(see the map of the physical-geographical zoning of Africa with links to photographs of the nature of this region)
In terms of the total volume of annual flow (4600 km 3), Africa ranks third after Eurasia and South America, and in terms of layer thickness (less than 160 mm) it is inferior to all continents except Australia and Antarctica.
Main watershed The African continent runs along its most elevated eastern edge, so more than 1/3 of the surface drains into the Atlantic Ocean, only about 1/4 in Indian Ocean, even less - to the Mediterranean Sea. About 1/3 of Africa's surface (approximately 9 million km 2) has no drain into the ocean and belongs to internal basins or is generally devoid of surface runoff.
Distributed surface water extremely across the mainland unevenly, and both the distribution and regime of flowing waters show a close dependence on the amount and regime of rainfall in a particular part of the continent. Snow and glacier feeding plays an insignificant role in Africa.
In the equatorial regions the rivers have a uniform flow throughout the year, without pronounced minimums, but with two periods of maximums due to zenithal rains. Areas with subequatorial climate (Sudan, the southern part of the Congo Basin, etc.) are characterized by a pronounced summer maximum flow and a corresponding increase in river flow. On the northwestern and southwestern edges of the continent, rivers have a clearly defined winter maximum associated with winter cyclonic rains in each hemisphere.
Between the areas with summer and winter runoff maximums there are vast territories, generally deprived constant flow. These are the Sahara in the northern and a significant part of the Kalahari in the southern hemisphere, which are practically devoid of watercourses; they are crossed by a network of dry riverbeds that fill with water only a short time after rare occasional rains.
A developed network of dry riverbeds and an abundance of dry depressions, only periodically filled with water and characteristic of the now arid regions of Africa, indicate the existence earlier of more humid climatic conditions within its borders. The last pluvial period corresponded to the period of the last glaciation in the high latitudes of the northern hemisphere.
All of Africa's most significant rivers irrigate vast basins separated from the oceans by plateaus and mountain ranges. The uplifts caused a revival of erosion activity and contributed to the formation of large rivers in the valleys of many rivers. rapids and waterfalls. They impede navigation and greatly reduce the transport importance of African rivers, but at the same time they contain enormous hydropower resources, the use of which has been expanding in recent decades in a number of African states.
River Nile
The longest river in Africa - the Nile (6671 km) - is the longest river on the ground. The area of the Nile basin is 2870 thousand km 2. The average water flow near Aswan is 2600 m 3 /s.
By features natural conditions basin, the nature of the hydrographic regime and the significance that the Nile has in the life of the peoples living in its valley, it is one of the most unique and remarkable rivers in the world.
Source The Nile is considered to be the Kagera River, which rises at an altitude of more than 2000 m on one of the massifs of East Africa, south of the equator, and flows into Lake Victoria. A river comes out of the lake called Victoria Nile. It flows through Lake Kyoga and empties into Lake Albert, below which it is called Albert Nile. Throughout this section of the flow the river has a mountainous character, is very rapid and forms several waterfalls. The largest waterfall is Kabalega(Murchison) on the river. Victoria Nile - reaches 40 m in height.
Coming out of the highlands under the Arabic name Bahr El Jabal, which means “river of the mountains,” the river enters a vast and flat basin. Its flow slows down, and the channel breaks up into branches. The largest tributaries in this part of the stream are El Ghazal (“river of gazelles”) and Sobat. Flowing from the mountains, Sobat carries muddy yellow water containing a large number of suspended material. Below Sobat the river gets its name White Nile(Bahr el Abyad). Near the Sudanese city of Khartoum White Nile merges with the Blue Nile (Bahr el-Azraq) and here receives the name Nile.
Blue Nile originates in the Ethiopian Highlands, flowing from Lake Tana. From the same highlands the Nile receives its last large tributary, the Atbaru. Below its confluence, the Nile cuts through a plateau composed of hard sandstones and crosses a series of rapids (cataracts). There are a total of six rapids between Khartoum and Aswan.
Below Aswan, the Nile flows in a valley 20-50 km wide, which at the beginning of the Anthropocene was a bay of the Mediterranean Sea. The Nile Valley ends delta, formed on the site of a bay, gradually filled with sediment from the river. The delta area is 24 thousand km 2.
The Nile is the only river in North Africa that crosses the Sahara and brings its waters to the Mediterranean Sea, being source of life in a waterless desert. The permanent flow of the Nile exists due to the precipitation that falls in more southern regions and feed its origins. White Nile, starting at equatorial belt, receives nutrition from the rains that fall throughout the year. In the upper reaches, the water level in the river is very high and fairly constant, as it is regulated by lakes. But within the Upper Nile Basin, a large amount of water is lost to evaporation, and in the supply of the Nile below Khartoum, the White Nile plays a smaller role than the Blue Nile, which carries abundant water (60-70% of the total flow) after the summer rains that fall on the Ethiopian Highlands. The highest flow on the lower Nile during this period is approximately five times higher than the flow during low water. The tributaries of the Nile, flowing from the Ethiopian Highlands, bring large amounts of silt, which settles during the flood.
Before the construction of the Aswan High Dam, there was no through navigation route along the Nile due to numerous rapids. Overcoming rapids throughout the year was only possible by boat. For permanent shipping, areas between Khartoum and Juba, Aswan and Cairo, Cairo and the mouth of the Nile were used.
Several were built on the Nile dams and reservoirs allowing you to regulate water flow throughout the year. At one time, a large hydroelectric complex was created near Aswan to irrigate cotton fields. However, these outdated hydraulic structures did not solve the most important economic problems - expanding acreage and obtaining cheap energy.
With help Soviet Union at the end of the 60s. A large dam was built in the Nile Valley near Aswan, thanks to which the area of Egypt's irrigated land was increased by 1/3, the electricity necessary for the development of the country's economy was generated, and navigation conditions were improved. Above the dam, in a flooded valley, a huge reservoir was formed, called Lake Nasser.
Congo River
The Congo ranks second among African rivers in terms of length, but in terms of basin area and water content, the Congo ranks first in Africa and second in the world after the Amazon.
Origins The Congo is considered to be the Lualaba and Chambeshi rivers (a tributary of the Luapula that flows into the Lualaba). The length of the river from the first source is 4320 km, from the second - 4700 km. The basin area is about 3.7 million km2. The average annual flow at the mouth is 46 thousand m 3 /s, i.e. it is more than 15 times the average flow of the Nile.
The Congo flows in the northern and southern hemispheres, crossing the equator twice. Before flowing into the Atlantic Ocean, the river cuts through a highly elevated array of crystalline rocks.
Large tributaries Kongo - Ubangi, Sanga (right), Kwa (Kasai), Ruki, Lomami (left). The upper reaches of the Congo and its tributaries, crossing high plateaus and mountains, are replete with rapids and waterfalls. Rivers form seven rivers at the equator waterfalls, named after the African explorer Stanley. Stanley Falls (or, as they now appear on maps, Boyoma Falls) ends the upper section of the Congo.
In the middle reaches, within the basin, the Congo flows calmly in a wide valley. The river bed in some places forms lake-like extensions, reaching 20 km in diameter. Here the Congo receives its largest tributaries. In the lower reaches, cutting through the crystalline massif, the Congo again forms a series of waterfalls (there are 32 of them), united common name Livingston Falls. Having reached the coastal plain, the Congo expands, reaches great depth(up to 70 m) and becomes navigable. The river at its mouth splits into branches and ends in a wide and deep estuary. IN Atlantic Ocean The Congo channel continues in the form of an underwater groove at a distance of 150 km from the coast. Large masses of water carried out by the Congo desalinate the ocean at a distance of several tens of kilometers.
Huge amount of runoff The Congo is explained by the equatorial position of the basin and the fact that the river receives inflows from the northern and southern hemispheres, in which maximum precipitation occurs in different time of the year. Northern tributaries bring the bulk of water to the Congo from March to November. The discharge in the middle and lower Congo, gradually increasing, reaches a maximum in October-November. The second maximum, more significant, is associated with rains in the southern hemisphere and occurs in February - April. The diet and regime of the Congo and the Amazon have much in common.
During floods, the Congo in its middle reaches overflows its banks and floods the flat surface of the basin for hundreds of kilometers.
All rivers of the Congo Basin have enormous water energy reserves. Several hydroelectric power plants have been built in the Shaba region, the most important mining area within the Democratic Republic of the Congo.
Niger River
The Niger River is inferior to the Congo and the Nile in terms of length and basin area, but is still one of the largest rivers Earth. The length of the Niger is 4184 km, the basin area is more than 2 million km 2. Its average annual flow significantly exceeds the flow of the Nile (9300 m 3 /s). The Niger begins on the North Guinea Upland, at an altitude of 900 m. Its sources are located just a few tens of kilometers from the ocean, from where the Niger flows first to the northeast, and on the border of the Sahara it sharply changes direction to the southeast. In this part of the basin there is the vast inland delta of the Niger, formed during the period of the existence of an ancient reservoir into which the upper Niger carried its waters.
Flowing into the Gulf of Guinea, the river forms a vast delta. Largest influx The Niger - Benue - flows into it in the lower reaches from the left. In the upper and lower reaches of the Niger there are rapids, on average it has the character of a flat river.
Peculiarities mode The Niger is due to the fact that its upper and lower reaches are located in areas rich in precipitation, and the middle reaches basin is characterized by great dryness and strong evaporation. In the lower reaches of the Niger there are two flood, in the middle and upper - one. Flood in upper reaches depends on summer rains, lasts from June to September and is transmitted downstream. In the middle reaches there is a gradual rise in level. The Niger is flooded, water fills numerous branches, and dry riverbeds accompanying the main watercourse. Due to the dry climate, a lot of water in the middle reaches is spent on evaporation; this flood is transmitted to the lower reaches in a weakened form around January. In the lower reaches there is another flood associated with local summer rains.
On the border with the Sahara, Niger is of great importance in the system irrigation: Several dams and canals have been built there, and a large rice growing area has been created.
Zambezi River
Zambezi is the most big river South Africa and the largest of the mainland rivers flowing into the Indian Ocean. Its length is 2736 km, the basin area is 1330 thousand km 2. The average annual flow of the Zambezi is very high (16,000 m 3 /s): it is more than 1.5 times the flow of the Niger and many times the average flow of the Nile.
The Zambezi originates at an altitude of more than 1000 m on the Congo-Zambezi watershed plateau. On its way, the river crosses flat basins and plateaus separating them, forming numerous rapids and waterfalls. The largest waterfall on the Zambezi and one of the largest in the world - Victoria- has a height of 120 m and a width of 1800 m (). The water rushes into a basalt gorge located perpendicular to the river bed. For the deafening noise of falling water, which can be heard at a great distance, and the snow-white column of spray local residents They gave the waterfall a figurative name - “thundering smoke” (
1*. Identify the similarities and differences between the Zambezi and Niger rivers according to the plan (see appendix). To do this, use physical and climate map Africa.
1) In what part of the continent does it flow?
2) Source, direction of flow, mouth, length of the river.
3)Which ocean basin does it belong to?
4) Dependence of the nature of the flow on the relief.
5) Nutrition and regime of the river.
1) Flows in the southern part of continent Africa.
2) Originates from the Bie plateau, flows to the Southeast, Mouth-Sofala Bay (Mozambique Strait), length - 2,574 km.
4) In the upper reaches up to the Victoria Falls, the Zambezi is a wide, calm river. As the waters of the Zambezi approach Victoria Falls, the river's flow becomes more rapid and turbulent.
5) Rain power, summer mode.
1) Flows in western Africa.
2) Source on the Guinean Highlands, mouth-Gulf of Guinea, runs from southwest to northeast, length: 4180 km.
3) Refers to the Indian Ocean basin.
4) The source is located on the slopes of the Leon-Liberian Upland. In the upper and lower reaches, the Niger has rapids and flows mainly in a narrow valley. In the middle reaches, the Niger has the character of a flat river.
5) Rain power. Main features water regime The Niger is due to the fact that its upper and lower reaches are located in areas rich in precipitation, and the middle reaches basin is characterized by great dryness and strong evaporation.
2. Using the example of any river, prove that the characteristics of rivers depend on the topography and climate.
Rivers originating in mountainous areas, are characterized by stormy and fast current unlike those that flow on the plains. Mountain rivers form narrow valleys, while those flowing on the plains have a winding channel. Typical examples of mountain rivers include the Terek, Colorado.
Classic lowland rivers- Volga, Amazon.
The river's feeding regime and its level are highly dependent on climate. For example, the Kolyma River is characterized by summer floods due to the cold climate of the area where it flows, while most rivers European Russia have spring floods.
In arid areas, many rivers dry up. This phenomenon is typical, for example, for central regions Australia, where such rivers are called creeks. In areas with constant moisture and warm climate the rivers are full throughout the year with slight changes in level (Amazon, Congo).
3. Why are the shores of Lake Chad indicated on the map with a broken line?
Because coastline fickle. There is no actual line, there are swamps, and in times of drought there is less water, rainy season- more. The surface area of the water changes several times. The dotted line indicates something in between.
4. How do African people use inland waters?
Inland waters, Africa have great value to supply the population with water and irrigate fields, as well as generate electricity.
Zambezi River is the fourth longest river in Africa. In addition, in its flow there is one of the most beautiful waterfalls in the world Victoria Falls. And among rafters, the river is known as the most extreme in the world river for rafting. The Zambezi River was first explored by Livingstone only in 1851, and already in 1959 people created here one of the largest artificial lakes in the world - Lake Kariba. The Kariba HPP provides electricity to Zambia and Zimbabwe.
Rafting on the Zambezi River, video:
See also the beautiful 360 aerial panorama taken over Victoria Falls. You can see all the surroundings.
Characteristics of the Zambezi River
River length: 2,660 km.
Drainage basin area: 1,570,000 sq. km.
Where does it occur: The river originates in northwestern Zambia. The height of the source above sea level is 1500 m. To the east of the source there is a series of hills separating the basins of the Zambezi and Congo rivers. In addition to Victoria Falls, there are several other notable waterfalls on the Zambeza River. On the border of Zambia and Angola, these are Chavuma Falls and Nagambwe Falls, in western Zambia. Up to Victoria Falls the river flows in a wide shallow channel. Below the waterfall, the river changes the nature of its flow and forms a series of rapids that attract many rafters to these places. The river turns northeast and then flows east to the Chikaronda rapids. From here the river flows in a south-easterly direction in a wide channel and narrows only in one place passing through the Lupata hills. Flowing into the Indian Ocean, the Zambezi River forms a wide delta with an area of 5000 square meters at its mouth. km. The delta channels are covered dense thickets mangrove forests. True, with the construction of dams its size was halved.
Food, river mode: Zambezi is powerful river. Although the Zambezi ranks only fourth in Africa in terms of length, it ranks second in terms of annual runoff and is second only to Congo River. The Zambezi mainly receives its nutrition from heavy summer rains (at these latitudes, summer lasts from November to March). At other times of the year the river is much less full. The river regime is characterized by a rapid decrease in water level in March and a subsequent rise in November.
Interesting fact: the river has a large volume of solid runoff; in terms of this parameter, among the rivers of Africa, it is second only to Orange. It is thanks to such a large volume of solid runoff that the river forms a delta at the mouth.
Main tributaries: Luene, Lungoeungo, Madchilu, Kabompo, Kwando, Gwai, Umphule, Gamyanu, Luangwa, Shire and others.
Biological resources, inhabitants: hippopotamuses like to cool off in the waters of the river; they can be found here in very large quantities. Also, there are crocodiles, pelican herons, and African eagles. Bull sharks often swim out of the ocean.
Zambezi Riveron the map:
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