West Siberian Plain- the plain is located in northern Asia, occupies the entire western part of Siberia from the Ural Mountains in the west to the Central Siberian Plateau in the east. In the north it is limited by the coast of the Kara Sea, in the south it extends to the Kazakh small hills, in the southeast the West Siberian Plain, gradually rising, gives way to the foothills of Altai, Salair, Kuznetsk Altai and Mountain Shoria. The plain has the shape of a trapezoid tapering towards the north: the distance from its southern border to the northern reaches almost 2500 km, the width is from 800 to 1900 km, and the area is only slightly less than 3 million km².
The West Siberian Plain is the most populated and developed (especially in the south) part of Siberia. Within its borders are the Tyumen, Kurgan, Omsk, Novosibirsk and Tomsk regions, the Yamalo-Nenets and Khanty-Mansi Autonomous Okrugs, the eastern regions of the Sverdlovsk and Chelyabinsk regions, a significant part of the Altai Territory, the western regions of the Krasnoyarsk Territory (about 1/7 of the area of Russia). In the Kazakh part, within its boundaries there are areas of the North Kazakhstan, Akmola, [[Pavlodar region|Pavlodar], Kustanai and East Kazakhstan regions of Kazakhstan.
Relief and geological structure
The surface of the West Siberian Lowland is flat with a fairly insignificant difference in elevation. However, the relief of the plain is quite diverse. The lowest areas of the plain (50-100 m) are located mainly in the central (Kondinskaya and Sredneobskaya lowlands) and northern (Nizhneobskaya, Nadymskaya and Purskaya lowlands) parts. Along the western, southern and eastern outskirts stretch low (up to 200-250 m) hills: North Sosvinskaya and Turinskaya, Ishim Plain, Priobskoye and Chulym-Yenisei Plateau, Ket-Tymskaya, Verkhnetazovskaya and Lower Yenisei uplands. A clearly defined strip of hills is formed in the inner part of the plain by the Siberian Uvals (average height - 140-150 m), stretching from the west from the Ob to the east to the Yenisei, and the Vasyugan Plain parallel to them.
The relief of the plain is largely determined by its geological structure. At the base of the West Siberian Plain lies the epi-Hercynian West Siberian Plate, the foundation of which is composed of intensely dislocated Paleozoic sediments. The formation of the West Siberian plate began in the Upper Jurassic, when, as a result of breaking off, destruction and degeneration, a huge area between the Urals and the Siberian platform subsided, and a huge sedimentation basin arose. During its development, the West Siberian Plate was repeatedly captured by marine transgressions. At the end of the Lower Oligocene, the sea left the West Siberian plate, and it turned into a huge lacustrine-alluvial plain. In the middle and late Oligocene and Neogene, the northern part of the plate experienced uplift, which gave way to subsidence in Quaternary time. The general course of development of the plate with the subsidence of colossal spaces resembles an incomplete process of oceanization. This feature of the slab is emphasized by the phenomenal development of wetlands.
Individual geological structures, despite the thick layer of sediments, are reflected in the relief of the plain: for example, the Verkhnetazovskaya and Lyulimvor hills correspond to gentle anticlinal uplifts, and the Barabinskaya and Kondinskaya lowlands are confined to the syneclises of the foundation of the plate. However, in Western Siberia, discordant (inversion) morphostructures are also common. These include, for example, the Vasyugan Plain, formed on the site of a gently sloping syneclise, and the Chulym-Yenisei Plateau, located in the zone of basement deflection.
Horizons are enclosed in a collar of loose sediments groundwater- fresh and mineralized (including brine), there are also hot (up to 100-150°C) waters. There are industrial deposits of oil and natural gas (West Siberian oil and gas basin). In the area of the Khanty-Mansi syneclise, Krasnoselsky, Salym and Surgut regions, in the layers of the Bazhenov formation at a depth of 2 km, there are the largest shale oil reserves in Russia.
Climate
West Siberian Plain. Flood of the Taz and Ob rivers. July 2002
The West Siberian Plain is characterized by a harsh, fairly continental climate. Its large extent from north to south determines a clearly defined climate zonation and significant differences in climatic conditions in the northern and southern parts of Western Siberia. The continental climate of Western Siberia is also significantly influenced by the proximity of the Arctic Ocean. The flat terrain facilitates the exchange of air masses between its northern and southern regions.
During the cold period, within the plain there is an interaction between an area of relatively high atmospheric pressure, located over the southern part of the plain, and the area low blood pressure, which in the first half of winter stretches in the form of a trough of the Icelandic pressure minimum over the Kara Sea and the northern peninsulas. In winter, continental air masses of temperate latitudes predominate, which come from Eastern Siberia or are formed locally as a result of cooling of the air over the plain.
Cyclones often pass through the border zone of areas of high and low pressure. Therefore, in winter the weather in the coastal provinces is very unstable; on the coast of Yamal and the Gydan Peninsula occur strong winds, the speed of which reaches 35-40 m/sec. The temperature here is even slightly higher than in neighboring forest-tundra provinces, located between 66 and 69° N. w. However, further south winter temperatures again gradually increase. In general, winter is characterized by stable low temperatures and few thaws. Minimum temperatures throughout Western Siberia are almost the same. Even near the southern border of the country, in Barnaul, there are frosts down to −50…−52°. Spring is short, dry and relatively cold; April, even in the forest-swamp zone, is not yet quite a spring month.
In the warm season, low pressure is established over Western Siberia, and an area of higher pressure forms over the Arctic Ocean. high pressure. In connection with this summer, weak northern or northeastern winds predominate and the role of westerly air transport noticeably increases. In May there is a rapid increase in temperatures, but often, when arctic air masses invade, there are returns of cold weather and frosts. Most warm month- July, average temperature of which - from 3.6° on Bely Island to 21-22° in the Pavlodar area. The absolute maximum temperature is from 21° in the north (Bely Island) to 44° in the extreme southern regions (Rubtsovsk). High summer temperatures in the southern half of Western Siberia are explained by the arrival of heated continental air from the south - from Kazakhstan and Central Asia. Autumn comes late.
The duration of snow cover in the northern regions reaches 240-270 days, and in the south - 160-170 days. The thickness of the snow cover in the tundra and steppe zones in February is 20-40 cm, in the forest-swamp zone - from 50-60 cm in the west to 70-100 cm in the eastern Yenisei regions.
The harsh climate of the northern regions of Western Siberia contributes to soil freezing and widespread permafrost. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is found everywhere. In these areas of continuous (merged) distribution, the thickness of the frozen layer is very significant (up to 300-600 m), and its temperatures are low (in watershed areas - 4. -9°, in valleys -2. -8°). To the south, within the northern taiga to a latitude of approximately 64°, permafrost occurs in the form of isolated islands interspersed with taliks. Its power decreases, temperatures rise to 0.5–1°, and the depth of summer thawing also increases, especially in areas composed of mineral rocks.
Hydrography
The territory of the plain is located within the large West Siberian artesian basin, in which hydrogeologists distinguish several second-order basins: Tobolsk, Irtysh, Kulunda-Barnaul, Chulym, Ob, etc. Due to the large thickness of the cover of loose sediments, consisting of alternating water-permeable (sands) , sandstones) and water-resistant rocks, artesian basins are characterized by a significant number of aquifers confined to formations of various ages - Jurassic, Cretaceous, Paleogene and Quaternary. The quality of groundwater in these horizons is very different. In most cases, artesian waters of deep horizons are more mineralized than those lying closer to the surface.
More than 2,000 rivers flow on the territory of the West Siberian Plain, the total length of which exceeds 250 thousand km. These rivers carry about 1,200 km³ of water into the Kara Sea annually - 5 times more than the Volga. The density of the river network is not very large and varies in different places depending on the topography and climatic features: in the Tavda basin it reaches 350 km, and in the Barabinsk forest-steppe - only 29 km per 1000 km². Some southern regions of the country with a total area of more than 445 thousand km² belong to areas of closed drainage and are distinguished by an abundance of drainless lakes.
The main sources of nutrition for most rivers are melted snow waters and summer-autumn rains. In accordance with the nature of the food sources, the runoff is uneven over the seasons: approximately 70-80% of its annual amount occurs in spring and summer. Especially a lot of water flows down during the spring flood, when the level large rivers rises to 7-12 m (in the lower reaches of the Yenisei even up to 15-18 m). For a long time (in the south - five, and in the north - eight months), Western Siberian rivers are frozen. Therefore on winter months accounts for no more than 10% of the annual runoff.
The rivers of Western Siberia, including the largest ones - the Ob, Irtysh and Yenisei, are characterized by slight slopes and low flow speeds. For example, the fall of the Ob riverbed in the area from Novosibirsk to the mouth over a distance of 3000 km is only 90 m, and its flow speed does not exceed 0.5 m/sec.
On the West Siberian Plain there are about one million lakes, the total area of which is more than 100 thousand km². Based on the origin of the basins, they are divided into several groups: those occupying the primary unevenness of the flat terrain; thermokarst; moraine-glacial; lakes of river valleys, which in turn are divided into floodplain and oxbow lakes. Peculiar lakes - “fogs” - are found in the Ural part of the plain. They are located in wide valleys, overflow in the spring, sharply reducing their size in the summer, and by autumn many disappear altogether. In the southern regions, lakes are often filled with salt water. The West Siberian Lowland holds the world record for the number of swamps per unit area (the area of the wetland is about 800 thousand square kilometers). The reasons for this phenomenon are the following factors: excess moisture, flat topography, permafrost and the ability of peat, which is available here in large quantities, to retain a significant amount of water.
Natural areas
The large extent from north to south contributes to a pronounced latitudinal zonality in the distribution of soils and vegetation cover. Within the country there are gradually replacing one another
WEST SIBERIAN PLAIN, West Siberian Lowland, one of the largest plains globe(third largest after the Amazon and East European Plains), in northern Asia, Russia and Kazakhstan. Occupies the entire Western Siberia, stretching from the coast of the Arctic Ocean in the north to the Turgai plateau and the Kazakh small hills in the south, from the Urals in the west to the Central Siberian Plateau in the east. The length from north to south is up to 2500 km, from west to east from 900 km in the north to 2000 km in the south. The area is about 3 million km 2, including 2.6 million km 2 in Russia. The prevailing heights do not exceed 150 m. The lowest parts of the plain (50–100 m) are located mainly in the central (Kondinskaya and Sredneobskaya lowlands) and northern (Lower Obskaya, Nadymskaya and Purskaya lowlands) parts. The highest point of the West Siberian Plain - up to 317 m - is located on the Priob Plateau.
At the base of the West Siberian Plain lies West Siberian Platform. In the east it borders Siberian platform, in the south - with the Paleozoic structures of Central Kazakhstan, the Altai-Sayan region, in the west - with the folded system of the Urals.
Relief
The surface is a low accumulative plain with a fairly uniform topography (more uniform than the relief of the East European Plain), the main elements of which are wide flat interfluves and river valleys; Characterized by various forms of manifestation of permafrost (extended up to 59 ° N latitude), increased swampiness and developed (mainly in the south in loose rocks and soils) ancient and modern salt accumulation. In the north, in the area of distribution of marine accumulative and moraine plains (Nadym and Pur lowlands), the general flatness of the territory is broken by moraine gently ridged and hilly-ridged (North-Sosvinskaya, Lyulimvor, Verkhne-, Srednetazovskaya, etc.) hills with a height of 200–300 m, whose southern border runs around 61–62°N. sh.; they are covered in a horseshoe shape from the south by flat-topped hills, including the Poluyskaya Upland, the Belogorsk Continent, the Tobolsk Continent, the Sibirskie Uvaly (245 m), etc. In the north, exogenous permafrost processes (thermoerosion, soil heaving, solifluction) are widespread, deflation is common on sandy surfaces, in swamps there is peat accumulation. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is widespread; The thickness of the frozen layer is very significant (up to 300–600 m).
To the south, the area of moraine relief is adjacent to flat lacustrine and lacustrine-alluvial lowlands, the lowest (40–80 m high) and the most swampy of which are the Kondinskaya lowland and the Middle Ob lowland with the Surgut lowland (height 105 m). This territory, not covered by Quaternary glaciation (south of the Ivdel-Ishim-Novosibirsk-Tomsk-Krasnoyarsk line), is a weakly dissected denudation plain, rising to 250 m to the west, to the foot of the Urals. In the area between the Tobol and Irtysh rivers there is a sloping, in some places with ragged ridges, lacustrine-alluvial Ishim Plain(120–220 m) with a thin cover of loess-like loams and loess overlying salt-bearing clays. Adjacent to it are alluvial Baraba Lowland, Vasyugan Plain and Kulunda Plain, where the processes of deflation and modern salt accumulation are developed. In the foothills of Altai there are the Priob Plateau and the Chulym Plain.
For geological structure and mineral resources, see Art. West Siberian Platform ,
Climate
The West Siberian Plain is dominated by a harsh, continental climate. The significant extent of the territory from north to south determines a well-defined latitudinal zonation climate and noticeable differences in climatic conditions between the northern and southern parts of the plain. The nature of the climate is significantly influenced by the Arctic Ocean, as well as the flat terrain, which facilitates the unhindered exchange of air masses between north and south. Winter in polar latitudes is severe and lasts up to 8 months (the polar night lasts almost 3 months); The average January temperature is from –23 to –30 °C. In the central part of the plain, winter lasts almost 7 months; The average temperature in January is from –20 to –22 °C. In the southern part of the plain, where the influence of the Asian anticyclone increases, with the same average monthly temperatures winter is shorter – 5–6 months. The minimum air temperature is –56 °C. The duration of snow cover in the northern regions reaches 240–270 days, and in the southern regions – 160–170 days. The thickness of the snow cover in the tundra and steppe zones is 20–40 cm, in the forest zone – from 50–60 cm in the west to 70–100 cm in the east. In summer, the westerly transport of Atlantic air masses predominates with invasions of cold Arctic air in the north, and dry warm air masses from Kazakhstan and Central Asia in the south. In the north of the plain, summer, which begins under polar day conditions, is short, cool and humid; in the central part it is moderately warm and humid, in the south it is arid and dry with hot winds and dust storms. The average July temperature increases from 5 °C in the Far North to 21–22 °C in the south. The duration of the growing season in the south is 175–180 days. Precipitation falls mainly in summer (from May to October - up to 80% of precipitation). The most precipitation - up to 600 mm per year - falls in the forest zone; the wettest ones are the Kondinskaya and Sredneobskaya lowlands. To the north and south, in the tundra and steppe zones, the annual precipitation gradually decreases to 250 mm.
Surface water
More than 2,000 rivers flowing through the West Siberian Plain belong to the Arctic Ocean basin. Their total flow is about 1200 km 3 of water per year; up to 80% of the annual runoff occurs in spring and summer. The largest rivers - the Ob, Yenisei, Irtysh, Taz and their tributaries - flow in well-developed deep (up to 50–80 m) valleys with a steep right bank and a system of low terraces on the left bank. The rivers are fed by mixed water (snow and rain), the spring flood is extended, and the low water period is long in summer, autumn and winter. All rivers are characterized by slight slopes and low flow speeds. Ice cover on rivers it stays in the north for up to 8 months, in the south – up to 5 months. Large rivers are navigable, are important rafting and transport routes and, in addition, have large reserves hydropower resources.
On the West Siberian Plain there are about 1 million lakes, the total area of which is more than 100 thousand km 2. Largest lakes– Chany, Ubinskoye, Kulundinskoye, etc. Lakes of thermokarst and moraine-glacial origin are common in the north. In the suffusion depressions there are many small lakes (less than 1 km2): in the interfluve of the Tobol and Irtysh - more than 1500, in the Barabinskaya Lowland - 2500, among them many are fresh, salty and bitter-salty; There are self-sedating lakes. The West Siberian Plain is distinguished by a record number of swamps per unit area (the area of the wetland is about 800 thousand km 2).
Types of landscapes
The uniformity of the relief of the vast West Siberian Plain determines a clearly defined latitudinal zonation of the landscapes, although compared to the East European Plain, the natural zones here are shifted to the north; landscape differences within the zones are less noticeable than on the East European Plain, and there is no zone of broad-leaved forests. Due to the poor drainage of the territory, hydromorphic complexes play a prominent role: swamps and swampy forests occupy about 128 million hectares here, and in the steppe and forest-steppe zones there are many solonetzes, solods and solonchaks.
On the Yamal, Tazovsky and Gydansky peninsulas, under conditions of continuous permafrost, landscapes of arctic and subarctic tundra with moss, lichen and shrub (dwarf birch, willow, alder) vegetation on gley soils, peat gley soils, peat podburs and turf soils were formed. Polygonal grass-hypnum bogs are widespread. The share of indigenous landscapes is extremely small. To the south, tundra landscapes and swamps (mostly flat-hilly) are combined with larch and spruce-larch woodlands on podzolic-gley and peat-podzolic-gley soils, forming a narrow zone of forest-tundra, transitional to the forest (forest-swamp) zone of the temperate zone, represented by the subzones northern, middle and southern taiga. What is common to all subzones is swampiness: over 50% of the northern taiga, about 70% - middle, about 50% - southern. The northern taiga is characterized by flat and large-hilly raised bogs, the middle one – ridge-hollow and ridge-lake bogs, the southern one – hollow-ridge, pine-shrub-sphagnum, transitional sedge-sphagnum and lowland tree-sedge. The largest swamp massif - Vasyugan Plain. Forest complexes of different subzones formed on slopes with to varying degrees drainage.
Northern taiga forests on permafrost are represented by sparse, low-growing, heavily swampy, pine, pine-spruce and spruce-fir forests on gley-podzolic and podzolic-gley soils. Indigenous landscapes of the northern taiga occupy 11% of the plain's area. Indigenous landscapes in the middle taiga occupy 6% of the area of the West Siberian Plain, in the southern - 4%. What is common to the forest landscapes of the middle and southern taiga is the wide distribution of lichen and dwarf shrub-sphagnum pine forests on sandy and sandy loam ferruginous and illuvial-humus podzols. On loam soils in the middle taiga, along with extensive swamps, there are spruce-cedar forests with larch and birch forests on podzolic, podzolic-gley, peat-podzolic-gley and gley peat-podzols.
In the subzone of the southern taiga on loams - spruce-fir and fir-cedar (including urmans - dense dark coniferous forests with a predominance of fir), small grass forests and birch forests with aspen on sod-podzolic and sod-podzolic-gley (including with a second humus horizon) and peat-podzolic-gley soils.
The subtaiga zone is represented by parkland pine, birch and birch-aspen forests on gray, gray gley and soddy-podzolic soils (including with a second humus horizon) in combination with steppe meadows on cryptogleyed chernozems, sometimes solonetzic. Indigenous forest and meadow landscapes have practically not been preserved. Swampy forests turn into lowland sedge-hypnum (with ryams) and sedge-reed bogs (about 40% of the zone's territory). For forest-steppe landscapes of sloping plains with loess-like and loess covers on salt-bearing tertiary clays, birch and aspen-birch groves on gray soils and solods in combination with forb-grass steppe meadows on leached and crypto-gleyed chernozems are typical, to the south - with meadow steppes on ordinary chernozems, in some places solonetzic and solonchakous. There are pine forests on the sands. Up to 20% of the zone is occupied by eutrophic reed-sedge bogs. In the steppe zone, indigenous landscapes have not been preserved; in the past these were forb-feather grass steppe meadows on ordinary and southern chernozems, sometimes saline, and in the drier southern regions - fescue-feather grass steppes on chestnut and cryptogley soils, gley solonetzes and solonchaks.
Environmental problems and protected natural areas
In oil production areas, due to pipeline breaks, water and soil are polluted with oil and petroleum products. In forestry areas there are overcuttings, waterlogging, the spread of silkworms, and fires. In agricultural landscapes there is an acute problem of lack of fresh water, secondary salinization of soils, destruction of soil structure and loss of soil fertility during plowing, drought and dust storms. In the north, there is degradation of reindeer pastures, in particular due to overgrazing, which leads to a sharp reduction in their biodiversity. No less important is the problem of preserving hunting grounds and natural habitats of fauna.
To study and protect typical and rare natural landscapes, numerous reserves, national and natural parks. Among the largest reserves: in the tundra - Gydansky Reserve, in the northern taiga - Verkhnetazovsky Reserve, in the middle taiga - Yugansky Reserve and Malaya Sosva, etc. In the sub-taiga it was created national park Pripyshminskie Bors. Natural parks have also been organized: in the tundra - Oleniy Ruchi, in the north. taiga - Numto, Siberian Uvaly, in the middle taiga - Kondinsky lakes, in the forest-steppe - Bird Harbor.
The first acquaintance of Russians with Western Siberia probably took place back in the 11th century, when the Novgorodians visited the lower reaches of the Ob River. With the campaign of Ermak (1582–85), a period of discoveries in Siberia and the development of its territory began.
The eastern territories of Russian Asia open from the Ural Mountains to the West Siberian Plain. Its settlement by Russians began in the 16th century, from the time of Ermak’s campaign. The expedition's route ran from the south of the plain.
These territories are still the most densely populated. However, we must remember that already in the 11th century the Novgorodians established trade relations with the population on the lower Ob.
Geographical position
The West Siberian Plain is washed from the north by the harsh Kara Sea. In the east, along the border of the Yenisei River basin, it neighbors the Central Siberian Plateau. The southeast is protected by the snowy foothills of Altai. In the south, the Kazakh small hills became the border of flat territories. The western border, as stated above, is the oldest mountains of Eurasia - the Ural Mountains.
Relief and landscape of the plain: features
A unique feature of the plain is that all the heights on it are very weakly expressed, both in absolute and relative values. The area of the West Siberian Plain, very low-lying, with many river channels, is swampy on 70 percent of the territory.
The lowland stretches from the shores of the Arctic Ocean to southern steppes Kazakhstan and almost all of it is located within the territory of our country. The plain provides a unique opportunity to see five natural areas with their characteristic landscape and climate conditions.
The relief is typical of low-lying river basins. Small hills alternating with swamps occupy the interfluve areas. The south is dominated by areas with saline groundwater.
Natural areas, cities and plain regions
Western Siberia is represented by five natural zones.
(Swampy area in the tundra of the Vasyugan swamps, Tomsk region)
The tundra occupies a narrow strip in the north of the Tyumen region and almost immediately turns into forest-tundra. In the extreme northern areas you can find massifs of a combination of lichens and mosses of Western Siberia. The area is dominated by swampy terrain, turning into open forest-tundra. Vegetation here includes larch and bushes.
The taiga of Western Siberia is characterized by dark coniferous zones with a variety of cedar, northern spruce and fir. Occasionally you can find pine forests occupying areas between the swamps. Most of the lowland landscape is occupied by endless swamps. One way or another, the whole of Western Siberia is characterized by swampiness, but there is also a unique natural massif here - the largest swamp in the world, the Vasyugan swamp. It occupied large territories in the southern taiga.
(Forest-steppe)
Closer to the south, nature changes - the taiga brightens, turning into forest-steppe. Aspen-birch forests and meadows with coppice appear. The Ob basin is decorated with pine island forests that arose naturally.
The steppe zone occupies the south of the Omsk and southwestern parts of the Novosibirsk regions. Also, the area of distribution of the steppe reaches the western part of the Altai Territory, which includes the Kulundinskaya, Aleiskaya and Biyskaya steppes. The territory of ancient water drainages is occupied by pine forests
(Fields in the taiga of the Tyumen region, Yugra)
The West Siberian Plain provides the opportunity for active land use. It is very rich in oil and almost all of it is lined with production rigs. The region's developed economy attracts new residents. Big cities the northern and central parts of the West Siberian Plain are well known: Urengoy, Nefteyugansk, Nizhnevartovsk. In the south are the cities of Tomsk, Tyumen, Kurgan, Omsk.
Rivers and lakes of the plain
(Yenisei River on hilly-flat terrain)
Rivers flowing through the West Siberian Lowland flow into the Kara Sea. The Ob is not only the longest river of the plain, but together with its tributary the Irtysh, it is the longest water artery in Russia. However, there are also rivers on the plain that do not belong to the Obi basin - Nadym, Pur, Taz and Tobol.
The territory is rich in lakes. They are divided into two groups according to the nature of their occurrence: some were formed in pits dug by a glacier passing through the lowlands, and some - in places of ancient swamps. The area holds the world record for swampiness.
Plain climate
Western Siberia in its north is covered with permafrost. A continental climate is observed throughout the plain. Most of the plain's territory is very susceptible to the influence of its formidable neighbor - the Arctic Ocean, whose air masses unhindered dominate the lowland region. Its cyclones dictate precipitation and temperature patterns. In areas of the plain where the Arctic, subarctic and temperate zones converge, cyclones often occur, leading to rain. In winter, cyclones generated at the junctions of the temperate and arctic zones soften the frosts in the north of the plains.
More precipitation falls in the north of the plain - up to 600 ml per year. Temperatures in the north in January on average do not rise above 22°C, in the south at the same time frosts reach 16°C. In July in the north and south of the plain, it is 4°C and 22°C, respectively.
The West Siberian Plain is one of the largest accumulative lowland plains on the globe. It extends from the shores of the Kara Sea to the steppes of Kazakhstan and from the Urals in the west to the Central Siberian Plateau in the east. The plain has the shape of a trapezoid tapering towards the north: the distance from its southern border to the northern reaches almost 2500 km, width - from 800 to 1900 km, and the area is only slightly less than 3 million. km 2 .
In the Soviet Union there are no longer such vast plains with such weakly rugged terrain and such small fluctuations in relative heights. The comparative uniformity of the relief determines the distinct zoning of the landscapes of Western Siberia - from tundra in the north to steppe in the south. Due to the poor drainage of the territory, hydromorphic complexes play a very prominent role within its boundaries: swamps and swampy forests occupy a total of about 128 million hectares. ha, and in the steppe and forest-steppe zones there are many solonetzes, solods and solonchaks.
The geographical position of the West Siberian Plain determines the transitional nature of its climate between the moderate continental climate of the Russian Plain and the sharply continental climate of Central Siberia. Therefore, the country’s landscapes are distinguished by a number of unique features: the natural zones here are somewhat shifted to the north compared to the Russian Plain, there is no zone of broad-leaved forests, and landscape differences within the zones are less noticeable than on the Russian Plain.
The West Siberian Plain is the most populated and developed (especially in the south) part of Siberia. Within its boundaries are the Tyumen, Kurgan, Omsk, Novosibirsk, Tomsk and North Kazakhstan regions, a significant part of the Altai Territory, Kustanai, Kokchetav and Pavlodar regions, as well as some eastern regions of the Sverdlovsk and Chelyabinsk regions and western regions Krasnoyarsk Territory.
The first acquaintance of Russians with Western Siberia probably took place in the 11th century, when the Novgorodians visited the lower reaches of the Ob. The campaign of Ermak (1581-1584) ushered in the brilliant period of the Great Russian geographical discoveries in Siberia and the development of its territory.
However, scientific study of the country’s nature began only in the 18th century, when detachments of first the Great Northern and then academic expeditions were sent here. In the 19th century Russian scientists and engineers are studying the conditions of navigation on the Ob, Yenisei and the Kara Sea, the geological and geographical features of the route of the Siberian Railway that was then being designed, and salt deposits in the steppe zone. A significant contribution to the knowledge of the Western Siberian taiga and steppes was made by the research of soil-botanical expeditions of the Resettlement Administration, undertaken in 1908-1914. in order to study the conditions of agricultural development of areas allocated for the resettlement of peasants from European Russia.
The study of the nature and natural resources of Western Siberia acquired a completely different scope after the Great October Revolution. In the research that was necessary for the development of productive forces, it was no longer individual specialists or small detachments that took part, but hundreds of large complex expeditions and many scientific institutes created in various cities of Western Siberia. Detailed and comprehensive studies were carried out here by the USSR Academy of Sciences (Kulundinskaya, Barabinskaya, Gydanskaya and other expeditions) and its Siberian branch, the West Siberian Geological Department, geological institutes, expeditions of the Ministry of Agriculture, Hydroproject and other organizations.
As a result of these studies, ideas about the country's topography changed significantly, detailed soil maps of many regions of Western Siberia were compiled, and measures were developed for the rational use of saline soils and the famous Western Siberian chernozems. The forest typological studies of Siberian geobotanists and the study of peat bogs and tundra pastures were of great practical importance. But the work of geologists brought especially significant results. Deep drilling and special geophysical research have shown that in the depths of many regions of Western Siberia there are rich deposits natural gas, large reserves iron ores, brown coal and many other minerals, which already serve as a solid basis for the development of industry in Western Siberia.
Geological structure and history of development of the territory
Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
Many features of the nature of Western Siberia are determined by the nature of its geological structure and history of development. The entire territory of the country is located within the West Siberian epi-Hercynian plate, the foundation of which is composed of dislocated and metamorphosed Paleozoic sediments, similar in nature to similar rocks of the Urals, and in the south of the Kazakh hillocks. The formation of the main folded structures of the basement of Western Siberia, which have a predominantly meridional direction, dates back to the era of the Hercynian orogeny.
The tectonic structure of the West Siberian plate is quite heterogeneous. However, even its large structural elements appear in the modern relief less clearly than the tectonic structures of the Russian Platform. This is explained by the fact that the surface relief of Paleozoic rocks, descended to great depths, is leveled here by a cover of Meso-Cenozoic sediments, the thickness of which exceeds 1000 m, and in individual depressions and syneclises of the Paleozoic basement - 3000-6000 m.
Mesozoic formations of Western Siberia are represented by marine and continental sandy-clayey deposits. Their total capacity in some areas reaches 2500-4000 m. The alternation of marine and continental facies indicates the tectonic mobility of the territory and repeated changes in conditions and sedimentation regime on the West Siberian Plate, which subsided at the beginning of the Mesozoic.
Paleogene deposits are predominantly marine and consist of gray clays, mudstones, glauconitic sandstones, opokas and diatomites. They accumulated at the bottom of the Paleogene sea, which, through the depression of the Turgai Strait, connected the Arctic basin with the seas then located in Central Asia. This sea left Western Siberia in the middle of the Oligocene, and therefore the Upper Paleogene deposits are represented here by sandy-clayey continental facies.
Significant changes in the conditions for the accumulation of sediments occurred in the Neogene. Formations of rocks of Neogene age, outcropping mainly in the southern half of the plain, consist exclusively of continental lacustrine-fluvial deposits. They were formed in the conditions of a poorly dissected plain, first covered with rich subtropical vegetation, and later with broad-leaved deciduous forests of representatives of the Turgai flora (beech, walnut, hornbeam, lapina, etc.). In some places there were areas of savannah where giraffes, mastodons, hipparions, and camels lived at that time.
The events of the Quaternary period had a particularly great influence on the formation of the landscapes of Western Siberia. During this time, the country's territory experienced repeated subsidence and continued to be an area predominantly of accumulation of loose alluvial, lacustrine, and, in the north, marine and glacial sediments. The thickness of the Quaternary cover in the northern and central regions reaches 200-250 m. However, in the south it noticeably decreases (in some places to 5-10 m), and in the modern relief the effects of differentiated neotectonic movements are clearly expressed, as a result of which swell-like uplifts arose, often coinciding with the positive structures of the Mesozoic cover of sedimentary deposits.
Lower Quaternary sediments are represented in the north of the plain by alluvial sands filling buried valleys. The base of alluvium is sometimes located in them at 200-210 m below the modern level of the Kara Sea. Above them in the north usually lie pre-glacial clays and loams with fossil remains of tundra flora, which indicates a noticeable cooling of Western Siberia that had already begun. However, in the southern regions of the country dark coniferous forests with an admixture of birch and alder predominated.
The Middle Quaternary in the northern half of the plain was an era of marine transgressions and repeated glaciations. The most significant of them was Samarovskoe, the sediments of which form the interfluves of the territory lying between 58-60° and 63-64° N. w. According to currently prevailing views, the cover of the Samara glacier, even in the extreme northern regions of the lowland, was not continuous. The composition of the boulders shows that its food sources were glaciers descending from the Urals to the Ob valley, and in the east - glaciers of the Taimyr mountain ranges and the Central Siberian Plateau. However, even during the period of maximum development of glaciation on the West Siberian Plain, the Ural and Siberian ice sheets did not meet one another, and the rivers of the southern regions, although they encountered a barrier formed by ice, found their way to the north in the interval between them.
The sediments of the Samarova strata, along with typical glacial rocks, also include marine and glaciomarine clays and loams that formed at the bottom of the sea advancing from the north. Therefore, the typical forms of moraine relief are less clearly expressed here than on the Russian Plain. On the lacustrine and fluvioglacial plains adjacent to the southern edge of the glaciers, forest-tundra landscapes then prevailed, and in the extreme south of the country loess-like loams formed, in which pollen of steppe plants (wormwood, kermek) is found. Marine transgression continued in the post-Samarovo period, the sediments of which are represented in the north of Western Siberia by the Messa sands and clays of the Sanchugov Formation. In the northeastern part of the plain, moraines and glacial-marine loams of the younger Taz glaciation are common. The interglacial era, which began after the retreat of the ice sheet, in the north was marked by the spread of the Kazantsev marine transgression, the sediments of which in the lower reaches of the Yenisei and Ob contain the remains of a more heat-loving marine fauna than that currently living in the Kara Sea.
The last, Zyryansky, glaciation was preceded by regression of the boreal sea, caused by uplifts of the northern regions of the West Siberian Plain, the Urals and the Central Siberian Plateau; the amplitude of these uplifts was only a few tens of meters. At the maximum stage of development of the Zyryan glaciation, glaciers descended to the areas of the Yenisei Plain and the eastern foot of the Urals to approximately 66° N. sh., where a number of stadial terminal moraines were left. In the south of Western Siberia at this time, sandy-clayey Quaternary sediments were overwintering, aeolian landforms were forming, and loess-like loams were accumulating.
Some researchers of the northern regions of the country paint a more complex picture of the events of the Quaternary glaciation era in Western Siberia. Thus, according to geologist V.N. Saksa and geomorphologist G.I. Lazukov, glaciation began here in the Lower Quaternary and consisted of four independent eras: Yarskaya, Samarovskaya, Tazovskaya and Zyryanskaya. Geologists S. A. Yakovlev and V. A. Zubakov even count six glaciations, attributing the beginning of the most ancient of them to the Pliocene.
On the other hand, there are supporters of a one-time glaciation of Western Siberia. Geographer A.I. Popov, for example, considers the deposits of the glaciation era of the northern half of the country as a single water-glacial complex consisting of marine and glacial-marine clays, loams and sands containing inclusions of boulder material. In his opinion, there were no extensive ice sheets on the territory of Western Siberia, since typical moraines are found only in the extreme western (at the foot of the Urals) and eastern (near the ledge of the Central Siberian Plateau) regions. During the glaciation era, the middle part of the northern half of the plain was covered with the waters of marine transgression; the boulders contained in its sediments were brought here by icebergs that broke away from the edge of the glaciers that descended from the Central Siberian Plateau. Geologist V.I. Gromov recognizes only one Quaternary glaciation in Western Siberia.
At the end of the Zyryan glaciation, the northern coastal regions of the West Siberian Plain subsided again. The subsided areas were flooded by the waters of the Kara Sea and covered with marine sediments making up post-glacial marine terraces, the highest of which rises by 50-60 m above modern level Kara Sea. Then, after regression of the sea, a new incision of rivers began in the southern half of the plain. Due to the small slopes of the channel, lateral erosion prevailed in most river valleys of Western Siberia; the deepening of the valleys proceeded slowly, which is why they usually have a significant width but small depth. In poorly drained interfluve spaces, the reworking of the glacial relief continued: in the north it consisted of leveling the surface under the influence of solifluction processes; in the southern, non-glacial provinces, where more precipitation fell, the processes of deluvial washout played a particularly prominent role in the transformation of the relief.
Paleobotanical materials suggest that after the glaciation there was a period with a slightly drier and warmer climate than now. This is confirmed, in particular, by the finds of stumps and tree trunks in the deposits of the tundra regions of Yamal and the Gydan Peninsula at 300-400 km north of the modern border of tree vegetation and the widespread development in the south of the tundra zone of relict large-hilly peat bogs.
Currently, on the territory of the West Siberian Plain there is a slow shift of borders geographical zones to the south. Forests in many places encroach on the forest-steppe, forest-steppe elements penetrate into the steppe zone, and tundras slowly displace woody vegetation near the northern limit of sparse forests. True, in the south of the country man interferes with the natural course of this process: by cutting down forests, he not only stops their natural advance on the steppe, but also contributes to the shift of the southern border of forests to the north.
Relief
See photographs of the nature of the West Siberian Plain: Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
Scheme of the main orographic elements of the West Siberian Plain
The differentiated subsidence of the West Siberian Plate in the Mesozoic and Cenozoic led to the predominance within its boundaries of processes of accumulation of loose sediments, the thick cover of which levels out the surface irregularities of the Hercynian basement. Therefore, the modern West Siberian Plain has a generally flat surface. However, it cannot be considered as a monotonous lowland, as was recently believed. In general, the territory of Western Siberia has a concave shape. Its lowest areas (50-100 m) are located mainly in the central ( Kondinskaya and Sredneobskaya lowlands) and northern ( Nizhneobskaya, Nadym and Pur lowlands) parts of the country. Along the western, southern and eastern outskirts there are low (up to 200-250 m) elevations: Severo-Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye and Chulym-Yenisei plateaus, Ketsko-Tymskaya, Verkhnetazovskaya, Nizhneneiseyskaya. A clearly defined strip of hills forms in the inner part of the plain Sibirskie Uvaly(average height - 140-150 m), stretching from the west from the Ob to the east to the Yenisei, and parallel to them Vasyuganskaya plain.
Some orographic elements of the West Siberian Plain correspond to geological structures: for example, the Verkhnetazovskaya and Lyulimvor, A Barabinskaya and Kondinskaya the lowlands are confined to the syneclises of the slab foundation. However, in Western Siberia, discordant (inversion) morphostructures are also common. These include, for example, the Vasyugan Plain, which formed on the site of a gently sloping syneclise, and the Chulym-Yenisei Plateau, located in the zone of basement deflection.
The West Siberian Plain is usually divided into four large geomorphological regions: 1) marine accumulative plains in the north; 2) glacial and water-glacial plains; 3) periglacial, mainly lacustrine-alluvial plains; 4) southern non-glacial plains (Voskresensky, 1962).
The differences in the relief of these areas are explained by the history of their formation in Quaternary times, the nature and intensity of recent tectonic movements, and zonal differences in modern exogenous processes. In the tundra zone, relief forms are especially widely represented, the formation of which is associated with the harsh climate and widespread permafrost. Thermokarst basins, bulgunnyakhs, spotted and polygonal tundras are very common, and solifluction processes are developed. Typical of the southern steppe provinces are numerous closed basins of suffusion origin, occupied by salt marshes and lakes; The network of river valleys here is sparse, and erosional landforms in the interfluves are rare.
The main elements of the relief of the West Siberian Plain are wide, flat interfluves and river valleys. Due to the fact that the interfluve spaces account for most of the country's area, they determine the general appearance of the plain's topography. In many places, the slopes of their surfaces are insignificant, the flow of precipitation, especially in the forest-swamp zone, is very difficult and the interfluves are heavily swamped. Large areas are occupied by swamps north of the Siberian railway line, on the interfluves of the Ob and Irtysh, in the Vasyugan region and the Barabinsk forest-steppe. However, in some places the relief of the interfluves takes on the character of a wavy or hilly plain. Such areas are especially typical of some northern provinces of the plain, which were subject to Quaternary glaciations, which left here piles of stadial and bottom moraines. In the south - in Baraba, on the Ishim and Kulunda plains - the surface is often complicated by numerous low ridges stretching from northeast to southwest.
Another important element of the country's topography is river valleys. All of them were formed under conditions of slight surface slopes and slow and calm river flows. Due to differences in the intensity and nature of erosion, the appearance of the river valleys of Western Siberia is very diverse. There are also well-developed deep ones (up to 50-80 m) valleys of large rivers - the Ob, Irtysh and Yenisei - with a steep right bank and a system of low terraces on the left bank. In some places their width is several tens of kilometers, and the Ob valley in the lower reaches reaches even 100-120 km. The valleys of most small rivers are often just deep ditches with poorly defined slopes; During spring floods, water completely fills them and even floods neighboring valley areas.
Climate
See photographs of the nature of the West Siberian Plain: Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
Western Siberia is a country with a fairly harsh continental climate. Its large extent from north to south determines a clearly defined climate zonation and significant differences in climatic conditions in the northern and southern parts of Western Siberia, associated with changes in the amount of solar radiation and the nature of the circulation of air masses, especially the westerly transport flows. The southern provinces of the country, located inland, at a great distance from the oceans, are also characterized by a more continental climate.
During the cold period, two baric systems interact within the country: an area of relatively high atmospheric pressure located over the southern part of the plain, and an area of low pressure, which in the first half of winter stretches in the form of a trough of the Icelandic baric minimum over the Kara Sea and the northern peninsulas. In winter, continental air masses of temperate latitudes predominate, coming from Eastern Siberia or are formed locally as a result of cooling of the air over the plain.
Cyclones often pass through the border zone of areas of high and low pressure. They recur especially often in the first half of winter. Therefore, the weather in the coastal provinces is very unstable; on the coast of Yamal and the Gydan Peninsula there are strong winds, the speed of which reaches 35-40 m/sec. The temperature here is even slightly higher than in neighboring forest-tundra provinces, located between 66 and 69° N. w. However, further south, winter temperatures gradually rise again. In general, winter is characterized by stable low temperatures; there are few thaws here. Minimum temperatures throughout Western Siberia are almost the same. Even near the southern border of the country, in Barnaul, there are frosts down to -50 -52°, i.e. almost the same as in the far north, although the distance between these points is more than 2000 km. Spring is short, dry and relatively cold; April, even in the forest-swamp zone, is not yet quite a spring month.
In the warm season, low pressure sets over the country, and an area of higher pressure forms over the Arctic Ocean. In connection with this summer, weak northern or northeastern winds predominate and the role of westerly air transport noticeably increases. In May there is a rapid increase in temperatures, but often, when arctic air masses invade, there are returns of cold weather and frosts. The warmest month is July, the average temperature of which ranges from 3.6° on Beloy Island to 21-22° in the Pavlodar region. The absolute maximum temperature is from 21° in the north (Bely Island) to 40° in the extreme southern regions (Rubtsovsk). High summer temperatures in the southern half of Western Siberia are explained by the arrival of heated continental air from the south - from Kazakhstan and Central Asia. Autumn comes late. Even in September the weather is warm during the day, but November, even in the south, is already a real winter month with frosts down to -20 -35°.
Most of the precipitation falls in the summer and is brought by air masses coming from the west, from the Atlantic. From May to October, Western Siberia receives up to 70-80% of the annual precipitation. There are especially many of them in July and August, which is explained by intense activity on the Arctic and polar fronts. The amount of winter precipitation is relatively small and ranges from 5 to 20-30 mm/month. In the south, during some winter months there is sometimes no snow at all. There are significant fluctuations in precipitation in different years. Even in the taiga, where these changes are less than in other zones, precipitation, for example, in Tomsk, falls from 339 mm in a dry year up to 769 mm in wet. Especially large ones are observed in the forest-steppe zone, where, with an average long-term precipitation amount of about 300-350 mm/year in wet years it falls up to 550-600 mm/year, and on dry days - only 170-180 mm/year.
There are also significant zonal differences in evaporation values, which depend on the amount of precipitation, air temperature and the evaporative properties of the underlying surface. The most moisture evaporates in the precipitation-rich southern half of the forest-swamp zone (350-400 mm/year). In the north, in the coastal tundras, where air humidity is relatively high in summer, the amount of evaporation does not exceed 150-200 mm/year. It is approximately the same in the south of the steppe zone (200-250 mm), which is explained by the already low amount of precipitation falling in the steppes. However, evaporation here reaches 650-700 mm Therefore, in some months (especially in May) the amount of evaporated moisture can exceed the amount of precipitation by 2-3 times. The lack of precipitation is compensated in this case by reserves of moisture in the soil accumulated due to autumn rains and melting snow cover.
The extreme southern regions of Western Siberia are characterized by droughts, occurring mainly in May and June. They are observed on average every three to four years during periods with anticyclonic circulation and increased frequency of arctic air intrusions. Dry air coming from the Arctic, when passing over Western Siberia, warms up and is enriched with moisture, but its heating is more intense, so the air moves further and further away from the saturation state. In this regard, evaporation increases, which leads to drought. In some cases, droughts are also caused by the arrival of dry and warm air masses from the south - from Kazakhstan and Central Asia.
In winter, the territory of Western Siberia is covered with snow cover for a long time, the duration of which in the northern regions reaches 240-270 days, and in the south - 160-170 days. Due to the fact that the period of solid precipitation lasts more than six months, and thaws begin no earlier than March, the thickness of the snow cover in the tundra and steppe zones in February is 20-40 cm, in the forest-swamp zone - from 50-60 cm in the west up to 70-100 cm in the eastern Yenisei regions. In treeless - tundra and steppe - provinces, where there are strong winds and snowstorms in winter, the snow is distributed very unevenly, as the winds blow it from elevated relief elements into depressions, where powerful snowdrifts form.
The harsh climate of the northern regions of Western Siberia, where the heat entering the soil is not enough to maintain a positive temperature of the rocks, contributes to soil freezing and widespread permafrost. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is found everywhere. In these areas of continuous (merged) distribution, the thickness of the frozen layer is very significant (up to 300-600 m), and its temperatures are low (in watershed areas - 4, -9°, in valleys -2, -8°). To the south, within the northern taiga to a latitude of approximately 64°, permafrost occurs in the form of isolated islands interspersed with taliks. Its power decreases, temperatures rise to?0.5 -1°, and the depth of summer thawing also increases, especially in areas composed of mineral rocks.
Water
See photographs of the nature of the West Siberian Plain: Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
Western Siberia is rich in underground and surface waters; in the north its coast is washed by the waters of the Kara Sea.
The entire territory of the country is located within the large West Siberian artesian basin, in which hydrogeologists distinguish several second-order basins: Tobolsk, Irtysh, Kulunda-Barnaul, Chulym, Ob, etc. Due to the large thickness of the cover of loose sediments, consisting of alternating water-permeable ( sands, sandstones) and water-resistant rocks, artesian basins are characterized by a significant number of aquifers confined to formations of various ages - Jurassic, Cretaceous, Paleogene and Quaternary. The quality of groundwater in these horizons is very different. In most cases, artesian waters of deep horizons are more mineralized than those lying closer to the surface.
In some aquifers of the Ob and Irtysh artesian basins at a depth of 1000-3000 m There are hot salty waters, most often of calcium-sodium chloride composition. Their temperature ranges from 40 to 120°, the daily flow rate of wells reaches 1-1.5 thousand. m 3, and total reserves - 65,000 km 3; such pressurized water can be used for heating cities, greenhouses and greenhouses.
Groundwater in the arid steppe and forest-steppe regions of Western Siberia is of great importance for water supply. In many areas of the Kulunda steppe, deep tube wells were built to extract them. Groundwater from Quaternary deposits is also used; however, in the southern regions due to climatic conditions, poor surface drainage and slow circulation, they are often highly saline.
The surface of the West Siberian Plain is drained by many thousands of rivers, the total length of which exceeds 250 thousand km. km. These rivers carry about 1,200 km 3 waters - 5 times more than the Volga. The density of the river network is not very large and varies in different places depending on the topography and climatic features: in the Tavda basin it reaches 350 km, and in the Barabinsk forest-steppe - only 29 km per 1000 km 2. Some southern regions of the country with a total area of more than 445 thousand. km 2 belong to territories of closed drainage and are distinguished by the abundance of closed lakes.
The main sources of nutrition for most rivers are melted snow waters and summer-autumn rains. In accordance with the nature of the food sources, the runoff is uneven over the seasons: approximately 70-80% of its annual amount occurs in spring and summer. Especially a lot of water flows down during the spring flood, when the level of large rivers rises by 7-12 m(in the lower reaches of the Yenisei even up to 15-18 m). For a long time (in the south - five, and in the north - eight months), Western Siberian rivers are frozen. Therefore, no more than 10% of the annual runoff occurs in the winter months.
The rivers of Western Siberia, including the largest ones - the Ob, Irtysh and Yenisei, are characterized by slight slopes and low flow speeds. For example, the fall of the Ob riverbed in the area from Novosibirsk to the mouth for 3000 km equals only 90 m, and its flow speed does not exceed 0.5 m/sec.
The most important water artery of Western Siberia is the river Ob with its large left tributary the Irtysh. The Ob is one of the greatest rivers on the globe. The area of its basin is almost 3 million hectares. km 2 and the length is 3676 km. The Ob basin is located within several geographical zones; in each of them the nature and density of the river network are different. Thus, in the south, in the forest-steppe zone, the Ob receives relatively few tributaries, but in the taiga zone their number increases noticeably.
Below the confluence of the Irtysh, the Ob turns into a powerful stream up to 3-4 km. Near the mouth, the width of the river in some places reaches 10 km, and depth - up to 40 m. This is one of the most abundant rivers in Siberia; it brings an average of 414 to the Gulf of Ob per year km 3 waters.
The Ob is a typical lowland river. The slopes of its channel are small: the fall in the upper part is usually 8-10 cm, and below the mouth of the Irtysh does not exceed 2-3 cm by 1 km currents. During spring and summer, the flow of the Ob River near Novosibirsk is 78% of the annual rate; near the mouth (near Salekhard), the distribution of runoff by season is as follows: winter - 8.4%, spring - 14.6, summer - 56 and autumn - 21%.
Six rivers of the Ob basin (Irtysh, Chulym, Ishim, Tobol, Ket and Konda) have a length of more than 1000 km; the length of even some second-order tributaries sometimes exceeds 500 km.
The largest of the tributaries is Irtysh, whose length is 4248 km. Its origins lie outside the Soviet Union, in the mountains of the Mongolian Altai. For a significant part of its course, the Irtysh crosses the steppes of Northern Kazakhstan and has almost no tributaries up to Omsk. Only in the lower reaches, already within the taiga, several large rivers flow into it: Ishim, Tobol, etc. Throughout the entire length of the Irtysh, the Irtysh is navigable, but in the upper reaches in the summer, during the period of low water levels, navigation is difficult due to numerous rapids.
Along the eastern border of the West Siberian Plain flows Yenisei- the most abundant river Soviet Union. Its length is 4091 km(if we consider the Selenga River as the source, then 5940 km); The basin area is almost 2.6 million. km 2. Just like the Ob, the Yenisei basin is elongated in the meridional direction. All its large right tributaries flow through the territory of the Central Siberian Plateau. Only the shorter and shallower left tributaries of the Yenisei begin from the flat, swampy watersheds of the West Siberian Plain.
The Yenisei originates in the mountains of the Tuva Autonomous Soviet Socialist Republic. In the upper and middle reaches, where the river crosses the bedrock spurs of the Sayan Mountains and the Central Siberian Plateau, there are rapids (Kazachinsky, Osinovsky, etc.) in its bed. After the confluence of the Lower Tunguska, the current becomes calmer and slower, and sandy islands appear in the channel, breaking the river into channels. The Yenisei flows into the wide Yenisei Bay of the Kara Sea; its width near the mouth, located near the Brekhov Islands, reaches 20 km.
The Yenisei is characterized by large fluctuations in costs according to the seasons of the year. The minimum winter flow rate near the mouth is about 2500 m 3 /sec, the maximum during the flood period exceeds 132 thousand. m 3 /sec with an annual average of about 19,800 m 3 /sec. Over the course of a year, the river carries more than 623 km 3 waters. In the lower reaches the depth of the Yenisei is very significant (in places 50 m). This makes it possible for sea vessels to climb up the river by more than 700 km and reach Igarka.
On the West Siberian Plain there are about one million lakes, the total area of which is more than 100 thousand hectares. km 2. Based on the origin of the basins, they are divided into several groups: those occupying the primary unevenness of the flat terrain; thermokarst; moraine-glacial; lakes of river valleys, which in turn are divided into floodplain and oxbow lakes. Peculiar lakes - “fogs” - are found in the Ural part of the plain. They are located in wide valleys, overflow in the spring, sharply reducing their size in the summer, and by autumn many disappear altogether. In the forest-steppe and steppe regions of Western Siberia there are lakes that fill suffusion or tectonic basins.
Soils, vegetation and fauna
See photographs of the nature of the West Siberian Plain: Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
The flat terrain of Western Siberia contributes to pronounced zonality in the distribution of soils and vegetation cover. Within the country there are gradually replacing one another tundra, forest-tundra, forest-swamp, forest-steppe and steppe zones. Geographical zoning thus resembles in general terms the zoning system of the Russian Plain. However, the zones of the West Siberian Plain also have a number of local specific features, significantly differentiating them from similar zones of Eastern Europe. Typical zonal landscapes are located here in dissected and better drained upland and riverine areas. In poorly drained interfluve spaces, where drainage is difficult and the soils are usually highly moist, swamp landscapes predominate in the northern provinces, and landscapes formed under the influence of saline groundwater in the south. Thus, here, much more than on the Russian Plain, the role in the distribution of soils and plant cover is played by the nature and density of the relief, causing significant differences in the soil moisture regime.
Therefore, there are, as it were, two independent systems of latitudinal zoning in the country: the zoning of drained areas and the zoning of undrained interfluves. These differences are most clearly manifested in the nature of the soils. Thus, in drained areas of the forest-swamp zone, mainly strongly podzolized soils are formed under coniferous taiga and sod-podzolic soils under birch forests, and in neighboring undrained areas - thick podzols, swamp and meadow-swamp soils. The drained spaces of the forest-steppe zone are most often occupied by leached and degraded chernozems or dark gray podzolized soils under birch groves; in undrained areas they are replaced by marshy, saline or meadow-chernozemic soils. In the upland areas of the steppe zone, either ordinary chernozems, characterized by increased fatness, low thickness and tongue-like (heterogeneity) soil horizons, or chestnut soils predominate; in poorly drained areas, spots of malts and solodized solonetzes or solonetzic meadow-steppe soils are common among them.
Fragment of a section of the swampy taiga of Surgut Polesie (according to V. I. Orlov)
There are some other features that distinguish the zones of Western Siberia from the zones of the Russian Plain. In the tundra zone, which extends much further north than on the Russian Plain, large areas are occupied by arctic tundra, which are absent in the mainland regions of the European part of the Union. The woody vegetation of the forest-tundra is represented mainly by Siberian larch, and not spruce, as in the regions lying west of the Urals.
In the forest-swamp zone, 60% of the area of which is occupied by swamps and poorly drained swampy forests 1, pine forests dominate, occupying 24.5% of the forested area, and birch forests (22.6%), mainly secondary. Smaller areas are covered with damp dark coniferous cedar taiga (Pinus sibirica), fir (Abies sibirica) and ate (Picea obovata). Broad-leaved species (with the exception of linden, which is occasionally found in the southern regions) are absent in the forests of Western Siberia, and therefore there is no broad-leaved forest zone here.
1 It is for this reason that the zone is called forest swamp in Western Siberia.
The increase in climate continentality causes a relatively sharp transition, compared to the Russian Plain, from forest-swamp landscapes to dry steppe spaces in the southern regions of the West Siberian Plain. Therefore, the width of the forest-steppe zone in Western Siberia is much smaller than on the Russian Plain, and the main tree species found in it are birch and aspen.
The West Siberian Plain is entirely part of the transitional Euro-Siberian zoogeographical subregion of the Palearctic. There are 478 species of vertebrates known here, including 80 species of mammals. The fauna of the country is young and in its composition differs little from the fauna of the Russian Plain. Only in eastern half countries there are some eastern, Trans-Yenisei forms: Djungarian hamster (Phodopus sungorus), chipmunk (Eutamias sibiricus) etc. In recent years, the fauna of Western Siberia has been enriched by muskrats acclimatized here (Ondatra zibethica), brown hare (Lepus europaeus), American mink (Lutreola vison), teledut squirrel (Sciurus vulgaris exalbidus), and carp were introduced into its reservoirs (Cyprinus carpio) and bream (Abramis brama).
Natural resources
See photographs of the nature of the West Siberian Plain: Tazovsky Peninsula And Middle Ob In chapter Nature of the world.
The natural resources of Western Siberia have long served as the basis for the development of various sectors of the economy. There are tens of millions of hectares of good arable land here. The land in the steppe and forested steppe zones is especially valuable, with its favorable conditions for Agriculture climate and highly fertile chernozems, gray forest and non-saline chestnut soils, which occupy more than 10% of the country's area. Due to the flatness of the relief, land development in the southern part of Western Siberia does not require large capital expenditures. For this reason, they were one of the priority areas for the development of virgin and fallow lands; In recent years, more than 15 million hectares have been involved in crop rotation here. ha new lands, the production of grain and industrial crops (sugar beets, sunflowers, etc.) increased. Lands located to the north, even in the southern taiga zone, are still underutilized and are a good reserve for development in the coming years. However, this will require significantly greater expenditures of labor and funds for drainage, uprooting and clearing of bushes from the land.
Pastures in the forest-swamp, forest-steppe and steppe zones are of high economic value, especially water meadows along the Ob, Irtysh, Yenisei and their large tributaries. The abundance of natural meadows here creates a solid base for further development livestock farming and significantly increasing its productivity. Reindeer reindeer pastures of the tundra and forest-tundra, which occupy more than 20 million hectares in Western Siberia, are important for the development of reindeer husbandry. ha; More than half a million domestic reindeer graze on them.
A significant part of the plain is occupied by forests - birch, pine, cedar, fir, spruce and larch. The total forested area in Western Siberia exceeds 80 million. ha; timber reserves are about 10 billion. m 3, and its annual growth is over 10 million. m 3. The most valuable forests are located here, which provide wood for various sectors of the national economy. The forests most widely used at present are along the valleys of the Ob, the lower reaches of the Irtysh and some of their navigable or raftable tributaries. But many forests, including especially valuable tracts of pine, located between the Urals and Ob, are still poorly developed.
Dozens of large rivers of Western Siberia and hundreds of their tributaries serve as important shipping routes connecting the southern regions with the far north. The total length of navigable rivers exceeds 25 thousand. km. The length of the rivers along which timber is rafted is approximately the same. The country's deep rivers (Yenisei, Ob, Irtysh, Tom, etc.) have large energy resources; if fully utilized, they could generate more than 200 billion. kWh electricity per year. The first large Novosibirsk hydroelectric power station on the Ob River with a capacity of 400 thousand. kW entered service in 1959; above it a reservoir with an area of 1070 km 2. In the future, it is planned to build hydroelectric power stations on the Yenisei (Osinovskaya, Igarskaya), in the upper reaches of the Ob (Kamenskaya, Baturinskaya), and on the Tomskaya (Tomskaya).
The waters of large Western Siberian rivers can also be used for irrigation and water supply of semi-desert and desert regions of Kazakhstan and Central Asia, which are already experiencing a significant lack of water resources. Currently, design organizations are developing the basic provisions and feasibility study for transferring part of the flow of Siberian rivers to the Aral Sea basin. According to preliminary studies, the implementation of the first stage of this project should ensure the annual transfer of 25 km 3 waters from Western Siberia to Central Asia. For this purpose, it is planned to create a large reservoir on the Irtysh, near Tobolsk. From it to the south along the Tobol valley and along the Turgai depression into the Syr Darya basin, the Ob-Caspian canal, more than 1500 long, will go to the reservoirs created there km. It is planned to lift water to the Tobol-Aral watershed by a system of powerful pumping stations.
At the next stages of the project, the volume of annually transferred water can be increased to 60-80 km 3. Since the waters of the Irtysh and Tobol will no longer be enough for this, the second stage of work involves the construction of dams and reservoirs on the upper Ob, and possibly on the Chulym and Yenisei.
Naturally, the withdrawal of tens of cubic kilometers of water from the Ob and Irtysh should affect the regime of these rivers in their middle and lower reaches, as well as changes in the landscapes of the territories adjacent to the projected reservoirs and transfer channels. Forecasting the nature of these changes now occupies a prominent place in the scientific research of Siberian geographers.
Until quite recently, many geologists, based on the idea of the uniformity of the thick strata of loose sediments composing the plain and the seeming simplicity of its tectonic structure, very cautiously assessed the possibility of discovering any valuable minerals in its depths. However, geological and geophysical research carried out in recent decades, accompanied by the drilling of deep wells, showed the fallacy of previous ideas about the country's poverty in mineral resources and made it possible to imagine in a completely new way the prospects for the use of its mineral resources.
As a result of these studies, more than 120 oil fields have already been discovered in the Mesozoic (mainly Jurassic and Lower Cretaceous) deposits of the central regions of Western Siberia. The main oil-bearing areas are located in the Middle Ob region - in Nizhnevartovsk (including the Samotlor field, where oil can be produced up to 100-120 million tons). t/year), Surgut (Ust-Balyk, West Surgut, etc.) and South-Balyk (Mamontovskoe, Pravdinskoe, etc.) regions. In addition, there are deposits in the Shaim region, in the Ural part of the plain.
In recent years, the largest natural gas fields have also been discovered in the north of Western Siberia - in the lower reaches of the Ob, Taz and Yamal. The potential reserves of some of them (Urengoy, Medvezhye, Zapolyarny) amount to several trillion cubic meters; Gas production at each can reach 75-100 billion. m 3 per year. In general, the forecast gas reserves in the depths of Western Siberia are estimated at 40-50 trillion. m 3, including categories A+B+C 1 - more than 10 trillion. m 3 .
Oil and gas fields of Western Siberia
The discovery of both oil and gas fields is of great importance for the development of the economy of Western Siberia and neighboring economic regions. The Tyumen and Tomsk regions are turning into important areas of the oil production, oil refining and chemical industries. Already in 1975, more than 145 million were mined here. T oil and tens of billions of cubic meters of gas. To deliver oil to areas of consumption and processing, the Ust-Balyk - Omsk oil pipelines (965 km), Shaim - Tyumen (436 km), Samotlor - Ust-Balyk - Kurgan - Ufa - Almetyevsk, through which oil received access to European part USSR - to the places of its greatest consumption. For the same purpose, the Tyumen-Surgut railway and gas pipelines were built, through which natural gas from Western Siberian fields goes to the Urals, as well as to the central and northwestern regions of the European part of the Soviet Union. In the last five-year period, the construction of the giant Siberia-Moscow supergas pipeline was completed (its length is more than 3000 km), through which gas from the Medvezhye field is supplied to Moscow. In the future, gas from Western Siberia will go through pipelines to Western European countries.
Brown coal deposits also became known, confined to the Mesozoic and Neogene deposits of the marginal regions of the plain (North Sosvinsky, Yenisei-Chulym and Ob-Irtysh basins). Western Siberia also has colossal peat reserves. In its peatlands, the total area of which exceeds 36.5 million. ha, concluded a little less than 90 billion. T air-dry peat. This is almost 60% of all peat resources of the USSR.
Geological research led to the discovery of the deposit and other minerals. In the southeast, in the Upper Cretaceous and Paleogene sandstones of the vicinity of Kolpashev and Bakchar, large deposits of oolitic iron ores were discovered. They lie relatively shallow (150-400 m), the iron content in them is up to 36-45%, and the predicted geological reserves of the West Siberian iron ore basin are estimated at 300-350 billion. T, including in the Bakcharskoye field alone - 40 billion. T. Hundreds of millions of tons of table salt and Glauber's salt, as well as tens of millions of tons of soda, are concentrated in numerous salt lakes in the south of Western Siberia. In addition, Western Siberia has huge reserves of raw materials for production building materials(sand, clays, marls); Along its western and southern outskirts there are deposits of limestone, granite, and diabase.
Western Siberia is one of the most important economic and geographical regions of the USSR. About 14 million people live on its territory (the average population density is 5 people per 1 km 2) (1976). In cities and workers' settlements there are machine-building, oil refining and chemical plants, forestry, light and food industries. Various branches of agriculture are of great importance in the economy of Western Siberia. About 20% of the USSR's commercial grain, a significant amount of various industrial crops, and a lot of oil, meat and wool are produced here.
The decisions of the 25th Congress of the CPSU planned further gigantic growth of the economy of Western Siberia and a significant increase in its importance in the economy of our country. In the coming years, it is planned to create new energy bases within its borders based on the use of cheap coal deposits and hydropower resources of the Yenisei and Ob, to develop the oil and gas industry, and to create new centers of mechanical engineering and chemistry.
The main directions of development of the national economy plan to continue the formation of the West Siberian territorial-production complex, to transform Western Siberia into the main base of the USSR for oil and gas production. In 1980, 300-310 million will be mined here. T oil and up to 125-155 billion. m 3 natural gas (about 30% of gas production in our country).
It is planned to continue the construction of the Tomsk petrochemical complex, put into operation the first stage of the Achinsk oil refinery, expand the construction of the Tobolsk petrochemical complex, build oil gas processing plants, a system of powerful pipelines for transporting oil and gas from the northwestern regions of Western Siberia to the European part of the USSR and to oil refineries in the eastern regions of the country, as well as the Surgut-Nizhnevartovsk railway and begin construction of the Surgut-Urengoy railway. The tasks of the five-year plan provide for accelerating the exploration of oil, natural gas and condensate fields in the Middle Ob region and in the north of the Tyumen region. Wood harvesting and the production of grain and livestock products will also increase significantly. In the southern regions of the country, it is planned to carry out a number of large reclamation measures - to irrigate and water large tracts of land in Kulunda and the Irtysh region, to begin construction of the second stage of the Alei system and the Charysh group water supply system, and to build drainage systems in Baraba.
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