Egypt's arable land stretches out over the map of North Africa like a green kite on a desert background. The string uncoils northwards from the Aswan high dam until it reaches the Nile Delta, where it opens into a triangle to meet the Mediterranean Sea.
This narrow fertile strip, fed by the world's longest river, is where Egypt lives. Eighty million people are crammed into less than five per cent of the land. In most of the country it never rains and 90 per cent of the water on which the civilisation that built the pyramids depends comes from the river.
As Herodotus observed in the 5th century BC, Egypt is a gift of the Nile. And it is a gift that Cairo has worked assiduously to ensure nobody takes it away.
Two treaties signed more than half a century ago gave Egypt the lion's share of the water from the Nile. But those deals, so crucial to one country, also set up an epic imbalance of resources that has led analysts to look to this river system as the likely theatre for the first of the long-heralded water wars. Now a fresh crisis has emerged to threaten Cairo's hegemony of this most political of rivers as five of the 10 Nile basin countries have signed up to a new agreement that would give them a greater share of the waters and has been greeted in the Egyptian press as a "death sentence".
The White Nile rises in East Africa in Lake Victoria and drains through Uganda into Sudan where it meets in Khartoum with the Blue Nile flowing from Ethiopia's Lake Tana.
An exchange of letters in the Egyptian capital between the British ambassador and the Prime Minister of Egypt on 7 May, 1929 was sufficient to conclude the Nile Water agreement.
It read: "No irrigation or power works are to be constructed on the River Nile or its tributaries, or on the lakes from which it flows... which would entail prejudice to the interests of Egypt."
In other words Egypt had monopoly of the waters. On behalf of its colonial possessions – Sudan, Kenya, Tanzania and Uganda – Britain, which was primarily concerned with the Suez Canal and the passage to India, had just signed away their most precious resource.
Egypt had the right to veto any project along the Nile and full rights of inspection. In 1959, this deal was overtaken by a new agreement between Egypt and Sudan splitting the waters 75 per cent to 25 per cent and guaranteeing Cairo "full control of the river".
The results of this control are nowhere more clearly seen than at Lake Nasser, a man-made reservoir 550 kilometres long, created when Egypt completed the Aswan high dam. The country's largest engineering project – constructed with Soviet assistance at the height of the Cold War -- it took six years to build and another 5 years to fill.
Some 55.5 billion cubic metres of water gush from the Aswan dam into Egypt annually. It has enabled Cairo to regulate the life-giving annual flood, to irrigate its otherwise parched landscape, and at the point it was finished supplied half the country's electricity needs.
With control of the Nile, Egypt's agriculture has expanded fivefold in the ensuing years.
It also marks the effective border between downstream development and upstream poverty. Today, Egypt is approximately 10 times wealthier than Ethiopia. Militarily and economically it dwarfs every state on the banks of the river.
Without the water all this could change rapidly. "Egypt's historic rights to Nile waters are a matter of life and death. We will not compromise them," said Moufid Shehab, the Egyptian Minister of Legal Affairs.
Countries like Ethiopia, which accounts for 85 per cent of the river's flow, never recognised the "colonial relic" treaties and are now seeking to right what they see as a historical wrong.
"Some people in Egypt have old-fashioned ideas based on the assumption that the Nile water belongs to Egypt," Ethiopia's premier Meles Zenawi said recently. "But the circumstances have changed and changed forever."
Under pressure from upstream countries, Egypt agreed to take part in the Nile Basin initiative set up in Uganda's Entebbe on the shore of Lake Victoria in 1999. While Cairo saw it as a talking shop with a mandate to share scientific data, the other states saw it as an opportunity to renegotiate the use of the Nile.
After a decade of talks with no sign of concessions from Egypt, five African countries – Ethiopia, Kenya, Rwanda, Tanzania and Uganda – made their own agreement on more favourable terms than the six per cent of water currently allowed them.
"We've been grappling with this since the 80s, Egypt didn't want anyone to talk about the Nile," said a senior UN official close to the talks. "Egypt has really pissed off other countries and this time unless there's a miracle they will have to give ground."
The Aswan is no longer the only mega-dam on the river. Ethiopia this month opened the 460MW Tana Beles dam, which would have been considered an act of war in Sadat's time. A string of new dams are planned to join the Beles on the Blue Nile. On the White Nile Uganda is opening the controversial Bujagali dam.
The new framework agreement has been rejected by Egypt and its ally Sudan – while Eritrea has signalled its support for Cairo. Burundi is expected to back the new deal as soon as the current elections are over and DR Congo is expected to ignore lobbying from Egypt and follow suit.
With support from seven of the 10 riparian, or riverside, states the deal could be ratified and backed by the African Union.
Even Sudan's support could be split along with the country itself if the south votes to break away from Khartoum at a referendum expected early next year. Diplomats believe the newly established South Sudan would back its upstream neighbours, while some are expecting the new state to even call itself the Nile Republic.
Behind the heated rhetoric of death sentences and lifeblood most observers believe that the current crisis will be resolved politically rather than militarily. The era in which Egyptian foreign policy was based on backing insurgencies and destabilising its southern neighbours may have past. David Grey, a visiting professor at Oxford University and senior water advisor to the World Bank, says the Nile Basin initiative for all its failures suggests a future in which shared water resources could yoke together former adversaries rather than divide them.
But he also warns of the far bigger crisis that's coming:
"If you add climate change and growing populations the future is a very unpredictable, risky one."
The Nile Basin is home to countries with rapidly expanding populations. Egypt's population is expected to reach 121 million by 2050. Uganda's population is expected to double long before then. The number of Ethiopians is projected to increase from 83 million to 183 million.
The bigger question is not whether a more equitable sharing of the Nile can avert a war, but whether the overexploited river can continue to meet the growing demands placed on it.
The great drought of the late 1980s provided a possible answer to that question. In Egypt, the drought is remembered as the "great water crisis" where the water level at the Aswan high dam dropped dangerously by 1988. Agriculture and industrial output were hit drastically, severely depleting foreign exchange reserves and hitting economic growth. A similar crisis now could destabilise the government with unpredictable consequences.
In Ethiopia the drought is remembered for the accompanying famine in 1984-5 – severely exacerbated by civil conflict and disastrous government policies – that claimed hundreds of thousands of lives and brought the the country international attention.
Unless the current standoff is broken to provide for a unified management of the Nile basin for the first time then the next great drought could send the region back to the brink of a water war.
The Nile in literature
From John Keats' 'To The Nile':
Nurse of swart nations since the world began,
Art thou so fruitful? or dost thou beguile
Such men to honour thee, who, worn with toil,
Rest for a space 'twixt Cairo and Decan?
From 'God dies by the Nile' by Egyptian psychiatrist and writer Nawal El-Saadawi:
The light of dawn glimmered on the river, revealing the minute waves, like tiny wrinkles in an old, sad, silent face. Deep underneath, its waters seemed immobile, their flow as imperceptible as a moment of passing time, or the slow movement of the clouds in the dark sky.
From 'Rhadopis of Nubia', by Egyptian Nobel Prize winner Naguib Mahfouz:
They left their houses and hurried to the bank of the Nile to witness the first ripples, bearers of bounty and good fortune. The voice of the priest of Sothis resounded through Egypt's still air, announcing the good news to the South: "Come celebrate the holy festival of the Nile!"