UNESCO is publishing the first-ever world map of shared aquifers. Almost 96% of the planet’s freshwater resources are to be found in underground aquifers, most of which straddle national boundaries. This publication is to coincide with the submission to the General Assembly of the United Nations on 27 October of a draft Convention on Transboundary Aquifers. Despite its strategic importance, no global inventory of this resource had been compiled to date. Since 2000, UNESCO’s International Hydrological Programme (IHP) has been participating in the establishment of a groundwater database. It is now presenting a detailed map of transboundary aquifers – available online – showing the delineations of aquifers that are shared by at least two countries. It also provides information about the quality of their water and rate of replenishment. So far, the inventory comprises 273 shared aquifers: 68 are on the American continent, 38 in Africa, 65 in eastern Europe, 90 in western Europe and 12 in Asia.
The aquifers, which contain 100 times the volume of fresh water that is to be found on the Earth’s surface, already supply a sizeable proportion of our needs. The growth in the demand for water since the second half of the 20th century has been met by the increased use of underground resources. Globally, 65% of this utilization is devoted to irrigation, 25% to the supply of drinking water and 10% to industry.
Underground aquifers account for more than 70% of the water used in the European Union, and are often one of the only – if not the only – source of supply in arid and semi-arid zones (100% in Saudi Arabia and Malta, 95% in Tunisia and 75% in Morocco). Irrigation systems in many countries depend very largely on groundwater resources (90% in the Libyan Arab Jamahiriya, 89% in India, 84% in South Africa and 80% in Spain).
Although aquifer systems exist in all continents, not all of them are renewable. For example, those in north Africa and the Arabian peninsula were formed more than 10,000 years ago when the climate was more humid and are no longer replenished. In some regions, even if the aquifers are renewable – being fed on a regular basis by rainfall – they are in some cases endangered by over-exploitation or pollution. In the small islands and coastal zones of the Mediterranean, populations often use groundwater more rapidly than it is replenished.
The aquifers in Africa, however, which are some of the biggest in the world, are still largely under-exploited. They have considerable potential, provided that their resources are managed on a sustainable basis. Since they generally extend across several State boundaries, their exploitation presupposes agreed management mechanisms in order, for example, to prevent pollution or over-exploitation by particular States.
Mechanisms of this kind have begun to emerge in recent years. For example, in the 1990s Chad, Egypt, the Libyan Arab Jamahiriya and Sudan established a joint authority to manage the Nubian aquifer system in a concerted manner. In their project concerning the Iullemeden aquifer, Niger, Nigeria and Mali approved in principle a consultative mechanism for administering the aquifer system. But such mechanisms are the exception.
The draft Convention on transboundary aquifers, prepared by the United Nations International Law Commission with the assistance of experts from UNESCO’s International Hydrological Programme (IHP), is therefore intended to fill a gap in the law. The text to be submitted to the General Assembly of the United Nations on 27 October, calls on aquifer States not to harm existing aquifers, to cooperate and to prevent and control their pollution.
The World-wide Hydrological Mapping and Assessment Programme (WHYMAP) was launched in 1999* to improve knowledge and management of the Earth’s resources, particularly groundwater. In 2000 the IHP launched the Internationally Shared Aquifer Resources Management (ISARM) project to compile an inventory and to evaluate the world’s transboundary aquifer systems (delineating them, estimating their volume, their replenishment rates, etc.). A region-by-region evaluation has been launched. In its initial phase it will identify geographical locations and then itemize the legal systems of each country as they relate to aquifer management.
* By UNESCO with the assistance of the Commission for the Geological Map of the World (CGMW), the International Association of Hydrogeologists (IAH), the International Atomic Energy Agency (IAEA) and the German Federal Institute for Geosciences and Natural Resources (BGR).
- For more info on WHYMAP and to download maps
- For more information on the ISARM project
- Contact :
Agnès Bardon, Bureau of Public Information
Tel : + 33 (0) 1 45 68 17 64