CAIRO (Reuters) - It looks like a mirage but the lush fields of cauliflower, apricot trees and melon growing among a vast stretch of sand north of Cairo's pyramids is all too real -- proof of Egypt's determination to turn its deserts green.
While climate change and land over-use help many deserts across the world advance, Egypt is slowly greening the sand that covers almost all of its territory as it seeks to create more space for its growing population.
Tarek el-Kowmey, 45, points proudly to the banana trees he grows on what was once Sahara sands near the Desert Development Centre, north of Cairo, where scientists experiment with high-tech techniques to make Egypt's desert bloom.
"All of this used to be just sand," he said. "Now we can grow anything."
With only five percent of the country habitable, almost all of Egypt's 74 million people live along the Nile River and the Mediterranean Sea. Already crowded living conditions -- Cairo is one of the most densely populated cities on earth -- will likely get worse as Egypt's population is expected to double by 2050.
So the government is keen to encourage people to move to the desert by pressing ahead with an estimated $70 billion plan to reclaim 3.4 million acres of desert over the next 10 years. Among the incentives are cheap desert land to college graduates.
But to make these areas habitable and capable of cultivation, the government will need to tap into scarce water resources of the Nile River as rainfall is almost non-existent in Egypt.
The plan has raised controversy among some conservationists who say turning the desert green is neither practical nor sustainable and might ultimately backfire.
Anders Jagerskog, director of the Stockholm International Water Institute in Sweden, questions the wisdom of using precious water resources to grow in desert areas unsuited to cultivation and where water will evaporate quickly under the scorching sun.
"A desert is not the best place to grow food," he said. "From a political perspective, it makes sense in terms of giving more people jobs even though it is not very rational from a water perspective," he added.
The scope of the reclamations could also add to regional tension over Nile water sharing arrangements as in order to green its desert Egypt might need to take more than its share of Nile water determined by international treaties.
Egypt's project to reclaim deserts in the south, called "Toshka", would expand Egypt's farmland by about 40 percent by 2017, using about five billion cubic meters of water a year.
That worries neighbors to the south who are already unhappy about Nile water sharing arrangements. Under a 1959 treaty between Egypt and Sudan, Egypt won rights to 55.5 billion cubic meters per year, more than half of the Nile's total flow.
Ethiopia, where the Blue Nile begins, receives no formal allocation of Nile water, but it is heavily dependent on the water for its own agricultural development in this often famine ravaged country.
"The Toshka project will complicate the challenge of achieving a more equitable allocation of the Nile River with Ethiopia and the other Nile basin countries ," said Sandra Postel, director of the U.S.-based Global Water Policy Project.
"Egypt may be setting the stage for a scenario that's ultimately detrimental to itself."
But other experts suggest that in the delicate arena of water politics, it may be more of an imperative for Egypt's government to mollify its own population rather than heed its neighbors concerns.
Overcrowding is straining infrastructure in the cities and the government is worried that opposition groups such as the Islamist Muslim Brotherhood, which has a fifth of the seats in Parliament, might capitalize on discontent.
"The government feels it needs to reduce the number of people in high density areas, which puts a lot of pressure on resources like fertile land," said Mostafa Saleh, professor of ecology at Al Azhar University in Cairo.
"They are trying to spread the population to other parts of the country."
Some critics say that Egypt should look at desert tourism rather than agriculture, which might not be sustainable or particularly profitable and could destroy fragile wildlife habitats that might otherwise be a drawcard for tourists.
A desert reclamation project last decade, south of Cairo, destroyed much of the Wadi Raiyan oasis and its population of slender horned gazelles.
"The price tag on these assets is huge, both as natural heritage and as a resource for tourism," said ecologist Saleh.
Saleh is vice president of an Egyptian firm that built an electricity-free ecolodge, consisting of rock salt and mud houses, amid olive and palm groves in the desert oasis of Siwa.
The lodge, which costs $400 per night and has attracted guests such as Britain's Prince Charles and Belgium's Queen Paola, shows that the desert would be better used for ecotourism than farming, he says.
"In Egypt, water is the most critical resource and we should be careful to use it to maximize revenue," Saleh explained. "Agriculture is not the best option for Egypt. Nature-based tourism could bring in much more money."
At the Desert Development Center, irrigation water comes through a canal connected to the Nile, about 15 km (nine miles) away, where it is used to keep crops flourishing and grass green for hardy hybrid cows to graze.
Experts at the centre believe greening the Sahara might be Egypt's best hope of bringing prosperity to its people.
Workers graft fruit-bearing plants onto the stems of plants that survive well in the desert. Favorite fruits are citrus as they flourish in hot climates and can land on supermarket shelves in Europe hours after harvesting.
Proximity to markets in Europe and a lack of pests, which usually thrive in humid environments, make desert farming economically viable, said Richard Tutwiler, director of the Desert Development Center at the American University in Cairo.
Water supply, Tutwiler said, shouldn't be an issue at least for the next ten years. It makes sense, he says, to expand agriculture onto land that was once useless.
"There is no frost and there is sun all the time here," he said. "Plants just go nuts."