Underneath Egypt's Western Desert lies an ocean of water. The country should tap into it, but it is crucial that it does not waste it.
The ocean, locked in sandstone, stretches for about 2 million square kilometres across Egypt, Libya, Chad and Sudan. It contains approximately 375,000 cubic kilometres of water, according to the International Atomic Energy Agency (IAEA), which began a two-and-a-half-year study in 2005.
If all the water locked in the sea, known as the Nubian Aquifer, could be tapped, it would be enough to keep the equivalent of the Nile flowing for about 500 years, the IAEA says.
Over the past year, the government has put forth plans to drill into the aquifer to irrigate one million feddans of desert land for agriculture (one feddan equals 0.42 hectares). In August, it added yet another 500,000 feddans to the project.
It plans to spend 6 billion Egyptian pounds (Dh2.8bn) to drill more than 5,000 wells in various parts of the Western Desert, Al Ahram newspaper in October quoted an irrigation ministry official as saying, with 600 wells already drilled.
All this sounds good, but the problem is that the water is almost entirely fossil, meaning it is ancient and not regularly replenished. Indeed, it is the biggest freshwater fossil aquifer in the world.
The IAEA, using isotope hydrology techniques, tracked the movement of particles to create a three-dimensional map of the aquifer, allowing it to estimate the water's age and to study its quantity and quality.
What it established was that the aquifer was most recently replenished during the last glacial period about 20,000 years ago. Since then it has been slowly draining. Only in the south-east is there a small amount of groundwater inflow from the Nile.
In the 1960s, the region's governments began pumping ever greater amounts of ground-water out of the aquifer, mainly for irrigating farmland.
In Libya, the government in the 1980s began the $25bn Great Man-Made River project to tap into the aquifer by drilling wells in Kufra and other oases in the south to move water to coastal cities in the north through a four-metre-diameter pipeline.
The goal, much of it attained, was to move 3.6 million cubic metres per day.
In Egypt, the government has been pumping water out of the aquifer since the 1960s, especially in the oases of the Western Desert, where some of the groundwater has sat for several hundred thousand to more than a million years.
As a result of the drilling, the water tables in the oases have been getting lower and lower, and some wells have run dry. This is mainly because the water is being extracted too quickly. If left alone, water would migrate through the sandstone from other areas and recharge the wells.
One problem with extracting the water is that it is expensive. Much of it lies more than a kilometre below the surface. In areas close to the Mediterranean the water is brackish.
If the government presses ahead with its plans for wholesale exploitation, the more easily available water might be able to sustain many decades of agriculture. But eventually, it would run out. Desert farming is different from farming on, say, the delta, where small holdings are labour intensive. The desert agriculture requires high technology and big companies that have the financial resources to achieve economies of scale, and will never be a major employer.
Whatever use is made of the water, the financial return on each litre must be optimised. It should be much higher than that obtained by agriculture on the delta.
One alternative is to create small urban settlements for people making their livelihood from less water-intensive means. These could centre around other resources such as oil wells or mines, water bottling plants or solar power arrays.
Some water experts have suggested the government could set up desert-based information technology communities to cater to research and design professionals who might prefer a calm, clean environment, akin to the successful Smart Village on Cairo's north-west outskirts.
Yet another option might be desert eco-tourism, which thrives in precisely those locations that lie far away from population centres.
Should the government choose the non-agricultural route, it should start out slowly, putting its priority in first laying down the proper infrastructure.
Part of the failure of the Mubarak-era Toshka land reclamation project to take off was the failure of the government to complete infrastructure such as roads and schools.
Any agriculture that is allowed in the desert must be closely monitored to ensure it uses its water efficiently, and in a way that protects the aquifer itself.
Patrick Werr has worked as a financial writer in Egypt for 25 years.