The Nile River: Basin, Course, Facts, and Risks Facing It

By Eman Abdallah Kamel

Contact the author: emanabdallahkamel@gmail.com

Eman is a writer and an engineer. She is interested in writing about geography and many other topics.

In the world, the Nile River is considered to be one of the most important rivers. The Nile is also the longest river in the world. In this article, you will learn about the history, the countries of the basin, the course, and the main risks facing the Nile.

The Nile River. Image source: flickr.com

The Nile River

The Nile Basin contains the longest river canal system in the world, more than 6,500 km, which drains about one-tenth of the African continent.

The river basin extends at a latitude of 35° (4° S to 31° N) and includes a variety of climates, river systems, biomes, and topographies, from the plateau of equatorial lakes in the headwaters of the White Nile to the complex of deltas in the eastern Mediterranean. The total catchment area of the Nile is about 3,000,000 square kilometers.

The Nile River covers eleven countries: Tanzania, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea, South Sudan, the Republic of Sudan, and Egypt.

More than 180 million people live within the basin, and about half of this number depends almost entirely on the flows of the Nile for economic and domestic needs.

Wall painting from the tomb of Sennedjem, Dair al-Madinah, Thebes-West.

The Nile River and the Ancient Egyptian Civilization

God granted the Nile to Egypt to run through its land, to be a reason to bring goodness to it. The Nile River played an essential role in the rise of the ancient Egyptian civilization.

The river and fertile soil helped the Egyptians build an empire based on great agricultural wealth. The Egyptians were the first to cultivate on a large scale and to develop irrigation methods. The Egyptians planted wheat, barley, and flax. They also excelled at gardening.

The Nile brought silt that naturally fertilized the valley. In the floodplains, the Egyptians developed both horticulture and gardening. The gardens and orchards were generally used for growing vegetables, grapes, and fruit trees.

The Egyptians also planted dates, sorghum, beans, lentils, chickpeas, and root crops such as onions, garlic, and radishes, along with lettuce and parsley.

The fruit was a popular component of Egyptian art, indicating that its cultivation was also a major focus of agricultural efforts as civilization’s agricultural technology developed.

The Nile River was also an important commercial crossing between Egypt and neighboring countries.

The Basic Areas of the Nile Basin

The Nile Basin includes five main areas:

Equatorial lake plateau in the vertical waters of the White Nile, with densely forested tropical catchments with perpetual flow systems.
The dam and Central Sudan regions have rich, low-slope plains, extensive swamps, wide channel belts, and low concentrations of suspended sediments.
Ethiopian Highlands from the headwaters of the Blue Nile and Atbara rivers, with deep valleys, unstable slopes, and steep gravel-bottom streams with high seasonal flows and sediment loads.
Large bends and cataracts of the desert Nile, with systems of ephemeral tributary valleys and mud fans in the arid lands of Sudan and Egypt, cataracts, and extensive sedimentary tributaries of the main Nile with a highly modified flow and sediment system downstream of the Aswan High Dam.
The Egyptian region includes the low-sloping delta complex with its large branches, spurs, lagoons, highly modified drainage, and a dense network of irrigation canals.

Geomorphology of the Nile channel complex in the Dongola Reaches in northern Sudan at low flow. (a) A large sand bar and thick channel margin flood deposits. (b) A flood channel to the east of the main Nile. View looking downstream in each case, 1997. Image source: researchgate.net

A Brief History of the Nile

Opinions and theories about the history of the Nile vary.

According to an article on the geomorphology of the Nile by Woodward, Macklin, Krom, and Williams, at the end of the Miocene (around 6.5 million years BP), the evaporation of the Mediterranean Sea and the transfer to saline desert conditions across marine basins had deep impacts on the large river systems of the region, including the Nile. The fall in the base standard in the Eastern Mediterranean led to large-scale ﬂuvial silt, and the Nile carved a deep bedrock canyon to ca. 570 m below current sea level at Cairo and to 170 m at Aswan, some 1000 km upstream from the current coastline. This fall in elevation of about 400 meters between Aswan and Cairo for the Late Miocene Nile Valley compares with a fall of about 70 m for the current Nile over the same distance.

The triple tectonic events associated with the Rift of Africa and the secession of the Arabian Peninsula created high-altitude sub-basins for the Nile and determined its northern course towards the Mediterranean. The new research has shown that the lower White Nile is relatively young, and it is difficult to estimate the age of the Blue Nile.

Fluctuations in climate in tropical Africa during the Quaternary had an important influence on the behavior of the Nile sediment system as extended ice sheets cooled the global oceans and decreased the intensity of the monsoons. The effects of changes in sea level did not spread in the Quartet due to changes in the volume of ice downstream of the Nile in Egypt.

There followed the so-called marine isotope global LGM of stage 2. The Blue Nile and Desert Nile main channels exhibited apparent freezing during the global LGM, and sediments were deposited on the valley floor. The increased sediment supply to the fluvial system at this time resulted from reduced vegetation in the Ethiopian highlands, resulting in slope instability and valley and plate erosion. During that period, the White Nile system was seasonal and had shallow flows, with periods of complete dryness throughout the year. This is a significant contrast to the modern White Nile system. Due to the reduction of tropical rainfall and the absence of a connection with Lake Victoria, this flow system resulted. Thus, the White Nile in Sudan became isolated from its tropical sources in Uganda. The White Nile is currently responsible for maintaining the permanent flow of the main Nile, especially during drought years. With increased drought at that time, the White Nile Valley was characterized by extensive active Aeolian dune systems derived from the sandy bottom load, which were large enough to block the canal in some areas.

An increase in regional humidity and the transition to a perennial flow regime stabilized the dune systems on the White Nile valley floor. After that, the White and Blue Niles carried very large discharges from the floods that inundated a very large area in the Lower White Nile Valley. This submerged area was about 4 to 5 meters higher and 20 to 40 km wider than the present day and resulted in the deposition of new-grained sediments over a large area of the lower White Nile Valley. In the Ethiopian highlands, the climate became wetter due to the intensification of the summer monsoon and the increased water flow from the headwaters of the Blue Nile. This has resulted in increased vegetation, slope stabilization, soil formation, and decreased sediment flow from the Blue Nile basin.

After a transitional period of at least two thousand years, the current Nile reached Egypt about ten thousand years ago. This transitional period witnessed severe climatic fluctuations in the Lakes region, which led to a massive increase in the volume of the New Nile water (gamma New Nile), which was suffering from a constant shortage of water. This short period of immense and unusual floods was followed by a period of sculpture that led to the emergence of the modern Nile. The Nile used to receive its waters from the Ethiopian Plateau and the Equatorial Plateau through the White Nile. Floods and river resources on the Ethiopian plateau raised the level of the Nile and deposited large amounts of silt. After that, the rain continued in the Neolithic period during the rainy period, which decreased by about 2,350 BC at the end of the Fifth Dynasty in ancient Egypt. The oldest layer of modern silt dates back 10,000 years and is located 12 meters above the floodplain in Wadi Halfa.

According to Nature Geoscience, the Nile took its current course 30,000,000 years ago. Researchers from the University of Texas, USA, in cooperation with researchers at other universities, said that they had found a link between the flow of the river and the movement of rocks in the mantle of the Earth, which is the semi-solid mass in the ground that lies between the Earth’s dense core and its thin outer layer. The mantle is approximately 2,900 km thick and makes up 84% of the Earth’s total size. This study demonstrates that the slow movement of the esoteric mantle is one of the major forces that shape the landscape and geological processes of the Earth. In this study, the researchers traced the geological history of the Nile River by studying ancient volcanic rocks in the Ethiopian highlands and linking them with huge quantities of river sediments buried under the Nile Delta in Egypt, which led researchers to believe that the delta was higher than its current position by supporting mantle rocks from below, which gave it an elevation comparable to that of the Ethiopian plateau for millions of years.

The researchers linked the nature of the course of the Nile River from the south to the north, where its mouth is in the Mediterranean Sea, through the delta in Egypt, and the moving belt of mantle rocks that represent a thrust against the Ethiopian highlands in the south, as these rocks pull the river basin down, which is why the gentle gradient of the Nile has kept it steady northward over all these millions of years. The research team made a computer simulation to recreate 40 million years of Earth’s tectonic activity; the model showed that a warming mantle may have led to the pyroclastic flow and the formation of the Ethiopian highlands 30 million years ago.

Another study published in 2018 indicated that the Nile River is estimated to be more than 30 million years old. The results of the study showed this through the similarity of minerals in river sediments in the Nile Delta in Egypt with rocks upstream in Ethiopia.

Nile River Map. Image source: wikimedia.org

The Course of the Nile

The Ruvironza is the furthest source of the Nile, which flows into Lake Victoria through the Rovubo and Kagera rivers. Other rivers converge at Lake Victoria, the largest tropical lake in the Nile, including Simeo-Duma, Grumeti-Rawana, Mara, Gucha-Meguri, Sundo, Yala, Nzoia, Seo, Katonga, and Ruizi.

Lake Victoria has an area of about 66,700 2 kilometers. The lake occupies a large proportion of the entire subbasin. Three countries, Kenya (6%), Tanzania (51%), and Uganda (43%), share the lakeshore. Six countries share the basin: Burundi, the Democratic Republic of the Congo, Kenya, Rwanda, Tanzania, and Uganda.

Did You Know?

Lake Victoria is important for agriculture, domestic water supply, hydropower, fisheries, travel, tourism, industry, and the environment. The average annual precipitation over the sub-basin is nearly 1368 mm, and the annual average potential transpiration evaporation is 1486 mm.

From Jinja in Uganda, the White Nile emerges from Lake Victoria as the Victoria River and travels north, passing through two other tropical lakes, Kyoga and Albert. Through these two lakes, the Nile captures runoff from two mountainous and high-rainfall regions, the Mts. Rwenzori and Elgon, on the southwestern and southeastern ends of the basin.

The river appears again from Lake Albert as the Albert River and travels north to Nimule, near the border between South Sudan and Uganda. From this point, the Bahr al-Jabal River (the mountain river) flows over the Fula slopes and crosses the dam before it meets the Bahr al-Ghazal in Lake No in southern Sudan. Bahr al-Ghazal drains the high-rainfall regions of western South Sudan.

From Lake No, the river turns east to join with the Sobat River, which carries high and seasonally variable flows originating in the Ethiopian highlands. The Bahr al-Jabal and the Saubat River together form the White Nile, which continues its northward descent to meet with the Blue Nile at Khartoum, Sudan.

The Blue Nile is the second major tributary of the Nile River. The Blue Nile originates from Lake Tana in Ethiopia. Before the Blue Nile meets the White Nile, it joins with some rivers, such as the Rahad and Dinder rivers, which originate in the Ethiopian highlands.

Did You Know?

The White and Blue Nile derive their colors from the sediments they carry. The White Nile is rich in light gray deposits, while the Blue Nile picks up black sediments on its way to Khartoum.

Satellite Picture of the Nile Delta, Egypt. Image source: wikimedia.org

From Khartoum, the common rivers of the Nile are joined by the Atbara, which originates from the Ethiopian highlands.

The main Nile continues to journey north and flows into Lake Nasser, a major man-made dam on the border between Sudan and Egypt.

The Nile River eventually discharges into the Mediterranean Sea through the delta. In this region, the meeting of the river’s water with the sea, where neither one overwhelms the other, is one of the natural phenomena that deserve contemplation and which God told about in the Holy Qur’an more than 14 centuries ago, according to verses 19 and 20 of Surah Ar-Rahman (The Beneficent). As in the Quran, the English explanation of these verses is “In the Name of Allah, the Most Gracious, and the Most Merciful.

19. He merges the two bodies of ˹fresh and salt˺ water,

20. Yet between them is a barrier they never cross.
Nobel Quran, Surah 55: Ar-Rahman

The first to notice a water barrier between fresh groundwater and salt seawater was the Dutch scientist Willem Badon-Gibben in 1888, and the German scientist Alexander Herzberg in 1901. The two scientists derived a relationship that determines the depth of the barrier above sea level, called the Ghyben-Herzberg relation. The relationship relies on the fact that the density of salt water is higher than the density of freshwater, where the density of salt water is 1.025 grams per cubic centimeter, while the density of freshwater is one gram per cubic centimeter. Based on this fact, the two scientists found that the depth of the barrier between the two bodies below sea level is 40 times the height of the freshwater level above sea level, which means that the barrier will not arise if the freshwater level equals the saltwater level.

This water barrier is a water wall that surrounds the groundwater from the salt waterside. The barrier begins at the top of the salty sea surface and extends downward in a curve until it reaches the bottom of the freshwater. The barrier is an area of a certain thickness in which the salt concentration gradually decreases from its level on the saltwater side to its level on the freshwater side. Scientists have given the name saltwater-freshwater interface to this water barrier that separates the two bodies of water.

Risks That Face the Nile River

The Nile River faces three main risks:

Dam Crisis
Climate Change
Pollution

1. Dam Crisis

All the basin countries depend on the Nile, but to varying degrees. Egypt depends entirely on the Nile. Currently, 98% of Egypt’s freshwater comes from the Nile River. Egypt is ranked among the top ten countries in the world that will be most vulnerable to the threat of water shortages in the future.

Every year, Ethiopia has 123 billion cubic meters of surface water, which is 1.5 times the annual water of the Nile, but the country rarely uses any of this water. Only 3% of the water remains in Ethiopia, and the rest flows to neighboring countries. Ethiopia is one of the poorest countries in the world, with only 5% of the land suitable for irrigation developed, and its prosperity depends on the use of more water resources.

More than 3,000 kilometers (2,000 miles) upstream on the Blue Nile, the main tributary, thousands of workers have worked for nearly a decade to build the Grand Ethiopian Renaissance Dam, set to be the largest in Africa. Downstream countries, especially Egypt and Sudan, fear that the dam’s 145-meter (475-foot)-high wall will block off their main water supplies.

2. Climate Change

Warming will affect the Nile Basin region. The effects of climate change on the flow of the Nile will vary depending on the location of the different sub-basins, with more serious consequences later in some regions than in others.

3. Pollution

The waters of the Nile River suffer from increasing pollution. Water pollution is a major issue that threatens human health and economic development. Polluted water affects human health directly when consumed. It also affects crops indirectly when used to irrigate them. Irrigation water with a high level of pollutants increases pollutants in the soil and thus in fruit and vegetables.

The severity of the water pollution problem varies between different water bodies according to flow, usage patterns, the extent of industrialization, population density, and the availability of sewage systems. Discharge of treated or untreated industrial and domestic wastewater, fertilizer residues, pesticide filtration, solid waste, and navigation are sources of pollution.

Sources

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