Sahara yielding its deeply-held water

Press, 9 November 1984, Page 14

Sahara yielding its deeply-held water

Despite popular belief, the Sahara desert is rich in highquality water reserves — but they lie 80-450 m below the surface. Libya has just launched a multi-billion-dollar pipeline construction project to deploy the water in the service of irrigated agriculture. Controversy over its long-term effects has spilled into passionate debate in the scientific press. THOMAS LAND reports:

Libya has awarded the first contracts in a long-awaited, gigantic project for the construction of a 1900 km pipeline to carry water to the thristy agricultural regions of the north from its rich reserves beneath the Sahara Desert.

This is probably the most ambitious building project in the Arab world — paradoxically launched at a time of declining oil revenues. If it succeeds, the scheme will improve nutrition and public health standards, reduce food imports and reverse the relentless expansion of the deserts across north Africa.

But some specialists fear that the project could affect food production adversely by lowering the water table of the region. The controversy has sparkend off passionate debate in the scientific press. Phase one of the scheme alone is to cost about $5 billion and take six years to complete. Subsequent phases may treble the bill. The British subsidiary of the American company, Brown Root, has been appointed as project manager. The pipelines will be manufactured and laid by Dong Ah Construction and Industrial Company of South Korea. A contract for the sinking of the hundreds of wells needed for the project has been won by Geotechnika of Yugoslavia. Despite popular belief, the Sahara desert is rich in highquality fresh water — but it lies 80 to 450 metres beneath the surface. Like Libya’s oil, its subterranean fresh water reserves are contained in porous sandstone. Its aquifers extend into neighbouring Sudan and Chad as well as Egypt. The contro-

versy centers over the age of the underground water and the speed at which it is being renewed.

Libya plans to devote sixsevenths of its projected new water supply to food production and the rest to public health and industrial use. Indeed, the project could make the country into a net exporter of wheat.

The water will be tapped initially by 270 wells bored near the towns of Taserbo and Sarir. Phase one involves the construction of a 4-metre dameter pipeline to transport the water northwards, at a rate of two million cubic metres a day, to Ajdabiya via Jalu. Branchlines will lead the water to the coastal agricultural areasa of Benghazi and Sirte for the irrigation of about 180,000 acres, twice the land area at present under irrigation.

Taserbo is about 400 metres above sealevel; and the pipe will need only a few pumps to lift the water over gentle hills along the way to the coast. The second phase of the project is to extend the pipeline southwards from Taserbo to Kufra where further wells would increase the water supply to an estimated 3.6 million cubic metres a day. Another 400 kilometre pipeline is being planned in the longer term to supply Tripoli in the north-west with subterranean fresh water from the Hasawna region in the south.

Apart from the main pipeline, a further 600 kilometres of pipework will be required to link up the hundreds of wells. The pipes will be manufactured at two factories to be built specifically for the

project, one of them sited deep in the desert.

The pipes will be buried underground. Digging the necessary trench may be expensive, but not as expensive as dealing with the violent expansion and contraction of an overland pipeline exposed to the savage desert sun by day and the cold by night. Libya has given the project top priority in its national development plans. It may well finance the project internally despite the longterm world oil glut restricting its forign exchange income. The project promises to prove a bonanza for the world construction industry, with up to 50 contracts still to be awarded.

It could also prove a threat to food production over vast areas. Scientists fear that the wells may run out of economically accessible water long before the present investment is realized and that the project could affect the water supply of the entire region. Dr Ed Wright, of the British Geological Survey, and his associates consider, on the basis of carbon dating, that the water in the Libyan reservoirs is up to 34,000 years old, older indeed than the desert above. They assume that the reservoirs are connected by a slowly flowing channel of ground water and that they contain an essentially non-renewable resource. Writing in the scientific journal “Hydrology”, Dr Wright argues that Libya’s wells may not run out of water — but they would run down, making pumping ridiculously expensive.

All of which is dismissed by Professor Moid Ahmad, a hydrolo-

gist with the University of Ohio and scientific advisor to the Libyan Government. He counters that the Libyan aquifers are continually fed with fresh water from the mountain ranges of neighbouring Chad and Sudan and that the project would tap only a small proportion of the water available underground.

He considers that there is a free and continuous flow of water between the two reservoirs, and that they are being recharged with new water at a rate far greater than that assessed by Dr Wright. Also he insists that only a small proportion of the water to be drawn for irrigation would originate from long-term storage. If Professor Ahmad is correct, comments the authoritative British journal “New Scientist,” then even a massive development of well fields “should be able to keep going for decades, but the consequences both upstream in Sudan and downstream in Egypt could be considerable.”

Sudan is making great efforts to tap its groundwaters in order to bring fresh water to outlying villages, and if that groundwater does leak into the Libyan aquifers, as the professor suggests, then a lowering of the water levels in the aquifers could leave the Sudnese villages high and dry. And if as Professor Ahmad insists, large volumes of water also leak out of the Kufra aquifer towards the oases of Egypt, then the irrigation projects of that country, which are based on a long line of oases in a north-south strip, could be equally threatened.