Seas Beneath The Sands - IELTS Reading Answers & Explanations

You should spend about 20 minutes on Questions 1–12, which are based on Reading Passage 1 below.

Seas beneath the sands

A Look at a map of North Africa from Egypt to Algeria. Almost everything outside the Nile Valley and south of the coastal plain appears to be lifeless sand and gravel deserts. But peer deeper, under the sand, and you will find water. Under the Sahara lie three major aquifers, strata of saturated sandstones and limestones that hold water in their pores like a wet sponge. The easternmost of these, extending over two million square kilometres, contains 375,000 cubic kilometres of water—the equivalent of 3,750 years of Nile river flow. It is called the Nubian Sandstone Aquifer System, and lately it has come to the attention of practitioners of a subspeciality of nuclear science known as isotope hydrology.

B Isotope hydrology, which studies the atoms of the two elements making up groundwater—oxygen and hydrogen—and the trace elements in it, like carbon and nitrogen, is able to determine when, give or take a couple of thousand years, today's groundwater fell to earth as rain. In the case of the Nubian Aquifer, some water in the system is thought to be one million years old, but most of it fell between 50,000 and 20,000 years ago. Since then, as the region has slowly turned to desert, there has been little addition of water to the aquifer. What lies beneath the ground is called fossil water, and it will likely never be recharged.

C Because the Nubian Aquifer is shared among four nations, and because Libya and Egypt are now going forward with big water-pumping projects that tap the Nubian Aquifer, the International Atomic Energy Agency (IAEA), co-recipient of the 2005 Nobel Peace Prize, is trying to bring the countries together in a joint effort to plan for a rational shared use of the water.

D The stakes are certainly high. Egypt eventually hopes to use almost half a billion cubic metres of groundwater annually—more than the volume of Lake Erie. Libya is already pumping water from the Kufra Oasis, in its southeast corner, through a four-metre-diameter pipeline to its thirsty coastal cities. When fully operational, that project will pump some 3.6 million cubic metres per day. Still, at current extraction rates, the aquifer is not likely to be depleted for a thousand years.

E Dr Taher Muhammad Hassan of the EAEA (Egyptian Atomic Energy Authority) says "One thing that isotope studies have shown us is that there is surprisingly little aquifer recharge from the Nile. Nile water has a younger isotopic profile, and samples from wells dug as close as five kilometres from the river show no sign of the Nile fingerprint. In fact, some of that well water is dated at 26,000 years old." Hassan is confident there is little likelihood of international conflict over aquifer sharing. "We know that the velocity of underground flow in most places is just two metres a day," he says. "It's like sucking a thick milkshake through a straw—it doesn't happen fast, and eventually it stops completely." Even Libya's big extraction plans for Kufra will probably have only a minor effect on Egypt's East Uweinat farming area, given the distance between the two. If Kufra's water table drops 200 metres, the Egyptian side might see a drop of only 10 centimetres.

F At al-Agouza West in Egypt, a 10-story drilling rig, the same kind used to drill oil wells, has reached 800 metres and is now evacuating the drilling mud and widening the bore. It has taken 20 days to penetrate layers of shale and clay to reach the saturated sandstone—the basement of the Nubian formation is some 1,800 metres deep here—at a cost of about $400,000. Once the well is ready for testing, the ministry engineers check its static and dynamic levels with a sounder, a kind of fisherman's bob at the end of a tape measure that rises and falls with the water table.

G Dr Khaled Abu Zeid, of the Egyptian non-profit Center for Environment and Development of the Arab Region and Europe (CEDARE), stresses the social context of water-resource development, and the need to keep in mind traditional water users as well as new users. Small farmers and Bedouin who rely on shallow wells should not be ignored in favour of the big development schemes. "They need water today," he says, "and will still need it tomorrow. We must not let it run dry because deeper wells are more cost-effective. But neither should we have an absolutist conservationist approach, in which we try to keep fossil water in some kind of 'museum' for their benefit."

H The director of the Groundwater Research Institute at the Nile Barrage, Dr Ahmed Khater, finds it ironic that in a desert region like the Middle East, petroleum geology is much better understood than subsurface hydrology. "But water is what makes our life possible here, and we must use it wisely," he says. He cites the experience of President Nasser's "New Valley" project in the 1960s, which proposed a massive resettlement of Nile Valley farmers to the western oases. It was a failure. "These isotope studies hold the promise of learning more about what is really our most precious asset—water, not oil," he says. Nasser, he notes, got the New Valley project's motto wrong. "He said, 'When settlers come, then we will find water.' He should have said, 'When we find water, then settlers can come.'"