The Nile is a major north-flowing river in northeast Africa which empties into the Mediterranean Sea. At long, it is the longest river in the world, although the volume of water it carries is much smaller than other major rivers such as the Amazon or the Congo. The Nile has played a central role in the environmental, economic, and cultural history of Africa for millennia.
The Nile has two major tributaries: the White Nile and the Blue Nile. The White Nile is longer and is considered to be the headwaters, yet the Blue Nile contributes over twice the water volume of the White Nile. The White Nile begins near Lake Victoria and flows through Uganda and South Sudan, while the Blue Nile begins near Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at the Sudanese capital, Khartoum. From there, the Nile flows north through the Nubian Desert to Egypt's capital, Cairo, and finally empties into the Mediterranean Sea near Alexandria, where it has formed a large river delta.
Geologically, the Nile is a young river, having followed its present course for about 15,000 years. Its drainage basin extends across eleven countries. Most of the water in the Nile comes from rainfall in the upstream countries Ethiopia, Kenya, Tanzania, and Uganda. Downstream countriesEgypt, Sudan, and South Sudanare primarily desert and withdraw river water for irrigation. Other countries that lie wholly or partly in the Nile Basin are Burundi, the Democratic Republic of the Congo, Eritrea, and Rwanda.
The Nile was the foundation of the Ancient Egyptian civilization, which relied on the river for nearly every aspect of life. The annual flooding of the river deposited nutrient-rich silt along the riverbanks. This soil supported crops that enabled a sophisticated society to thrive in an otherwise inhospitable desert. The Nile facilitated trade, communication, transportation, and governance. South (upstream) of the second Nile cataract lay Nubia, the historical home of the ancient Kerma culture and the Kushite Empire. Many Europeans were fascinated by the Nile, and their explorations around Lake Victoria in the late 19th century located the source of the river. Among the cultures that live along the Nile in the modern era are the Nilotic peoples, semi-nomadic cattle herders who practice nomadic pastoralism, moving their cattle seasonally in response to the Nile's floods.
In the modern era, the Nile plays a critical role in the economies of Egypt and Sudan, which rely on it to irrigate extensive croplands. Since the late 20th century, over a dozen dams have been built in the Nile Basin to provide for irrigation and to generate electricity. The dams have altered the river's annual flood cycle and restricted the transport of silt downstream, causing the Nile Delta to shrink. Some damssuch as the Aswan High Dam and Grand Ethiopian Renaissance Damhave been the source of international political disputes about water scarcity, safety, food security, and forced displacement of peoples.
Names and etymology
The English word "Nile" is derived from the Latin and the Ancient Greek (Neilos), which possibly originated from the Semitic term naḥal, meaning 'river'.
In the ancient Egyptian language, the same word was used for 'Nile' and 'river': . Egyptians called their country meaning 'black', in reference to the dark color of the Nile floodwaters as they carried sediment from upriver. The English name "Blue Nile" is a translation of the Arabic name Al-Baḥr Al-Azraq.
In the modern era, the river goes by several names within the Nile Basin. In Egypt, it is referred to as Al-Nīl, Baḥr Al-Nīl or Nahr Al-Nīl. In South Sudan, it is sometimes referred to by the Arabic Baḥr el-Jebel, , literally 'Mountain River'. In Uganda, the speakers of Luganda use the name Kiyira. Some Nubian peoples of Egypt and Sudan use the Nobiin name Áman Dawū ('Great Water').
Several tributaries (smaller rivers that merge into the Nile) and segments of the river incorporate "Nile" in their names, including the following: Albert NileSegment of the White Nile flowing north from Lake Albert to Nimule Black NileAn alternate name for the Atbarah River Blue NileOne of the two major tributaries of the Nile Kyoga NileSegment of the White Nile from Lake Kyoga to Lake Albert Main NileSegment of the Nile downstream from the confluence of Blue Nile and White Nile Mountain NileSegment of the White Nile from the mountains of Uganda to the plains of South Sudan Victoria NileSegment of the White Nile from Lake Victoria to Lake Kyoga White NileOne of the two major tributaries of the Nile Yellow NileThe Wadi Howar, remnant of an ancient tributary that dried up several thousand years ago
Sources
The source of the Nile is a tributary of the Rukarara River, in Nyungwe National Park, Rwanda, at , at an elevation of . The source is defined as the starting point of the longest year-round watercourse in the Nile's drainage basin. From this source, the river runs to its mouth at the Mediterranean Sea. The distance was measured in 2009 along the centerline of the river using satellite imagery.
The highest sources of the Nile are on the slopes of the Rwenzori Mountains in Uganda. The legendary Mountains of the Moon, described by the Greek astronomer Ptolemy, have been associated with Rwenzori.
The southernmost source of the Nile is in Burundi at one of the heads of the Ruvyironza River, which feeds into the Kagera River. A monument was erected nearby in 1937 by Burkhart Waldecker close to the town of Rutovu, near Mount Kikizi.
Lake Victoriashared by Tanzania, Uganda, and Kenyais sometimes informally described as the source, because it feeds the White Nile from its outflow at Jinja, Uganda. However, some have suggested that the genuine source of the Nile is the rain clouds that are often found above Lake Victoria, because they contribute the vast majority of the lake's water.
The source of the Blue Nile tributary is near the town of Gish Abay, south of Lake Tana.
Geography
The Nile is a major river in northeast Africa which flows into the Mediterranean Sea. The Nile Basin is all land that drains into the Nile, and it covers 2,927,843 kmabout 10% of the African continent (see adjacent map). Eleven countries are wholly or partially within the basin: Burundi, Democratic Republic of the Congo, Egypt, Eritrea, Ethiopia, Kenya, Rwanda, South Sudan, Sudan, Tanzania, and Uganda. The basin covers a wide variety of climates, ecosystems, and topographiesranging from arid, sandy deserts in the north, to flat, swampy wetlands in the middle, to rainy, forested mountains in the south.
The basin can be divided into seven regions; five of these regions encompass the longest course of the Nile. Proceeding in a downstream sequence, these five regions are: the African Great Lakes, the Mountain Nile, the White Nile, the main Nile, and the Nile Delta. Two additional regions encompass major tributaries: the Blue Nile and the Atbarah River.
African Great Lakes
The African Great Lakes region contains the source of the Nile as well as several large lakes that are part of the Nile River system: Lake Victoria, Lake Albert, Lake George, and Lake Edward. The source of the Nile is the Rukarara River within Rwanda's Nyungwe National Park, and it leads to the Kagera River which drains into Lake Victoria. Although it is a large lakethe second-largest freshwater lake in the world Lake Victoria is relatively shallow, with an average depth of . The Nile River first assumes the name "Nile" where Lake Victoria empties on its north side: the stretch from there to Lake Albert is called the Victoria Nile. A pair of waterfalls Ripon Falls and Owen Falls were located where the Nile exits Lake Victoria, but have both been submerged by the construction of the Nalubaale dam. After Bujagali Falls and Bujagali Power Station, the Victoria Nile empties into Lake Kyoga. After exiting Lake Kyoga, the river is joined by the River Kafu tributary, then passes over Murchison Falls and flows into Lake Albert. Unlike Lake Victoria, Lake Albert is a deep lake surrounded by mountains. The river exits Lake Albert on its north shore, where it is called the Albert Nile; this stretch of the river is relatively flat and broad, and suitable for navigation by steamboats.
Mountain Nile
The second region of the Nile Basin, proceeding downstream, is the Mountain Nile (). This region begins near the town of Nimule, extends to Lake No, and is entirely within South Sudan. After passing through Nimule, the river goes through the Fula Rapids and on to Jubathe capital of South Sudan. After Juba, the Nile passes through the town of Bor, then enters the Sudd, a large swamp located in a flat plain.. Overview of Sudd. The incline of the ground in the Sudd is only 1:13,000 rise over run, so the river slows down and widens. Lush vegetation, including sedges, papyrus, and common water hyacinth (an invasive species) clog the waterways and make navigation difficult. At the north edge of the Sudd swamp, the Nile passes through Lake No, a small lake where the Nile is joined by the Bahr el Ghazal River (Arabic: 'gazelle river')a tributary from the west.
A major tributary in the Mountain Nile region is Bahr el Ghazal which arrives from west Sudan and joins the White Nile at Lake No. The drainage basin of the Bahr el Ghazal River is largeabout 860,000 square kmand receives a relatively large amount of rain, but its contribution to the Nile is small compared to other tributaries. Its basin includes Lake Kundi and Lake Keilak. The Bahr el Ghazal passes through the city of Wau, South Sudan: it is a permanent stream east of Wau, but a seasonal stream to the west.
White Nile region
Continuing downstream, the third region of the Nile Basin is the White Nile region which includes an stretch of river from near Malakal to Khartoum, the capital of Sudan. There it is joined by the Blue Nile. This portion of the river is a wide, calm stream with a fringe of swamps on both banks. The river here is shallow and undergoes significant losses due to evaporation.
Where the White Nile merges with the Blue Nile, they are noticeably distinct colors. The White Nile is a lighter shade because the sediment it carries includes a significant amount of quartz and feldspar. This is in contrast to the Blue Nile which carries dark clay sediments originating from Ethiopia's basaltic rocks.
The Sobat River is a tributary which joins the White Nile near the town of Malakal (after the Bahr el Ghazal confluence, before the Blue Nile). Its basinwhich includes the Machar Marshescovers about 225,000 square km. The Sobat floods between July and December.
Main Nile
The fourth region of the Nile Basinthe main Nileextends from Khartoum to Cairo, the capital of Egypt. This stretch has a relatively uniform width and depth: about wide and deep at its deepest point (when not in flood). Soon after leaving Khartoum, the river enters the Sabaloka Game Reserve and goes through large, powerful rapids that are impassable by boat. This is the sixth (and furthest upstream) of the six cataracts of the Nile. The Atbarah Rivera major tributaryjoins the Nile, which then follows a large S-shaped curve to the west. Four more cataracts (numbered 5, 4, 3, and 2) are encountered in this large S-curve, which render the river unnavigable; although ships may travel in certain calm stretches between the cataracts. The river then enters a reservoir: Lake Nasser. This lake the world's second-largest human-made lakewas formed when the Aswan High Dam was built in Egypt, and inundates more than of the Nile. The Aswan Low Damolder and smaller than the High Dam lies beneath the Aswan High Dam, near the location of the first Nile cataract (now submerged). From these dams, the Nile flows about through a limestone plateau, bordered by large amounts of irrigated farmland, until it reaches Cairo.
Nile Delta