On the territory of the Central Black Earth Region, as well as the adjacent Bryansk Region. there are about 1140 rivers over 10 km long and a large number of ravines.
There are about 600 rivers in the Don basin, 248 in the Dnieper basin and 185 in the Oka basin. Of the total number of rivers, hydrometric observations are currently being carried out on 90 rivers, with 150 gauging stations.
Recently, it is often said that a decrease in water runoff in river basins is due to a decrease in the forest area. Naturally, the flow of water in rivers varies with the frequency of climate change, and therefore, with the amount of precipitation. Generally speaking, there is no systematic decrease in river runoff from one century to the next. The water content of rivers changes in 3-5 years, as well as in 11-year, 22-25-year and other longer periods, which were mentioned earlier. As for the general shallowing of rivers, it will not happen as long as atmospheric precipitation in the basin exceeds evaporation from its surface, and excess water will inevitably find a way to the sea, which is carried out only along the rivers. However, the redistribution of runoff throughout the year in forested basins is very different from treeless ones. In forested catchments, low-water runoff is always higher than in treeless ones.
In small drainage basins with an area of 5-10 hectares and more, surface runoff is studied in order to clarify the features of the distribution of local runoff over the earth's surface. Its essential difference from the river one is that insignificant deepening of watercourses makes it possible to intercept only surface waters. significant portion atmospheric precipitation it is filtered into the underlying horizons on gentle slopes and often wedges out into adjacent drainage basins.
A significant number of works have been devoted to the local runoff in the Central Black Earth Region. These include observations in the Kamennaya Steppe, Voronezh Region. I.P.Sukharev (1965), in the Kursk region. A.M. Green and G.V. Nazarova (1965). For a number of regions of the Central Black Earth Region, separate elements of the water balance were published by I.N. Sorokin (1965). A large amount of data on local runoff is given by V. Ya. Frolov (1965), as well as by us (1966).
Long-term observations (1933-1958) to establish the water reserves in the snow, as well as observations of the surface runoff of atmospheric precipitation were carried out in the Kamennaya Steppe. According to these observations, water reserves in snow and runoff from various forested and field catchments vary greatly both from year to year and depending on the forest cover of catchments. The smallest values of spring runoff were observed where the forest cover in the catchment reached 18% (by the way, the highest), slightly higher runoff at the Lesnaya ravine with 6% forest cover, and even more in the basin of the Ozerki ravine (3.6% forest cover). Close by natural conditions In the steppe catchment area of the Krasnaya gully, the runoff from 1935 to 1941 ranged from 4.8 mm, with a coefficient of 0.08, to 111 mm, with a runoff coefficient of 0.89. On average, it was 42.8 mm, with an average flow coefficient of 0.64.
On the large Sukhaya Chigla ravine with a catchment area of 140 km 2, the spring runoff varied from 1.8 mm in 1954 to 65.1 mm in 1951. On average, for the period from 1951 to 1958, the average runoff was 29.7 mm. In the Berezovaya gully with a catchment area of IZ km 2, the spring runoff varied from 2.1 mm in 1954 to 87 mm in 1951, averaging 36.5 mm.
In the Talovaya gully with a drainage area of 90 km 2, the average spring runoff over 8 years was 36.0 mm with a minimum of 2.4 mm in 1954 and a maximum of 78 mm in 1951. A spring runoff close to the above data was observed in the Kamenka gullies. Khorolskaya and Dubovaya.
The largest runoff was observed from the drainage basin of Bolshaya Kamenka, on average 42.8 mm, and the smallest in the drainage basin of the Sukhaya Chigla. Here the runoff is regulated by ponds, reservoirs, which trap 7-8 mm of melt water annually.
The intensity of runoff is influenced by winter conditions during periods of snow melting, freezing of the soil and its moisture content, as well as precipitation.
Runoff from small catchments of the Kursk region. taken into account by the Ukrainian Hydrometeorological Service in the basin of the river. Kur from 1946 to 1959 in the Rat stream, Tsvetovo ravines, Erokhina apiary, Polonovskiy log Blizhnyaya oak forest.
In the Tsvetovo catchment, the runoff value ranges from 7.3 to 115.7 mm, and on average over 14 years it is 42.8 mm. The average runoff coefficient for the same time was 0.82, with fluctuations from 0.10 to 0.88. The amount and coefficient of runoff in the Tsvetovo catchment is noticeably lower than on the river. Chickens, where the smallest drain is 22.7 mm, the largest is 140 mm, and the average is 66.8 mm. The runoff coefficient varies from 0.35 to 0.92, with an average of 0.73. On the Rat brook, the average runoff is 74.3, the maximum is 133.5 and the minimum is 31.3 mm, the runoff coefficient varies from 0.31 to 0.96, averaging 0.75.
Erokhin's apiary and Polonovsky Log are completely plowed up, so the runoff from these catchments is the same. An orchard is located on the drainage basin of the Blizhnyaya Oak Forest. This caused a decrease in runoff from the catchment area.
Local runoff in the Central Black Earth Region is highly irregular compared to the runoff of the river network.
The ice crust has a significant effect on the spring runoff in the field. The runoff in areas covered with an ice crust is, on average, four times greater than in the absence of it.
Fluctuations in the weather conditions in autumn, winter and spring have a significant effect on the amount of runoff. In high-water years, the runoff is usually higher, and in low-water years it is greatly reduced.
At the Nizhnedevitskaya sewage station of the Voronezh region. surface runoff was studied in several streams. At the Desniansky drainage station, Mogilev region. the runoff layer and the runoff coefficient in the treeless Lipino ravine also vary from year to year.
In this case, the largest runoff layer in the Desnyanskaya station coincides with the largest runoff layer in the Voronezh region.
In the Tellermanovsky experimental forestry of the Laboratory of Forest Science of the USSR Academy of Sciences, located 10 km from the city of Borisoglebsk (Voronezh region), the study of runoff in various types of forest was carried out in connection with a change in the percentage of forest cover width.
Clear-cuttings have been carried out in catchment areas of various areas:
1) all over the entire catchment area of 2.5 hectares
2) on 49% of the catchment area equal to 3.25 hectares
3) 20% of the catchment area equal to 146.7 hectares
4) on 9% of the catchment area, equal to 878.3 hectares
5) for comparison, under identical conditions, a control catchment with an area of 129.62 hectares was selected, on which no felling was carried out. There was also a field catchment area - 25.12 hectares.
All of these catchments are characterized by hilly relief, mostly covered with dark gray soils with insignificant participation of areas with residual solodized and solonetz soils.
Water reserves in snow in the field (drainage basin No. 1) before the beginning of snow melting were 1.6-1.9 times less than in clear-cut areas 50-100 m wide in drainage basins No. 2 and 3. In drainage basin No. 5, covered with sedge oak forests -sludge group, and partly in the solonetz oak forest, water reserves in the snow are 138 mm, and in clearings 100-200 m wide and 1000 m long (catchment No. 1) 153 mm. In stands not cut by felling (catchment no. 6), they were expressed in 150 mm.
The increased runoff coefficient in drainage no. 7 in comparison with catchment no. 5 with forest cover of 9% is caused by a significant number of stands confined to solonetz oak forests located on the southern and southwestern slopes of the Krutets gully. On the surface of solonetz and residual solodized soils associated with solonetz oak forests, the surface runoff is much more intensive.
On the steep slopes of clearings, where before logging operations, the stand of linden-sedge oak forests grew, the surface runoff of melt water in spring (according to the runoff site) averaged 744 mm, and the runoff coefficient was 0.50.
On the southern slopes, occupied by euonymus and solonetz oak forests before felling, the surface runoff after felling was equal to the surface runoff in a solonetz meadow covered with grass vegetation.
The data are eloquent evidence of the enormous influence of vegetation on the distribution of precipitation. Treeless areas occupied by pasture for livestock, as well as saline meadows without cattle grazing, give rise to a high layer and coefficient of spring runoff. Slightly less runoff from catchments and slopes of the gully after felling (runoff coefficient 0.71 - 0.75).
The increase in the forest cover of the drainage basin is strongly reflected in the decrease in the runoff layer. When clearing only 49% of the catchment area, the runoff coefficient is 0.34, and when 20% of the area is cleared, it drops to 0.15.
On solonetz soils, with a decrease in forest cover to 45%, the runoff coefficient reaches 0.58, and with a forest cover of 80%, it decreases to 0.21.
In the summer period, the average annual runoff layer and its coefficient are very insignificant.
The highest runoff layer on dark gray forest soils was observed in catchment no. 3, where a spring flows continuously. The second largest runoff layer is occupied by treeless catchment No. 1, where runoff, however, is much less. The rest of the catchments were characterized by a very low layer and runoff coefficient in summer.
The average annual runoff is highest in catchment no. 3 with deforestation on 49% of the area. In this catchment, runoff is not interrupted all year round, even in dry years. On catchment No. 1, occupied by pasture for livestock and arable land, the runoff layer reaches 79 mm, the runoff coefficient is 0.15. Drainage basin No. 2, where the entire forest was cut down, is close to the treeless catchment area. On the rest of the catchments with dark gray forest soils, the runoff coefficients vary within the range of 0.02-0.06.
On solonetz soils, runoff is more closely related to the percentage of forest cover in catchments. A larger runoff, as expected, is confined to a solonetz glade (catchment no. 8), where, with an average runoff layer of 122 mm, the runoff coefficient was 0.23. The largest values of the layer and the runoff coefficient (181 mm and 0.67) were obtained at the drainage area of catchment no. 11.
On catchment No. 9 with a solonetz meadow, bordered by oak stands at the top and bottom, 82 mm of precipitation flows annually with a runoff coefficient of 0.16. On catchment No. 10, consisting of a solonetz meadow and covered in the rest of the area with oak stands of IV-V bonitet, the runoff layer is 32 mm, and the runoff coefficient is 0.06.
At the end of 1952, in the upper reaches of catchment No. 4, the south of oak forests was cut down, in 1953, clear felling was carried out on 7 hectares in the lower reaches of the same catchment, and in the spring of 1959 3 hectares of Aspen stands were ringed in the middle part of the catchment area.
Drainage basin No. 2 with an area of 2.5 hectares of oak stands at the end of 1954 was completely cut down, and drainage basin No. 3 with an area of 3.25 hectares, also occupied by oak stands, in 1957 was cleared on 49% of the area.
Catchment No. 5 with an area of 878.3 hectares until 1959 was covered by clear felling on an area of 9%. Most of the clearings are confined to the headwaters and southern slopes of the catchment area. On catchment no. 7 with an area of 134.6 hectares in the middle part of it in 1959, aspen was ringed and cut down completely after the withering away in 1962.
Watersheds 1 and 6 were control, the first of them is 70% occupied by pasture for livestock and 30% by arable soil, and the second remained completely forested.
On catchment no. 2, after the felling of the stand in 1954, the water runoff layer sharply increased both in comparison with the field catchment area and in comparison with the control forest catchment no. - more than 22 times.
In the first spring after felling, the felling area was covered with leaf litter. The grass cover develops only at the end of summer. Of the total amount of water in the snow, 30% is absorbed by the soil. In the second year after felling, the mass of the grass cover increases sharply, the penetration of melt water into the soil exceeds 40% of the water reserves in the snow. In the third summer, the mass of the grass cover becomes maximum and the penetration of precipitation into the soil reaches 35%. The water runoff layer after cuttings increases for five years, then drops sharply due to the soil covering not only by grass cover, but also by tree growth. Further changes in runoff in catchment No. 2 changed due to changes in water reserves in the snow, as well as in connection with evapotranspiration of woody vegetation, the growth of which increased from 1.6 m 3 / ha per year in 1954-1958. up to 3.9 m 3 / ha per year from 1962 to 1966 thinning was not carried out in the catchment area No. 2.
On catchment no. 3 from 1952 to 1957, inclusive, observations of the runoff were carried out under conditions of complete afforestation of the catchment. In the winter of 1957, oak stands were cut down on 49% of the area located in the lower part of the catchment area. This operation did not fail to influence the change in flow. In 1958, the runoff increased sharply, and then after five to six years it began to fall until intensive thinning was carried out again in 1963, which in 1964 caused a new rise in runoff in the catchment area. The effect of clearcutting on an increase in surface runoff lasts up to five to six years, if the water reserves in the snow do not sharply increase in some years.
In 1952, on drainage basin No. 4, clear felling was carried out on an area of 10 hectares in the upper reaches of the catchment, in 1953 - on 7 hectares in the lower reaches of the catchment, in 1957-1958. - in the lower reaches of the catchment area for 6 hectares, and then in 1959-1960. again in the headwaters of the catchment area on an area of 6 hectares.
The most dramatic effect on the change in the runoff layer is provided by clearcutting of forests in the lower reaches of the catchment. Under the influence of felling, the runoff layer from the catchment area increases for five to six years, then decreases as the young stands close in the felling. A particularly sharp decline is observed four to five years after clear felling. Carrying out measures to clarify young stands causes a new, but more short-term increase in runoff. Naturally, the water content in the snow also has a significant effect on the change in runoff, which in the drainage basin No. 4 is characterized by the following data:
However, as the comparison shows, the leading role is played by all deforestation, therefore, forestry methods can significantly change and regulate water supplies in the catchment.
In drainage basin No. 7, where 9% of the area has been cleared in different parts of it, there is no close relationship between the felling time and the runoff layer. But the runoff layer here increased in the years following the ringing of the aspen. This is evidenced by the reserves of water in the snow given below.
Before considering surface and wedging-out groundwater runoff in summer, it should be noted that in oak forests cut by beams, springs are often found that form from groundwater... There are eight such keys on the Krutets beam alone. All of them operate in winter and throughout the summer period with varying intensity. Some of them were included in the objects of our research. These springs increase the water runoff layer in the summer. They are found in drainage basins 3, 4, 5 and 7. In drainage basins 2 and 4, runoff is observed only in spring and early summer, despite the fact that the spillways are located below those catchments where runoff is observed throughout the summer.
Drainage basin no. 3 catches groundwater at the bottom of a ravine located at a depth of 17.2 m from the surface of the elevated plains. Catchment No. 4 catches water wedging out from a depth of 31.4 m from the surface of the elevated plains, and catchment No. 1, located in a treeless area, feeds on water only due to atmospheric precipitation, although the bottom of the gully at the spillway is located at a depth of 35 m from the surface of the elevated plains.
Drainage basin No. 7 is cut by a gully at a depth of 128.46 m or below the plain located at an altitude of 145.95 m above sea level.
The largest runoff layer was observed in drainage basins fed by groundwater. In the first place in terms of the amount of wedging out water is drainage basin No. 3. Here, in summer, the runoff is expressed in 94.9 mm, with a runoff coefficient of 0.45. The second place is occupied by a treeless catchment. It annually throws out a runoff layer of 15.4 mm in summer, with a coefficient of 0.08. Catchment No. 4 discharges 10 mm from the groundwater, or 4% of the total amount of summer precipitation. Catchment No. 7 of spring waters ejects only 3.5 mm over the summer, and the rest is less than 3 mm.
The given data give grounds to assert that atmospheric precipitation in the process of snow melting penetrates deeply into the ground and feeds the springs that emerge at the bottom of the ravine at a depth of 18 to 30 m from the surface of the surrounding hills. Thus, in the forest-steppe zone, water penetration through the soil and ground is quite possible. At the same time, in the southern steppe regions of our country, where precipitation falls much less than it evaporates, groundwater does not penetrate into the ground everywhere. In the forest zone, in contrast to the forest-steppe, groundwater recharge atmospheric precipitation occurs more intensively.
Groundwater wedging out has a significant effect on the change in runoff in individual drainage basins. This is especially pronounced in drainage basin No. 3. Here, due to groundwater, the runoff layer sharply increases in comparison with drainage basin No. 2, in which the forest is completely cut down over its entire area, and groundwater does not pass through the weir. Their pinching out to the day surface was never noticed. The difference in runoff between the aforementioned catchments reaches 122 mm.
As a result of the studies carried out in the forest-steppe zone, it can be said that under the influence of clear cuttings, the runoff layer in the catchment areas increases for five to six years, and then sharply decreases due to the increase in the density of woody and herbaceous vegetation.
In the steppe zone, hydrological studies were organized in 1955 at the Derkul Scientific Research Station of the Institute of Forestry of the USSR Academy of Sciences (Lugansk region). Spring runoff for 1955-1957 expressed here in the following figures.
The largest spring runoff layer was observed in 1956. In a drainage basin with a forest cover of 4%, it reached 116.0 mm, in a catchment with a forest cover of 7% - 60.4 mm, and with a forest cover of 10% - 35.6 mm. Such sharp differences are caused by unequal lowering of the erosion baseline. In 1957, the runoff layer in unplowed catchments with a forest cover of 7% does not exceed 25 mm. On the plowed catchment area - 11.9 mm, and on the others it is less - 1 mm. In 1955, the runoff layer in a weakly forested catchment was 13 mm, with 7% forest cover - 7.8 mm and with 10% - 5.6 mm.
Fully forested catchments absorb almost all of the spring runoff. Summer runoff is almost absent. Surface runoff primarily depends on the amount of winter precipitation. In summer, surface runoff occurs only during the period of heavy rains. With rainfall of 42 mm, the surface runoff coefficient, with a forest cover of 4%, was 0.03, and with 7% - 0.01. There was no drain in the forest.
In the steppe zone, in the process of spring snow melting, water penetrates up to 5 m, while in the forest-steppe zone near Borisoglebsk it penetrates through the entire thickness of loess-like loams to a depth of 18-20 m.
If you find an error, please select a piece of text and press Ctrl + Enter.
Twunnine Sep 06 2015
Answer 1:
Steppe zones of temperate zones - natural areas with a predominance in the natural landscapes of the steppes, located mainly in the inland regions of the temperate zones of the Northern and Southern hemispheres.
The steppe zones of temperate zones are characterized by:
- dry continental climate; droughts are frequent;
- amount of precipitation - 200-450 mm per year.
- surface runoff is insignificant;
- soils are mainly black earth, in dry areas - dark chestnut and chestnut.
- vegetation - perennial grasses, forbs.
Random exercise:
Russian language: Help write an essay: Portrait sketch (for example, a friend at work) plz very
necessary)
Answer 1:
They say that a person can be identified by a face. I have a school friend. His face is always affable, benevolent. He looks like an ordinary guy. He's thin. His forehead is high, his black hair is always cut short. The nose is straight. Wide black eyebrows, from under which large brown eyes with a reddish color look. He has a kind, childish look, but if he feels injustice, then the look changes dramatically, his eyes become angry and piercing. My friend is of average height, strong, dexterous, enduring, because he is constantly engaged in Karate.
Twunnine Sep 06 2015
salt?
Solution 1:
80 —-100%
?——9%
80 * 9 \ 100 = 7.2 g of salt
7,2 ——6%
?——100%
7.2 * 100 \ 6 = 120 g solution
120-80 = 40 g of water to be poured
Solution 2:
80 × 6% = 480
480/9=53,33
answer: 53.33
Random exercise:
Literature: Who wrote the story "when necessary" about an oak and a hare
Solution 1:
Kozlov Sergey Grigorievich
Solution 2:
S.G. Kozlov
_______________-
Twunnine Sep 06 2015
Solution 1:
North - Cape Galinas 12 ° 25 ′ N, 71 ° 39 ′ W
South (mainland) - Cape Froward 53 ° 54 ′ S, 71 ° 18 ′ W
South (island) - Diego Ramirez 56 ° 30 ′ S lat. 68 ° 43 ′ W
Western - Cape Parinyas 4 ° 40 ′ S, 81 ° 20 ′ W
Eastern - Cape Cabo Branco 7 ° 10 ′ S, 34 ° 47 ′ W
Solution 2:
m parinias 4yu.sh 82w.d.
m galinas 12 or 13 N 72 W
m Kaboo Branco 7 S 36 W
m Frauard 54 S 72 W
Random exercise:
Physics: the taken off plane, rising to an altitude of 11 km, picks up speed of 900 km / h. Compare the kinetic and potential energies acquired by the plane: what
more of them and how many times?
Solution 1:
Do not forget to convert numbers to SI (11km = 110000m, 900km / h = 3240m / s)
Kinetic:
Potential:
The kinetic is approximately 47.7 times larger.
Twunnine Sep 06 2015
Dec. 1:
These are just sketches, I got a 5 for it)
The adults weren't that different from the kids. They called Yushka “blessed”, “animal”. Because of Yushka's meekness, they became even more bitter, they often beat him. Once, after another beating, the daughter of the blacksmith Dasha asked in her hearts why Yushka lived in the world at all. To which he replied that the people love him, the people need him. Dasha objected that people beat Yushka to blood, what kind of love it is. And the old man replied that the people love him "without a clue", that "the heart in people is blind." And then one evening in the evening a passer-by clung to Yushka and pushed the old man so that he fell on his back. Yushka didn’t get up anymore: the blood went from his throat and he died.
The author urges us not to harden, not to harden our hearts. Let our heart "see" the need for every person on earth. After all, all people have the right to life, and Yushka also proved that he had not lived in vain.
Random exercise:
Literature: Please help with the work A Hero of Our Time based on the story of Princess Mary: Relations between Pechorin and Grushnitsky
Dec. 1:
They initially had a mutual dislike, tk. Pechorin understood the character of Grushnitsky, and he, in turn, guessed about it. But. they tried not to show their face and outwardly were friends. After the appearance of Princess Mary, this hostility grew into open enmity, which resulted in a duel.
Dec. 2:
From the outside, it seemed that Pechorin and Grushnitsky were very good friends, but in fact they hated each other. As Pecherin said, "I feel that someday we will run into him on a narrow road, and one of us will be uncomfortable." This hatred originated from different views on life. Pechorin lives with intelligence and reason, and Grushnitsky is a dreamy and false person.
Twunnine Sep 06 2015
Option 1:
O _________ S ____________ M
Random exercise:
Maths: Klava has 2 more candies than Marina, and Zina has 2 fewer candies than Marina. how to make all sweets
equally
Option 1:
x-marina
x + 2-claudia
x-2-zina
Klava must give Zina 2 candies
Arctic belt - the northernmost geographic zone Land that includes most of the Arctic. The border of the Arctic belt is usually drawn along the isotherm 5o From the warmest month (July or August).
The Arctic belt is characterized by negative or small positive values of the radiation balance, the dominance of the Arctic, a long polar night, low and surface ocean waters... The seas of the Arctic belt are characterized by stable ice cover.
On land, the Arctic zone includes a zone arctic deserts... The flora is poor, has a mosaic distribution. The life of animals (polar bears, walruses, seals) is associated with the sea. Birds nest on the islands in summer.
The Antarctic belt is the southern natural geographic belt of the Earth, including Antarctica with adjacent islands and the ocean waters washing it.
Usually, the border of the Antarctic belt is drawn along the 5o isotherm from the warmest month (January or February).
The Antarctic belt is characterized by: negative values of the radiation balance, the Antarctic with low temperatures air, long polar night, significant ocean ice coverage.
Antarctic deserts prevail on land. In the oases and on most of the islands, there is moss and lichen vegetation. Animal world not rich.
The Subarctic Belt is a natural geographic belt in the Northern Hemisphere between the Arctic belt in the north and the temperate belt in the south. The subarctic belt includes tundra and forest-tundra zones.
The subarctic zone has a cold climate; most of the atmospheric precipitation falls in solid form, the snow cover lasts 7-8 months. For subarctic belt permafrost and associated forms are characteristic.
The tundra zone is a natural land area, mainly in the Northern Hemisphere between the zones of forest-tundra and arctic deserts in Russia, Canada and the USA (Alaska). Tundra zones are characterized by strong swampiness, wide distribution, tundra-gley soils. The vegetation cover is dominated by lichens, mosses, low-growing grasses, shrubs and shrubs. In the summer, a huge number of migratory birds fly to the tundra. Both birds and animals are awake for a significant part of the day in conditions of a long polar day. In winter, birds leave the tundra, animals migrate to more southern regions. Some inhabitants of the tundra, for example, lemengi rodents, spend the winter under, many animals have warm fur.
Temperate zones - geographic zones of the Earth located in temperate latitudes:
- in the Northern Hemisphere - between the subarctic and subtropical belts: from 65o N. up to 40o N;
- in the Southern Hemisphere - between the subantarctic and subtropical belts: from 58o S. up to 42o S
The temperate zones are characterized by a clear seasonality of the thermal regime with a long snowy winter with the formation of a snow cover on land and a significant weakening or termination of plant vegetation in winter.
In the natural landscapes of temperate zones in Eurasia, coniferous, mixed and deciduous forests, forest-steppe, steppe, semi-desert and desert are successively replaced from north to south.
In the taiga, conifers have adapted to harsh conditions - they can withstand prolonged cold and lack of water. The taiga forest has more favorable conditions for the life of animals in comparison with the tundra. There are many fur animals.
Zone mixed forests is transitional between coniferous and deciduous forests. It is characterized by a combination of broad-leaved, small-leaved and coniferous trees.
A special zone is represented by monsoon forests Of the Far East that are diverse flora, an abundance of vines and layering.
Deciduous forests are formed by trees with falling leaves. The forests have varied undergrowth and dense grass. There are many ungulates, animals, birds, leaf-eating insects.
Steppes are herbaceous communities, represented by grasses with an admixture of heavily pubescent dicotyledonous plants. Nowadays, most of the territory of the steppe zones of the temperate zone is plowed up. Steppe is the habitat of ungulates, rodents, predators, birds nesting on the ground.
Subtropical zones - natural geographic zones of the Northern and Southern Hemispheres, approximately between 30o and 40o N. and south latitude, between temperate and tropical zones. The subtropical zones are dominated by a subtropical climate.
Subtropical zones are distinguished by the alternation of temperate (winter) and tropical (summer) air masses determining different temperatures and humidity. Thermal conditions allow year-round vegetation of plants.
Within the land of the Northern Hemisphere, the amount of atmospheric precipitation and their regime change significantly from oceanic regions to inland regions, which, combined with an increase in the continentality of the climate in the same direction, determines significant landscape differences and the formation of:
- zones of subtropical evergreen forests and shrubs (Mediterranean zone);
- zones of subtropical monsoon mixed forests;
- forest-steppe zones;
- zones of subtropical steppes;
- subtropical semi-deserts;
- subtropical deserts.
Mediterranean hard-leaved forests and shrubs are common in areas where temperatures in winter can drop to + 10o- + 5oC, but frost, as a rule, does not happen. This area is characterized by evergreen trees, a variety of conifers, shrubs with hard leathery leaves that secrete essential oils.
Tropical zones - natural geographic zones of the Northern and Southern Hemispheres, mainly from 20o to 30o N. and y.sh. between the subtropical and subequatorial belts.
The tropical zones are characterized by the predominance of trade wind circulation, which contributes to the formation of hot and dry tropical climate... In tropical zones, temperatures are constantly high, with less than 200 mm of precipitation per year. Wet and dry seasons are distinguished in the eastern sectors of the continents.
On land, semi-deserts and deserts prevail, in more humid places, savannas and deciduous forests prevail.
Semi-desert zones are natural zones in which natural landscapes are dominated by semi-deserts. Semi-desert zones occupy an intermediate position:
- between zones of deserts and steppes in temperate and subtropical zones;
- between zones of deserts and savannas in the tropical zone.
Semi-arid zones are common on all continents, except for Antarctica, mainly in the western oceanic and inland sectors.
Semi-desert zones are characterized by a dry continental climate with an annual precipitation usually not exceeding 300 mm. Surface runoff is small, rivers usually dry up in dry seasons. The vegetation of semi-desert zones is usually sparse, with a predominance of grass-wormwood communities, perennial grasses and shrubs.
Semi-desert zones are common in the temperate zone of the Northern Hemisphere, subtropical and tropical zones of the Northern and Southern Hemispheres.
Desert zones are natural zones in which natural landscapes are dominated by deserts. Distributed in the temperate zone of the Northern Hemisphere, subtropical and tropical zones of the Northern and Southern Hemispheres.
In desert zones, the climate is extremely dry, with annual precipitation below 200-250 mm. Vegetation - herbaceous and dwarf shrubs, sparse, covers only a small part of the surface, in the most arid conditions it is practically absent. Plants have a variety of moisture-saving devices. Many ephemeroids are plants with a short growing season. Among the animals there are many nocturnal and twilight species, which spend all the hot time in burrows and shelters. Some desert dwellers have a brisk run for long distances.
Zones rainforest- natural zones of the eastern sectors of the continents within the tropical zones of the Northern and Southern Hemispheres with a predominance of tropical forests in the landscapes.
Rainforest zones are common in southern Florida, West Indies, Central and South America, on the Indochina peninsula, the island of Madagascar, in Australia, on the islands of Oceania and the Malay archipelago; occupy mainly the windward slopes of mountainous areas. The climate is tropical humid or seasonally humid with a predominance of humid oceanic trade winds. The subzone of permanently moist forests is dominated by evergreen forests with exceptional species diversity on red-yellow lateritic soils. The zones of tropical forests are characterized by a thick weathering crust, intense runoff; in the subzone of seasonally moist forests, along with evergreen forests, deciduous forests on red ferallite soils are widespread.
Subequatorial belts are natural geographic belts of the Northern and Southern Hemispheres between the equatorial and tropical zones. Climate subequatorial belts characterized by the dominance of equatorial monsoons with dry winters and wet summers, constantly high temperature... On land, there are zones of savannas and woodlands and subequatorial monsoon mixed forests.
Savannah zones are natural zones, mainly in subequatorial zones, less often in tropical and subtropical zones. Widely distributed in Africa (40% of the territory), there are in South and Central America, Asia, Australia. The climate is seasonally humid, with a clear change between dry and rainy periods.
In the savannah zones, the duration of the rainy period ranges from 8-9 months (at the equatorial borders of the zones) to 2-3 months (at the outer borders). Parallel to the decrease annual quantity Precipitation changes the vegetation cover from tall-grass savannas and savanna forests on red soils to deserted savannas, xerophilic woodlands and shrubs on brown-red and red-brown soils. The abundance of plant food brings with it a variety of herbivores and a variety of carnivores. The alternation of wet and dry periods causes seasonal migrations of animals.
Subequatorial monsoon forest zones are natural subequatorial zones in Central and South America, Africa, southern Asia and northeastern Australia. In these zones, the climate is characterized by the dominance of equatorial monsoons. The dry season lasts 2.5-4.5 months. The soils are red-colored lateritic.
Equatorial belt - the geographic belt of the Earth, located on both sides of the equator: from 5o - 8o N. up to 4o - 11o S For equatorial belt characterized by constantly hot and humid equatorial climate due to the large influx. Climatic seasons not expressed or poorly expressed. For equatorial forests characterized by a great variety of species, multi-tiered, the absence of shrubs and grasses. The trees are evergreen, bloom and bear fruit all year round. Many animals spend their entire lives among the branches of trees. On the surface of the soil, either very small animals can live, or large ones, easily making their way among the dense forest thickets.
Site search.
- water discharge - the volume of water flowing per unit of time through the flow area of the river. It is usually expressed in m3 / s. Average daily water flow rates allow determining the maximum and minimum flow rates, as well as the volume of water flow per year from the basin area. Annual runoff - 3787 km and - 270 km3;
- drain module. It is called the amount of water in liters, flowing per second from 1 km2 of the area. It is calculated by dividing the amount of runoff by the area of the river basin. The tundra and rivers have the largest module;
- runoff coefficient. It shows what proportion of precipitation (in percent) flows into the rivers. The rivers of the tundra and forest zones have the highest coefficient (60-80%), in the rivers of the regions it is very low (-4%).
Loose rocks - foodstuffs - are carried away by the runoff into the rivers. In addition, the (destructive) operation of rivers also makes them a supplier of unconsolidated ones. In this case, a solid runoff is formed - a mass of suspended, carried along the bottom and dissolved substances. Their number depends on the energy of the moving water and on the resistance of the rocks to erosion. Solid runoff is divided into suspended and bottom, but this concept is conditional, since when the flow rate changes, one category can quickly change into another. At high speed, the bottom solid runoff can move in a layer up to several tens of centimeters thick. Their movements are very uneven, since the speed at the bottom changes sharply. Therefore, at the bottom of the river, sandy and rifts can form, which impede navigation. The turbidity of the river depends on the value, which, in turn, characterizes the intensity of erosional activity in the river basin. V large systems river solid runoff is measured in tens of millions of tons per year. For example, the runoff of elevated sediments of the Amu Darya - 94 million tons per year, the Volga river - 25 million tons per year, - 15 million tons per year, - 6 million tons per year, - 1,500 million tons per year, - 450 million tons per year, Nile - 62 million tons per year.
Flow rate depends on a number of factors:
- primarily from. The more precipitation and less evaporation, the more runoff, and vice versa. The amount of runoff depends on the form of precipitation and their distribution over time. The rains of the hot summer period will give less runoff than the cool autumn ones, since the evaporation is very high. Winter precipitation in the form of snow will not give surface runoff during the colder months; it is concentrated during a short period of spring floods. With an even distribution of precipitation in a year, the runoff is even, and sharp seasonal changes in the amount of precipitation and the amount of evaporation cause uneven runoff. With prolonged rains, the seepage of precipitation into the ground is greater than with torrential rains;
- from the terrain. When the masses rise along the slopes of the mountains, they cool, as they meet with colder layers, and water vapor, therefore, the amount of precipitation here increases. Already from insignificant heights, there is more runoff than from adjacent ones. So, on the Valdai Upland, the flow module is 12, and in the neighboring lowlands - only 6. There is an even greater volume of flow in the mountains, the flow module here is from 25 to 75. mountain rivers in addition to an increase in precipitation with height, there is also a decrease in evaporation in the mountains due to the lowering and steepness of the slopes. Water flows down quickly from highlands and mountainous areas, and slowly from lowland areas. For these reasons, lowland rivers have a more uniform regime (see. Rivers), while mountain rivers react sensitively and violently to;
- from the cover. In zones excessive moisture the soils are saturated with water for most of the year and give it to rivers. In zones of insufficient moisture during the snow melting season, soils are able to absorb all the melt water, therefore, the runoff in these zones is weak;
- from vegetation. Research recent years carried out in connection with the planting of forest belts in, indicate their positive effect on runoff, since it is in forest areas more significant than in the steppe;
- from influence. It is different in areas of excessive and insufficient moisture. Swamps are runoff regulators, and in the zone their influence is negative: they suck in surface and water and evaporate them into the atmosphere, thereby disrupting both surface and underground runoff;
- from large flowing lakes. They are a powerful regulator of the flow, however, their action is local.
From the above summary of the factors affecting runoff, it follows that its magnitude is historically variable.
The zone of the most abundant runoff is, the maximum value of its module here is 1500 mm per year, and the minimum is about 500 mm per year. Here, the runoff is evenly distributed over time. The largest annual flow in.
The zone of minimum flow is the subpolar latitudes of the Northern Hemisphere, covering. The maximum value of the runoff module here is 200 mm per year or less, with the largest amount occurring in the spring and summer.
In the polar regions, the runoff is carried out, the thickness of the layer in transfer to water is approximately 80 mm in and 180 mm in.
On each continent there are areas from which the discharge is carried out not into the ocean, but into inland water bodies - lakes. Such areas are called areas of internal flow or closed drainage. The formation of these areas is associated with the fallout, as well as with the remoteness of the inland territories from the ocean. The largest areas of internal drainage areas fall on (40% of the total territory of the mainland) and (29% of the total territory).
Water balance equation.
runoff coefficient
more than 2000 mm ).
198 mm 26.3 thousand m 3
turbidity almost up to 12000 g / m 3
Russian river network
more than 2 million 6.5 million km
Data Avanta +
drainage basin,watershed.
Inland water bodies
The number of inland natural reservoirs (lakes) on the territory of Russia does not lend itself to accurate counting and is estimated at more than 2 million (the number of rivers is the same); according to this indicator, Russia is in one of the first places in the world.
What is considered a lake?(low-threshold problem; example of secondary lakes in large raised bogs). [In Norway there are more than 210 thousand lakes with an area of 1 hectare, in Sweden - more than 83 thousand, in Finland more than 55 thousand - Nature of the North. Europe, 2001]. In Russia, mainly (95%) these are small reservoirs with an area of up to 1 km 2. About 140 lakes have an area of over 100 km 2 (Avanta +).
The average 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 exogenous processes. The total lake area of the territory, other things being equal, depends on the degree of its moisture content (climatic factor).
One of the main lake areas - " Lake District»- The North-West of the Russian Plain, together with the eastern edge of the Baltic Shield, coincides with the area of the last glaciation. It is here that Great European lakes(Ladoga, Onego, Ilmen, Saima; this group also includes Lake Peipsi and Pskov). There are many residual postglacial lakes, which often fill deep basins of various genesis, are supported by an excessively humid climate and the youthfulness of the river network, which did not have time to completely drain the postglacial reservoirs. In general, the lake area is more than 10%, in some areas it exceeds 20%.
Tundra and forest-tundra have a lake area of 5-10%.
The subarctic, as well as taiga permafrost landscapes, developed on a thick layer of loose Quaternary sediments (on the Kolyma-Indigirskaya, Leno-Vilyui lowlands, etc.) abound in small (tens - hundreds of meters across) shallow rounded lakes filling thermokarst depressions and sometimes occupying up to half of the territory. [According to Milkov and Gvozdetsky, the lakes in the areas of the Lena-Vilyui (Central Yakutsk) plain reaches 25%].
Lakes are very abundant (mainly secondary, formed during the development of swamp massifs) bogs of the taiga zone Zap. Siberia.
An outwardly similar picture is observed in the southern, forest-steppe and steppe parts West Siberian Plain , where vast practically endless interfluvial spaces are dotted with shallow lakes confined to flat depressions of suffusion and, apparently, relict thermokarst nature. The water of these lakes is often mineralized.
All lakes are "mortal" (they have an initial and final date of existence). The main "enemy" of lakes is the rivers that produce erosional work. In addition, the depressions of the lakes are gradually filled with mineral and organic matter, waterlogged and overgrown.
Outside the border of the last glaciation, in the area of maximum glaciation, the lacustrine content 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 old water bodies in river floodplains ( lakes less than 1%). [For example, in Udmurtia, almost all reservoirs are artificial "ponds" - reservoirs].
The number of lakes is negligible within the part of the Central Siberian Plateau that has not been subjected to glaciation.
In the Far East, the Caucasus, Altai and the Sayan Mountains, the lacustrine content does not exceed 1-2% (predominance of mountainous relief, strong erosion).
Only 9 lakes (including the Caspian Sea) have an area of more than 1,000 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 inflow of river (partly also ground) waters and atmospheric precipitation, and, accordingly, is spent on river runoff from the lake and evaporation, maintaining the water balance of water bodies.
Near Baikal time of complete water exchange is 330 years old, Lake Ladoga- 11, at Onega - 13.
Characteristics of (natural) lakes in Russia with an area of more than 1,000 km 2
Geogr data encyclopedia. dictionary (1988), Atlas of Russia (1998), A.G. I. (Ecological Geography of Russia), National Atlas of Russia, vol. 2 (2006)
For comparison: the area of the country's largest Kuibyshev reservoir (6.5 thousand km 2) would occupy the fifth row in this table.
Mineralization of river and lake waters and their chemical composition (map)
They depend on the composition of the drained rocks, but to a large extent they are subject to the climate, moisture and, accordingly, the intensity of the processes of dissolution, leaching and washing of soils and grounds. Therefore, in the spatial variability of chemistry surface waters first of all, the zoning is striking.
In the zone of excessive moisture, due to the abundance of precipitation, intensive runoff, the drained strata are quickly freed from readily 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 of 25–50 mg / l; during the summer and especially winter low-water period, when mineralization is due to groundwater feeding, it increases to 200–300 mg / l. Against the general zonal background, anomalies associated with the geological basement are observed (for example, a low content of soluble salts in the surface waters of the Baltic Shield: 20–50 mg / l during low water). As the total moisture decreases, the salinity 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 an increase in mineralization, the ionic composition of surface waters changes. In areas of excessive moisture, they are free of readily soluble salts and are predominantly hydrocarbonate-calcium; in zones of insufficient moisture, the predominance passes to waters of the sulfate and then chloride classes; sodium dominates among the cations. In excessively humid zones, water contains more organic matter, as well as iron, than in areas of insufficient moisture.
Lakes with mineralization less than 1000 mg / l (1 g / l) are considered insipid, with mineralization 1-35 g / l - salty and with a mineralization of more than 35 g / l - salty(higher than the average salinity of the World Ocean). Among the mineralized lakes stand out soda(Kulunda), sulfate, chloride(Baskunchak, Elton).
Marshes Map of Russia (NAR)
Depending on the conditions of water and mineral nutrition, bogs are subdivided into:
Eutrophic (lowland)
Mesotrophic (transitional)
Oligotrophic (riding)
The distribution of bogs over the territory of the country has a distinctly expressed zonal-sectoral nature; it is also associated with the nature of the relief of the territory and the tendency of neotectonic processes.
More than 80% of all bogs in the country are concentrated in the taiga zone.
Zap. Siberia is the most swampy region 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 wetlands in flow regulation is controversial(in periods of excess moisture, swamps discharge excess water into rivers, in summer with insufficient moisture, on the contrary, they retain moisture in a peat deposit) .
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 form in active water exchange zone the very top crust directly as a result of filtration of atmospheric precipitation and form the first from the surface a horizon of groundwater, mainly non-pressurized. Groundwater usually occurs above the incision level of the river network, as well as the water level of lakes, which ensures their unloading and water exchange in water-bearing rocks (mostly Quaternary). Constant water exchange leads to low groundwater salinity, which increases with depth as water exchange becomes more difficult.
Groundwater is distributed everywhere, but it is extremely uneven in abundance and quality, obeying the diversity of landscapes.
Latitudinal zoning groundwater:
decreases from north to south water cut the upper stratum of rocks in the zone of free water exchange;
increases burial depth groundwater;
their mineralization and rigidity(content of calcium and magnesium ions), regularly changes chemical composition;
the temperature rises (at the same depths);
the content of organic impurities decreases (to zero)(i.e., the degree of leaching is weakened).
In the zone of excessive atmospheric moisture, groundwater is fresh, mainly hydrocarbonate-calcium, in the zone of insufficient moisture it becomes brackish and salty, salinity reaches 3–10 g / l, and in some places and 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 for a long time (from several years to millennia) are in a cooled state at temperatures below 0 ° C (polygonal-veined ice, ice cores of peat mounds, ice intrusions, etc.)
To the area permafrost includes more than half of the territory of Russia (the total area of frozen rocks is about 11 million km 2), in the distribution of mm. are clearly manifested longitudinal and climatic factors.
Southern border island permafrost area(see the corresponding maps in the Atlas of the USSR) runs parallel to the coast Barents Sea through the Kola Peninsula, further sub-latitudinally close to the North. the polar 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, Mountain Altai and Kuznetsk Alatau(excluding the Minusinsk Basin), leaving the state. border of Russia. In the Far East from m. the Amur region is free (the southern border of the metro station is almost parallel to the Amur, to the north of it at a distance of an average of 200 km, crossing the state border above the confluence of the Zeya), Primorye (except for the upper Sikhote-Alin), Sakhalin, Kuril Islands and the Kamchatka plain (along the coasts The Sea of Okhotsk and The Pacific southern border of m.m. rises to 57-58 ° N
Southern border areas of continuous permafrost(there are different options for carrying out): from Pai-Khoya passes near the Arctic Circle to the Yenisei, then near Nizh. Tunguska, to the upper reaches of the Vilyui, Yakutsk and Okhotsk; from Magadan to Anadyr Bay.
Maximum thickness (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 (cited from Gvozdetsky and Milkov), in some parts of the Lena-Vilyui interfluve, the permafrost thickness exceeds 1000 m.
On Kola Peninsula the thickness of the frozen layer is less than 25 m; on 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 soil: 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 aquiclude, often causes waterlogging of the soil thawed in summer, promotes the formation of an oppressed root system, lowers the resistance of woody vegetation against the wind, etc. - in general, the set of tree species narrows sharply (larch is the most adapted); on the other hand, frozen moisture thawing by the middle of a rather dry summer is an additional source of moisture for woody vegetation in sharply continental areas; Siberian spruce at the eastern limit of the range grows only when the m.m. are close; sparse forests and swamps with close occurrence of the m.m. clearly visible from above.
in soils: specific permafrost soils, characteristic fracturing are formed.
Groundwater areas m.m. are divided into suprapermafrost, interpermafrost and subpermafrost.
Suprapermafrost waters freeze in whole or in part in winter; at the same time, a pressure is often created and, breaking through to the outside, they form ice.[In the Momo-Selenyakhskaya depression between the ridge. Chersky and Momsky mountains. the largest ice in Eurasia is located - Momsky Ulakhan-Taryn (Moma is a right tributary of the Indigirka) with an area of about 100 km 2; the largest icy province - Okhotsk-Chukotka Mountain 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 is most likely evidence of its inheritance from the Pleistocene glaciations.
On the other hand, the modern distribution of m.m. in areas with negative average annual temperatures air and cold winters with little snow indicates communication m.m. and with modern climatic conditions ... Apparently, the modern climate only supports, preserves the previously formed permafrost, in places causing either its degradation (for example, the formation of thermokarst lakes in Yakutia), or a new formation (for example, the mineral water appears in the newest river sediments and on newly formed islands on rivers of the Lena basin).
From north to south, the instability of m.m. increases. In the south of Siberia, a noticeable activation of permafrost processes is observed during construction railways... [At the beginning of the XX century. the construction of embankments for them led to a sharp increase in the thawing layer: on the mars (swampy 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 the excavation work was carried out next to the tracks, then ice appeared in the excavations. Some sections of the Transsib dropped by 2.5 m].
Due to climate warming, in a number of regions, a shift to the north of the boundary of permafrost was recorded (for example, in Mez 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 increased by 3 ° C over the past 40 years), active permafrost thawing began in the subarctic regions in the last 3-4 years. 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 per earth surface). Landscapes in an area larger than Germany and France combined are transformed into flooded areas with shallow lakes.
Permafrost monitoring network data show that near-surface permafrost temperatures in Northern Eurasia have increased by 1-3 ° C since the 1960s. According to the data of mathematical modeling, the decrease in the area of the area m.m. in the northern hemisphere will be (in brackets the figures for a decrease in the area of a solid mass): 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, theses of the report at the NEESPI / GOFC seminar, 2004].
Regularities of the distribution of the average annual runoff in the territory of Russia
Water balance equation.
The ratio of runoff and evaporation depends primarily on the heat supply of the landscape and is subordinate to the zonal pattern.
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 southern border 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 "sector anomaly" is represented by the taiga of Central Yakutia, where the runoff coefficient does not reach 0.1.
The zonal “ridge” of the runoff approximately 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.
V Leningrad region annual runoff 250-350 mm
In semi-deserts and deserts of the Caspian region, the annual runoff is less than 10 mm
At the same time, longitudinal-sector changes are clearly traced, so that in the extremely continental taiga of Central Yakutia, the annual runoff rate does not exceed 30 mm, i.e., it is close to the value typical for dry steppes. The highest rates are characteristic of mountain landscapes (more than 500 mm), especially the windward oceanic slopes, where the layer of annual runoff can exceed 1000 mm (Kamchatka; Bol. Caucasus, in some areas of the last runoff more than 2000 mm ).
According to the calculations of A.G. Isachenko (Ekol. Geogr. Russia, 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 per capita terms in 2002 this is 26.3 thousand m 3 the 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 United States (with Alaska), there are 8.1 thousand m3 × year of water runoff per inhabitant (according to A.G.I., 2004). The countries of Northern Europe are richer than Russia in this respect (Iceland - 230 thousand m3, Norway - 84 thousand m3 × 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 m3 / year) per capita and is growing every year, in rural areas this indicator decreases to 20-30 l / day (7-11 m3 /year).
On the territory of the country, surface runoff resources are distributed extremely unevenly. 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 flow.
[The river runoff is characterized by long-term and seasonal variability, which causes significant fluctuations in water availability over time. Long-term fluctuations in runoff are cyclical, but the phases of fluctuations in different areas do not coincide in time, as well as in amplitude. An increase in the long-term variability of the runoff with an increase in aridity is characteristic. V southern regions In Siberia, the coefficient of variation of the annual runoff (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 for, and in big rivers they are less palpable than small ones.]
When assessing river flow resources, it is important to take into account its stable part (“baseline flow”), which corresponds to groundwater flow. The share of underground (ground) supply in the total volume of the annual runoff varies greatly depending on the physical and geographical conditions. In the area of permafrost, the conditions of groundwater supply of rivers are unfavorable, since groundwater here is mainly in solid form. The most intense groundwater runoff is observed in the zone of excessive moisture outside the permafrost boundary, i.e., in the forest landscapes of the EPR, the southern taiga of Siberia and the Far East. The annual layer of groundwater runoff, as a rule, exceeds 50 mm, accounting for 20–30% (in some places, apparently, up to 40–50%) of the total.
In the zone of insufficient moisture, the level of groundwater lies at a great depth from the surface, the annual layer of groundwater flow is reduced to 10 mm or less.
[The erosional work of rivers is characterized by the indicator turbidity - the content of suspended solids. 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-term permafrost prevents soil erosion. The turbidity of the Baltic Shield rivers is very low. In the rest of the forested part of the country, the turbidity of the rivers increases, but remains low (up to 50 g / m 3). Strong forest vegetation prevents the flow of solid material into rivers. Lakes play an important role as sedimentation tanks. In treeless and plowed landscapes, the influx of solid particles into rivers increases sharply, especially in areas of loess and loess-like sediments. In the steppe zone, turbidity increases to 500, in some places up to 1000 g / m 3. The rivers flowing from the northern slopes of the eastern part of the Greater Caucasus ( almost up to 12000 g / m 3). The indicator under consideration is subject to sharp seasonal fluctuations, especially in arid and treeless landscapes. The rivers carry the greatest amount of sediment during floods and floods. In the rivers of the eastern part of the Greater Caucasus, during floods, an increase in turbidity up to 80–120 thousand g / m 3 was observed. - A.G.I., EGR-2001]
Russian river network
Rivers, along with forest and steppe, had the strongest (if not the strongest) impact on the development of the Russian ethnos and history The 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?" the answer is not so easy. Another question immediately arises: "What is considered a river?"
If, in general, any constantly flowing watercourse, mapped, then those on the territory of the country more than 2 million(Avanta +), and their total length exceeds 6.5 million km
Data Avanta +
The Neva River belongs to the latter category! (convention of splitting by length)
Where do the rivers come from? This question is also not trivial. By no means 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 Nizhny Novgorod for a long time they could not decide which of the two rivers to name the one that is formed from the confluence of the Oka and Volga. Then a competition was organized: which river can be sung more songs, 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 of not only the Oka, but also the Kama, which at the confluence is much deeper than the first.]
Often history, tradition, or just a case determine the primacy of one of the two rivers of equal size merging. 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 at many points. drainage basin, and the source (official or unrecognized) is most often located near watershed.
