QANATIR, Egypt — Squatting in a dirty robe, Muhammad Sayyid works with muddied hands and a mud-crusted hoe on furrows of roses and corn watered by a trickle pumped from the Nile River.

Like his father, like his grandfather, the barefoot 27-year-old peasant toils 12 hours a day under the blazing sun on a paltry plot roughly 100 feet by 150 feet. Steps away is his birthplace, a baked mud hut covered with grapevines and shared with two black goats.

It is a timeless scene in a timeless landscape, and in many ways, Sayyid and his routine symbolize Egypt--the peasant's spiritual connection to the land and the land's trust in the river.

Without the Nile, the world's longest river, Egypt would be a scorching waste--bereft of water, vegetation and civilization.

"Our life is the Nile," Sayyid said gently, his black eyes casting a lazy glance at the horizon. "The Nile is everything."

No wonder the storm of reaction that swept Egypt when neighboring Sudan threatened to block the river. Egyptian Foreign Minister Amr Moussa warned Sudan "not to play with fire and at the same time not to play with the water."

The two countries, at odds since Sudan's Islamist regime came to power in 1989, are united by the Nile, which snakes 4,160 miles from its remotest headstream in Burundi to the Mediterranean Sea. Its two branches--the White Nile and the Blue Nile--join in Sudan's capital, Khartoum.

But, increasingly, Egypt is facing a vastly different situation with the river--and the threat does not come just from Sudan.

Coping with growing populations and aiming to develop, central African countries that once ignored the Nile are now seeking to tame the river and its tributaries for irrigation and electricity.

In short, Egypt will see a smaller Nile within a generation, threatening to alter a livelihood shaped by millennia of history.

"There is quite simply not enough water in the Nile basin for all these countries to develop the way they want to develop," said Robert Engelman, director of the population and environment program at Washington-based Population Action International.

"They're headed for a collision between their very finite water resources and their continually growing populations," Engelman said in an interview.

That may come as a shock to Egypt, which has long considered the Nile the property of Egyptians, a gift from God. The pharaohs themselves were considered divine because they were believed to control the Nile floods through magical powers.