Egypt's geography: a black land the Nile flood stopped feeding in 1970

How the Nile divides Egypt into four regions

Egypt's land is a desert plateau with one trench cut through it from south to north. The Nile runs in that trench between cliffs from Lake Nasser to Cairo, where the cliffs fall away and the river fans out into its delta. Britannica counts the valley and the delta as the first of four physiographic regions. The trench splits the plateau into two unequal deserts, the Western Desert out to the Libyan frontier and the Eastern Desert to the Gulf of Suez and the Red Sea, and the Sinai Peninsula beyond the Suez Canal makes the fourth.

The figures depend on who measured. The Wikipedia geography article gives the area as 1,010,408 km² and the State Information Service as about 1,002,000 km², and the river runs about 1,532 km inside Egypt in the service's figure and some 1,600 km in Wikipedia's. By the Wikipedia account the Nile Valley and Delta cover about 5% of the country and support about 99% of its population, and 35,000 km², 3.5% of the land, is cultivated and permanently settled. The service puts the valley and delta at less than 4%, about 33,000 km².

Libya lies to the west, along 1,115 km of border by the service's figure, Sudan to the south along 1,280 km, and Israel and the Gaza Strip beyond Sinai. Two stretches of the Sudanese border are subject to differing claims, the Halaib Triangle on the Red Sea and Bir Tawil inland. The Wikipedia geography article describes Halaib as claimed by Sudan and claimed and administered de facto by Egypt, and Bir Tawil as land often included in Egypt and not claimed by it. This catalogue records both disputes and takes no position on either.

Where the water in the Egyptian Nile comes from

Hardly any of the river's water falls as rain in Egypt. Britannica gives annual averages of about 175 mm at Alexandria, 25 mm at Cairo and 2.5 mm at Aswan, and the World Bank's Climate Change Knowledge Portal puts the national average at 9.82 mm a year for 1995 to 2014. The river is made far to the south, by three tributaries whose shares swing with the season.

That split once ran the Egyptian year. The White Nile kept the river flowing through the dry months. The Blue Nile, carrying the late-summer rain of the Ethiopian Highlands and a heavy load of sediment, lifted the river over its banks and left a layer of fertile mud across the fields. The flood usually reached Egypt in August, September and October, and it often took until January to wane completely.

The river now enters Egypt as a lake. Lake Nasser reaches about 320 km south from the High Dam to the border and almost 160 km further into Sudan, and it covered the Nubian valley, about 250 km of narrow gorge between Aswan and the border. The people moved out of it are counted differently: about 100,000 in Britannica's article on Egypt, resettled mainly at New Nubia near Kom Ombo, and 100,000 to 120,000 across Egypt and Sudan in the Wikipedia article on the dam. Egypt began compensating the Nubians who lost their homes in 2019 and 2020.

What Egypt may take is fixed by treaty. Of the Nile's annual discharge, Britannica records about 74 billion cubic metres allocated between Egypt and Sudan, about 55.5 billion of it to Egypt. The Wikipedia economy article dates the agreement to 1959 and counts the High Dam's annual release of 55 billion cubic metres as 97% of Egypt's renewable water.

What changed below Aswan when the flood stopped

The High Dam is a rock and clay embankment 111 m high and 3,830 m long, built across the Nile at Aswan between 9 January 1960 and 21 July 1970 by the Wikipedia account. Britannica gives 1959 for the start and records a formal inauguration in January 1971. What the reservoir holds is printed four ways: a gross capacity of 169 billion cubic metres in Britannica, 132 billion and 162 billion in two places in the Wikipedia article on the dam, and 130 billion in the Wikipedia economy article.

In Britannica's account the dam put the annual flood under human control for the first time in history. It carried Egypt through the droughts of 1972 to 1973 and 1983 to 1987, let it reclaim about 2.0 million feddan and so raise the irrigated area by a third, and moved about 1 million feddan, mostly in Upper Egypt, from one flood crop a year to perennial irrigation. Lake Nasser loses about 10 cubic kilometres a year to evaporation, and other estimates run as high as 16.

Where the silt goes now

The silt was what renewed the black land. Britannica puts what the flood spread over the fields at 40 million tons a year, calls the 1 million tons of artificial fertiliser Egypt now applies annually an inadequate substitute, and holds that the dam has gradually decreased the fertility of the riverside farmland. The Wikipedia article on the dam reads the loss differently. In its account 88% of the sediment was carried to the sea before the dam was built, and the sediment's nutrient value has often been overestimated.

Most of the river's sediment load, about 134 million tons a year, now settles in the reservoir, fastest at the upper end of the lake, where it has already reached the live storage. At the coast its absence has contributed to erosion of the alluvial fan along the Mediterranean shore. The sardine catch off Egypt fell from 18,000 tons in 1962 to 460 tons in 1968, after the nutrients that fed it were trapped behind the dam, and had recovered to 8,590 tons by 1992. Brickmakers deprived of fresh sediment dug into the older alluvium under farmland instead, and an estimated 1,000 km² of it had gone by 1984, when the government prohibited further excavation.

Why the water table rose

Before the dam, groundwater in the valley rose and fell 8 to 9 m a year with the river. With irrigation running all year and no flood, it stayed high. Where it sat within 1 to 2 m of the surface, evaporation drew it up through the soil and left the salt behind, and most farmland had no subsurface drains to lower it.

Drainage became the repair. By 2003 more than 2 million hectares had subsurface drains, at a cost of about US$3.1 billion between 1973 and 2002, and the salinised area fell from about 1.2 million hectares in 1972 to 900,000 hectares in 2010. Salinity still affected 25% of irrigated agriculture in 2011, through poor drainage and, in the delta, through seawater pushing into aquifers that had been over-pumped.

How the valley narrows and the delta spreads

Upstream of Cairo the farmland is a ribbon 8 to 16 km wide in Britannica's figures, narrowing in places to a few hundred yards. At Aswan the granite of the Eastern Desert crosses the river and forms the First Cataract. At Qina limestone cliffs 300 m high turn the river south-west for about 60 km before it swings north-west towards Asyut, and north of Asyut the escarpments fall back and the valley widens to a maximum of 22 km. The ancient names of the two halves were Ta-Sheme'aw, the sedgeland, for the valley of Upper Egypt, and Ta-Mehew, the northland, for the delta of Lower Egypt.

At Cairo the river spreads over what was once a broad estuary, now a fan of silt about 250 km wide at the sea and about 160 km from north to south. The delta covers about 22,000 km² by the Wikipedia figure and 25,000 km² by Britannica's. It has been losing branches since the first century AD, when accounts describe seven. Two remain, the Damietta branch to the east and the Rosetta branch to the west, each named after the port at its mouth, and brackish lagoons take up much of the coast between Alexandria and Port Said. Perennial irrigation lets more than half of the delta carry two or three crops a year where the flood allowed one.

West of the valley, 60 km south-west of Cairo, the Faiyum depression holds a brackish lake, Birket Qarun, and artesian wells of fresh water have kept more than 1,800 km² of it under irrigation for centuries.

What lies west of the Nile

The Western Desert covers about 680,650 km², two-thirds of Egypt, and Britannica describes it as arid and without wadis; no river or stream drains into or out of it. It is a massive plain or low plateau of level sedimentary beds over basement rock, rising to more than 1,000 m on the plateau of the Gilf Kebir, and the Great Sand Sea lies on it between Siwa and the Gilf Kebir. Britannica maps almost a third of Egypt's land surface as Nubian sandstone, across the south of both deserts, and a further fifth as Eocene limestone some 35 to 55 million years old.

Seven important depressions break the plain, and all of them are oases except Qattara, whose water is salty. Qattara covers 19,605 km² and lies 133 m below sea level at its lowest, and Britannica calls it uninhabited and virtually impassable by modern vehicles. The other six have fresh water from the Nile or from local groundwater. Siwa, near the Libyan border, is isolated from the rest of Egypt and has been inhabited for thousands of years, and the other major oases form a chain of basins running south from the Faiyum through Bahariya, Farafra and Dakhla to Kharga.

Under the sand lies water that does not renew. About 826,000 km² of the Nubian Sandstone Aquifer System lies under Egypt, more than 80% of the country's land surface, but it is deep and costly to pump, and Egypt draws about 0.6 billion cubic metres a year from it, mostly for land reclamation.

Reclamation pushes farmland out into this desert. Egypt has reclaimed 2.6 million feddan since the 1930s, adding 44% to its agricultural land, and in 2010 its fertile area was about 3.6 million hectares. The current programme aims at 4.5 million feddan by 2027, and the Toshka Project, begun in the 1990s and since revived, aims at 1.5 million in the Western Desert, watered from Lake Nasser through the Sheikh Zayed Canal. Surface irrigation is forbidden by law on reclaimed land, where pressurised or localised irrigation is compulsory.

Why the mountains stand east of the river

East of the Nile the ground climbs abruptly. Britannica divides the Eastern Desert, about 221,900 km², into three tiers: a limestone plateau in the north that breaks into cliffs about 500 m high near Qina, a sandstone plateau south of Qina, and the Red Sea Hills with the coastal plain at their foot. The hills run from near Suez to the Sudanese border, several of their peaks pass 1,800 m and Shayeb al-Banat reaches 2,187 m. Their valleys are normally dry and carry torrents only after heavy storms, and coral reefs run almost continuously along the shore below them.

Sinai is a wedge of about 59,600 km² by Britannica's figure, its base on the Mediterranean and its point between the Gulf of Suez and the Gulf of Aqaba. The south is granite mountain rising above 2,400 m. Its summit, Mount Catherine, is 2,642 m high in Britannica and in the Wikipedia geography article and about 2,637 m in the State Information Service's figure, and the Wikipedia article adds that the Red Sea may have been named after these mountains, which are red. A few small streams among them are the only natural perennial surface water in Egypt outside the Nile. Northward the plateaus dip toward Wadi al-Arish, and lines of dunes, some more than 100 m high, run along the coast.

The Suez Canal cuts Sinai off from the rest of the country, and Africa from Asia. It runs 193.3 km from Port Said to Suez as a sea-level channel with no locks, and it opened on 17 November 1869. Israel occupied Sinai in the war of 1967, and by 1982 all of it had been returned to Egypt.

How dry and hot Egypt gets

Britannica describes two seasons, a winter from November to March and a summer from May to September; the State Information Service also counts two, with summer running to October. In June mean midday highs reach 33 °C at Cairo and 41 °C at Aswan, and the sun shines about 12 hours a day in summer. Rain falls mostly in winter and thins sharply southward. A thin strip of the northern coast can receive as much as 410 mm in a year, while south of Cairo the average is 2 to 5 mm and rain comes at intervals of many years. A very small amount of snow fell on Cairo on 13 December 2013, the first time in many decades.

Britannica names the desert's sand and dust storms khamsins, from the Arabic for "fifties", because they are said to come on fifty days a year, most often from March to June. A khamsin raises the temperature by 8 to 11 °C, often drops the relative humidity to 10% and brings thick dust on winds that can reach gale force.

The World Bank's portal records an annual mean temperature of 23.06 °C over 1995 to 2014 and warming of 0.4 °C a decade since 1970, and its median projection under the high-emission SSP3-7.0 scenario adds 1.81 °C by 2040 to 2059. At the Security Council on 8 July 2021, the executive director of the UN Environment Programme said models showed the Nile's flow growing more variable in the years up to 2040, with more floods and more intense droughts.

Who controls the water before it reaches Aswan

The Blue Nile and the Atbara, the two rivers that bring the flood, both rise in Ethiopia. Ethiopia began building the Grand Ethiopian Renaissance Dam on the Blue Nile in 2011, about 15 km from the Sudanese border, and its reservoir of 74 billion cubic metres began to fill for the first time in 2020, according to the UN Security Council record of 8 July 2021. In September 2025, the State Information Service records, Egypt wrote to the President of the Security Council about an event Ethiopia had organised to announce the dam's completion and operation, which Egypt deems a violation of international law. Ethiopia's economy article covers the dam as a power project, and its geography article the highlands the water comes from. Egypt and Ethiopia describe the dispute in opposite terms.

Egypt's case, as the State Information Service sets it out, rests on its share of 55.5 billion cubic metres under the agreements it has signed and on the Declaration of Principles that Egypt, Sudan and Ethiopia signed in Khartoum on 23 March 2015. At talks in Addis Ababa on 8 and 9 January 2020, Egypt held that 40 billion cubic metres of Blue Nile water should pass the dam each year, the river's average in drought years, and the service reports that Ethiopia asked for 35 billion during filling and drought. At the end of February 2020 Egypt initialled a filling and operating agreement drafted by the United States, the first of the three countries to do so.

At the Council on 8 July 2021, Egypt's foreign minister said that more than 100 million Egyptians faced "an existential threat" from the dam, and that Ethiopia had begun filling it unilaterally within days of Egypt's warning to the Council on 29 June 2020. Ethiopia's minister for water, irrigation and energy replied that the dam carried the hopes of "65 million Ethiopians that have no access to electricity", that Egypt and Sudan had built dams and canals without regard for other riparian countries, and that Ethiopia, with no considerable groundwater and no desalination, draws nearly 70% of its water from the Nile Basin. Speaking for the chair of the African Union, the Democratic Republic of the Congo reported a draft agreement with 90% of the technical problems resolved, and a dispute-resolution mechanism and the management of drought still open. This catalogue records the positions and takes no side between them.

What survives in the desert and along the river

Britannica lists the hippopotamus, the giraffe and the ostrich among the animals on ancient Egyptian friezes that no longer exist in Egypt, and records crocodiles only south of the High Dam. Papyrus, cultivated in antiquity, now grows only in botanical gardens. The aoudad, a bearded sheep, survives in the southern fastnesses of the Western Desert, the Nubian ibex and the Dorcas gazelle live in the deserts, and more than 200 kinds of migrating birds pass through each spring and autumn.

The legal framework for protected areas came with Law 102 of 1983, and Ras Muhammad, at the southern tip of Sinai, became the first protected area that year. By 2003 there were 24, covering almost 10% of the land and marine area in the Egyptian Environmental Affairs Agency's figure. The World Database on Protected Areas counted 50 in its October 2026 profile, covering 13.12% of the land and 5.07% of the marine and coastal area. The one natural property on Egypt's World Heritage list is Wadi Al-Hitan, the Whale Valley, inscribed in 2005.