations aquifères :

•

Bassins sédimentaire multicouches, à nappes souterraines phréatiques ou profondes et captive, souvent très étendus (la plupart sont transfrontaliers) dont la composition stratigraphique peut s’échelonner du Pré- cambrien au Quaternaire, constitués princi- palement de formations détritiques, mais aussi carbonatées Leur puissance atteint, pour la plupart, plusieurs milliers de m et les volumes d’eau qu’ils stockent se chiffrent en milliers de km³mais ne sont que très par- tiellement mobilisables.

Les caractéristiques des 13 plus importants de ces grands systèmes aquifères, générale-

Ressources et utilisations des eaux souterraines en Afrique

Jean Margat

Conseiller, BRGM

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ment endoréiques en zone aride, sont résumées dans le Tableau 1.

•

Domaines à structure complexe (chaînes plissées) à aquifères peu étendus et discontinus, notamment karstiques ou volca - niques, qui bénéficient d’alimentation notable en zone humide du fait de l’altitude et sont générateurs des principales sources.

Ils sont relativement localisés au Maghreb, en Afrique Australe et dans le sillon vol- canique d’Afrique de l’Est, ainsi que dans les îles périphériques, volcaniques pour la plupart, du Cap Vert à Maurice…

•

Aquifères alluviaux, de vallées ou deltas, à nappe phréatique ou parfois profonde, plus ou moins liés aux grands cours d’eau, transfrontaliers pour la plupart (Niger, Nil, Séné- gal, Zambèze…).

•

Aquifères du socle fissuré et altéré constitu- ant une grande partie du continent, formant des systèmes localisés souvent discontinus et sans réserve notable.

Quelles sont les ressources en eau souterraine de l’Afrique ?

Deux sortes de ressources en eau souterraine bien distinctes s’offrent en Afrique : des ressources renouvelables et des ressources non renouvelables.

•

Les ressources en eau souterraine renouvelables sont subordonnées aux conditions climatiques, donc très différemment distri- buées, et inégalement interdépendantes avec les eaux de surface. Les flux moyens annuels de recharge des aquifères auxquels ces ressources sont assimilées en théorie sont sujets à calcul dans la plupart des pays africains et ils varient localement à l’ex- trême : de moins d’1 mm /an à plusieurs centaines de mm/an suivant les moyennes calculées par pays, et en sommations par pays de 100 millions à plus de 100 milliards de m³/an, suivant le climat et l’étendue du pays (voir Tableau 2).

Toutefois l’approche par modélisation des

infiltrations à partir de données climatiques (par exemple la cartographie discrète élabo- rée par P. Döll (2003) et reproduite dans WHYMAP) aboutit généralement à des chif- frages plus élevés que l’approche par ana- lyse des débits de base des cours d’eau (cf.

la cartographie mondiale du « Groundwater Flow » élaborée par R.G. Dzhamalov et I.S.

Zekster (1999), généralement adoptée par les références nationales de la base AQUAS- TAT de la FAO.

Parvenir à une meilleure convergence des évaluations suivant ces deux approches serait un thème de recherche opportun.

La plus grande partie de ces apports aux aquifères (et même leur totalité dans les pays enclavés…) équivaut en zone humide à la composant régulière de l’écoulement des cours d’eau qui les drainent, donc aux ressources en eau de surface permanentes.

En zone aride et semi-aride, par contre, les eaux souterraines sont alimentées principa- lement par les infiltrations de cours d’eau, le plus souvent temporaires ou issus de zone humide (comme le Nil ou le Niger …). Elles sont donc aussi communes avec une partie des ressources en eau de surface.

Les eaux souterraines et les eaux de surface étant largement interdépendantes, les éva- luations des ressources respectives corres- pondantes doivent éviter tout double compte.

De plus la recharge des aquifères ne doit pas être identifiée intégralement aux ressources en eau souterraine renouvelables et mobilisables – seules réelles – à évaluer suivant différents critères technico-économiques, sociaux et environnementaux, notamment de conservation des eaux de surface permanentes subordonnées, variées suivant les pays.

•

Les ressources en eaux souterraine non renouvelables ou « eaux fossiles » sont constituées par la part jugée extractible – suivant là encore des critères écono- miques et environnementaux (absence d’impact inacceptable) – des réserves des aquifères à renouvellement négligeable,