Africa’s hidden groundwater resourcesParis - Solutions to resolve the world’s water crisis may lay hidden underground. More than half the world’s population already depends on groundwater that is pumped from the pore spaces of rock formations, known as aquifers, which lie hidden below the Earth’s surface. These formations can span thousands of kilometres and contain enough water to satisfy all of humanity’s demands for many decades.
Imagine filling a pool the size of Germany, several hundred metres deep with some of the purest water in the world to grasp the dimensions of the Nubian Sandstone Aquifer, for example, which lies under the desert sand of Libya, Egypt, Chad and Sudan.
To better understand this mysterious global capital, geohydrologists from more than 20 countries have drawn up the first continental survey of transboundary aquifers in Africa. They met in Tripoli (Libya), from June 2 to 4, through a UNESCO project entitled Internationally Shared Aquifer Resources (ISARM), which involves several international organizations, notably the International Association of Hydrologists, the Food and Agricultural Organization (FAO) and the United Nations Economic Commission for Europe (UNECE).
Like rivers, aquifers cross national borders and can be shared by two or more countries. Unlike rivers, little is known about these shared or transboundary aquifers. Substantial investment and scientific expertise is required just to identify or map the boundaries of an aquifer before beginning to accurately assess the quantity and quality of water it contains.
Political factors can further complicate the scientific process. Governments are often reluctant to admit that other countriesshare the aquifers they rely upon for drinking water and irrigation. Despite a growing body of international rules and conventions concerning shared rivers these don’t apply to aquifers. This legal vacuum can generate considerable misunderstanding and tension. Many experts predict a “race to the pump house,” in which countries scramble to use as much water as possible out of fear that a more powerful neighbour will dominate a transboundary aquifer by virtue of its financial and technical strength. Transboundary aquifers are therefore potential “hotspots” or sources of conflict, especially in arid regions where fierce competition for water resources will intensify in the future because of population growth and the expected impact of climate change.
Todefuse the potential for conflict, ISARM is bringing together scientists from around the world to create the first global map and inventory of transboundary aquifers within the next six years. This inventory will be based upon regional surveys, such as the one completed for Africa. Prior to this, there was practically no documentation of transboundary aquifers in Africa. Groundwater studies in general have been sorely lacking, despite the fact that many countries, such as Mauritania, rely upon this resource for 80 percent of their needs. Even in more humid regions and countries like Nigeria, people increasingly depend upon groundwater because of severe pollution of rivers or surface water. Though aquifers offer extremely safe and reliable resources, especially in drought-prone regions, they are nevertheless fragile. It is extremely difficult, if not impossible, to clean up an aquifer once it has been polluted by sewage and chemicals that seep down from communities, factories and farms.
The new African survey has uncovered about 20 transboundary aquifers, five of which have never been identified before. For example, geohydrologists from Benin learned that the aquifer providing water for the capital city, Cotonou, extends across the border into Togo. Both countries have expressed interest in developing a framework to jointly manage this aquifer, which will become increasingly important in the future as rainfall declines with climate change. According to the director of the Water Resources Department, Félix V. Azonsi, rainfall in the region is declining at a rate of two millimetres per year. In another surprise development, the survey uncovered a major aquifer between Ghana and Côte D’Ivoire. Hydrologists from Côte D’Ivoire had begun studying the aquifer, which provides 80 percent of the local population’s water needs. But experts from Ghana have just learned that the aquifer crosses into their territory. Plans are now underway to jointly study and manage the shared resource
The survey marks an important step in compiling a global inventory and database, which will offer assessments of the water quantity and quality of every transboundary aquifer. It will also provide detailed case studies of innovative techniques for managing these resources, fromboth a technical, socio-economic and legal perspective. Regional surveys have already been completed for South America, Western Europe (through UNECE) and the Euro-Mediterranean region.
The Mediterranean survey is politically the most sensitive. It was compiled during an ISARM workshop held in February 2002 in Beirut (Lebanon) by more than 20 geohydrologists from Israel and the Palestinian National Authority, Syria, Egypt, Jordan, Lebanon, Algeria, Tunisia, Morocco, Turkey and Cyprus as well as several European countries.
The Mountain Aquifer, for example, which straddles the West Bank and Israel, lies at the heart of the water dispute between the two governments. In a nutshell, Israel consumes about 85 percent of the aquifer’s yield even though most of the rain and surface water replenishing it originates in Palestinian territory. Yet geological conditions make it extremely difficult and expensive to tap into this water on the Palestinian side. In fact, most of the good-quality water naturally flows into Israel, where it is relatively easy to access. This resource has been the subject of intense negotiation, which collapsed with the outbreak of the intifadah. Nevertheless, geohydrologists from both sides met and exchanged data concerning the aquifer through ISARM.
This kind of exchange is just the first step in the ISARM initiative. While compiling and sharing data for the regional surveys and inventories, government representatives will also set up plans and possibly commissions to jointly manage shared resources and to protect the environment. There are also plans to broker legal agreements to further protect the aquifers.
Government representatives have recognized the need to develop a legal agreement concerning the Nubian Sandstone Aquifer System, for example, which spans Libya, Egypt, Chad and Sudan. This system consists of four aquifers, which contain a rough estimate of 120,000 cubic kilometres of “fossil” water, which is thousands and perhaps millions of years old. This is the liquid legacy of a bygone era, when the barren Sahara was a lush savannah about 10,000 years ago. The rains that fed the region disappeared some 3,000 years ago, leaving phenomenal but finite water supplies, which the Libyan government began mining in 1991 through the world’s largest civil engineering project. The Great Man-Made River Project delivers about half a million cubic metres of water a day to Libya’s coastal cities (where most of the population lives) through a network of concrete pipes, four metres in diameter or the size of subway tunnels. This “river” lies under the desert and covers a total length of 3,500 kilometres.
Considerable controversy surrounds the mining of fossil water and several environmental groups have condemned the Man-Made River. Supporters of the project maintain that countries like Libya have basically run out of renewable water sources and cannot solely rely upon desalination, which is extremely expensive. ISARM is now in the process of establishing international guidelines to manage this extremely rare resource. The challenge is to balance ethical, environmental and scientific concerns with the socio-economic needs of the current generation and those that follow. For example, while many experts will justify the use of fossil water for drinking and municipal needs, they consider it unethical and unduly expensive to direct such a precious resource for irrigation, especially in arid zones where half the water can be lost to evaporation.