Continents of the Earth and parts of the world: names and descriptions. Inland waters. The largest river systems of Eurasia. Lakes The largest river systems of the continents

The modern river network, lake and artesian basins were formed within each of, mainly at those stages of the development of nature, when Gondwana had already broken up, and the continents existed in isolation from each other, therefore, similar features of the hydrosphere of the Southern Tropical continents are explained mainly by the similarity of modern natural conditions.

Among the sources of water supply, rain absolutely prevails due to the fact that South America, Africa and Australia are located for the most part in the equatorial-tropical latitudes. Glacial and snow nutrition is of some importance only for mountain rivers and lakes in the Andes and the East Australian mountains.

The regime of rivers flowing in similar climatic regions on different continents has a certain similarity. Thus, the rivers of the equatorial regions of South America and Africa and the eastern shores in the tropical zone of all three continents are full of water all year round. On the rivers of the subequatorial zone, the summer maximum is well expressed, and in the areas of the Mediterranean type of climate - the winter maximum of the flow.

Lakes of arid and semi-arid regions are similar in properties. They, as a rule, are highly mineralized, do not have a permanent coastline, their area varies to a large extent depending on the inflow, lakes often dry up completely or partially, and solonchaks appear in their place.

However, these features practically limit the similarity of water bodies. Southern continents. Significant differences in the properties of the internal waters of the southern continents are explained by differences in the history of the formation of the hydrographic network at the last stages, in the structure of the surface, in the ratio of the areas of arid and humid climatic regions.

First of all, the continents differ sharply from each other in terms of water content. The average runoff layer of South America is the largest in the world - 580 mm. For Africa, this figure is about three times lower - 180 mm. Africa occupies the penultimate place among the continents, and the last (not counting Antarctica, where there is no hydrographic network common to the continents) belongs to Australia - 46 mm, more than ten times less than that for South America.

Large differences can be seen in the structure of the hydrographic network of the continents. Areas of internal flow and drainless territories occupy about 60% of the area of ​​Australia and 30% of the area of ​​Africa. In South America, such areas make up only 5-6% of the territory.

This is due both to climatic features (there are relatively few arid and semi-arid regions in South America), and to differences in the structure of the surface of the continents. In Africa and Australia, large and small basins play an important role in the relief. This contributes to the formation of centers of internal runoff, such as Lake Chad, the Okavango Basin in Africa, Lake Eyre in Australia. This structure of the relief also affects the aridization of climates, which in turn determines the predominance of drainage areas in dry regions of the continents. There are almost no closed basins in South America. There are small areas with internal runoff or completely devoid of surface water in the Andes and Precordillera, where they occupy intermountain basins with a dry climate.

The history of the development of the hydrographic network is also important. Neotectonic movements in South America were predominantly inherited. The pattern of the river network was determined already at the early stages of the geological history of the platform part of the mainland.

The largest water arteries - the Amazon, Orinoco, Parana, Parnaiba, San Francisco and their main tributaries occupy for the most part the axial zones of ancient syneclises. Ascending neotectonic movements along the peripheral parts of the river basins contributed to the incision of the erosion network and the drainage of existing lakes. Only lake-like extensions in the valleys of some rivers have survived from them.

In Africa, the most active ascending neotectonic movements are confined to the margins of the continent. This led to a significant restructuring of river systems. In the recent past, the areas of internal runoff areas were, apparently, much larger than now.

Extensive lakes occupied the bottoms of many basins, including the Congo, Okavango, Kalahari, Chad, Middle Niger, and others. Water from the sides of the basins collected in them. Short full-flowing rivers flowing from the well-irrigated rising margins of the continent, in the process of backward erosion, intercepted part of the flow of these basins. It is likely that this happened, for example, in the lower reaches of the Congo and Niger, in the middle reaches of the Nile. Lake Chad has lost part of its basin and shrunk in size, while the bottoms of other basins have completely lost their lakes. This is evidenced by lacustrine deposits in the central regions of vast inland depressions, the presence of inland deltas, an undeveloped equilibrium profile in some sections of river valleys, and other signs characteristic of the results of such a process.

In Australia, due to the widespread occurrence of arid climatic conditions, more or less full-flowing short rivers flow from the elevated margins in the east and north of the mainland into the seas of the Pacific and Indian Oceans.

On the west coast south of 20° S. sh. river channels are filled with water only during rather rare, mainly winter rains. The rest of the time, the rivers of the Indian Ocean basin turn into chains of small reservoirs connected by weak underflow. In the south, the karsted Nullarbor Plain is completely devoid of surface runoff. The only relatively long river in Australia - Murray (2570 km) flows in the southeast. It has a distinct summer flow maximum, however, this river does not dry up in winter either. The tributary of the river. Murray - r. The Darling is almost the same length, in the middle and lower reaches it flows through arid regions, receives no tributaries, and in dry times there is no runoff. All the interior regions of the mainland with a continental tropical and subtropical climate are practically devoid of runoff into the ocean, and for most of the year they are generally waterless.

Rivers of the Southern Continents

A number of rivers of the southern continents are among the largest in the world. First of all, this is the Amazon - unique in many ways. The river system is unparalleled: the river carries 15-17% of the total river flow of the Earth into the ocean. She desalinates sea ​​water at a distance of up to 300-350 km from the mouth. The width of the channel in the middle reaches is up to 5 km, in the lower reaches up to 20 km, and the main channel in the delta is 80 km wide. The water depth in some places is over 130 m. The delta begins 350 km before the mouth. Despite a small drop (from the foot of the Andes to its confluence with, it is only about 100 meters), the river carries a huge amount of suspended sediment into the ocean (estimated to be up to a billion tons per year).

The Amazon begins in the Andes with two sources of rivers - Maranion and Ucayali, receives a huge number of tributaries, which in themselves are large rivers, comparable in length and water flow with the Orinoco, Parana, Ob, Ganges. The rivers of the Amazon system - Zhurua, Rio Negro, Madeira, Purus, etc. - are typically flat, winding, slowly flowing for most of their course. They form the widest floodplains with swamps and many oxbow lakes. The slightest rise in water causes floods, and with an increase in precipitation or during high tides or surge winds, the bottoms of the valleys turn into huge lakes. It is often impossible to determine which river the floodplain, branches, and oxbow lakes belong to: they merge with each other, forming "amphibious" landscapes. It is not known what is more here - land or water. Such is the appearance of the western part of the vast Amazonian lowland, where muddy rivers carrying fine earth are called rios brancos - “white rivers”. The eastern part of the lowland is narrower. The Amazon flows here along the axial zone of the syneclise and retains the same flow pattern as above. However, its tributaries (Tapajos, Xingu, etc.) flow down from the Guiana and Brazilian highlands, cut through hard rock outcrops, and form rapids and waterfalls 100-120 km from the confluence with the main river. The water in these rivers is clear, but dark from organic substances dissolved in it. This is rios negros - "black rivers". A powerful tidal wave enters the mouth of the Amazon, which is called pororoca here. It has a height of 1.5 to 5 m and with a roar of a wide front of tens of kilometers moves upstream, damming the river, destroying the banks and washing away the islands. The tides do not allow the delta to grow, as the ebb currents carry the alluvium into the ocean and deposit it on the shelf. The action of the tides is felt 1400 km from the mouth. In the rivers of the Amazon basin a unique world aquatic plants, fish, freshwater mammals. The river is full-flowing all year round, as it receives tributaries with a summer maximum flow from both the Northern and Southern hemispheres. The river arteries connect the inhabitants of the Amazon with the rest of the world - sea vessels rise along the main river for 1700 km (although the channel in the delta has to be deepened and cleaned of sediments).

The second major river of the continent, the Parana, is significantly inferior to the Amazon in terms of the length and area of ​​the basin, and especially in terms of water content: the average annual water flow at the mouth of the Amazon is more than 10 times higher than that of the Parana.

The river has a difficult regime. There is a summer flood in the upper reaches, and an autumn flood in the lower reaches, and fluctuations in discharge can be quite significant: deviations from the average values ​​by almost 3 times in both directions. There are also catastrophic floods. In the upper reaches, the river flows through a lava plateau, forming numerous rapids and waterfalls on its steps. On its tributary - r. Iguazu near the confluence of the main river is one of the largest and most beautiful waterfalls in the world, bearing the same name as the river. In the middle and lower reaches, the Parana flows along the flat Laplat lowland, forming a delta with 11 large branches. Together with r. Uruguay Parana flows into the bay-estuary of La Plata. Muddy waters of the rivers can be traced in the open sea for 100-150 km from the coast. Sea vessels rise upstream up to 600 km. There are a number of major ports on the river.

The third significant river in South America is the Orinoco. Its regime is typical for rivers sub equatorial climate: the difference between the water flow in the dry and wet seasons is very significant.

During particularly high floods, the discharge at the head of the delta can be more than 50 thousand m 3 /sec, and in the dry season of a dry year, it decreases to 5-7 thousand m 3 /sec. The river originates in the Guiana Highlands and flows through the Orinoco Lowland. Before the mouth of the left tributary - the Meta, there are a number of rapids and rapids on the main river, and in the middle reaches of the Orinoco it turns into a real flat river, 200 km from the mouth forming a vast marshy delta with 36 large branches and numerous channels. On one of the left tributaries of the Orinoco - r. Casiquiare, the phenomenon of classical bifurcation is observed: about 20-30% of its waters are carried to the Orinoco, the rest enter through the upper reaches of the river. Rio Negro in the river basin. Amazons. Orinoco is navigable up to 400 km from the mouth for ocean-going vessels, and during the wet season, river vessels can pass to the river. Guaviare. The left tributaries of the Orinoco are also used for river navigation.

On the African continent, the most full-flowing river. Congo (in terms of water content, the second in the world after the Amazon). With the Amazon Congo is very similar in many ways. This river is also full-flowing throughout the year, since it flows for a considerable distance in the region of the equatorial climate and receives tributaries from both hemispheres.

In the middle reaches of the river The Congo occupies a flat swampy bottom of the basin and, like the Amazon, has a wide valley, a winding channel, many branches and oxbows. However, in the upper reaches of the The Congo (in this section more than 2000 km long it is called Lualaba) either forms rapids with a steep drop, or flows calmly in a wide valley. Just below the equator, the river descends from the ledges of the plateau into the basin, forming a whole cascade of Stanley Falls. In the lower reaches (length - about 500 km), the Congo breaks through the South Guinea Upland in a narrow deep valley with numerous rapids and waterfalls. They are wearing common name Falls of Livingston. The mouth of the river forms an estuary, the continuation of which is an underwater canyon with a length of at least 800 km. Only the lowest section of the current (about 140 km) is accessible to sea vessels. In the middle reaches of the Congo, it is navigable for river vessels, and the waterways are widely used in the countries through which this river and its large tributaries flow. Like the Amazon, the Congo is full of water throughout the year, although it has two rises in water associated with floods on its tributaries (Ubangi, Kasai, etc.). The river has a huge hydropower potential, which is just beginning to be used.

The Nile is considered the longest river artery of the Earth (6671 km), has a vast basin (2.9 million km 2), but the water content is tens of times less than other large rivers.

The source of the Nile is the river. The Kagera flows into Lake Victoria. Coming out of this lake, the Nile (under various names) crosses plateaus and forms a series of waterfalls. The most famous waterfall is Cabarega (Murchison) 40 m high on the river. Victoria Nile. After passing through several lakes, the river enters the plains of Sudan. Here, a significant part of the water is lost to evaporation, transpiration, and filling of depressions. After the confluence of the river El-Ghazal river gets the name of the White Nile. In Khartoum, the White Nile merges with the Blue Nile, which originates in Lake Tana in the Ethiopian Highlands. Most of the lower reaches of the Nile pass through the Nubian Desert. There are no tributaries here, water is lost to evaporation, seepage, and is disassembled for irrigation. Only a small part of the flow reaches the Mediterranean Sea, where the river forms a delta. Neil has a difficult regime. The main rise of water and spills in the middle and lower reaches occur in the summer-autumn period, when precipitation falls in the Blue Nile basin, which in summer brings 60-70% of water into the main river. A number of reservoirs have been built to regulate the flow. They protect the Nile Valley from floods, which used to happen quite often. The Nile Valley is a natural oasis with fertile alluvial soils. No wonder the river delta and its valley in the lower reaches - one of the centers of ancient civilization. Prior to the construction of dams, navigation along the river was difficult due to low water and the presence of six large rapids (cataracts) between Khartoum and Aswan. Now the navigable sections of the river (using canals) are about 3,000 km long. There are a number of hydroelectric power plants on the Nile.

In Africa, there are also large rivers of great natural and economic importance: Niger, Zambezi, Orange, Limpopo, etc. The Victoria Falls on the river are widely known. Zambezi, where the waters of the channel (1800 meters wide) fall from a height of 120 meters into a narrow tectonic fault.

In Australia, the largest river is the Murray, which originates in the Snowy Mountains of the East Australian mountain system. Flowing through an arid plain, the river is shallow (average annual water flow is only 470 m 3 / sec). In the dry season (in winter) it becomes shallow, and sometimes dries up in places. Several reservoirs have been built to regulate the flow of the river and its tributaries. Murray is of great importance for the irrigation of land: the river flows through an important agricultural region of Australia.

Lakes of the Southern Continents

In the arid regions of Africa and Australia, there are numerous endorheic salt lakes, mainly of residual origin. Most of them are filled with water only during rare heavy rains. Rain moisture enters through the channels of temporary streams (weeddams and screams). There are few similar lakes in the high plains of the Central Andes, in the Precordillera and the Pampian Sierras of South America.

Large freshwater lakes are found only on the African continent. They occupy the tectonic depressions of the East African and Ethiopian highlands. The lakes located within the eastern branch of the rift fault are elongated in the submeridional direction and are very deep.

The depth of Lake Tanganyika, for example, reaches almost one and a half kilometers and is second only to Baikal. This is the largest of the rift lakes in Africa (34,000 km 2). Its banks are sometimes steep, precipitous, usually rectilinear. In some places, lava flows form narrow peninsulas, deeply protruding into the lake. Tanganyika has a rich fauna with many endemics. There are several national parks along its banks. The lake is navigable and connects a number of countries (Tanzania, Zaire, Burundi) by waterways. Another large lake in East Africa - Victoria (Ukereve) - the second largest freshwater reservoir after the North American Lake Superior (68,000 km 2), is located in a tectonic trough. Compared to rift lakes, it is shallow (up to 80 meters), has a round shape, low-lying winding shores, and many islands. Due to its large area, the lake is subject to the action of tides, during which its area increases significantly, as water floods the low banks. The river flows into the lake. Kagera, which is not without reason considered the source of the Nile: it has been experimentally established that the water flow of Kagera crosses Victoria and gives rise to the Victoria Nile River. The lake is navigable - it links between Tanzania, Uganda and Kenya.

There are many small fresh lakes in the East Australian mountains, in Southern Andes, and at the foot of the eastern slopes of the Patagonian Andes there are quite large lakes of glacial origin. The alpine lakes of the Central Andes are very interesting.

On the plains of Pune, there are many small, usually salty reservoirs. Here, at an altitude of over 3800 m, in a tectonic depression, there is the largest of the high mountain lakes in the world - Titicaca (8300 km 2). The drain from it goes to salt Lake Poopo, similar in properties to the reservoirs of the arid regions of Africa and Australia.

There are very few lakes on the plains of South America, except for oxbow lakes in the floodplains of large rivers. On the northern coast of South America there is a vast lake-lagoon Maracaibo. There are no large reservoirs of this type on any of the southern continents, but there are many small lagoons in the north of Australia.

Groundwater of the Southern Continents

Significant reserves of groundwater play a significant role in natural processes and in the life of people on the southern continents. Extensive artesian basins are formed in the tectonic depressions of the platforms. They are widely used in the economy, but are of particular importance in the arid regions of Africa and Australia. Where groundwater comes closer to the surface - in the depressions of the relief and along the thalwegs of temporary watercourses, conditions for the life of plants and animals appear, natural oases are formed with very special ecological conditions compared to the deserts surrounding them. In such places, people extract and store water in various ways, create artificial reservoirs. Artesian waters are widely used in the water supply of arid areas of Australia, Africa and some regions of South America (Gran Chaco, Dry Pampas, intermountain basins).

Swamps and wetlands of the Southern Continents

Many areas of the Southern Tropical Continents are swampy due to the flat relief and the occurrence of water-resistant rocks close to the surface. The bottoms of basins in the humid zones of Africa and South America, where the amount of precipitation exceeds the evaporation rate, and the moisture coefficient is more than 1.00, are highly susceptible to the process of swamping. These are the Congo basin, the Amazonian lowland, the interfluve of the Paraguay and Uruguay rivers, the low plains of the Humid Pampa and some other areas. However, in some places even such territories are swamped, within which there is a shortage of moisture.

Basin in the upper reaches of the river. Paraguay, called Pantanal, which means "swamp" in translation, is very swampy. However, the moisture coefficient here barely reaches 0.8. In some places, even arid territories are swamped, for example, the White Nile basins in North Africa and the Okavango in South Africa. The precipitation deficit here is 500-1000 mm, and the moisture coefficient is only 0.5-0.6. There are swamps in the Dry Pampa - arid regions of the right bank of the river. Paranas. The reason for the formation of swamps and wetlands within these areas is poor drainage due to low surface slopes and the presence of water-resistant soils. In Australia, swamps and wetlands occupy very small areas due to the dominance of arid climates. There are some swamps on the flat, low northern coasts, on the eastern shores of the Great Australian Bight, and along river valleys and temporary watercourses in the low-lying basin of the Darling-Murray basin. Humidity coefficients in these areas are different: from exceeding 1.00 in the very north of the Arnhem Land peninsula to 0.5 in the southeast, but small surface slopes, the presence of water-resistant soils and the close occurrence of groundwater contribute to swamping even with a sharp moisture deficit.

Glaciers of the Southern Continents

Glaciation within the Southern Tropical Continents has a limited distribution. There are no mountain glaciers at all in Australia and very few in Africa, where they cover only individual peaks in the equatorial regions.

The lower boundary of the chionosphere is located here at an altitude of 4550-4750 m. Mountain ranges exceeding this level (Kilimanjaro, Kenya, some peaks of the Rwenzori mountains) have ice caps, but their total area is about 13-14 km2. The largest area of ​​mountain glaciers in the Andes of South America. There are areas where mountain-cover glaciation is also developed: the Northern and Southern Ice Plateaus south of 32 ° S. sh. and mountains of Tierra del Fuego. In the Northern and Central Andes, mountain glaciers cover many peaks. Glaciation here is the largest in the equatorial and tropical latitudes of the Earth, since there are high and highest mountains that cross the lower boundary of the chionosphere even in those areas where it is located at high altitude. The snow line varies greatly depending on the amount of precipitation. In equatorial and tropical latitudes, it can be located at altitudes from 3000 m to 7000 m in mountains with different moisture conditions, which is mainly due to the exposure of the slopes to the prevailing air currents that carry moisture. South of 30°S sh. the height of the snow line with an increase in the amount of precipitation, and with a decrease in temperatures at higher latitudes, falls rapidly and already at 40 ° S. sh. on the western slopes, it does not even reach 2000 m. In the very south of the mainland, the height of the snow line is not more than 1000 m, and outlet glaciers descend to ocean level.

The ice sheet occupies a special place. It arose about 30 million years ago, and since then its size and shape, apparently, have changed little. This is the largest accumulation of ice on the globe (the area is 13.5 million km 2, including about 12 million km 2 - the continental ice sheet and 1.5 million km 2 - ice shelves, especially extensive in the Weddell and Ross). Volume fresh water in solid form is approximately equal to the flow of all the rivers of the Earth for 540 years.

In Antarctica there are ice sheets, mountain-cover, shelf and various mountain glaciers. Three ice sheets with their own feeding areas contain about 97% of the entire ice reserve of the mainland. From them, the ice spreads at different speeds and, reaching the ocean, forms icebergs.

The ice sheet of Antarctica is fed by atmospheric moisture. In the central parts, where there are predominantly anticyclone conditions, nutrition is carried out mainly by sublimation of steam on the surface of ice and snow, and closer to the coast, snow falls during the passage of cyclones. Consumption ice is coming due to evaporation, melting and runoff into the ocean, the removal of snow by winds outside the mainland, but most of all - due to the breakaway of icebergs (up to 85% of the total ablation). Icebergs are already melting in the ocean, sometimes very far from the Antarctic shores. Ice consumption is uneven. It is not amenable to accurate calculations and forecasts, since the magnitude and speed of iceberg breakaway is influenced by many different factors that cannot be taken into account simultaneously and completely.

The area and volume of ice in Antarctica change literally by the day and hour. Different sources indicate different numerical parameters. It is equally difficult to calculate the mass balance of the ice sheet. Some researchers have a positive balance and predict an increase in the area of ​​ice, while others have a negative balance, and we are talking about the degradation of the ice cover. There are calculations according to which the state of ice is assumed to be quasi-stationary with fluctuations during the year and over longer periods. Apparently, the last assumption is closest to the truth, since the average long-term data on the assessment of the area and volume of ice, made at different times and by different researchers, differ little from each other.

The presence of a powerful continental glaciation, comparable in size to the Pleistocene glaciation of the Northern Hemisphere, plays a huge role both in the general global moisture circulation and heat transfer, and in the formation of all the natural features of Antarctica. The existence of this continent, completely covered with ice, has a great and varied influence on climates, and through them on other components of the nature of the southern continents and the whole Earth.

The ice of Antarctica is a huge reservoir of fresh water. They are also an inexhaustible source about the past of the Earth and about the processes characteristic of the glacial and near-glacial regions of the Earth in the past and at the present time. It is not for nothing that the ice sheet of Antarctica is the object of a comprehensive study of specialists from many countries, despite the difficulties associated with research work in the extremely harsh conditions prevailing on the continent.

K.S. LAZAREVICH

In No. 5/2006, diagrams of the river systems of Russia were printed. The experience turned out to be successful: the schemes allowed teachers to navigate the difficult (and very confusing textbook authors who do not take the trouble to think about the numbers) question of “the longest rivers” and “the longest watercourses” in Russia or in its individual territories.

It publishes schemes for all continents, built on the same principle as the schemes for Russia. Schemes allow you to set the length of rivers, compare rivers and systems with each other, make a visual representation of river systems and watersheds of the seas.

Within the diagram for each continent, the rivers are placed in the order in which their mouths are located along the coast. oceans circling the area in a clockwise direction. Rivers that do not flow into the World Ocean are given after all, on a gray background.

The rivers - the main ones and their tributaries - are depicted by vertical lines. The flow of rivers is everywhere from the bottom up, so that the left tributaries and components of the rivers are on the left, the right ones are on the right. The lengths of the rivers are given on a scale, they are depicted by vertical lines, the horizontal segments are given only to show the ratio of the rivers, and have no conditional length.

The numbers written on the diagram at the sources of the rivers and at the horizontal segments indicate the distances along the channel from the mouth of the main river; the numbers written along the vertical segments indicate the length of these segments; all values ​​are in kilometers. Along the upper frame of the scheme, reservoirs are marked, where the rivers flow. All signed figures are taken from reference books; It should be borne in mind that for little-studied territories (for example, in Africa, South America), the lengths of many rivers are given with an accuracy of hundreds or even thousands of kilometers. If you want to determine the distances that are not signed on the diagram (for example, between the mouths of tributaries), use the scale bar. But at the same time, remember that such measurements will only give an approximate result: the constructions were made by measuring on the map.

It is better to use the scheme with a map in front of your eyes, then the relative position of the rivers will be clear. In the comments to the diagram, only those places that may cause doubt are explained: unusual forms of mouths and the questions that arise in connection with this about the lengths of rivers; the flow of a river from one drainage basin to another, the temporary drying up of rivers.

Eurasia is the only continent where the drainage basins of all four oceans are located.

River systems are placed in the order of their mouths along the coast of Asia, from the northern end Ural mountains, skirting the continent, to the Sea of ​​Azov. Next comes Europe - first south, then west and north. At the end of the diagram - the rivers of endorheic basins. The Jordan River in Western Asia, although very famous, is not shown, its length is only 250 km, that is, less than a centimeter in the diagram.

AT Asia the rivers of the Arctic Ocean basin flow through the territory of Russia, only some rivers of the Ob and Selenga systems in the Yenisei system begin outside our country.

The longest river in Asia and Eurasia, the Yangtze (other names are Changjiang, Yangtzyjiang), flows in the Pacific Ocean. The Huaihe River, which flows into it in its lower reaches, carries and deposits a lot of solid material (sand, clay), so the channel mainly lies above the adjacent plain, which often caused catastrophic floods, the river flowed either into the Yangtze or the Huanghe. After the construction of the irrigation system in the 50-60s of the twentieth century. The threat of flooding has been largely eliminated, but part of the flow of the Huaihe continues to flow into the Huanghe, which is reflected in the diagram.

The Mekong River flowing into the South China Sea is one of the longest rivers in Asia, full of water, but the basin area is very small (with a length of 4.5 thousand km, the average width of the basin is 180 km), since the system of parallel ridges of the Sino-Tibet Mountains creates a series of isolated long and narrow watersheds.

The Ganges and Brahmaputra flow into the Bay of Bengal of the Indian Ocean, forming a common delta, the left channel of which is called Meghna, or Meghna. In reference books, the length of the Ganges is 2700 km, the Brahmaputra - 2900 km; apparently, Meghna is included in this length, on the basis of which the scheme is built.

The Tigris and Euphrates rivers in historical times flowed into the Persian Gulf separately, but then merged and formed the Shatt al-Arab river 195 km long.

Of the rivers flowing into the seas of the Atlantic Ocean, we note only the Turkish Kyzylyrmak and our Kuban; the latter is assigned to Asia, as it flows south of the Kuma-Manych depression.

Europe is studied at school in more detail than other parts of the world, many geographical features of Europe are constantly heard, so the scheme also includes small, by the standards of other territories, but well-known rivers. Of the rivers of Europe, only the Volga and Danube can be compared with the largest Asian rivers, although they are significantly smaller.

Europe is essentially a peninsula of the Eurasian continent. Within its limits, Western Europe, located outside the former USSR, and Eastern Europe, within its borders, stand out.

In Eastern Europe, mostly flat, rivers flow from its central part to the Azov, Black, Baltic, White and Barents Sea, as well as in the Caspian Sea, which is not connected to the ocean. From the center of the Russian Plain to the seas - one and a half to two thousand kilometers, and a river two (Dnepr, Don), or even three and a half thousand kilometers long (Volga) is not surprising.

And in the long and narrow Western Europe there is generally no point more than 600 km from the sea, and almost all rivers are short. Only the Danube, starting less than four hundred kilometers from the Mediterranean and five hundred from the North, managed to go half Western Europe along and get almost three thousand kilometers to the Black Sea. Rivers south of the Danube flow into the Mediterranean Sea, north - into the North and Baltic. To the west of the source of the Danube, the watershed runs through southern Europe - these are the Alps, the Central French Massif, the mountains of southern Spain (Cordillera Betica, Sierra Nevada), and the rivers that flow into the Mediterranean Sea are quite short, and the longer ones flow directly into the Atlantic Ocean, into Bay of Biscay and the English Channel. That is why the Mediterranean Sea is somewhat saltier than the Atlantic Ocean. An exception from the rivers flowing into the Mediterranean is the Ebro, which, starting in the Cantabrian Mountains, just fifty kilometers from the Bay of Biscay, cuts off the entire Iberian Peninsula, bravely breaks through to the Mediterranean Sea and, after passing 928 km, flows into it.

On the diagram, the French rivers Garonne and Dordogne, which form a common Gironde estuary 75 km long, can cause difficulty. The length of both rivers is counted from the outlet of the Gironde to the Bay of Biscay.

The scheme of the river of endorheic basins is being completed. The Caspian Sea washes the southeastern outskirts of Europe only for a short distance, but the Caspian drainage basin occupies 1/7 of Europe, and the Volga is certainly in first place among European rivers in terms of basin area.

The Amu Darya and Syr Darya flow into the Aral Sea. But that is why the Aral Sea dies, because these rivers do not flow into it all year long - their water is taken apart for irrigation; the channels in the lower reaches are shown by a dashed line. The bed of the Tarim (in the upper reaches of the river is called Yarkand) is very unstable, the Tarim only occasionally feeds Lake Lobnor, sometimes it goes into other water bodies or into the ground, so we can only speak about its length approximately.

The river network belongs to the basins of the Atlantic and Indian oceans. The Nile system is located in the eastern part of the continent, very close to Indian Ocean, but the Nile flows into the Mediterranean Sea - the sea of ​​\u200b\u200bthe Atlantic Ocean.

The Volta River, which flows into the Gulf of Guinea of ​​the Atlantic Ocean, was previously formed from the confluence of the White Volta and the Black Volta; the latter is longer and is considered the main source of the Volta. Now that the Volta reservoir has been created (the largest in the world in terms of area, almost 400 thousand km 2), the White and Black Volta flow into it, and the Volta River begins from the dam of the reservoir.

North America

The rivers of North America belong to the basins of three oceans. The great rivers Mackenzie (in the Beaufort Sea) and Nelson (in the Hudson Bay) flow into the Arctic Ocean. To the south, the relief of the continent predetermines a sharp asymmetry of the river network: the basin of the Atlantic Ocean is much larger than the basin of the Pacific. The largest river system of the continent, the Mississippi system, belongs to the Atlantic Ocean.

The river system that creates runoff from the Great Lakes has no analogues in the world. It does not have a single river longer than 1000 km, but in general the system, consisting of four lakes and five rivers, is only slightly inferior in length to the Volga. (Which of the Great Lakes was not included in this system and why?)

South America

The continent is washed by two oceans, and the length of the coastline of the oceans does not differ much. Nevertheless, all the rivers included in the scheme refer only to the basin of the Atlantic Ocean - directly to the ocean or the Caribbean Sea, and there is not a single river of any length that flows into the Pacific Ocean. As in North America, only to a much greater extent, the asymmetry of the relief is manifested, the position of the interoceanic watershed is very close to the western margin of the mainland. The diagram shows a bifurcation - the division of one river into two: in the upper reaches of the Orinoco, the 410 km long Casiquiare River separates from it, flowing into the Rio Negro - a tributary of the Amazon; the broken arrow on the diagram shows where the Casiquiare flows into, but, of course, it is impossible to measure the distance along this arrow. We have already met with a similar division of the river in the Yangtze system, but there the phenomenon is temporary.

Australia

Geography textbooks say that Australia is the driest continent. This is confirmed by the diagram: only one big river flowing into the ocean - Murray. And is it so big if it carries about 10 km 3 of water into the ocean per year? For comparison: the Amazon - almost 7000, the Lena - more than 500, the Volga - 250. And there is also Coopers Creek, which reaches Lake Eyre only during heavy summer rains, otherwise it just goes into the ground somewhere halfway.

Tasks for working with diagrams,
printed on p. 10–18

Give assignments to students little by little; it is up to the teacher to indicate or not to indicate in which river system the solution should be sought; it is quite possible that the same teacher in one class will give additional explanations, but not in another.

1. Determine the distances along the rivers between characteristic points of rivers of the same system; such points can be the sources of different rivers, the mouths of tributaries and the main river, the exit of the river from the lake, etc. For example:

From the source of the Don to the mouth of the Seversky Donets;

From the source of the Tisza to the source of the Danube;

From the mouth of the Saone to the exit of the Rhone from Lake Geneva;

From the source of the Maranyon to the source of the Ucayali (remember which river system they belong to).

There can be many tasks of this type. Invite students to create several of these tasks on their own. Let them familiarize themselves with how the diagrams were drawn up (the introductory part of the explanatory text to the diagrams), and answer which of the tasks proposed by you and which of those compiled by them can be solved exactly, which - only approximately and why.

2. When solving each example from task 1 mark which rivers, up or down their course, you move from the starting point to the final point.

3. Using any cards, arrange on the schemes of the rivers of the city.(Let the teacher offer a list of cities himself. Considering that in the next task it is proposed to measure the distances between cities, several cities should be selected in the same river system.) If students do not know where to look for these cities, let them look in the index of geographical names of the atlas . If the city is located on both banks of the river or you do not know which bank it is on, put the circle on the line denoting the river, if on one bank, then on the corresponding side of the line.

Which of these cities did you manage to draw exactly, which approximately? Why?

4. Measure at least 10 distances between by you river cities. Which of these distances did you manage to measure accurately, which approximately? Why?

5. Place a north-south arrow next to each river system. The rivers are winding, so it can only be placed approximately, given the general direction of the main river. For the Mississippi system, place (dashed) the second arrow corresponding to the Missouri source being taken as the main source.

6. Check black triangle in diagram mouths of rivers with deltas. Not all deltas are visible on the map, indicate only those that are expressed to scale on physical maps of the continents and parts of the world in school atlases.

In the scheme of Russian rivers (“Geography”, No. 5/2006), in the system of the Northern Dvina, Lake Kubenskoye and the Kubena River flowing into it were skipped. If you use this diagram, please supplement it, just remember that the diagrams in that issue and here are built on different scales.

LESSON 33 LARGEST RIVER SYSTEMS

Learning goal: to acquaint with the general features of the waters of the land of the mainland, the main river systems; promote understanding of the influence of climate and topography on the formation and distribution of land waters; to improve the skills and abilities to characterize the largest river systems of the mainland.

Equipment: physical map South America, textbooks, atlases, contour maps.

Basic concepts: land waters, river basins, river system, regime, nutrition, waterfall, tectonic lake, lagoon lake, glacier, groundwater.

Type of lesson: learning new material.

II. Updating of basic knowledge and skills

Complete the sentences.

South America is located in climatic zones: equatorial ...

Rainfall on the east coast is about...

A special type of climate that forms in the Andes is called ...

The inland waters of the mainland include: rivers ...

The most full-flowing river in the world, located in South America, is called ...

III. Motivation of educational and cognitive activity

The idea is well-known: "The water network of the mainland is a mirror of its climate and relief." Do you agree with him? Today in the lesson, studying the inland waters of South America, you have the opportunity to confirm or refute this statement.

IV. Learning new material

1. General characteristics of the inland waters of South America

In terms of water supply, South America ranks first. The continent covers about 12% of the land area, but accounts for 27% of the total global water flow. This is primarily due to the exceptionally humid climate. Large river systems have formed here. The vast majority of them belong to the Atlantic Ocean basin. The most powerful rivers: Amazon, Parana, Sao Francisco, Orinoco.

Most of the rivers are fed by rain, only some rivers receive water from the melting of snow and ice in the mountains. Flowing in the Andes, crossing the plateau, the rivers of South America form numerous rapids and waterfalls. On one of the tributaries of the Orinoco River there is the highest waterfall in the world - Angel (1054 m), and on the tributary of the Parana there is a powerful waterfall - Iguazu (72 m).

There are relatively few lakes in South America. The largest lake on the mainland is the lake-lagoon of tectonic origin Maracaibo. In the Central Andes, in a depression at an altitude of 3812 m, there is the largest of the high mountain lakes in the world - Titicaca. Extensive swamps form on well-moistened lowlands. Significant areas of the mainland are well provided with groundwater, which is of great importance for the water supply of cities.

There are few mountain glaciers in the Andes. As you move south, the height of the snow line gradually decreases.

Student presentations with messages.

2. Major river systems

Compose brief characteristics rivers of South America according to the plan. Arrange the results in the form of a table:

Name	Leak location	Current direction	The nature of the flow	Where does it flow
1. Amazon
3. Orinoco

Amazon (6516 km) - the deepest river in the world, has the largest river basin in the world (its area is equal to the area of ​​the whole of Australia). It originates in the Peruvian Andes from its main source - the Maranhoin River. After its confluence with the Ucayali, the river is called the Amazon. The Amazon is second only to the Nile in length. It has as much water as the Congo, Mississippi, Yangtze and Ob combined. The Amazon has more than 1,100 tributaries, 20 of which are between 1,500 and 3,500 km long. More than a hundred tributaries of the Amazon are navigable. Thanks to numerous tributaries, the Amazon remains full-flowing all year round.

Other major rivers of South America - Parana and Orinoco, unlike the Amazon, have a pronounced seasonal flow. The maximum rise in the water level occurs in the summer season, and in the dry period they become very shallow. With the advent of moist equatorial air, the rainy season begins, the rivers overflow, flooding vast territories and turning them into swamps. Such floods are often catastrophic.

The rivers of the Parana system collect water on the Brazilian Plateau and the interior plains, the Orinoco River with tributaries - on the Gvian Plateau. In the upper reaches, these rivers are full of rapids and form numerous waterfalls. In the middle and lower reaches of the Parana and Orinoco - typical flat rivers, convenient for navigation.

The rivers of South America have significant hydro potential; in the arid regions of the interior plains, river water is used to irrigate fields.

V. Consolidation of the studied material

What are the reasons for the high rate of river flow in South America?

Which ocean basin does most of the rivers of South America belong to? What explains this?

What type of food is typical for most rivers on the mainland?

What is the origin of the lakes of South America? In which areas are the largest of them located?

What do the river systems of South America and Africa have in common? What makes them different?

Why did the process of glaciation in the Andes not become widespread?

V I. The result of the lesson

VII. Homework

Work on a paragraph...

Implementation of practical work 8 (continued). Outline the major rivers and lakes of South America on a contour map.

Leading (individual students): prepare reports on the natural areas of South America, individual animals and plants, changes natural complexes man.

Remember the importance of water for other components of nature and for humans. What properties does water have? Which of them are geographically significant? What bodies of water are land waters?

Distribution of inland waters. Water is distributed across the continents extremely unevenly. There are areas where there is an abundance of rivers, lakes, there are extensive swamps, and in some areas there is practically no surface water, except for rare drying lakes. Of all the continents, the most "wet" (water-provided) is South America. If all the waters flowing down from this continent in a year are distributed in an even layer over its area, then a layer of water more than 500 mm thick will be obtained. This quantity is called the sink layer (8.1). In Antarctica, almost all water is in solid form, and does not flow into the ocean, but collapses in large blocks, forming icebergs. But in terms of the volume of fresh water, Antarctica is many times greater than all the continents combined. It is estimated that the fresh water reserves contained in Antarctic ice, are approximately equal to the flow of all the rivers of the Earth for more than 500 years.

The distribution of inland waters over the territory of the continents most of all depends on the climate, but other factors also play a role. The distribution of rivers, lakes, swamps, glaciers, the shape of river valleys and lake basins, the conditions for the occurrence of groundwater are affected by the relief and geological structure of the area. For example, even with low rainfall, swamps can occur if the terrain is flat and difficult to drain.

All types of inland waters play a huge role in nature and in people's lives. However, the most prominent place is occupied by rivers.

Rivers. On all continents of the Earth, except for Antarctica, there are large and small river systems. South America has the most extensive river network, receiving the most precipitation.

There are almost no territories on this continent devoid of rivers. The huge basins of the Amazon, Orinoco, Parana occupy most of the mainland (8.2). Most rivers originate in the mountains, cut through mountain ranges and high plateaus and plateaus, forming rapids and waterfalls. Then they come out onto flat plains, overflow widely, turn into a dense network of water arteries. The material that rivers carry from elevated places fills the depressions of the earth's crust. The Amazonian, Orinokskaya, Laplatskaya lowlands are vast flat plains composed of river sediments.

The river network of North America has a similar structure. Here, the areas of endorheic regions are also small. Many rivers carry water to the Atlantic Ocean and the Gulf of Mexico. The largest of these is the Mississippi system, which collects water from the Cordillera, the Appalachians, and the American plains (8.3). Stormy rivers flow into the Pacific Ocean, cutting through the Cordillera. The Mackenzie River, which has an extensive network of tributaries, flows into the Arctic Ocean. Short full-flowing rapids flow into the Hudson Bay.

A continent is a large landmass surrounded by seas and oceans. In tectonics, continents are characterized as sections of the lithosphere with a continental structure.

Mainland, continent or part of the world? What is the difference?

In geography, another term is often used, denoting the mainland - the continent. But the concepts of "mainland" and "continent" are not synonymous. Different countries have adopted different points of view on the number of continents, called continental models.

There are several such models:

• In China, India, as well as in the English-speaking countries of Europe, it is customary to consider that continents 7 - Europe and Asia, they consider separately;
• In Spanish-speaking European countries, as well as in the countries of South America, they mean the division into 6 parts of the world - with a united America;
• in Greece and some countries of Eastern Europe a model with 5 continents was adopted - only those where people live, i.e. except for Antarctica;
• in Russia and the countries of Eurasia adjacent to it, they traditionally designate 4 - continents united into large groups.

(The figure clearly shows different representations of continental models on Earth, from 7 to 4)

Continents

There are 6 continents in total on Earth. We list them in descending order by area size:

1. - the largest continent on our planet (54.6 million sq. km)
2. (30.3 million sq. km)
3. (24.4 million sq. km)
4. (17.8 million sq. km)
5. (14.1 million sq. km)
6. (7.7 million sq. km)

All of them are separated by the waters of the seas and oceans. Four continents have a land border: Eurasia and Africa are separated by the Isthmus of Suez, North and South America - the Isthmus of Panama.

Continents

The difference is that the continents do not have a land border. Therefore, in this case, we can talk about 4 continents ( one of the continental models of the world), also in descending order by size:

1. AfroEurasia
2. America

Parts of the world

The terms "mainland" and "continent" have a scientific meaning, but the term "part of the world" divides the land on a historical and cultural basis. There are 6 parts of the world, only unlike the continents, Eurasia differs by Europe and Asia, but North and South America are defined together as one part of the world America:

1. Europe
2. Asia
3. America(both North and South), or New World
4. Australia and Oceania

Speaking of parts of the world, they mean the islands adjacent to them.

The difference between the mainland and the island

The definition of the mainland and the island is the same - a part of the land washed by the waters of the ocean or seas. But there are significant differences.

1. Size. Even the smallest continent, Australia, is much larger in area than the world's largest island, Greenland.

(Formation of the Earth's continents, a single continent of Pangea)

2. Education. All continents have a tiled origin. According to scientists, there was once a single continent - Pangea. Then, as a result of the split, 2 continents appeared - Gondwana and Laurasia, which later split into 6 more parts. The theory is confirmed both by geological surveys and by the shape of the continents. Many of them can be put together like a puzzle.

Islands are formed in many ways. There are those that, like the continents, are located on the fragments of the most ancient lithospheric plates. Others are formed from volcanic lava. Still others - as a result of the activity of polyps (coral islands).

3. Habitability. All continents are inhabited, even Antarctica, which is harsh in terms of climatic conditions. Many islands are still uninhabited.

Characteristics of the continents

- the largest continent, occupying 1/3 of the land. Two parts of the world are located here at once: Europe and Asia. The border between them runs along the line of the Ural Mountains, the Black and Azov Seas, as well as the straits connecting the Black and Mediterranean Seas.

This is the only continent that is washed by all the oceans. The coastline is indented, it forms a large number of bays, peninsulas, islands. The mainland itself is located immediately on six tectonic platforms, and therefore the relief of Eurasia is incredibly diverse.

Here are the most extensive plains, the most high mountains(Himalayas from Everest), the most deep lake(Baikal). This is the only continent where everything is presented at once climatic zones(and, accordingly, all natural zones) - from the arctic with its permafrost to the equatorial with its hot deserts and jungles.

¾ of the world's population lives on the mainland, 108 states are located here, of which 94 have the status of independent.

- the hottest continent on Earth. It is located on an ancient platform, so most of the area is occupied by plains, mountains are formed along the edges of the mainland. Africa is home to the longest river in the world, the Nile, and the largest desert, the Sahara. Climate types presented on the mainland: equatorial, subequatorial, tropical and subtropical.

Africa is usually divided into five regions: North, South, West, East and Central. There are 62 countries on the mainland.

It is washed by the waters of the Pacific, Atlantic and Arctic oceans. The result of the movement of tectonic plates was a heavily indented coastline of the mainland, with a huge number of bays, straits, bays and islands. The largest island is in the north (Greenland).

The Cordillera Mountains stretch along the western coast, and the Appalachians along the eastern coast. The central part is occupied by a vast plain.

All climatic zones are represented here, except for the equatorial one, which determines the diversity natural areas. Most rivers and lakes are located in the northern part. The largest river is the Mississippi.

Indigenous people- Indians and Eskimos. Currently, 23 states are located here, of which only three (Canada, the United States and Mexico) are on the mainland itself, the rest are on the islands.

Washed by the Silent and Atlantic Oceans. Along the west coast stretches the world's longest mountain system - the Andes, or South American Cordillera. The rest of the mainland is occupied by plateaus, plains and lowlands.

This is the rainiest continent, since most of it is located in the equator zone. Here is the largest and most abundant river in the world - the Amazon.

The indigenous people are the Indians. Currently, there are 12 independent states on the territory of the mainland.

- the only continent on the territory of which there is only 1 state - the Commonwealth of Australia. Most of the mainland is occupied by plains, mountains are located only along the coast.

Australia is a unique continent with the largest number of endemic animals and plants. The indigenous people are Australian Aborigines, or Bushmen.

- the southernmost continent, completely covered with ice. The average thickness of the ice cover is 1600 m, the largest is 4000 m. If the ice in Antarctica melted, the level of the world's oceans would immediately rise by 60 meters!

Most of the mainland is icy desert, life glimmers only on the coasts. Antarctica is also the coldest continent. In winter, temperatures can drop below -80 ºC (record -89.2 ºC), in summer - up to -20 ºC.