Groundwater in the Volta Basin (PDF, 571 KB - BGR

1.0 Introduction
GROUNDWATER IN THE VOLTA BASIN
The Volta is a transboundary river, which is shared by six countries in West Africa; Bénin, Burkina Faso,
Cote d’Ivoire, Ghana, Mali and Togo. It stretches from north to south over a distance of 1850 km with a
basin covering an area of approximately 400,000 km 2 (Fig. 1).
The basin area in the six countries varies. It ranges from 2.48% in Cote d’Ivoire to 42.9% in Burkina Faso.
On the other hand, while the Volta basin covers 70.1% of the land area of Ghana, it dwindles to 1.0 % in
Mali.
2.0 Hydrogeology
The geology of the main Volta (Fig. 2) is dominated by the Voltaian system, which together with the
basement complex dominate the hydrogeological systems (Barry et al., 2006). In Ghana for example, the
basement complex covers 54 % of the land area and contributes 50% of groundwater resources. The
sedimentary formation underlies about 45% of the country and provides 39 % of groundwater (Fig. 3).
3.0 Transboundary Groundwater
At a recent UNESCO Workshop on Inventory of Transboundary Aquifers in West Africa, in Cotonou,
Benin, from 30 May to 01 June 2007, the following shared basins were identified in the Volta basin (Table
1).
Table 1 Transboundary Groundwater in the Volta Basin
Shared Basin Characteristics Countries
Iullimeden 3 aquifer basins with River Niger as the Mali, Niger, Nigeria Bénin,
southern limit.
Algeria
Taoudéni Various types of sandstone. The basin is Burkina, Mali, Mauritania,
virtually unknown
Algeria
Tano Coastal sedimentary basin located in the
lower reaches of the Tano River in Ghana. 3
aquifer horizons with potential to supply
Abidjan. Not much information available.
Cote d’Ivoire, Ghana
Keta Coastal sedimentary basin, which includes
the Volta estuary. 3 transboundary aquifers,
which supply water to key coastal urban
centres including Lome, Cotonou, Lagos
and Port Harcout
Ghana, Togo, Bénin and Nigeria
Volta Information is very scanty. The basin is
virtually unknown.
Burkina, Bénin, Togo
Liptako Gourma* Crystalline basement aquifer Burkina Faso, Niger
*Not included in workshop list but could occur in the Volta basin (Fig. 4)
While some of the aquifers were virtually unknown, information on the others was scanty. From available
information, inconsistencies occur in data and information on groundwater in the Volta basin as a result of
inadequate knowledge on the resources. For example, the aquifers identified during the above workshop
did not include the Liptako Gourma, which is shared by Burkina Faso and Niger.
In spite of this, it can be inferred that all the six riparian countries of the Volta share, at least, one
groundwater basin with another country (Table 2). Benin shares as many as four basins with the other
riparian countries. Two basins, the Tano and Volta are shared solely by the riparian countries of the Volta
while four basins are shared with other non-riparian countries (Fig. 4).

Table 2 Shared Groundwater Basins
No. of Shared Groundwater Basins
Country
With Riparian Countries With Non-Riparian Countries
Benin 3 2
Burkina Faso 2 2
Cote d’Ivoire 1 -
Ghana 2 1
Mali 2 2
Togo 1 1
4.0 Utilization and Problems
Groundwater resources in the Volta basin are used mainly for domestic water supply in both urban and
rural areas. Key cities such as Ouagadougou, Cotonou and Lomé all rely on groundwater for a significant
proportion of their water supplies. In many rural areas, groundwater is the only source of safe portable
water supply. Groundwater is also used for watering of livestock and crop irrigation but on a comparatively
limited scale. In general many groundwater sources are untapped although the rate of use is rapidly
increasing (ECOWAS-SWAC/OECD, 2006).
The major problems associated with utilization of groundwater in the Volta basin include:
• Over exploitation as a result of population pressure;
• Contamination and pollution problems from poor domestic and industrial waste disposal practices;
• Deforestation and creation of irrigation dams resulting in reduced aquifer recharge;
• Intrusion of saline waters and high fluoride and iron concentrations affecting water quality;
• Impacts of reduced rainfall and global climatic change.
5.0 Management of Groundwater in the Volta Basin
The management of groundwater occurs at different levels in the various countries. While some countries
including Burkina Faso, Cote d’Ivoire and Benin have established systems to monitor shared aquifers,
others such as Ghana and Togo do not have such systems in place. Monitoring is mainly by the use of
networks of piezometers. However, in all cases, installed monitoring systems are not adequate.
Data and information are not sufficient to neither map out the aquifers nor assess their recharge. Also, both
public and private sector institutions continue to operate sectorally, with little coordination. At the
transboundary level, there is virtually no contacts or cooperation between the various national institutions
responsible for the management of groundwater resources.
Legislation for the management of groundwater resources is not common. It usually forms part of general
codes for protection of water resources or the environment and is not specific to ground water. However,
efforts are being made to improve the situation as in Ghana, which has recently passed ‘Drilling License
and Groundwater Development Regulations’ in attempt to control drilling and improve data collection.
6.0 Way Forward
Many recommendations exist for improved management of groundwater resources in West Africa of which
the Volta basin is a part. These include the following:
Tripoli June 2002 UNESCO/ISARM Workshop on Managing Shared Aquifers Resources in Africa, which
highlighted the need to:
• Conduct inventories of African shared aquifers;
• Prepare guidelines for sound and sustainable development of shared aquifers;
• Initiate activities with the support of partners within the framework of ISARM Africa;
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• Include the NEPAD and AMCOW process
Groundwater Capacity Building Initiative in Africa (BGR/Cap-Net/WA-Net/Waternet), whose survey
resulted in key recommendations for improvement in groundwater management as follows:
• Groundwater assessment and development;
• Institutional and legal arrangements;
• Groundwater protection;
• Groundwater education and training
Cotonou June 2007 UNESCO/ISARM Workshop on Inventory of Transboundary Aquifers in West Africa,
which made recommendations to:
• Prepare an atlas of shared aquifers in West Africa;
• Conduct case studies for selected aquifer basins;
• Increase participation of decision makers in management of shared basins
All the above recommendations are still valid and relevant and the Volta Basin Authority supports them as
providing the right direction for improving management of shared groundwater resources. The VBA
therefore wishes to participate fully in these activities. Although VBA, just as other basin organizations in
West Africa, is named on the basis of the more obvious Volta River, its Statutes indirectly take into
consideration the management of groundwater resources, with references to ‘development of natural
resources’ and ‘adoption of integrated water resources management’.
At this stage, due to the need to minimize duplication and conserve resources, it is not necessary to create
new institutions within the Volta basin or in West Africa specifically for management of groundwater
resources. Also, since all water resources should be managed together, VBA and other existing basin
organizations as well as institutions such as ECOWAS Water Resources Coordination Unit should be
strengthened to integrate management of groundwater resources into their scope of activities. This can be
achieved through the modification or expansion of activities such as the operation of observatories and
implementation of the HYCOS projects. The Statutes or other relevant international agreements of the
basin organizations can also be modified to specifically include groundwater.
While it is urgent to improve the management of groundwater resources in the area of the Volta basin, with
particular emphasis on shared aquifer basins, repeating the mistake of management of water resources on a
sectoral basis should be avoided, even though it appears to be an easier option.
In addition to the required cooperation among the riparian countries of the Volta basin, is is important to
strengthen inter-basin cooperation since majority of the riparian countries share aquifer basins with some
non-Volta countries. Also, in view of the growing importance of groundwater to the improvement of
livelihoods in the Volta basin, more reliable data and information should be generated to support
sustainable management of the resources. The VBA therefore wishes to solicit the support of its
international technical and financial partners to undertake a case study of the transboundary aquifers of the
Volta basin.
8.0 REFERENCES
Barry, B. Obuobie, E., Andreini, M., Andah, W. and Pluquet, M., 2006. The Volta River Basin ;
Comparative study of river basin development and management. IWMI, Comprehensive Assessment of
Water Management in Agriculture
ECOWAS-SWAC/OECD. 2006. http:www.atlas-ouestafrique.org/spip.php?article 133.
Volta HYCOS, 2003. Project Document
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Fig. 1 Map of the Volta Basin and Riparian Countries (Volta HYCOS, 2003)
Fig.2 Geological Map of the Volta Basin (Barry et al., 2006)
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Fig. 3 Hydrogeological Provinces and River Systems of Ghana (Geological Survey of Ghana 1969)
Source: ISARM Africa
3. Taoudéni
4. Iullimeden
12. Liptako Gourma
13. Tano
14. Keta
The Volta aquifer is not represented
Fig. 4 Shared Aquifer Basins in the Volta Basin
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