Hidden treasure: The ancient aquifer sustaining nations beneath the Sahara
Key topics:
Discovery and scale of the Nubian Sandstone Aquifer System
Libya’s Great Man-Made River and its water supply impact
Global freshwater scarcity and underground resource potential
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By Peter Dearlove
Under the driest of all dry places on earth there is a pool of ancient fresh water that supplies most of the daily needs of an entire nation and may well go on doing so for the next thousand years without replenishment. Now known as The Nubian Sandstone Aquifer System, it was only discovered by accident in 1953 during a Libyan Sahara Desert drilling program looking for oil. What they uncovered instead could be many times more valuable than oil, and hugely significant at a time when scientists are warning that the demand for freshwater may yet become a nightmare.
The size, scope, history and future potential of the enormous underground resource make truly mind-boggling reading. The Aquifer lies below the Sahara Desert stretching across more than 2.5million square kilometres and spanning Chad, Libya, Sudan and most of Egypt. Its reserves are thought to be equivalent to 500 years of Nile River discharge and as much as 20 times as much as is held by the American Great Lakes. Thanks to a development called the Great Man Made River, it now supplies Libya with 70% of its freshwater needs; 6.5 million cubic metres a day. All of it is described as ‘fossil’ water, having been deposited during the last great ice age and never replenished since then.
The Great Man-Made River is a vast network of wells, drill holes and massive pipes running the length and breadth of the country and delivering water from the Aquifer to wherever it is needed, both for agriculture and human consumption. The project was drawn up nearly twenty years after the discovery of the aquifer, but then vigorously worked on as a massive national scheme costing many billions of dollars, all funded by the Libyans themselves. The GMMR, for short, involved the excavation of nearly 100 million cubic metres of ground, and the manufacture and transport of 1,750 miles of giant pipes, the drilling of 1300 wells, many more than 500m deep. The water began to flow in 1991, and it was soon dubbed ‘the Eighth Wonder of the World’.
Large and important as it is, the Nubian Aquifer is not the only underground water system attracting attention and interest. Sparked without doubt by the astonishing facts of the Nubian one, water experts and scientists have been looking for more. And the result has already been dramatic. In all there are thought to be nearly a hundred that could make truly significant contributions to the world’s freshwater needs. And there are others too that hold water that is only slightly saline but could be cheaply treated. Large ones of this particular kind have been found in Australia, China, North America and South Africa. Together they have a half a million cubic kilometres of treatable water.
Canada, the United States, Russia, Europe, Asia, and Latin America, also have their own underground resources. The Guarani Aquifer, widely spread below the countries of Argentina, Brazil, Paraguay and Uruguay, is one of the world’s largest, covering about 1.2m sq km and holding 40 000 cubic kilometres of fresh water.
In the US there is another of the truly great ones. The Ogallala Aquifer lies under eight central states and now provides water for massive irrigation projects as well as industrial needs. Increasing municipal use of Ogallala water has scientists worried that it could soon be depleted beyond recovery.
The Edwards Aquifer in Texas is a rare example of an underground water resource that is constantly being replenished. Despite providing the daily fresh water needs of nearly 2 million people, it is still full. Annual rainfall finds its way underground through a network of streams, rivers and lakes.
The planet has a great abundance of water but less than 3% is ‘fresh’. The rest is salt and can only be made fresh by expensive desalination. 70% is frozen at the Poles. Only 1% is readily available.. Of what we do have, agriculture uses roughly two thirds, and the rest we use to drink, and for cooking and washing. Unfortunately, however, even that meagre amount is under pressure from population growth, climate change, and in some places, poor water management. There is a distinct possibility, scientists say, that this trilogy could lead to serious water scarcity and shortages in many regions. A significant portion of the world’s population, over two billion people, already do not have access to enough safe drinking water. It is a growing global issue because the population explosion shows no sign of abating.
Of itself, climate change is more of a great disrupter than an actual threat to the planet’s quantum of fresh water. By altering weather patterns it can, and does, affect the availability of safe fresh drinking water. Severe droughts in some areas with dramatic flooding in others has a boom and bust bounce. A year of abundant rainfall may be followed by years of none, and vice versa. The unpredictability of such swings adds to the problem by making attempts at relief supply in emergency difficult and sometimes impossible.
The United Nations has been aware of and concerned by these issues for some time. In 2003 it established UN Water, specifically to keep a watchful eye on the one resource we cannot live without, and to co-ordinate coherence and action on all issues affecting its safe supply. Some commentators believe there will soon be calls to add to the body’s responsibility with the creation of something like a ‘water bank’. Among its functions could well be to formalise and create an agenda for a co-ordinated effort at asset identification. Exactly how much do we have hidden away in our caverns underground? Where, how much, how deep, what quality, and how can we make use it? Some may baulk at the idea, others will see it as an important start towards a wider acceptance of the need to safeguard something precious.