The word "desert" alone evokes the appropriate associations in us. This space, which is almost completely devoid of flora, has a very specific fauna, and is also located in a zone of very strong winds and monsoons. The desert zone is about 20% of the entire land mass of our planet. And among them are not only sandy, but also snowy, tropical and many others. Well, let's get to know this natural landscape more closely.
What is a desert
This term corresponds to flat terrain, the type of which is homogeneous. The flora here is almost completely absent, and the fauna has a very specific characteristic. The relief zone of the desert is vast territories, most of which are located in tropical and subtropical zones. The desert landscape also occupies a small part of South America and most of Australia. Among its features, in addition to plains and plateaus, are also the arteries of dry rivers, or closed reservoirs, where lakes could previously have been. Also, the desert zone is a place where there is very little rainfall. On average, this is up to 200 mm per year, and in especially dry and hot areas - up to 50 mm. There are also desert regions where precipitation does not fall for ten years.
Animals and plants
The desert is characterized by completely sparse vegetation. Sometimes the distances that lie between the bushes reach kilometers in length. The main representatives of the flora in such a natural zone are thorny plants, only a few of which have the usual green foliage for us. Animals that live on such lands are the simplest mammals or reptiles and reptiles that accidentally wandered here. If we are talking about an icy desert, then only animals live here that tolerate low temperatures well.
Climate indicators
To begin with, we note that in terms of its geological structure, the desert zone is no different, say, from the flat terrain in Europe or Russia. And such severe weather conditions that can be traced here were formed due to the trade winds - winds that are characteristic of tropical latitudes. They are literally above the terrain, preventing them from irrigating the ground with precipitation. So, in the climatic sense, the desert zone is a region with very sharp temperature changes. During the day, due to the scorching sun, it can be as much as 50 degrees Celsius here, and at night the thermometer will drop to +5. In deserts that lie in more northern zones (temperate and arctic), daily temperature fluctuations have the same indicator - 30-40 degrees. However, here during the day the air heats up to zero, and at night it cools down to -50.
Semi-desert and desert zone: differences and similarities
In temperate and subtropical latitudes, any desert is always surrounded by a semi-desert. This is a natural area in which there are no forests, tall trees and coniferous plants. All that is available here is flat terrain or plateaus, which are covered with herbs and shrubs that are unpretentious to weather conditions. characteristic feature semi-desert is not aridity, but, unlike the desert, increased evaporation. The amount of precipitation that falls on such a belt is sufficient for the full existence of any animals here. In the eastern hemisphere, semi-deserts are often referred to as steppes. These are vast flat areas where one can often find very beautiful plants and see stunning landscapes. On the western continents, this area is called the savannah. Its climatic features are somewhat different from the steppe ones, strong winds always blow here, and there are much fewer plants.
The most famous hot deserts of the Earth
The zone of tropical deserts literally divides our planet into two parts - North and South. Most of them are in the Eastern Hemisphere, and there are very few in the West. Now we will consider the most famous and beautiful such zones of the Earth. Sahara is the largest desert on the planet, which occupies the entire North Africa and many lands of the Middle East. It is divided by locals into many "under-deserts", among which Belaya is popular. It is located in Egypt and is famous for its white sands and extensive limestone deposits. Along with it in this country there is also Black. Here the sands are mixed with a stone of a characteristic color. The widest red sandy expanses are the lot of Australia. Among them, the landscape called Simpson deserves respect, where you can find the highest dunes on the continent.
arctic desert
The natural zone, which is located in the northernmost latitudes of our planet, is called the Arctic desert. It includes all the islands that are located in the Arctic Ocean, the extreme coasts of Greenland, Russia and Alaska. Throughout the year, more than half of this natural area covered with glaciers, because there are practically no plants here. Only in the area that comes to the surface in summer, lichens and mosses grow. Coastal algae can be found on the islands. Among the animals here there are the following individuals: the Arctic wolf, deer, arctic foxes, polar bears - the kings of this region. Near the waters of the ocean we see pinnipeds - seals, walruses, fur seals. Birds are the most common here, which, perhaps, are the only source of noise in the Arctic desert.
Arctic climate
The ice zone of the desert is the place where the polar night passes and which are comparable to the concepts of winter and summer. The cold season here lasts about 100 days, and sometimes more. The air temperature does not rise above 20 degrees, and in especially harsh times it can be -60. In summer, the sky is always covered with clouds, it rains with snow and there is constant evaporation, due to which the humidity of the air rises. The temperature on summer days is about 0. Like in the sandy deserts, winds constantly blow in the Arctic, which form storms and terrible snowstorms.
Conclusion
On our planet there is whole line deserts, which are different from sandy and snowy. These are salt expanses, Akatama in Chile, where a bunch of flowers grow in an arid climate. Deserts can be found in the USA, where they overlap with red canyons, forming unrealistically beautiful landscapes.
When you hear the word "desert", what immediately comes to mind? For most people, the desert evokes images of endless sandy expanses, high temperatures, and scrub vegetation. To some extent, this representation is accurate. Many deserts of the world are characterized large quantity sand and high temperatures (at least during daylight hours).
However, there are Arctic deserts that are fundamentally different from the rest of the deserts. There is no sand here, and temperatures are often far from hot, but rather sub-zero.
If you know anything about the Arctic, you are probably wondering who came up with the idea to call this region a desert. After all, the Arctic has the Arctic Ocean. However, arctic temperatures are so low that the ocean is almost always covered in ice. Severe frost also means that the air is unable to retain moisture. Thus, the air is dry, as in a classic desert.
Another weighty argument is the insignificant amount of precipitation in the form of rain or snow. In fact, the Arctic receives about the same amount of rainfall as the Sahara. All of the above factors have led to the emergence of the concept of "arctic or cold desert".
Natural conditions of the Arctic desert zone
For determining natural conditions arctic desert, below is a brief description and a table of the main factors (geographical location, relief, soil, climate, Natural resources, flora and fauna) that influence the lives of people in this natural area.
Geographical position
Arctic desert on the map of the main natural areas of the world
Conventions: - Antarctic desert.
The natural zone of the Arctic desert is located above 75 ° north latitude and is adjacent to the North Pole of the Earth. It covers a total area of more than 100 thousand km². The Arctic Desert covers Greenland, the North Pole and several islands, many of which are inhabited by humans and animals.
Relief
The relief of the Arctic desert consists of various physical features: mountains, glaciers and flat areas.
The mountains: the arctic desert contains mountainous regions where a cold and dry climate prevails. In appearance, some of the region's mountains resemble mountains in Central America.
Glaciers: due to extremely low temperatures, the arctic desert is replete with numerous glaciers of various shapes and sizes.
Flat areas: make up the bulk of the region's territory and have a distinct patterned texture, which is the result of cycles of melting and freezing water.
If you watched the series "Game of Thrones", then the lands beyond the Wall give general idea what the arctic desert looks like. These scenes were filmed in Iceland, which is not officially part of the Arctic desert, but has a superficial resemblance to it.
Soils
In the main part of the territories of the natural zone of the Arctic desert, the soils remain frozen for most of the year. The permafrost reaches 600-1000 m deep and makes it difficult to drain water. In summer, the surface of the Arctic desert is covered with lakes from the melt water of the upper soil layer. Rubble and rocks, due to the movement of glaciers are scattered throughout the natural zone.
The soil horizon of the Arctic deserts is very thin, poor in nutrients, and also includes a lot of sand. In warmer areas, there are soil types that contain little organic matter and are capable of supporting the growth of small shrubs, algae, fungi, and mosses. One such soil type is brown soils.
Climate
The climate of the natural zone of the Arctic desert is characterized by long, very cold winters and short, cool summers. During the cold months (typically December to January), temperatures can drop as low as -50°C. During the warmer months (typically July), temperatures can rise to +10°C. However, over many months, average temperatures range from -20° to 0°C.
The arctic desert receives very little rainfall. The average annual rainfall is below 250 mm. Precipitation, as a rule, falls in the form of snow and light drizzle, more often in the warm season.
During the summer months, the sun does not set at all in the Arctic desert. In fact, for 60 days, the sun is above the horizon around the clock.
Animals and plants
In total, about 700 plant species and about 120 animal species are found in the natural zone of the Arctic deserts. Flora and fauna have adapted to survive and even thrive in such extreme conditions. Plants were able to adapt to nutrient-poor soils, low temperatures environment and low rainfall. , as a rule, have a thick layer of fat and thick wool to protect from the cold. They breed during the short summer and often hibernate or migrate during the winter. The birds usually fly south during the cold winter months.
Only about 5% of the territories of the natural zone of the Arctic desert has vegetation cover. Although this is not surprising, given the status of the desert. Most of the plant life consists of the following plants: lichens, mosses and algae, which can survive in the extreme conditions of the Arctic.
Every year (especially in the warm season), some types of low (from 5 to 100 cm) shrub plants bloom. They typically include sedges, liverworts, herbs and different kinds colors.
Animal life in the Arctic desert is very diverse. There are numerous mammals, birds, fish and insects. All these animals are adapted to extremely low temperatures. Here are some examples of animals from the natural zone of the Arctic deserts:
- Mammals: arctic foxes, polar bears, wolves, squirrels, hares, arctic voles, lemmings, reindeer, seals, walruses and whales.
- Birds: crows, falcons, loons, sandpipers, snipes, terns and various types of gulls. Most of these birds are migratory (i.e. spend only part of their life cycle in the arctic desert).
- Fishes: trout, salmon, flounder and cod.
- Insects:
Natural resources
The Arctic includes significant reserves (oil, gas, minerals, fresh water and commercial fish species). also in last years tourist interest in this region has increased significantly, which also provides additional economic benefits.
The pristine and vast deserts of the Arctic play an important role in the conservation of biodiversity due to the growing human presence, as well as the fragmentation of vital habitats. The Arctic deserts are particularly susceptible to land cover depletion and habitat disturbance of the region's rare animals. The Arctic also contains 20% of the world's fresh water.
Table of the natural zone of the Arctic deserts
| Geographical position | Relief and soil |
Climate | Flora and fauna | Natural resources |
| Arctic regions located above 75° north latitude and receiving low rainfall (less than 250 mm per year). | The relief is mostly flat, but sometimes there are mountainous areas. Soils are very poor in organic nutrients and remain frozen for much of the year. |
The climate is dry and cold. Average temperatures range from 0° to -20° C. In winter, the air temperature can drop below -50° C, and in summer it can rise to +10° C. | Animals
mammals: polar foxes, polar bears, wolves, reindeer, hares, squirrels, voles, lemmings, walruses, seals and whales; birds: crows, falcons, loons, sandpipers, snipes, terns and gulls; fishes: trout, salmon, flounder and cod; insects: grasshoppers, arctic bumblebees, mosquitoes, moths, midges and flies. Plants shrubs, grasses, lichens, mosses and algae. |
oil, gas, minerals, fresh water, commercial fish species. |
Peoples and cultures
The most numerous inhabitants of the Arctic deserts are the Inuit. If the word "Inuit" is not clear to you, then most likely you have heard of the Eskimos.
The Inuit have adapted their lives to the difficult conditions of the Arctic wilderness. As a rule, in the Arctic there are practically no building materials. The Eskimos build snow huts called igloos. In the summer, when the Igloo is melted, they live in tents made from animal skins and bones.
Considering extreme conditions desert, the Inuit do not grow grains and vegetables. They eat mainly meat and fish. Thus, their main food sources are fishing, as well as hunting for seals, walruses and whales.
For transportation, the Inuit usually use dog sleds. Sleighs are made of skins and bones. They are pulled by strong, hardy, sledding breeds of dogs (huskies, malmutes, samoyeds). When moving through the water, they use kayaks or umiaks. Kayaks are small boats suitable for carrying one or two people. Umiaks are large enough to carry several people, dogs, and supplies.
Eskimo communities are in various parts arctic desert and . In Greenland, they are known as Iñupiat or Yup'ik. In Russia they are called Eskimos. Regardless of name or geographic location, the Inuit speak the same language, Inuktitut. They also have similar cultural traditions and way of life.
Significance for a person
In recent years, the Arctic wilderness has experienced an increase in tourism. Visitors to the cold desert come here for the unique ecosystem and mesmerizing snowy landscapes. Lakes, rivers, streams and mountains provide additional leisure activities for tourists from all over the world. Some recreational activities include sea cruises, boating, sport fishing, mountain climbing, hunting trips, white water rafting, hiking, dog sledding, skiing, snowshoeing, and more. The non-setting sun during the Arctic summer is another reason for the interest of tourists who visit the Arctic wilderness for this surreal phenomenon. Visitors also experience Inuit culture and life by visiting their settlements. The Arctic desert, being the polar region of the planet, plays a key role in regulating the Earth's climate.
Environmental threats
The population of people in the natural zone of the Arctic desert and adjacent areas is quite low. The most pronounced threat comes from exploration and extraction of mineral deposits. Global warming also has negative impact on the Arctic desert environment, upsetting the delicate balance of this ecosystem. As the planet's temperature rises, it heats up and melts, releasing carbon from the soil into the atmosphere, which accelerates the processes of climate change. Due to global warming melt polar ice, which contributes to sea level rise and increases the threat of flooding of the planet's coastal regions. Melting ice caps also threaten polar bears. They need ice to hunt, and melting ice cuts and fragments their hunting grounds. In addition, orphaned cubs have even lower survival rates because they are left to fend for themselves.
Protection of the Arctic deserts
To protect the natural zone of the Arctic deserts, it is necessary to provide assistance, cooperation, coordination and interaction between states with the participation of communities of the indigenous peoples of the Arctic on issues of sustainable development and environmental protection of the region.
The main goals of Arctic desert conservation include:
- Preservation of the rich biodiversity of the region;
- Sustainable use of renewable natural resources;
- Reduce pollution and wasteful consumption.
To achieve these goals, it is necessary to focus international attention on the following problematic aspects:
- Marine environment;
- fresh water;
- biodiversity;
- Changing of the climate;
- Pollution;
- Oil and gas.
Only the political will and interaction of states can give positive result in the struggle for the conservation of both the natural zone of the Arctic desert and the nature of the world as a whole.
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Water balance equation.
runoff coefficient
over 2000 mm ).
198 mm 26.3 thousand m 3
turbidity up to almost 12000 g/m 3
River network of Russia
more than 2 million 6.5 million km.
Avanta+ Data
drainage basin,watershed.
Inland waters
The number of internal natural reservoirs (lakes) on the territory of Russia cannot be accurately counted and is estimated at more than 2 million (the number of rivers has the same order); According to this indicator, Russia is in one of the first places in the world.
What is considered a lake?(the problem of the lower threshold of reference; an example of secondary lakes in large raised bogs). [In Norway, there are more than 210 thousand lakes with an area of 1 ha, in Sweden - more than 83 thousand, in Finland more than 55 thousand. - Nature of the North. Europe, 2001]. In Russia, these are mainly (95%) small water bodies up to 1 km2 in area. About 140 lakes have an area of more than 100 km2 (Avanta+).
The average number of lakes in the country (excluding the Caspian Sea) is 2.4%.
Lakes are distributed unevenly within the territory of the country ( lake map). The largest of them (according to the latest data, except for Ladoga) are confined to vast ancient tectonic depressions. The origin of small lakes is diverse and is more closely related to the "enclosing" landscapes, their history, structure and specific features. exogenous processes. The total lake area of the territory, with other equal conditions, depends on the degree of its humidity (climatic factor).
One of the main lake areas - " Lake District» - The north-west of the Russian Plain, together with the eastern margin of the Baltic Shield, coincides with the area of the last glaciation. It is here that Great European Lakes(Ladoga, Onego, Ilmen, Saimaa; this group also includes Lake Peipsi and Pskov). Here, many residual post-glacial lakes, which often fill deep basins of various genesis, are supported by an excessively humid climate and the youth of the river network, which did not have time to completely drain the post-glacial reservoirs. In general, the lake content of the territory is more than 10%, in some areas it exceeds 20%.
Tundra and forest tundra have a lake content of 5-10%.
The subarctic, as well as taiga permafrost landscapes, developed on a thick layer of loose Quaternary deposits (on the Kolyma-Indigirskaya, Lena-Vilyui lowlands, etc.) abound in small (tens to hundreds of meters in diameter) shallow rounded lakes that fill thermokarst depressions and occupying sometimes up to half of the territory. [The lake content of sections of the Lena-Vilyui (Central Yakut) plain, according to Milkov and Gvozdetsky, reaches 25%.]
Very abundant lakes (mostly secondary, formed in the process of development of swamps) swamps of the taiga zone Zap. Siberia.
Outwardly, a similar picture is observed in the southern, forest-steppe and steppe parts of the West Siberian Plain, where vast almost empty interfluve spaces are dotted with shallow lakes confined to flat depressions of a suffusion and, apparently, relic thermokarst character. The water of these lakes is often mineralized.
All lakes are “mortal” (have a start and end date of existence). The main "enemy" of the lakes is the rivers that carry out erosive work. In addition, the basins of the lakes are gradually filled with mineral and organic matter, swamped and overgrown.
Outside the boundary of the last glaciation, in the area of maximum glaciation, the number of lakes sharply decreases (to 1–2%); the remaining residual lakes are shallow and intensively overgrown.
V southern, non-glacial part of the Russian Plain erosional relief with a well-developed and deeply incised network of river valleys and a climate with insufficient moisture do not favor the development of lakes, which are represented only by small oxbow reservoirs in river floodplains ( lake content less than 1%). [For example, in Udmurtia, almost all water bodies are artificial "ponds" - reservoirs].
The number of lakes within the part of the Central Siberian Plateau that was not subjected to glaciation is negligible.
In the Far East, the Caucasus, Altai, and the Sayan Mountains, the lake content does not exceed 1-2% (the predominance mountainous terrain, severe erosion).
Largest lakes
Only 9 lakes (including the Caspian Sea) have an area of more than 1 thousand km 2 each. In this group, it is necessary to highlight the three largest freshwater reservoirs - Lake Baikal, Ladoga and Onega. Every year, only a small part of their water supply is renewed due to the influx of river (sometimes also underground) waters and precipitation, and, accordingly, is spent on river runoff from the lake and evaporation, maintaining the water balance of water bodies.
Near Baikal full water exchange time is 330 years, near Lake Ladoga - 11, near Onega - 13.
Characteristics of (natural) lakes in Russia with an area of more than 1 thousand km 2
Geogr. encycle. dictionary (1988), Atlas of Russia (1998), A.G.I. (Ecological Geographic of Russia), National Atlas of Russia, vol. 2 (2006)
For comparison: the area of the largest Kuibyshev reservoir in the country (6.5 thousand km 2) would occupy the fifth line in this table.
Mineralization of river and lake waters and their chemical composition (map)
They depend on the composition of drained rocks, but to a large extent they are subject to climate, moisture and, accordingly, the intensity of the processes of dissolution, leaching and washing of soils and soils. Therefore, in the spatial variability of chemism surface water First of all, zoning is striking.
In the zone of excessive moisture, due to the abundance of precipitation and intensive runoff, the drained strata are quickly freed from easily soluble salts; surface waters are characterized by low mineralization, usually not exceeding 200 mg/l . The rivers and lakes of the Subarctic and taiga are especially weakly mineralized. For the rivers of the East European taiga during the spring flood, a typical mineralization value is 25–50 mg/l; in summer and especially winter low water, when mineralization is caused by ground feeding, it increases to 200–300 mg/l. Against the general zonal background, anomalies associated with the geological basement are observed (for example, a reduced content of soluble salts in the surface waters of the Baltic Shield: 20–50 mg/l in low water). As the total moisture decreases, the mineralization of surface waters increases; thus, in the Eastern European subtaiga it exceeds 200 mg/l, in the steppe, as well as in the Central Yakut taiga, it reaches 500–1000 mg/l, and in the semi-desert and desert - more than 1000 mg/l.
Simultaneously with the increase in mineralization, the ionic composition of surface waters changes. In areas of excessive moisture, they are free from easily soluble salts and are predominantly bicarbonate-calcium; in zones of insufficient moisture, the predominance passes to waters of sulfate and then chloride classes, sodium dominates among cations. In excessively humid zones, waters contain more organic matter, as well as iron, than in zones of insufficient moisture.
Lakes with mineralization less than 1000 mg/l (1g/l) are considered fresh, at mineralization 1-35 g/l - brackish and with mineralization more than 35 g / l - salty(higher than the average salinity of the waters of the oceans). Among the mineralized lakes stand out soda(Kulunda), sulfate, chloride(Baskunchak, Elton).
Map of swamps of Russia (NAR)
Depending on the conditions of water and mineral nutrition, swamps are divided into:
Eutrophic (lowland)
Mesotrophic (transitional)
Oligotrophic (riding)
The distribution of swamps across the country has a distinct zonal-sectoral character; it is also associated with the nature of the relief of the territory and the trend of neotectonic processes.
More than 80% of all swamps of the country are concentrated in the taiga zone.
Zap. Siberia is the most swampy area not only in Russia, but also in the world (in some areas, swamps occupy up to 90% of the area). In the swamps Zap. Siberia has concentrated water reserves estimated at 1 thousand km 3 of water, which is 2.5 times more than the annual runoff of the Ob.
More than half of the world's peat reserves are concentrated in Russia.
The role of swamps in flow regulation is ambiguous(during periods of excess moisture, swamps dump excess water into rivers, in summer with insufficient moisture, on the contrary, they retain moisture in peat deposits) .
The different types of swamps will be discussed in more detail in the lectures on individual zones.
ground water
Groundwater plays an important role in feeding river runoff and serves as an independent source of water supply. They are formed in zone of active water exchange the uppermost part of the earth's crust directly as a result of precipitation filtration and form the first horizon of groundwater from the surface, mostly non-pressure. Groundwater usually occurs above the level of the incision of the river network, as well as the water level of lakes, which ensures their discharge and water exchange in water-bearing rocks (mostly Quaternary). Constant water exchange causes low mineralization of groundwater, which increases with depth as water exchange becomes more difficult.
Groundwater is ubiquitous, but extremely uneven in abundance and quality, subject to the diversity of landscapes.
Latitudinal zoning ground water:
decreasing from north to south water cut the upper strata of rocks in the zone of free water exchange;
increases depth groundwater;
increase them mineralization and rigidity(content of calcium and magnesium ions), regularly changes chemical composition;
the temperature rises (at the same depths);
decreases (to zero) the content of organic impurities(i.e. the degree of washout is weakened).
In the zone of excessive atmospheric humidification, groundwater is fresh, predominantly bicarbonate-calcium; in the zone of insufficient moisture, it becomes brackish and saline, mineralization reaches 3–10 g/l, and in some places even more; in the ionic composition, the predominance passes to sulfates and chlorides.
Permafrost in Russia (map)
The essence of the phenomenon mm. (incorrectly called permafrost): rocks long time(from several years to millennia) are in a chilled state at temperatures below 0°C (polygonal-vein ice, ice cores of peat mounds, ice intrusions, etc.)
More than half of the territory of Russia belongs to the permafrost area (the total area of permafrost is about 11 million km 2), in the distribution of m.m. are clearly manifested longitude and climatic factors.
southern border insular permafrost areas(see the corresponding maps in the Atlas of the USSR) runs parallel to the coast of the Barents Sea through the Kola Peninsula, then sublatitudinally close to the North. the Arctic Circle (in some places south of it) to the Urals, then drops to about 62 ° N, crosses the Urals, then goes parallel to the Ob (from the right bank), descending to 60 ° N, to the Yenisei and along the Yenisei it drops much to the south, capturing the Sayan Mountains, Gorny Altai and Kuznetsk Alatau (excluding the Minusinsk Basin), leaving for the state. the border of Russia. In the Far East from m.m. the Amur region is free (the southern border of the m. m. runs almost parallel to the Amur, north of it at an average distance of 200 km, crossing the state border above the confluence of the Zeya), Primorye (except for the upper mountains of the Sikhote-Alin), Sakhalin, the Kuriles and the plains of Kamchatka (along the coasts Sea of Okhotsk and Pacific Ocean southern border rises to 57-58°N.
southern border areas of continuous permafrost(exists different variants conduction): from Pai-Khoi passes near the Arctic Circle to the Yenisei, then near the Nizh. Tunguska, to the upper Vilyui, Yakutsk and Okhotsk; from Magadan to the Gulf of Anadyr.
Maximum power (more than 500 m) m.m. reaches in the north of Yamal, Gydan, Taimyr, in the North. the island of Novaya Zemlya, Severnaya Zemlya, the New Siberian Islands, in Central Yakutia. According to K.K. Markov (quoted by Gvozdetsky and Milkov), in some parts of the Leno-Vilyui interfluve, the permafrost thickness exceeds 1000 m.
On the Kola Peninsula, the thickness of the frozen layer is less than 25 m; in the NE of the Bolshezemelskaya tundra, it increases to 100–200 m.
The presence of permafrost leaves an imprint on almost all components of the landscape:
in relief and soils: solifluction, swelling mounds - bulgunnyakhs, polygonal soils, peat mounds, etc. (will be discussed in more detail in the corresponding "zonal" lectures);
in the regime of rivers, the nature of lakes(see above);
in vegetation: m.m., being a good waterproof material, often causes waterlogging of the soil thawing in summer, contributes to the formation of an oppressed root system, reduces the resistance of woody vegetation against the wind, etc. - in general, the set of species of tree species is sharply narrowed (larch is the most adapted); on the other hand, frozen moisture that thaws by the middle of a rather dry summer is an additional source of moisture for woody vegetation in sharply continental regions; Siberian spruce at the eastern limit of the range grows only at a close occurrence of m.m.; sparse forests and swamps with a close occurrence of m.m. clearly visible from above.
in soils: specific permafrost soils and characteristic fissuring are formed.
Ground waters of districts m.m. are divided into suprapermafrost, interpermafrost and subpermafrost.
The supra-permafrost waters completely or partially freeze in winter; in this case, pressure is often created and, breaking through, they form frost.[In the Momo-Selennyakhskaya basin between the ridge. Chersky and Momsky ridges. there is the largest icing in Eurasia - Momsky Ulakhan-taryn (Moma - the right tributary of the Indigirka) with an area of \u200b\u200babout 100 km 2; the largest ice province is the Okhotsk-Chukotka mountainous country, where they occupy almost 2% of the territory].
In the thickness of frozen rocks, groundwater in liquid form is found only fragmentarily.
On the one hand, mm. - ancient phenomenon(evidence - burials of mammoths, etc.); its enormous thickness indicates, most likely, heredity from the period of the Pleistocene glaciations.
On the other hand, the modern distribution of m.m. in areas with negative average annual air temperatures and cold winters with little snow indicates communications m.m. and with modern climatic conditions. Apparently, the modern climate only supports, conserves the previously formed permafrost, in some places causing either its degradation (for example, the formation of thermokarst lakes in Yakutia) or a new formation (for example, m. rivers of the Lena basin).
From north to south instability m.m. increases. In the south of Siberia, a noticeable activation of permafrost processes is observed during the construction railways. [At the beginning of the 20th century. the construction of embankments for them led to a sharp increase in the thawing layer: on mars (boggy plains) its depth increased by 2 times, on stone ruins - by 3.5 times. Because of these changes, road structures were spreading to the sides. If excavation were carried out next to the tracks, then ice appeared in the excavations. Some sections of the Trans-Siberian have sunk by 2.5 m].
In connection with climate warming, in a number of regions, a shift to the north of the border of permafrost was recorded (for example, in Meuse e nsky district of the Arkhangelsk region over the past 160 years, it has shifted to the north by 50-60 km - "Poisk", 12/21/2001, data from the Institute of Ecology. problems of the North).
Data from S. Kirpotin (botanist from Tomsk State University), Y. Markand (Oxford University):
Due to warming Western Siberia, which is happening faster than anywhere else on the planet (average monthly temperatures have risen by 3°C over the past 40 years), in the last 3-4 years, active permafrost thawing has begun in subarctic regions. This can lead to powerful emissions into the atmosphere of methane preserved in frozen peat (methane reserves are estimated at 70 billion tons, which is a quarter of the total amount of methane on the earth's surface). Landscapes on an area larger than Germany and France combined are turning into flooded areas with shallow lakes.
Data from the permafrost monitoring network show that since the 1960s, the temperature of the near-surface frozen layer in Northern Eurasia has increased by 1-3°C. According to mathematical modeling data, a decrease in the area of the m.m. in the northern hemisphere will be (in parentheses, the figures for the decrease in the area of continuous m.m.): by 2030 - 10-18% (15-25%), by 2050 - 15-30% (20-40%), by 2080 - 20-35% (25-50%). Predicted changes in the depth of seasonal thawing: 10-15% by 2030, 15-25% by 2050, 30-50% or more by 2080 [O. Anisimov, T. Khromova, V. Romanovsky, M. Ananicheva , A. Georgiadi, abstracts of the report at the NEESPI / GOFC seminar, 2004].
Patterns of the distribution of the average annual runoff on the territory of Russia
Water balance equation.
The ratio of runoff and evaporation depends primarily on the heat supply of the landscape and is subject to zonal patterns.
The share of precipitation spent on runoff ( runoff coefficient ) on the territory of Russia naturally decreases from north to south - from 0.6–0.8 in the tundra to 0.4 near the southern border of the taiga, 0.1 in the steppe zone and less than 0.01 in the desert. With increasing continentality, the runoff coefficient also decreases. The most pronounced "sectoral anomaly" is the taiga of Central Yakutia, where the runoff coefficient does not reach 0.1.
The zonal "crest" of runoff roughly corresponds to the subzone of the northern taiga and forest-tundra. Here, the value of the annual runoff layer in Eastern Europe is 350-450 mm; from here it decreases both to the north and to the south.
In the Leningrad region, the annual runoff is 250-350 mm
In the semi-deserts and deserts of the Caspian Sea, the annual runoff is less than 10 mm
At the same time, longitudinal-sectoral changes are clearly visible, so that in the extremely continental taiga of Central Yakutia annual rate runoff does not exceed 30 mm, i.e. close to the value typical for dry steppes. The highest rates are characteristic of mountain landscapes (more than 500 mm), especially windward oceanic slopes, where the layer of annual runoff can exceed 1000 mm (Kamchatka; Bol. Kavkaz, in some areas of the latter runoff over 2000 mm ).
According to the calculations of A.G. Isachenko (Ekol. geogr. Rossii, 2001), the average annual runoff layer for the territory of Russia is 198 mm, which corresponds to a volume of about 3.4 thousand km 3 /year. In terms of per capita in 2002, this is 26.3 thousand m 3 total average annual river runoff (A.G.I., 2004). For most European countries this figure is much lower (for example, France 4.0; England 2.7; Germany 1.3). In the USA (with Alaska), there are 8.1 thousand m 3 × year of water flow per inhabitant (according to A.G.I., 2004). Richer than Russia in this respect Northern Europe(Iceland - 230 thousand m 3, Norway - 84 thousand m 3 × year), Canada (87), Congo (192), Brazil (60) and some other states (Lvovich, 1974, A.G.I, 2004) .
In large cities, specific water consumption is 300-600 l / day (or 110-220 m 3 / year) per capita and is growing every year, in rural areas this figure decreases to 20-30 l / day (7-11 m 3 /year).
Surface runoff resources are distributed extremely unevenly across the country. To assess the real water supply, it is necessary to take into account not only the local, but also the transit component of the river runoff.
[River flow is characterized by long-term and seasonal variability, which causes significant fluctuations in water availability over time. Long-term fluctuations in runoff are cyclic, but the phases of fluctuations in different areas do not coincide in time, as well as in amplitude. Characteristically, there is an increase in long-term runoff variability as aridity increases. In the southern regions of Siberia, the annual runoff variation coefficient (the ratio of the standard deviation to the long-term norm) reaches 0.4–0.5, and in the northern regions it decreases to 0.2–0.1. With an increase in the catchment area, territorial differences in long-term fluctuations seem to be compensated, and big rivers they are less perceptible than in small ones.]
When assessing river runoff resources, it is important to take into account its stable part (“basic runoff”), which corresponds to underground runoff. Share of underground (ground) power in the total volume of annual runoff varies greatly depending on physical and geographical conditions. In the area of permafrost, the conditions for ground feeding of rivers are unfavorable, since The groundwater they are predominantly in solid form. The most intense ground runoff is observed in the zone of excessive moisture outside the boundary of permafrost, i.e. in the forest landscapes of the ETR, the southern part of the taiga of Siberia and Far East. The annual layer of ground runoff, as a rule, exceeds 50 mm, amounting to 20–30% (in some places, apparently, up to 40–50%) of the total.
In the zone of insufficient moisture, the groundwater level lies at a great depth from the surface, the annual layer of underground runoff is reduced to 10 mm or less.
[The erosional work of rivers is characterized by the indicator turbidity - the content of solid suspended particles. The lowest turbidity (up to 20 g/m 3) is inherent in the rivers of the Subarctic and permafrost-taiga landscapes, where permanent or long-seasonal permafrost of soils prevents their erosion. The turbidity of the rivers of the Baltic Shield is very low. In the rest of the forest part of the country, the turbidity of the rivers increases, but remains low (up to 50 g/m3). Thick forest vegetation prevents the entry of solid material into the rivers. Lakes play a significant role as settling basins for sediments. In treeless and plowed landscapes, the entry of solid particles into rivers increases sharply, especially in areas of loess and loess-like deposits. In the steppe zone, turbidity increases to 500, in some places up to 1000 g/m 3 . The highest turbidity is observed in the rivers flowing from the northern slopes of the eastern part of the Greater Caucasus ( up to almost 12000 g/m 3). This indicator is subject to sharp seasonal fluctuations, especially in arid and treeless landscapes. The rivers carry the greatest amount of sediment during floods and high waters. In the rivers of the eastern part of the Greater Caucasus, an increase in turbidity up to 80–120 thousand g/m 3 was observed during floods. – A.G.I., EGR-2001]
River network of Russia
The rivers, along with the forest and the steppe, had the strongest (if not the strongest) influence on the development of the Russian ethnos and history. Russian state. Most of the large (and played an important role in the history of the country) cities in Russia are located on the rivers.
To the “simple” question “How many rivers are there in Russia?” answer is not so easy. Another question immediately arises: “What is considered a river?”
If at all any constantly flowing watercourse plotted on a map, then those in the territory of the country more than 2 million(Avanta+), and their total length exceeds 6.5 million km.
Avanta+ Data
The Neva River belongs to the latter category! (conditional splitting by length)
Where do rivers flow from? This question is also not trivial. Not in all cases it is possible to objectively establish the only source of any large river, not to mention small ones.
[According to legend, the inhabitants of Nizhny Novgorod for a long time could not decide which of the two rivers to name the one that is formed from the confluence of the Oka and the Volga. Then they arranged a competition: which river you can sing more songs about, that one will be considered the main one. If the Volga had not won, then the waterway to the Caspian would have to be counted from the source of the Oka. The Volga could be a tributary not only of the Oka, but also of the Kama, which at its confluence is much more full-flowing than the first.]
Often, history, tradition, or just chance determine the primacy of one of the two merging rivers of equal size. Sometimes a river starting from the confluence of two tributaries is called a third name (Ob, Amur).
In fact, any river begins at the same time in many points. drainage basin, and the source (official or unrecognized) is most often located near watershed.
Answer left a guest
Arctic desert zone. Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, and the New Siberian Islands lie in this zone. The zone is characterized by a huge amount of ice and snow in all seasons of the year. They are the main element of the landscape. All year round arctic air prevails here, the radiation balance for the year is less than 400 mJ/m2, the average temperature in July is 4-2°C. Relative humidity is very high - 85%. Precipitation is 400-200 mm, and almost all of it falls in solid form, which contributes to the formation of ice sheets and glaciers. However, in some places the supply of moisture in the air is small, and therefore, with an increase in temperature and a strong wind, a large lack of it is formed and strong evaporation of snow occurs. The soil-forming process in the Arctic takes place in a thin active layer and is located on initial stage development. In the valleys of rivers and streams and on sea terraces, two types of soils are formed - typical polar desert soils on drained polygonal plains and polar desert solonchak soils in saline coastal areas. They are characterized by a low content of humus (up to 1.5%), weakly expressed genetic horizons and very small power. In the Arctic deserts, there are almost no swamps, few lakes, and salt spots form on the surface of the soil in dry weather with strong winds. Vegetation cover It is extremely sparse and spotty, characterized by poor species composition and exceptionally low productivity. Low-organized plants dominate: lichens, mosses, algae. The annual growth of mosses and lichens does not exceed 1-2 mm. Plants are extremely selective in their distribution. More or less close groupings of plants exist only in places sheltered from cold winds, on fine earth, where the thickness of the active layer is greater. The main background of the Arctic deserts is formed by scale lichens. Hypnum mosses are common, sphagnum mosses appear only in the south of the zone in very limited quantities. From higher plants saxifrage, polar poppy, grits, starfish, arctic pike, bluegrass and some others are characteristic. Cereals grow luxuriantly, forming hemispherical pillows up to 10 cm in diameter on a fertilized substrate near nesting gulls and lemming burrows. An ice ranunculus and a polar willow grow near the snow patches, reaching only 3-5 cm in height. The fauna, like the flora, is poor in species; there are lemmings, arctic foxes, reindeer, polar bears, and among the birds the white partridge and snowy owl are ubiquitous. On the rocky shores there are numerous bird bazaars - mass nesting of sea birds (guillemots, little auks, white gulls, fulmars, eiders, etc.). The southern shores of Franz Josef Land, the western shores of Novaya Zemlya are a continuous bird colony.
In and between and the desert in the tropics.
Semi-deserts are formed under conditions. What they all have in common is a long and hot warm period ( average temperature 20-25°C, and in the tropics up to 30°C), strong evaporation, which is 3-5 times the amount (100-300 mm per year), weak surface, inland waters poorly developed, many drying channels, vegetation is not closed.
In spite of common features, inherent in all semi-deserts, they also have many differences.
1. Semi-deserts of the temperate zone in they stretch in a wide strip (up to 500 km) from the western part of the Caspian lowland, through, to the East. In the Northern and semi-deserts, they are found in shorter broken sections in the inner parts and foothills. From semi-deserts located in the tropical and subtropical zones, they differ in cold winters (down to -20 ° C). here are light chestnut, which brings them closer to the steppe, and brown desert, often saline. If you move south along the semi-deserts of the temperate zone, you will notice that the signs of the steppes are fading and the features of the deserts are intensifying. Still meet steppe feather grasses and fescue, but among them you can already notice wormwood and saltwort. Of the animals, saigas and turtles are found, snakes and lizards are more common.
2. Semi-deserts of the subtropical zone.
They are mainly located in the transitional part from deserts to mountain steppes in the form of an altitudinal zone in the inland parts and the Andes of America, in western Asia, and especially widely in. The soils here are gravelly, gray-brown and gray soils. Cereals and various types of shrubs, a wide variety of cacti are common here. From the animal world, rodents, snakes, lizards predominate.
These are deserted savannahs. They delineate deserts, both inland and oceanic - in Africa and, in South America north of the Atacama and northwest of the Brazilian Plateau, in Asia and Australia.
The soils here are thin, red-brown. The temperature in tropical semi-deserts does not fall below +10°C even in the coldest months, and in summer it rises to 35°C. Rain falls very rarely here. Precipitation is not more than 200 mm per year. With a lack of moisture, the bark is very thin. The waters in tropical deserts lie very deep and may be partly saline.
In such conditions, only plants that can tolerate overheating and dehydration can live. They have a deep branched root system, small narrow leaves or spines; in some plants, the leaves are pubescent or covered with a wax coating, which protects them from sunlight. These include tree-like cereals, agaves, cacti, sandy acacias.