Interesting facts about rivers. Features of rivers in the European part of Russia

Introduction
More than 2000 rivers and streams flow in the Moscow region with a total length of 18.7 thousand km, of which 352 are more than 10 km long. Moscow's water fund is represented by 70 small rivers with a total length of 165 km. Only 7 of them have a completely open channel - Yauza, Setun, Skhodnya, Ramenki, Ochakovka, Ichka and Chechera. There are only 13 large rivers with a length of more than 100 km in the region. The largest of them are the Volga, Oka, Klyazma and Moscow, the latter is considered the water “axis” of the Moscow region. In terms of total length and quantity, small rivers predominate in the region. For example, in the Moscow River basin they account for 99%.

Characteristics of rivers:
Plain type.
Calm, not too fast current (no more than 0.5 m/sec).
Wide, well-developed valleys with floodplains and one or more terraces.
The main sources of nutrition are melted snow water (up to 60% of the annual runoff), rainwater (12-20% of the runoff), the rest is spring water.
The highest water level in rivers is in spring. The highest levels during floods are in large rivers, especially the Oka (up to 15 m), and in medium-sized rivers such as Pakhra (6 m and higher).
The rivers are covered with ice for about 5 months of the year. Freeze-up is usually observed in mid-November, and river opening in mid-April. The flood lasts about 2 weeks. The ice thickness reaches 0.8 m. Ice drift in different years lasts from 2 to 10 days.
The rivers of the Moscow region are stocked with more than 30 species of fish. Several fish farms conduct commercial fishing. A huge number of waterfowl and semi-aquatic birds, especially ducks and waders, nest on river banks and stop to rest during migration. Many animals live near the water, including rare and valuable ones such as beaver, muskrat and muskrat.

The largest rivers in the region

River name	Where does it flow	Length within area
Volga	Caspian Sea	9
Oka	Volga	206
Dubna	Volga	137
Sister	Dubna	138
Moscow	Oka	445
Klyazma	Oka	230
Sturgeon	Oka	149
Protva	Oka	146
Nara	Oka	118
Ruza	Moscow	145
Pakhra	Moscow	135
Istra	Moscow	113

Problems:
Due to the rejuvenation of forests due to excessive logging, the Moscow region has lost half of its springs and a third of its small rivers over the past 130 years. So, if 10% of the forest in the basin is cut down small river 10 km long, it shortens by 200-400 m, and when the forest is completely cleared, it disappears.

Several decades ago, there were a lot of fish in the rivers of the Moscow region, and they attracted the attention of many fishermen. In recent years, as a result of pollution, reclamation work, and straightening of river channels, fish stocks here have decreased significantly. Fishing places have been preserved only in a few areas of the lower reaches of these rivers. Roach, pike, perch, bream, and ide are found here.

The composition of the ichthyofauna of the Moscow River and Oka River in the Moscow region has undergone significant changes over the past 30-40 years, mainly caused by pollution and hydraulic construction. In the Moscow River basin, the numbers of dace, subdace, gudgeon, asp, and chub have decreased significantly. Podust, dace, asp, and sterlet have become rare in the Oka.
Volga:

Detailed history

The Volga (in ancient times - Ra, in the Middle Ages - Itil), the largest river in Europe - basin area 1360 thousand sq. km. Originates on the Valdai Hills, flows into the Caspian Sea, forming a delta with an area of ​​19 thousand sq. km. km. The average water consumption near Volgograd is 7240 m3/s. The Volga receives about 200 tributaries, the largest being the Kama and Oka. Due to the construction of a cascade of hydroelectric power stations with reservoirs, the flow of the Volga is highly regulated. The largest hydroelectric power stations are Volzhskaya (Kuibyshevskaya), Volzhskaya (Volgogradskaya), Cheboksary. The Volga connects with the Baltiysky metro station. Volgo-Baltiysky by water, with the White Sea - the North Dvina water system and the White Sea-Baltic Canal, with the Azov and Black Seas - the Volga-Don shipping canal, with Moscow - the Canal named after. Moscow. In the Volga basin there are nature reserves: Volzhsko-Kama, Zhigulevsky, Astrakhan; natural national park Samarskaya Luka. As a result of anthropogenic impacts, the environmental situation has sharply deteriorated; a search is underway for scientifically based ways to restore the natural complexes of the Volga.

Starting at the gentle hills of Valdai, the Volga collects water from huge swimming pool, which occupies almost a third of the Russian Plain, and flows it into the Caspian Sea. In length - 3688 km - the Volga ranks first among the rivers of Europe and surpasses all the rivers of the world that flow into inland water bodies.

The deep Volga tributaries serve as roads to the ridges of the Urals, the dense forests of the North, and the fertile plains of the steppe strip. Among the many rivers flowing into the Volga are Tvertsa, Medveditsa, Mologa, Sheksna, Kostroma, Unzha, Oka, Kerzhenets, Sura, Vetluga, Sviyaga, Kama.

The Kama is one of the most important river routes in our country; its length exceeds 2000 km. Oka is slightly inferior to it, stretching for almost 1500 km.

Gardens and riverside neighborhoods of Tver, Rybinsk, Yaroslavl, Kostroma, Nizhny Novgorod, Kazan, Ulyanovsk, Samara, Saratov, Volgograd, Astrakhan look into the Volga waters.

Many thousands of years ago, the fires of primitive man burned over the Volga waters. Rough canoes, hollowed out or scorched from tree trunks, lay on the sand near ancient settlements. Even in those distant times, different tribes moved along the river; archaeological finds prove this.

Ptolemy in the 2nd century AD mentioned the Volga, calling it by the ancient name Ra. Over the years, the importance of the mighty river has increased. Since the 8th century, it has already become one of the main trade routes for a vast territory. Ancient chronicles tell how the Russian Slavs descended down the Volga, fearlessly sailed across the Caspian Sea and carried their goods far to the east, to the fabulous Baghdad.

Both during the times of Kievan Rus, and during the times when “Mr. Veliky Novgorod” reached a special peak, the ties of the Russian people with the Volga grew stronger. Cities were built on the banks of the Volga, arable lands were opened up, and forest wilds were developed.

When Kazan fell and Astrakhan surrendered, water roads to the Urals, to fur-rich Siberia, to the vastness of the Caspian Sea, to the countries of Central Asia opened before Russia. Never-before-seen caravans of 500-600 plows, loaded with goods and guarded by archers, were taken onto its waters by the Volga, which became the main route of communication between Rus' and the East.

Gradually the Volgari learned to build strong and light ships. Especially notable among them were the barks that walked along the Volga from the 17th and even in the 19th century. In windy weather they raised sails; and when there was no wind, the barks were pulled against the current by barge haulers, to whose hard work I.E. dedicated his famous painting. Repin.

In the Volga basin there were up to 600 thousand barge haulers in the 19th century. The barge haulage generated by serfdom remained a dark spot in the history of domestic shipping. But barge haulers were not only in the history of Russia. Human labor to move ships on a towline was used in all European countries.

The first steamship in the Volga basin was built in 1816 by craftsmen from the Pozhevsky plant on the Kama. In 1817 he reached the Volga. The Volga Shipping Company began to develop especially quickly after the abolition of serfdom in Russia.

On the Volga, for the first time in the world, bulk oil transportation was widely used. Before this, oil was transported in wooden and metal barrels, which took up a lot of space in ship holds, which was both expensive and inconvenient. Following the oil sailing ships, the Volgars built the world's first iron oil barges, Elena and Elizaveta. The method of transporting oil in bulk, called the “Russian method” in many countries, has spread to all seas and oceans of the globe.

Volga shipbuilding has overtaken the shipbuilding of Western European countries. It was on the Volga that the type of comfortable passenger ship was created, which has survived to the present day without significant changes.

Early 20th century marked a very important event in world shipping. The Vandal oil tanker built by the Sormovsky plant was equipped with internal combustion engines that ran on oil instead of kerosene. In 1903, this ship, the world's first motor ship, went on a voyage.

The following year, the Sarmat was ready, the second ship, significantly improved compared to the Vandal. Then the world’s first towing motor ship “Mysl”, the passenger wheeled motor ship “Ural” and, finally, the famous screw motor ship “Borodino” sailed along the Volga.

Until the beginning of the 20th century. at the height of summer on the Volga, due to shallow water, the movement of steamships above Rybinsk stopped; near Kostroma and Yaroslavl one could find fords. Near some Volga rifts, during low water (the average water level after a flood), sometimes several dozen ships accumulated.

Even after the significant dredging work carried out on the Volga before the First World War, the “main street of Russia” still remained in a rather neglected state. There were no specially equipped river ports on it either. Warehouses and storage sheds along the shore, shaky walkways along which, bending under the exorbitant weight of bales and boxes, longshoremen, or, as they were called, hookmen, walked in a line - this is a picture of the old Volga pier.

Already in the first years of the existence of the USSR, changes began on the great river. In the pre-war years, after the construction of the White Sea Canal, the Volga gained access to the North Polar Basin, and the Volga-Moscow Canal connected it with the capital.

The plan for further work on the great river, developed at the direction of the party and government, was called the Greater Volga plan. This plan provided for a radical reconstruction of the river and its best use. The problem was solved comprehensively, so that at the same time shipping conditions were improved, transport connections between the Volga and the seas and main river basins of the European part of the country were strengthened and developed, so that the constructed hydroelectric power stations provided the national economy with cheap energy, and the Volga water was used for irrigation and watering of lands.

The Greater Volga Cascade includes, first of all, eight main waterworks: Ivankovsky, Uglichsky, Rybinsky, Gorky, Cheboksary, Kuibyshevsky, Saratov, Volgograd. The scheme of the Greater Volga also provided for the construction of waterworks on the Volga tributaries - the Kama, Oka, Vetluga, and Sura.

Over the course of two decades, the connection of the Volga basin with all the seas washing the European part of the country was completed to transform the Volga into the highway of five seas: the White, Baltic, Caspian, Azov and Black. These works began with surveys on the route of the White Sea-Baltic Canal in 1931 and ended with the first voyage of Volga ships along the Volga-Don Canal in the summer of 1952. And in 1964, construction of the deep-water Volga-Baltic Canal was completed.

What is it rich in:

In the Upper Volga basin there are large forested areas, in the Middle and partly in the Lower Volga region, large areas are occupied by grain and industrial crops. Melon growing and gardening are developed. The Volga-Ural region has rich oil and gas deposits. Near Solikamsk there are large deposits of potassium salts. In the Lower Volga region (Lake Baskunchak, Elton) - table salt.

The Volga is home to about 70 species of fish, of which 40 are commercial (the most important: roach, bream, pike perch, carp, catfish, pike, sturgeon, sterlet). Its drainage area covers 136 million hectares. This great basin is home to 60 million people, produces a quarter of agricultural and industrial production and more than 20% of the fish caught in the country's rivers. More than 70% of cargo transported by river transport is transported along the Volga and its tributaries. The famous Russian river brings the Caspian an average of 240 cubic meters per year. meters of water, which is collected for it by 150 thousand rivers, streams and springs.

Problems:

In the last 40-50 years, vast and mighty forests have been cleared, everything that was possible has been plowed across the steppes and forest-steppes, the bowels of the earth have been dug into thousands of quarries, more than 300 reservoirs have been built, thousands of industrial and agricultural industries have been created, tens of thousands of kilometers of canals have been dug and water has been irrigated. millions of hectares of land, moved the thickness of salt-bearing accumulations into fertile soils, blocked the main water artery of the basin - the Volga - with blind dams - blood clots, precisely blood clots, because in ecological systems rivers act as venous systems, and precipitation acts as arterial systems.

Currently, the Volga from a flowing river has turned into a chain of weakly flowing reservoirs, where all its physical, chemical and biological properties have changed radically. Throughout the Volga hydrographic system, water exchange decreased by 12 times. Of the named 150 thousand tributaries of the river, more than 30% disappeared. Most of the sources of rivers, streams, and springs are clogged, polluted, compacted, deforested, dug up, drained, and are often used for industrial and civil development, fuel and pesticide warehouses, and livestock camps. All this led to a sharp deterioration in water quality. The self-cleaning ability of the Volga, which back in the fifties was considered drinking water, decreased tens of times and it became an unsanitary reservoir over a large area. More than a million chemicals have been found in it, many of which are toxic. Bottom and suspended sediments coming from the basin and previously fertilizing floodplain and flood lands are 90% retained in reservoirs and deposited on their bottoms, polluting the water and being lost irretrievably. The 300 million tons of earth that annually falls from the banks into the Volga water also go there, so that its turbidity is coastal zone in bad weather it reaches 10 thousand milligrams in one liter, which is comparable to the turbidity of the water of the muddiest river in the world - the Yellow River.

OKA:

Story:

It originates near the small town of Maloarkhangelsk in the Oryol region, collects tributaries from fifteen regions of Central Russia: Oryol, Yaroslavl, Kaluga, Lipetsk, Bryansk, Smolensk, Tambov, Tula, Moscow, Ryazan, Vladimir, Ivanovo, Penza, Nizhny Novgorod regions and Mordovia, and flows into the Volga near Nizhny Novgorod. The Moscow River also flows in the Oka basin, giving its name to the capital of Russia that stands on it. The Moscow River flows into the Oka near the city of Kolomna.

Even before the pre-Mongol Slavs, the banks of the Oka were inhabited by Finno-Ugric tribes. However, already in Arabic sources of the 9th-10th centuries the Oka is called the “Slavic river” or “Rus river”. A waterway passed through it from the Kyiv and Chernigov lands to the northeast to the lands of Ryazan, Suzdal, Murom, actively developed by the Slavs in X-XII centuries. In the XV-XVI centuries, Oka was one of the most important lines of defense on the approaches to the Moscow Principality from the south and southeast. In this regard, it was often called the “belt of the Virgin Mary.” And at the end of the 15th century, a monastery was founded on the modern territory of the Stupinsky district near the banks of the Oka River, which received the name Holy Trinity Belopesotsky. It owes its second name to the dazzling white sands on the once endless river beaches. The monastery became an important outpost in the defense of the borders of the Moscow state from Tatar raids, as it blocked the crossing of the Oka River and the road to Moscow lands, and was a reliable refuge for the surrounding residents.

Until the 17th century, Oka remained border river: the cities of Serpukhov, Kashira, Tula, Kaluga, Tarusa, Aleksin occupied an important strategic place in the defensive line of the southern borders of the Moscow state. At all times, the Oka has been a convenient means of communication, the most important water artery Muscovy, since it connected it with the Volga region and led it to the Caspian Sea.

And today the Oka is one of the largest rivers in the European part of Russia, has more than a hundred tributaries and countless coastal and bottom springs. The Oka enters the Moscow region as a full-flowing river with a low-water width of up to 250 meters. The average depth of the Oka is 1.5 meters. The riverbed of the Oka is for the most part slightly tortuous, and in some places it forms sharp turns. The fairway is more winding than the river itself. The reaches are replaced by rifts - one rift is on average per 2.7 kilometers of the riverbed; in total there are 425 rifts on the Oka River, of which about 50 are rocky.
The length of the Oka is 1,480 kilometers. The area of ​​the Oka basin is 245,000 square kilometers, which is comparable to the territory of a reputable European state, approximately the same as Great Britain.
The opening of the Oka from ice usually occurs in the first ten days of April, freeze-up - in early December. In winter, the ice thickness on the Oka reaches 64 centimeters. The rise in water levels during a flood is very high and in high-water years reaches 12 meters near Kashira. The speed of the Oka flow during the flood period reaches 2.5 m/sec, during low water on the rapids it reaches 1 m/sec, on the reaches - 0.6 m/sec.

At 984 km from the mouth, above the city of Serpukhov, the Oka receives the Protva tributary (length 130 km). In the Oka floodplain there are many long narrow lakes and meadows stretching along the river. Near Serpukhov, the Nara River flows into the Oka, also heavily polluted by urban wastewater(Nara length 106 km), slightly lower is the Rechma River (length 26 km). The left bank of the Oka below Serpukhov is characterized by an abundance of large floodplain lakes. At the heights of the left bank, a magnificent pine forest approaches the riverbed itself. Below the confluence of the Lopasni River (length 109 km) beyond the village of Priluki and up to the Sokolovaya Hermitage, the Oka Valley is occupied by shifting sands, partially hilly into dunes. Further, elevated sandy banks depart from the Oka, forming a wide floodplain.

Near the city of Ozyory, the bank of the Oka is low, with many lakes. After the confluence of the Bolshaya Smedva River (length 55 km), the left bank becomes steep with limestone outcrops, overgrown with mixed forest, with numerous outlets of key springs up to the village of Belye Kolodezi. Floodplain meadows up to two kilometers wide stretch to the village of Akatevo. From the right bank opposite from Akatevo, the Osetr River flows into the Oka (length 160 km). From here to Kolomna, a continuous wall of limestone outcrops stretches along the banks of the Oka. The left bank here is very high - up to 30 meters from the water's edge.

Six kilometers downstream from the city of Kolomna, the Moscow River flows into the Oka. The flow of the Oka becomes slower, the channel winds strongly. The width of the floodplain increases to 15 kilometers. Numerous oxbow lakes, thickets of alder and willow trees alternate with oak forests and pine forests. The right bank to the city of Lukhovitsa is elevated, steep, close to the Oka. Along the left bank of the Oka near the village of Dedinovo there are famous water meadows. Near the village of Lyubichi the Tsna River (90 km long) flows into the Oka. Further, the Oka section is blocked by two dams with sluices, which are removed during floods.
At the 803rd kilometer from the mouth in the Moscow region, near the border with the Ryazan region, the Beloomutsky hydroelectric complex is located. Below it along the river, already in Ryazan region, the Kuzminsky lock is located 75 kilometers from the mouth. The backwater from these dams extends up 20 kilometers upstream, which is clearly not enough to reliably regulate the water level along the entire riverbed.

What is it rich in:

Among the fish of commercial importance are: bream, pike, pike perch, asp, catfish, podust, ide. Oka plays a huge role in supplying settlements and industrial facilities with water. The main fish in the Oka is bream, followed by roach and silver bream in terms of population size. On the fast rifts there are podust, dace, and a lot of sabrefish. Quite rare fish today are pike perch, pike, asp, ide and chub. Sterlet and catfish have almost disappeared. On the rocky reaches of the Oka near White Wells, Kolomna and other places, many crayfish are still found.

Problems:

The main reason for the depletion of fish stocks and impoverishment species composition fish is pollution of the Oka River by sewage,

The most powerful plume of pollution is carried into the Oka River by the Moscow River. Below its mouth, the fish in the Oka do not stay in a large space in winter, sliding downstream, they go into non-watery tributaries. Above the mouth of the Moscow River, the Oka is much cleaner and abundant in fish.
Klyazma:

The Klyazma River flows through the territory in the European part Russian Federation, through the territory of the city of Moscow, Moscow, Ivanovo, Vladimir and Nizhny Novgorod regions. It is the second largest, after the Moscow River, the left tributary of the Oka.

The length of the Klyazma is about 686 kilometers, and the total area of ​​the basin is more than 42.5 thousand square meters. km. The river is fed mainly by snow. Ice begins to form on the river in November, but only breaks up in April.

The source of the Klyazma is located within the Moscow Upland, near the city of Solnechnogorsk. In the upper reaches, the river goes to the southeast, on the banks of the Khimki district, then the river flows along the border of the Molzhaninovsky district of Moscow, near the village of Cherkizovo it turns in an easterly direction. In the upper reaches of the Klyazma River, the banks are high, and the river floodplain is very narrow. At the confluence with the Klyazma Reservoir, the river bed increases to 12 meters.

The river flows through the Pirogovskoye and Klyazminskoye reservoirs. The river flows through the Meshcherskaya lowland, where the left bank is higher than the right. And after the confluence of the Teza River, the Balakhninskaya Lowland is located along the gently sloping left bank, and the right one becomes steeper, reaching a height of 90 meters.

Near the city of Noginsk, the width of Klyazma reaches 50 meters, towards Vladimir it is already 130 meters, and the maximum width exceeds 200 meters. Most deep places reach 8 meters, and average depths are about 1-2 meters.

The following tributaries flow into the Klyazma: Lukh, Vorya, Sudogda, Ucha, Polya, Chernogolovka, Uvod, Nerl, Sherna, Koloksha, Kirzhach, Teza, Peksha and Suvoroshch. Starting from the city of Shchelkovo to major tributaries located in the Vladimir region, the water in the river is not suitable for drinking, swimming and fishing.

Story

It was along the Klyazma in 1155 that Prince St. Andrei Bogolyubsky sailed from Kyiv to Vladimir in order to make Vladimir the capital of the Rostov-Suzdal principality, which became the strongest in Rus' and acted as the core of the modern Russian state.

The Klyazma River was the crossroads of the most important ancient water roads, connecting Kyiv, Chernigov, Smolensk, Ryazan, Moscow, Vladimir, Tver and Veliky Novgorod through a system of portages.

Therefore, a trip to the sources of the Klyazma River is not only a visit to an outstanding natural monument, but also a journey to the origins of our native history.

Why is she rich?

The Klyazma River is largely polluted in its upper reaches, however, it is still quite rich in fish. Podust, bream, ide, perch, asp, roach, pike, ruff, gudgeon, burbot, bleak and chub live here.

Willow and sedge, chastuha, reeds, cattails, nettles and forest geranium grow along the banks. The water is covered with aquatic vegetation: egg capsule, duckweed, water lily, hornwort, Elodea and pondweed. From May to September the Klyazma River is used for kayaking.

Problems:

1. At the study site on the river there are no industrial enterprises, mineral fertilizer warehouses.

But the river is heavily polluted by industrial waste from enterprises in the Moscow and Vladimir regions.

The Klyazma River is “dirty” – class 5 pollution.

A) contamination of the territory;

B) trampling of slopes.

3.Shallowing of the river.

Since 1887 on Klyazma

there was a lively

parachute message.

Currently only part

the river bed is suitable for shipping
Moscow river

story

Moskva river, commonly called Moscow River, is the largest river flowing from source to mouth in the Moscow region. Only a small section (~16 km) in the upper reaches of the Moscow River enters the Smolensk region. The Moscow River originates in the Smolensk-Moscow Upland and flows into the Oka River.

Source of the Moscow River- located 5 km southeast of the Drovnino railway station in the Belarusian direction, in the Starkovsky swamp, also called the “Moskvoretskaya puddle”. Length of the Moscow River ~502km, width in the upper reaches 20-50m, after the confluence of the Ruza River 40-70m, in the lower reaches 70-200m, depth up to 14m. In the upper reaches of the Moscow River it was formed Mozhaisk Reservoir- length ~28km, width up to ~2km, depth up to ~23m. In the city of Moscow there is a large Stroginsky backwater, connected by a channel to the Moscow River, its dimensions ~1.9 km on ~1.25km, depth up to ~19m. In the lower reaches of the Moscow River there are several bays the width 400m-900m. Mouth of the Moscow River– is located in the Golutvin district of the city of Kolomna, where the Moscow River flows into the Oka River.
River name - Moscow, according to one version, comes from Slavic "mozgva" - "swampy shore", on the other hand from the Baltic "mask-ava", "mazg-uva" - "swampy place", according to the third from Finno-Ugric "mosk" and "va" - "cow (bear) river". There is also a legend about the connection between the name Moscow and the name of the biblical hero Mosoch (grandson of Noah, son of Japheth) and his wife Kva.

The Moscow River basin was inhabited already in the Stone Age, as evidenced by the Neolithic sites in Krutitsy, Kolomenskoye, Aleshkino, Shchukino, Serebryany Bor, and Trinity-Lykovo. Monuments of the Bronze Age (Fatyanovo culture of the second millennium BC) were found in the center of Moscow, in Dorogomilovo, on the Sparrow Hills, in the Andronikov Monastery, in Davydkovo, Zyuzino, Alyoshkino, Tushino.

With the advent of the Iron Age in the middle of the first millennium BC. e. and climate change (forest-steppes were replaced by forests), arable farming spread in the river basin and numerous settled settlements formed. The so-called Dyakovo culture existed here for more than a thousand years from the 7th-6th centuries BC. e. until the 6th-9th centuries AD e. These pre-Slavic fortifications and settlements were found near the village of Dyakovo (in the Kolomenskoye region), on the Vorobyovy Gory, in Tushino, Kuntsevo, Fili, on the banks of Setun, in the Lower Kotly.

Since the 8th century, Slavic (Vyatichi) settlements arose on the banks of the Moskva River, Yauza, Neglinnaya, Setun, Ramenka, Kotlovka, Chertanovka, Gorodnya. Thus, settlements appeared on Samotyok, Lyshchikovo, Andronevskoye, Obydenskoye; villages Yauzskoye, Kudrinskoye, in Neskuchny Garden, Golovinskoye, Brateevskoye, Zyuzinskoye, Matveevskoye, Setunskoye. In those same years they formed numerous groups burial mounds (Filyovskaya, Matveevskaya, Ramenskaya, Ochakovskaya, Krylatskaya, Troparevskaya, Yasenevskaya, Cheryomushkinskaya, Orekhovskaya, Borisovskaya, Brateevskaya, Konkovskaya, Derevlevskaya, Chertanovskaya, Tsaritsynskaya).

Since ancient times, the Moscow River has been an important transport route; waterways connected it with Novgorod and Smolensk, with the Volga and Don.
What is it rich in:

Currently, the Moscow River is inhabited by about 35 types fish The most numerous populations are roach, bream, and perch. Less common are pike perch, pike, asp, chub, silver bream, and carp. Ide, catfish, podust, vendace, and sterlet are very rare. Attempts are being made to restore the sterlet population - juveniles bred under artificial conditions are being released into the Moscow River. As a result of human activity, fish appear in the Moscow River that have never been found there. These are primarily fugitives from fish farms and reservoirs adjacent to the Moscow River - carp, silver carp, trout, eel. Probably, through the Moscow Canal, saber fish got from the Volga River into the Moscow River. As a result of the activities of aquarists in the Kuryanovo area of ​​Moscow, a population of guppies lives near the discharge of water from wastewater treatment plants.

Problems:

According to the results comprehensive examination water bodies of Moscow, conducted by Rosprirodnadzor in 2004-05, the Moscow River is classified as very dirty water bodies of the sixth quality class with a water pollution index (WPI) from 6.0 to 10.0. The high rate of WPI on rivers of this class is caused by the contamination of water discharged into the reservoir with nitrites, ammonium nitrogen, phenols, petroleum products, organic substances, copper, zinc, and iron. Based on the results of the analysis of water and silt samples taken from the Moscow River in the summer of 2005, it turned out that most of the pollutants are located in bottom sediments. Their content exceeds the maximum permissible concentration by 30-40 times. The river is also heavily polluted with highly toxic salts of heavy metals.

The main source of nutrition for the rivers of the Black Sea-Caspian slope, like most rivers in the European part of the country, is melted snow water. However, the share of snow supply in the total annual runoff varies in different parts of this vast territory. There is a natural increase in the role of snow supply in the direction from the wetter and warmer west to the colder and more continental east. While in the west the share of snow supply does not exceed 40-50%, in the east and especially in the southeast (Lower Volga region) its share increases to 80-90%, i.e. approximately 2 times. At the same time, to the southeast the share of ground and rain nutrition decreases. An increase in the role of snow nutrition and a corresponding decrease in the share of other sources of nutrition also occurs in the direction from north to south.

Types of rivers in the European part of Russia

Depending on the ratio of individual types of food within the region, the following main types of rivers can be distinguished:

1. Rivers of mixed feeding with a predominance of snow (the share of snow feeding is less than 50%). The rivers of the west and southwest (Dniester basins) belong to this type. They are characterized by an increased role of rain and groundwater recharge (the latter in the Pripyat basin in some places accounts for up to 50% of the annual runoff).
2. Rivers are predominantly snow-fed (the share of snow-fed is from 50 to 80%). The vast majority of rivers in the region (the Dnieper, Don and Volga basins) belong to this type.
3. Rivers are almost exclusively snow-fed (the share of snow-fed is more than 80%). Small rivers of the Lower Volga region and the south of the steppe zone (the region of the Black Sea lowland) belong to this type. Here, moisture from summer rains is lost almost entirely to evaporation and usually does not produce runoff, and the groundwater level lies deep, below the bottom of river valleys.
It must be borne in mind that the ratio of food sources depends on the size of the river, especially in the forest-steppe and steppe zones. The smaller the river, the less deeply its valley is cut, as a rule, and the less, therefore, its groundwater supply. Small rivers of the forest-steppe and steppe zones do not reach the level of deep groundwater and therefore are fed almost exclusively by melting snow. Thus, the smaller the river basin, the greater the share of snow supply.

The change in the share of spring (mainly runoff from melted snow waters) depending on the size of the catchment area can be seen from Table. 1, compiled according to data from K. P. Voskresensky.

Table 1. Change in the share of spring runoff depending on the size of the catchment area

Forest-steppe zone		Steppe zone
catchment area, km 2	share of spring runoff, %	catchment area, km 2	share of spring runoff, %
up to 50	up to 100	up to 1000	100
50-100	80-85	1000-2000	90-95
100-500	70-75	2000-3000	80-90
>500	55-65	3000-4000	70-75
		>4000	60-65

Thus, on small rivers of the forest-steppe zone with a catchment area of ​​up to 50 km 2, and in the steppe - up to 1000 km 2, runoff occurs exclusively in the spring due to snow melting. In the Sal steppes, on rivers with a drainage area of ​​up to 10,000 km 2, flow occurs exclusively in the spring.

Regime of rivers in the European part of the country

The overwhelming majority of rivers in the region are characterized by the following main features of the regime: high spring flood, low summer low water, only occasionally interrupted by rain floods, and winter low water. On the rivers of the forest zone, in addition, the autumn flood is clearly visible, formed due to water from heavy rains. On the rivers of the forest-steppe and steppe zones, summer floods are extremely rare, and autumn floods are absent, since here, as noted above, moisture not only from summer, but also from autumn rains is almost completely filtered into the soil and spent on evaporation. This is a significant difference between the regime, for example, of the Upper Volga, located in the forest zone, and the Don, the basin of which is entirely located in the forest-steppe and steppe zones.

In the southern and especially in the southeastern parts of the region, where local watercourses are almost exclusively snow-fed, the rivers are characterized by high spring floods and almost complete or complete absence of flow in other seasons.

At sudden changes water content throughout the year, the river regime is characterized by large amplitudes of level fluctuations, reaching 16-17 m on the Volga, 18 m on the Oka, 10-12 m on the Don and 12-14 m on the Dnieper. On medium and small rivers, level fluctuations also significant - up to 6-8 m. The magnitude of surface runoff and the relative water content of rivers drop sharply in the direction from north to south. This, on the one hand, is explained by a decrease in the number of atmospheric precipitation, on the other hand, by a sharp increase in relative evaporation losses.

The rivers of the forest zone have the highest relative water content, where the runoff coefficient is on average 0.4-0.5, and the annual runoff module is 5-10 l/sec km 2. The rivers of the Carpathians and the western slopes of the Urals are particularly water-bearing, where the runoff module increases to 15-20 and even 25 l/sec km 2 (Vishera basin).

The rivers of the western part and especially Polesie, where the annual flow module, despite the large amount of precipitation, is equal to 4 l/sec km 2, are characterized by lower relative water content within the forest zone. This is explained by a very low runoff coefficient, which in turn is associated with the flat nature of the area and large losses of moisture through evaporation. In the forest-steppe zone, evaporation losses increase significantly and the runoff coefficient decreases to 0.2-0.3, and the relative water content usually does not exceed 2-4 l/sec km 2.

In the steppe zone, approximately only 10% of precipitation goes to the formation of surface runoff, and 90% is spent on evaporation. Therefore, the runoff modules here are low and usually do not exceed 0.5-2.0 l/sec km 2. And finally, in the semi-desert zone (Caspian lowland), with low precipitation, only a small proportion (less than 5%) goes to runoff. The river network in these conditions is extremely rare or completely absent.

As you move south, not only the relative water content of rivers decreases, but its fluctuations also increase. While in the northern parts of the region (the Kama, Upper Volga, upper Dnieper basins) the amount of runoff over a long period of time fluctuates within relatively small limits, in the south in the steppe zone the differences in water content of individual years are more pronounced. This is confirmed by regular changes in the coefficient of variation of annual runoff from 0.2-0.3 in the north to 0.85 or more in the south.

The maximum water flows of the year are observed on most rivers during periods of spring floods. Summer and autumn rain floods are significantly lower in height than spring floods. Only in the southwest (the Dniester and Prut basins and on the Ural rivers) the maximum of summer rain floods in some years can reach and even exceed the maximum of spring floods. The above is true only for relatively large rivers; on small watercourses, the intensity of rain floods increases sharply and from a certain limit, which reaches the catchment areas, rain maximums begin to prevail everywhere over snow peaks. The reason for this lies in the fact that in the European part of the country, particularly intense downpours can simultaneously cover only small areas.

While in the forest zone rain maxima can prevail over snow maxima only in very small basins - less than 50-100 km2, in the south in the steppe zone rain maxima are higher than snow maxima already on large rivers, with drainage areas of up to 4-5 thousand km. km 2. In very small basins (beams), the modules of rainfall maximums can reach very high values: for catchment areas; with areas of 0.4-0.5 km 2 - 50-70 thousand l/sec km 2.

The further you go south, the more shallow the rivers become during low water periods. In the north, in the forest zone, flow modules, even during low-water periods, do not fall below 1.0-1.5 l/sec km 2; in the south, in the steppe zone, the minimum flow in rivers is characterized by very low values ​​- up to 0.1-0.05 l /sec km 2; Many rivers dry up completely and their flow stops in the summer. In the basins of the upper Dnieper, Upper Volga and Kama, only small rivers with drainage areas of no more than 100-250 km 2 can dry out in the summer or freeze in the winter.

To the south, in the forest-steppe zone, much larger rivers, with catchment areas of up to 500 km 2, may dry up. Finally, in the steppe zone, flow may stop on rivers whose basin areas reach 5-10 thousand km 2. In cases where a river carries its waters through a semi-desert zone, the phenomenon of drying out is observed even on such relatively large rivers as the Embe (catchment area 45,800 km 2).

Most rivers in the region experience freeze-up every year. Only in the extreme south and especially in the southwest (the Dniester and Prut basins) may there be no freeze-up in some years with mild winters. Freeze-up is relatively rare on the Danube.

Freezing of rivers begins earlier in the northeast of the region (in the Kama basin) - usually in the first half of November. From here, the freezing process gradually spreads towards the southwest, and in the extreme southwest (the Dniester and Prut basins) freezing is observed later - at the end of December or at the beginning of January.

The opening, on the contrary, begins earlier in the southwest (in the Dniester basin) - at the beginning of March - and from here it spreads to the northeast, where it occurs in the second half of April. Thus, the duration of freeze-up increases from 60-70 days in the southwest to 150-170 days in the northeast. As the duration of freeze-up increases, the thickness of the ice cover also increases.

In the direction from northeast to southwest, the long-term amplitude of fluctuations in the timing of opening and freezing also increases. In the Kama basin, for example, the difference between early and late periods does not exceed 40-50 days, and in the Dnieper basin it increases to 70-90 days. In the Dniester basin, in general, the concept of the amplitude of the periods of opening and freezing becomes uncertain, since in some years the Dniester may not freeze at all.

Water erosion of rivers

Let us dwell briefly on the characteristics of the erosion activity of rivers and their hydrochemistry. It has been noticed that the erosion activity of rivers increases in the direction from north to south. While in the forest zone the development of erosion is hampered by forests and swamps, in the forest-steppe and especially steppe zones, with their almost complete treelessness, as well as with large plowed slopes, the consequences of water erosion in some places acquire catastrophic proportions. Widespread loess-like soils, which are easily eroded, also contribute to the development of erosion. On rivers, this is manifested in an increase in the turbidity of their waters from 30-50 g/m 3 in the forest zone to 600-1000 g/m 3 in the steppe (Table 2).

Table 2. Changes in river water turbidity in various landscape zones

In small basins of forest-steppe and steppe zones, the annual removal of substances suspended in water often reaches enormous values ​​- up to 50-80 tons, and sometimes up to 250 t/ha; in this case, the most fertile soil particles are carried away. If we also take into account that gully erosion is widespread here, we can say that, in general, the erosive activity of water in the steppe and forest-steppe zones causes great damage to agriculture.

In the forest zone, all waters are fresh (mineralization less than 100 mg/l), soft and very soft (hardness 0-8°). In the forest-steppe zone, mineralization increases to 100-500 mg/l, signs of salinization appear, and waters become harder. In the steppe zone, all the waters of small rivers are mineralized to one degree or another (up to 500-1000 mg/l) and are characterized by high hardness (18-30°). Finally, in the semi-desert, mineralization and water hardness are even higher (mineralization increases to 1000-1500 mg/l or more, hardness exceeds 30°). At first glance, the significant excess of the chemical runoff over the suspended sediment runoff seems somewhat unexpected. In the rivers of the forest zone of the region, the runoff of chemically dissolved substances is 2-4 times greater than the sediment runoff.

A river is a natural permanent water stream (watercourse) of significant size with a natural flow along the channel (the natural depression it has created) from the source down to the mouth and fed by surface and underground runoff from its basin.

Rivers are an integral part of the hydrological cycle. Water in a river is usually collected from surface runoff resulting from precipitation from a certain area limited by a watershed (river basin), as well as from other sources, such as groundwater reserves, moisture stored in natural ice(during the melting of glaciers) and snow cover.

In places of natural or artificial obstacles to the flow of a river, reservoirs (flowing lakes or artificial seas) appear. Limnology (Greek λίμνε - lake, λόγος - study) or lake science is a branch of hydrology, the science of the physical, chemical and biological aspects of lakes and other fresh water bodies, including reservoirs. In turn, rivers are the subject of one of the largest sections of land hydrology - river hydrology or potamology (from ancient Greek ποταμός - river, λόγος - study - literally the science of rivers), which studies the structure of river networks, river flow, morphometry of rivers swimming pools and so on. As a rule, rivers make their way and flow through zones of least stress and resistance - along tectonic faults.

For a long time, the energy of fast rivers and waterfalls has been widely used in human economic activity as a source of renewable energy for the operation of water mills and turbines of hydroelectric power stations.

General information

In each river, a distinction is made between its place of origin - the source and the place (section) where it flows into the sea, lake or confluence with another river - the mouth.

Rivers that directly flow into oceans, seas, lakes or are lost in sands and swamps are called main; flowing into main rivers - tributaries.

The main river with all its tributaries forms river system, characterized by density.

The land surface from which a river system collects its waters is called a catchment, or drainage area. The drainage area, together with the upper layers of the earth's crust, which includes a given river system and is separated from other river systems by watersheds, is called a river basin.

Rivers usually flow in elongated low forms of relief - valleys, the lowest part of which is called a channel, and the part of the valley bottom flooded with high river waters is called a floodplain, or floodplain terrace.

The channels alternate between deeper places - reaches and shallow areas - rifts. Line greatest depths the channel is called thalweg, close to which the shipping channel or fairway usually passes; the line of highest flow velocities is called the core.

The boundary of a river's watercourse is the bank; depending on its location along the stream relative to the center line of the watercourse's bed, the right and left banks of the watercourse are distinguished.

The difference in height between the source and the mouth of a river is called the fall of the river; The ratio of the fall of a river or its individual sections to their length is called the slope of the river (section) and is expressed as a percentage (%) or in ppm (‰).

Rivers are distributed extremely unevenly across the surface of the globe. On each continent, it is possible to outline the main watersheds - the boundaries of the areas of runoff entering various oceans. The main watershed of the Earth divides the surface of the continents into 2 main basins: the Atlantic-Arctic (the flow from the area of ​​which flows into the Atlantic and Arctic oceans) and the Pacific (the flow into the Pacific and Indian oceans). The volume of runoff from the area of ​​the first of these basins is significantly greater than from the area of ​​the second.

The density of the river network and the direction of flow depend on the complex of modern natural conditions, but often, to one degree or another, retain the features of previous geological eras. The river network reaches its greatest density in equatorial belt where they flow greatest rivers world - Amazon, Congo; in tropical and temperate zones it is also high, especially in mountainous regions (Alps, Caucasus, Rocky Mountains, and so on). In desert areas, sporadically flowing rivers are common, occasionally turning into powerful streams during snowmelt or intense rainfall (the rivers of lowland Kazakhstan, the Ueds of the Sahara, the Creek (a drying up river) and Australia, and others).

Classification

Classification of rivers by size

• Large rivers are lowland rivers with a basin area of ​​more than 50,000 km2, as well as predominantly mountain rivers with a drainage area of ​​more than 30,000 km2. As a rule, their basins are located in several geographical zones, and the hydrological regime is not typical for the rivers of each geographical zone separately.
• Middle rivers are lowland rivers, the basins of which are located in the same hydrographic zone, having an area from 2000 to 50,000 km2, the hydrological regime of which is characteristic of rivers in this zone.
• Small rivers are rivers whose basins are located in the same hydrographic zone, have an area of ​​no more than 2000 km2 and whose hydrological regime, under the influence of local factors, may not be typical for rivers in this zone.

Topographic classification

Depending on the topography of the area within which the rivers flow, they are divided into mountainous and flat. Many rivers alternate between mountainous and flat areas.

• Mountain rivers, as a rule, are distinguished by large slopes, rapid currents, and flow in narrow valleys; erosion processes predominate.
• Lowland rivers are characterized by the presence of channel meanders, or meanders, formed as a result of channel processes. On lowland rivers there are alternating areas of channel erosion and accumulation of sediment on it, as a result of which muddy bars and riffles are formed, and deltas are formed at the mouths. Sometimes branches that branch off from a river merge with another river.

Hydrobiological classification

Classification according to the possibility of water sports

According to the International River Difficulty Scale, there are six levels of difficulty.

Classification by tributary network configuration

There are 12 classes of rivers based on the nature of the network of tributaries, determined by the Strahler Number. The headwaters of the rivers according to this system belong to the first class, and the Amazon River to the twelfth.

Use of rivers

Since ancient times, rivers have been used as a source of fresh water, for obtaining food (fishing), for transport purposes, as a protective measure, to delimit territories, as a source of inexhaustible (renewable) energy (rotation of machines (for example, a water mill) or hydroelectric turbines), for bathing, irrigation of agricultural land and as a means of disposing of waste.

Rivers have been used for navigation purposes for thousands of years. The earliest evidence of river navigation dates back to the Indus Valley Civilization, which existed in the northwest of modern Pakistan around 3300 BC. The use of river navigation in human economic activity provides cheap (water) transport, and is still widely used in the most large rivers world, such as the Amazon, Indus, Ganges, Nile and Mississippi (river). The amount of harmful emissions produced by river vessels throughout the world is not clearly regulated or regulated, which contributes to the constant release of large amounts of greenhouse gases into the Earth's atmosphere, as well as an increase in the incidence of malignant neoplasms among the local population as a result of the constant inhalation of harmful particles emitted into the air by water transport .

The rivers are playing important role in determining political borders and protecting the country from the invasion of external enemies. For example, the Danube was part of the ancient border of the Roman Empire, and today the river forms much of the border between Bulgaria and Romania. The Mississippi in North America and the Rhine in Europe are the main borders dividing the east and west of countries located on their respective continents. In southern Africa, the Orange and Limpopo rivers form the boundaries between provinces and countries along their routes.

Flood

A flood (or flood) is part of the natural cycle of a river - one of the phases of the river’s water regime, repeating annually in the same season of the year - a relatively long and significant increase in the river’s water content, causing its level to rise. Usually accompanied by the release of water from the low-water channel and flooding of the floodplain.

Flood is a phase of the water regime of a river - a relatively short-term and non-periodic rise in the water level in the river, caused by increased melting of snow, glaciers or an abundance of rain. Unlike a flood, a flood does not recur periodically and can occur at any time of the year. Significant flooding may cause flooding. As the flood moves along the river, a flood wave is formed.

Flood - flooding of an area as a result of rising water levels in rivers, lakes, seas due to rain, rapid snow melting, wind surge of water to the coast and other reasons, which damages people's health and even leads to their death, and also causes material damage . Wind surges of water in sea estuaries and on windy areas of the coast of seas, large lakes, and reservoirs. Possible at any time of the year. They are characterized by a lack of periodicity and a significant rise in water levels.

Much of the process of erosion of river beds and deposition of eroded rocks on the corresponding floodplains occurs during floods. In many developed areas of the globe, human economic activity has changed the shape of river beds, influencing the magnitude (intensity) and frequency of floods. Examples of human impacts on the natural state of rivers include the construction (creation) of dams, straightening of riverbeds (construction of canals), and drainage of natural wetlands. In most cases, human mismanagement in floodplains leads to a sharp increase in the risk of floods:

• artificially straightening a river bed allows water to flow faster downstream, increasing the risk of flooding in areas downstream;
• changing the nature of the river floodplain (straightening) removes natural flood control reservoirs, thereby increasing the risk of floods in the lower reaches of rivers;
• creating an artificial embankment or dam can only protect the area downstream of the river (behind the dam), and not those areas that are located upstream;
• The presence of a dam, as well as straightening and strengthening of banks (for example, the creation of embankments, etc.) can also increase the risk of flooding in areas located upstream of the river. As a result, there is a difficulty in outflow and an increase in pressure exerted on the downward flow, associated with an obstacle to the normal outflow of water due to the narrowness of the channel enclosed between the reinforced banks.

underground river

Most, but not all rivers flow on the surface of the Earth. Underground rivers flow underground in caves. Rivers of this kind are often found in regions with limestone (karst) deposits in geological formations. In addition, there are caves formed in the body of glaciers by melt water. Such caves are found on many glaciers. Melted glacial waters are absorbed by the body of the glacier along large cracks or at the intersection of cracks, forming passages that are sometimes passable for humans. The length of such caves can be several hundred meters, depth - up to 100 m or more. In 1993, a giant glacial well “Isortog” with a depth of 173 m was discovered and explored in Greenland; the influx of water into it in summer was 30 m3 or more. Due to the presence of a “roof” formed from geological rocks impenetrable to water (or ice) and high pressure directed towards the overlying glacier masses, a so-called topographic gradient is created - such streams can even flow uphill. Another type of glacial caves are caves formed in a glacier at the point of release of intraglacial and subglacial waters at the edge of the glaciers. Meltwater in such caves can flow both along the glacier bed and over glacial ice.

Water is usually found in many caves, and karst caves owe their origin to it. In caves you can find condensation films, drops, streams and rivers, lakes and waterfalls. Siphons in caves significantly complicate passage and require special equipment and special training. Underwater caves are often found. In the entrance areas of caves, water is often present in a frozen state, in the form of ice deposits, often very significant and perennial.

Puerto Princesa Underground River is an underground river near the Philippine city of Puerto Princesa, on the island of Palawan (Philippines). This river, about 8 km long, flows underground, in a cave, towards the South China Sea. In the area where it is located, the Puerto Princesa Subterranean River National Park has been created - a nature reserve located 50 km from the city. The park is located in the St. Paul Mountain Range in the northern part of the island and is bounded by St. Paul Bay and the Babuyan River. A similar river is known on the Yucatan Peninsula in Mexico, but this one is recognized as the largest. Both underground rivers owe their origin to the karst topography. The water in these rivers changed direction, finding its way down, thanks to the dissolution of carbonate rocks and the formation of a vast underground river system.

The Hamza River (port. Rio Hamza) is the unofficial name for the underground flow under the Amazon. The opening of the “river” was announced in 2011. Unofficial name given in honor of the Indian scientist Walia Hamza, who spent more than 45 years exploring the Amazon.

Largest rivers in the world

The Greatest Rivers of the World

№	Name	Length (km)	Basin area (thousand km²)	Average water flow at the mouth (thousand m³/s)	Highest water flow at the mouth (thousand m³/s)	Solid waste (million tons/year)
1.	Amazon
2.	Nile
3.	Yangtze
4.	Mississippi - Missouri
5.	Yellow River
6.	Ob (with Irtysh)
7.	Parana (from the origins of Paranaiba)
8.	Mekong
9.	Amur (from the sources of Arguni)
10.	Lena
11.	Kongo (with Lualaba)
12.	Mackenzie (from the headwaters of the Peace River)
13.	Niger
14.	Yenisei (from the origins of the Small Yenisei)
15.	Volga
16.	Indus
17.	Yukon
18.	Danube
19.	Orinoco
20.	Ganges (with Brahmaputra)
21.	Zambezi
22.	Murray
23.	Dnieper

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The material was found and prepared for publication by Grigory Luchansky

Source: Report "Movement along rivers". Types of rivers

Our country has a large number of rivers on which you can sail on tourist boats. All of them are different from each other and at the same time have common characteristics that allow them to be combined into types. Water tourists have developed at least five classifications. Their use allows you to correctly solve the problem that each tourist group sets for itself when choosing a route; where to go, when to go and why to go.

TERRAIN AND RIVER

This classification primarily reflects the nature of the river depending on the topography of the geographical area where it flows. According to this classification, rivers are divided into lowland, mountain-taiga (sometimes called foothill) and mountain.

Plain rivers. There are a lot of lowland rivers in Russia. They have wide valleys, with insignificant depth and steepness of the slopes, small slopes, their channels are, as a rule, tortuous and composed of soft sedimentary materials (sand and clay), the speed of water flow in the channel is low, as a rule, no more than 1 m/s , the banks are most often covered with forest or bushes. There are usually no rocks in the channel; obstacles are represented by sandbanks and riffles, as well as rubble from trees washed away or carried by water. This type of river is most clearly represented by the large rivers of the European part of the country - the Volga, Dnieper, Western Dvina and their tributaries, for example Vetluga, Desna, tributaries of the lower reaches of the Ob, for example Lyapin.

However, in the riverbeds of the European part, flowing through hills and mountain ranges, there are areas where bedrock comes to the surface, forming rapids. The most famous are the now flooded Dnieper rapids and the Migei rapids on the river. Southern Bug, Opechenskie rapids river. Msta. There are large numbers of rapids on the rivers of the Northern European part. The rapids alternate with long, calm, almost flowless reaches. These rivers belong to a special Karelian type, for example the river. Okhta in Karelia, r. Leather in the Arkhangelsk region.

Mountain taiga rivers. This type includes rivers in old mountainous regions, for example the Urals or relatively low mountain systems Sayan, Eastern Siberia and the Far East. Rivers often flow in rocky banks, forming rapids, rifts, waterfalls, and cheeks. There are also rubble, as well as shallows and rifts made of large pebbles and cobblestones. The slopes of mountain taiga rivers reach 10 m/km, the flow speed in the rapids is 4 m/s. Mountain taiga rivers, as a rule, have fairly developed gorges and valleys; rapid areas are interrupted by rather long reaches and rapids. Typical mountain taiga rivers can be considered the river. Kozhim in the Urals, r. Kantegir in Sayany, r. Vitim in Transbaikalia.

Mountain rivers. These include rivers in the high mountain regions of the Caucasus, Tien Shan, Pamir-Alai, Pamir, and Altai. Compared to the mountain-taiga ones, they have an even steeper drop (up to 20 m/km), there are very few reaches, the rapids pass one into another often without interruption, the flow speed in the rapids reaches 6-7 m/s. Mountain river valleys are located at considerable heights and are often poorly developed. Examples of mountain rivers are Obihingou and Muksu in the Pamirs, Zeravshan in the Pamir-Alai, Nary in the Tien Shan, Shavla in Altai. Some steep rivers of the Carpathians, for example, the sources of the Cheremosh and Prut, belong to the same type.

It should be noted that the boundaries between the types of mountain and mountain-taiga rivers are somewhat blurred. In addition, the same river can belong to three or two types, usually in the upper, middle and lower reaches, respectively. Thus, Chulyshman, along almost its entire length, is a mountain river, Biya, which is, as it were, a continuation of Chulyshman below Lake Teletskoye, is a mountain-taiga river, and the Ob, one of the sources of which is Biya, is a plain river. Kosyu, a tributary of the Usa, is a mountain-taiga river in its upper reaches, and a flat river in its lower reaches. There are examples of reverse alternation. Thus, the Tsipa, a tributary of the Bitim, is a lowland river in the upper reaches, within the Bauntovskaya Basin, and a mountain taiga river in the lower reaches.

SIZE OF RIVERS AND WATER CONTAINMENT

TO big rivers include rivers flowing within several geographical zones and having a basin area of ​​more than 50,000 km 2, for example the Volga, Dnieper. Medium-sized rivers flow within the same geographical zone and have a basin area from 2,000 to 50,000 km 2, for example, the Kem, Meta, Sakmara, Obihingou, Chulyshman rivers. Small rivers include rivers with a basin area from 1,000 to 2,000 km 2, for example, the Sandalash and Ulug-O rivers.

NATURE OF NUTRITION AND WATER REGIME

Rivers with high spring floods. Most of the rivers in our country that flow in areas with abundant snow cover (East European Plain, West Siberian Lowland, Ural) belong to this type. Spring floods caused by melting snow provide up to 40-60%, and sometimes more, of the entire annual runoff. The flood passes into the summer low-water level, which can be low in dry summer, average in summers with average precipitation and high in rainy summers. The low water level is very stable and changes slowly.

Rivers with moderate spring floods and summer rain floods. These are the rivers of the Carpathians, the western foothills of the Caucasus and Transcaucasia, and the mountains of Southern Siberia. The fairly high spring flood, caused by snow melting, extends until the beginning of summer due to the height of the basins above sea level. Heavy summer rains cause flash floods. Due to the narrowness of the valleys and steep slopes, rainwater quickly flows into rivers. Therefore, the spring flood almost without interruption turns into summer floods, of which there are 8-10 per summer. Thus, the share of summer runoff increases, and the share of spring flow drops to 30-40%.

Rivers with low spring floods and predominant summer floods. This type includes rivers in the highlands of the Caucasus and the mountains of Central Asia and rivers located in the eastern regions of the country with monsoon climate(most of Eastern Siberia and the Far East). On the rivers of the highlands, a stable summer flood is caused by the melting of glaciers; on the rivers of Eastern Siberia and the Far East, by monsoon rains. The share of spring runoff drops to 20-30, the share of summer runoff increases to 50-60%.

COMPLEXITY OF THE ALLOY

This classification is purely tourist. It is contained in the “List of Classified Tourist Routes” and is revised once every four years in connection with the emergence of new vessels, the development of water tourism technology, and the emergence of new means and methods of ensuring safety. It can also change depending on the water flow in the river (with high water flow during the flood or flood period, the difficulty of passing the river usually increases). This classification also depends on the class of vessels used: for kayaks, the river is usually more difficult.

All lowland rivers in their technical complexity do not exceed the first category, that is, they do not contain obstacles that have individual character and requiring an individual approach (thresholds and shivers). The exception is Karelian-type rivers with routes up to the third category of difficulty inclusive.

The most typical obstacles on rivers of the first category of complexity are shoals, rifts and blockages, as well as artificial obstacles - low bridges, dams, etc. However, these same rivers represent increased danger during the spring flood period.

Large rivers are interesting for water tourism, as a rule, in the upper reaches, significantly above the beginning of navigation. On medium and small mountain taiga and mountain rivers, routes from the second to the sixth category of difficulty are possible. It is safer to take routes along the rivers of the highlands in the spring before the start of the summer flood or in the fall after it ends.

MAIN ELEMENTS OF THE VALLEY AND RIVER BED

Rivers are natural, significant and continuous flows of water, fed mainly by precipitation (rain, melted snow water, glacial water), and are formed wherever the terrain has at least a slight slope. The river itself forms the channel along which it flows, and in this way it differs from artificial watercourses. The connection of rivers with each other, the totality of all rivers pouring their waters into one lake or sea, is called a river system. In each river system, there is a main river and its tributaries, which, in turn, can receive tributaries of the second, third order, etc.

Each river system collects surface and The groundwater from the territory occupied by it, which is called the drainage area, or river basin. The basins of neighboring rivers are separated from each other by watersheds, usually passing through the most elevated places in the region. Occasionally, bifurcations occur, that is, the division of rivers into two streams, one of which flows into a river in another basin.

The place where the water forming a river first takes the form of a surface flow is called the source. A river can begin as a spring, flow out of a lake, swamp, or originate from the tongue of a glacier.

Some rivers are formed from the confluence of two rivers that are usually close in water content, for example, the Ob begins from the confluence of the Biya and Katun, the Northern Dvina - from the Sukhona and the South. In this case, when determining the length of the river, the longer of the component rivers is taken as the source.

The final section of a river where it flows into the sea, lake or other river is called the mouth. At the mouth, the speed of water flow slows down and most of the particles carried by the water are deposited opposite the mouth in the form of a shoal.

River Valley – These are narrow and elongated, mostly winding, hollow landforms formed as a result of the activity of a river flow. Valleys are limited by coastal slopes, or sides.

Rice. 1. Elements of a river valley:

1 - edge; 2 and 3 - left and right slopes (sides); 4 - floodplain; 5 - level during high water; 6 - level during low water; 7 - shore height; 8 is the width of the river at high water; 9 - river width at low water; 10-terrace; 11 - valley width

The lowest point of the valley is called the bottom, the upper edge of the coastal slope is called the edge. The bed of the river along which it flows into the low-water level is called the channel. During a flood, that is, with a rise in water, the river leaves the channel and floods the bottom of the valley - the floodplain.

The slopes of a river valley have the form of ledges or steps with more or less horizontal surfaces, which are called terraces. There may be several terraces. Each river terrace is a trace of an ancient, higher valley floor.

The classic form of a river valley with a full set of its elements is found only on lowland rivers. On mountain rivers there is often no floodplain and the river bed occupies the entire bottom of the valley and comes close to the bedrock bank.

In mountainous and mountain-taiga areas, rivers often flow in deep narrow valleys with steep slopes - canyons, which, depending on the hardness of the rocks, can be of one form or another. Rocky, steep high banks of a river (in mountain taiga regions) are called cheeks(Siberian name). Cliffs located opposite each other on both sides of the river are also called cheeks. A sheer rocky wall more than 5 m high in a narrow place in a river valley or a cape protruding into the river and making it difficult to walk along the shore is called bom.

The cross-section of a river bed is rarely symmetrical; it is especially asymmetrical at turns, where water circulation occurs along the surface from the convex bank to the concave one, and vice versa at the bottom. Therefore, the concave bank erodes at turns, gradually approaching the side of the valley, where it eventually reaches the bedrock bank, composed of more ancient rocks.

The highest, steepest and steepest part of the bedrock bank is called rage. The part of the ravine upstream of the river, connecting to a straight section of the bank, is called the upper arm of the ravine, and the downstream part of the ravine, connecting to a straight section of the bank, is called the lower arm.

The erosion products of the concave, or outer, bank are transported by the bottom current and deposited near the convex, or inner, bank, forming a low, gently sloping sandbank. The depth of the channel from the convex bank to the concave bank (ditch) increases slowly. Immediately beyond the end of the ravine, the sand becomes cut off, that is, the shore looks like a low wall with a depth sufficient for all tourist vessels near the shore. In the immediate vicinity of the ravine and cutting sand there is rod - line of highest water speed in a stream. Behind the lower shoulder of the ravine, the core passes to the opposite bank, therefore, near the ravine bank, the flow speed slows down and behind the lower shoulder of the ravine a a bit - underwater sandbank of relatively small size.

All river valleys, and especially the channels, are tortuous, that is, they consist of alternating turns, or meander. Meanders with closely converging beginning and end are called bows. A typical example is the famous Samara bow on the Volga in the area of ​​​​the city of Kuibyshev, which contains Zhiguli Mountains. The path along the river between the beginning and end of the Samara Luka is more than 7 times greater than the shortest distance between them by land.

At the beginning of the Samara Luka the river flows into the Volga. The mustache flowing very close to the end of the bow at the village. Transfers. This made possible the well-known circular water route with a small portage of the first category of complexity “Zhigulevskaya Around the World”.

The river bed often meanders within the valley. Gentle meanders of the riverbed within the valley are called bends, steep and short ones are called knees. The meanders of the river channel within the valley often change, the river washes out a new channel, and an island is formed, washed by two channels. The shorter and straight channel becomes the main channel, the longer channel, which was previously a bend or elbow, is closed by sediments, first at the outlet, and then at the entrance, forming an elongated floodplain lake - an oxbow lake. The oxbow in high water connects with the river.

Rice. 2. Turns of the river bed and valley:

1 - gyrus; 2 - valley border; 3 - bend; 4 - bow

OBSTACLES ON RIVERS

Roll. A complex formation of two shallows growing from opposite banks towards each other. Riffles often exist in places where the direction of channel turns changes, that is, in places where the flow core passes from one bank to another. Rifles long time exist at the same place in the riverbed. There are three types of rifts: normal (Fig. 3), shifted and scattered. All riffles consist of upper and lower spits or shallows, between which there is the crest of the riffle, where the depth is smallest and the current speed is highest. In the crest of the riffle there is a trough - a channel with the greatest depths. From above, a pressure slope with a gradually decreasing depth leads to the crest of the riffle; immediately behind the ridge downstream there is a basement of the riffle with a sharp increase in depth.

The parts of the channel located above and below the crest of the riffle are called upper and lower reach valley.

On lowland rivers, all elements of a sandy riffle can be easily identified on the river by the color of the water - the deeper places are dark, in the shallower places yellow sand shines through. On mountain and mountain-taiga rivers there are also rifts, shallows and other elements described above, composed of products of channel erosion; they can be composed of both sand and pebbles of various sizes, up to cobblestones.

The shifted riffle (Fig. 4) is distinguished by the fact that the upper and lower reach valleys strongly overlap each other, each continuing along its own bank, while the ridge

The roll can be directed along the longitudinal axis of the river or even so that the direction of the flow in the trough will make an angle of more than 90° with the direction of the river flow. In a shifted riffle, swell currents appear across the ridge in addition to the trough, which can mislead the tourist and drag the ship aground. Placer rifts have several ridges, vaguely defined troughs and spits located in the channel without any visible pattern, so they are especially difficult to pass.

The tourist navigation guide classifies elements of the bed and water flow that are not found on navigable rivers and are characteristic mainly of small and medium-sized rivers on which sports tourist trips are carried out.

Threshold. A section of a river bed with a sharp increase in slope and flow speed relative to sections above and below the threshold. Rapids are formed in places where a river crosses rocky ridges, moraines, outcrops of hard-to-erode bedrock, accumulations of boulders, products of mountain falls and mudflows, and the consequences of human activity, such as blasting when laying roads (artificial or explosive rapids). In front of local rapids with a particularly steep drop, areas of calm water (reaches) sometimes form due to the damming of the river by the rapid.

Characteristic elements of a rapid are weirs, water holes or barrels, and standing waves.

Spillways. They are divided into waterfalls (angle of incidence more than 45°), waterfalls (angle of incidence about 45°) and simply plums (angle of incidence less than 45°). Gentle drains usually have the shape of a triangle formed by the line of greatest inflection of the longitudinal profile of the river bed and oblique streams from the rocks limiting the drain at the base. Converging oblique jets lead to the appearance of a standing wave or a track of standing waves behind the vertex of the triangle. Steep drains, waterfalls and waterfalls usually form immediately behind the drain a water hole, or barrel - an area of ​​​​reverse flow along the surface, and behind it a system of standing waves. In this case, a triangle is not formed. A rapid may have one drain the entire width of the river; it can also be divided by protruding rocks and stones into several drains of varying widths and thicknesses.

The threshold may also consist of several successive discharges. If in a threshold one discharge or successive discharges of the threshold occur one after another with an interval not exceeding the length of the vessel, the threshold is called single-stage. If between successive discharges of the threshold the ship can freely maneuver to move from one bank to the other, the threshold is called multi-stage. If between two successive discharges it is possible to moor to the shore on a raft, it is advisable to consider these discharges as belonging to different rapids. If the line of greatest inflection of the longitudinal profile of the river bed in the drainage is perpendicular to the direction of water flow, then the drainage is called straight. The drain is called oblique when the angle between the inflection line of the longitudinal profile and the flow is acute. Sometimes in a narrow oblique drain on the line of inflection of the longitudinal profile, the depth of the channel near the banks is very different, then the drain will be twisted, or helical.

Standing waves, or waves. They are formed during the movement of water in drains due to the addition of longitudinal, transverse and reverse local velocities of water in the flow, which arise when water encounters heterogeneities in the cross-section of the channel. A standing wave is formed below the inhomogeneity to which it owes its birth. Waves are called standing waves because they are motionless relative to the shores, in contrast to moving wind and tidal waves. The height of standing waves reaches several meters and depends on the water flow in the river, the speed of the current, the depth of the river and the bottom topography.

Standing waves whose crests are perpendicular to the direction of water flow are called straight waves, waves whose crests are located at an acute angle to the flow are called oblique. The sources of direct standing waves are, as a rule, distortions in the flow cross-section at the river bottom, for example, a ridge of underwater rocks. Oblique standing waves are most often formed due to distortions of the coastline, for example, near coastal ledges. Standing waves also occur when two streams merge, for example at the confluence of a large tributary. In such places, a system of many steep point standing waves sometimes appears. An important characteristic of a standing wave is the length of its slope, which is compared with the length of a tourist ship. Waves can be steep, or short, when the slope is less than half the length of the tourist vessel, and flat, or long, when the wave slope is equal to or greater than the length of the tourist vessel. Very short standing waves have a reverse crest, like a water peak, directed against the current.

Water holes or barrels. They form behind very powerful and steep plums (Fig. 5). They are characterized by a strong reverse flow of water at the surface. A barrel can be considered small if its size is less than half the length of the vessel, and large if it is larger. Water in barrels often contains a lot of air, so it has a lower specific gravity and holds the vessel worse.

Shivera. Rocky section of the river bed with fast current, shallow depths and randomly scattered underwater and protruding stones in the riverbed. On rifts, due to the high flow speed, standing waves, reverse currents, and sometimes water holes (barrels) appear in the stream. Unlike thresholds, shivers do not have clean, powerful drains; in a shiver, the drains are local, the connection between successive drains with each other is poorly visible, so it is difficult to identify the line of predominant water flow - the jet. The length of the rift varies from several tens of meters to several kilometers. Rapids often begin and end with shivers.

Clamps. On fast-flowing rivers, pressure often forms, that is, piles of water on the steep, most often rocky, outer bank of the river bend under the influence of centrifugal forces. Clamps are formed at very sharp turns, since at turns the flow core is located close to the outer bank of the turn, a significant mass of water falls on it, and directly near the shore various distributions of velocities are created across the flow. If the river's water content is significant and the turn is very sharp, breaker shafts are formed near the shore. The distribution of currents in the clamp in this case will have the form shown in Fig. 6b. When the river's water content is high, but at a less sharp turn, as well as when the bank has a negative steepness under water, a breaker shaft may not occur. Then the distribution of flows in the clamp will have the form shown in Fig. 6 a. A similar picture occurs in the clamp at a fairly sharp turn in a flow with low water flow. Clamps with a breaker shaft are easily recognized on the river by their breaker shaft, clamps without a breaker shaft are much more difficult to recognize, and the suction to the shore in them is much stronger.

Catches. On fast-flowing rivers, countercurrents can form in planes parallel to the river bottom - catches (Fig. 7). Their occurrence is associated with the separation of the flow from

banks for one reason or another (bank protrusion, tributary confluence, etc.). Catches are created at pressure points, near riffles, during sharp expansions of the channel, on shallows and during sharp accelerations of individual parts of the flow (jet), for example, when two channels merge. It can sometimes be difficult to get out of a catch, since you need to have time to leave the stream that forms the catch, crossing it in a short time.

Boundary of opposing currents or currents with different speeds. It occurs when tributaries flow into a river (especially if the tributaries are comparable in water flow to the main river), when the flow flows around large surface obstacles (stones, rocks, slabs). These boundaries are very small in length (sometimes the length of the transition from one speed to another is 30-50 cm) and are dangerous because a tourist vessel, having the speed of one stream, suddenly, in its individual parts, falls into a stream with other speeds, instantly experiencing the action of various forces . To avoid capsizing the vessel when crossing the border of opposing currents, it is necessary to use a variety of technical techniques.

A blockage or a crease. Characteristic obstacles characteristic of lowland rivers of the taiga zone and mountain taiga rivers are formed by tree trunks placed on the top of the island, at the entrance to a small channel, on the outer bank of a river bend. During the flood, the rubble is carried away, but when the water recedes, they appear again, they also appear during summer floods, and on small and narrow taiga rivers they can exist and increase in size for years. The blockage is a very dangerous obstacle; it is difficult to recognize, since from a distance it seems to be part of the shore and only in the immediate vicinity does a strong current begin to be felt, sucking under the blockage. On mountain taiga rivers, a great danger is posed by trees located on the outer banks of the river's bends that are being washed away, partially washed away but not yet fallen, and bent low over the water. Such trees are especially dangerous for ships with relatively high rowers - rafts and catamarans.

On rivers flowing in populated areas, there are artificial, that is, created by people, obstacles.

Bridges. There are often transport and pedestrian bridges and footbridges. Bridges are installed on supports standing in the riverbed. The supports pose the same danger to a tourist vessel as single surface rocks in an area with a fast current; the width of the passage between the supports and the direction of the current matter. Near modern reinforced concrete bridges, there are usually a lot of concrete blocks and reinforcement in the riverbed. Pedestrian bridges often have wooden supports located closer together and low decks. Near modern, new bridges in the riverbed there may be remains of supports or piles of old bridges located nearby.

Dams. There are mainly two types of dams - modern reinforced concrete operating dams and ancient stone-wood mill dams or regulating flow for timber rafting. Dams of the second type are in various stages of destruction and represent spillways of varying steepness and height, and are clogged to varying degrees. Often these spillways are passable, especially for kayaks. Reinforced concrete dams require demolition.

Stabs. Fences made of wooden stakes driven into the river bottom, blocking the entire river. The piers have narrow gates where tops for catching fish are installed. Stakes are mostly found as remains on small rivers, but stakes can pose a hazard to the hull of vessels.

Cables. The cables of ferry crossings hanging over the water pose a danger to tourist ships. Typically, these cables are raised high above the water near the banks of the river, where you should pass under them. It is very important to notice this cable in time.

Mole alloy. Although moth rafting of timber is almost no longer used, tourists may still have to encounter it. During rafting, tourists are not allowed to go out onto the river. Mole rafting usually begins immediately after the flood. On small rivers it ends quickly, on medium rivers it can last until the middle, and on large rivers until the end of summer. The rivers along which timber rafting has been carried out for many years are usually clogged with driftwood logs, one end of which lies at the bottom of the river, and the other end is shallow under the surface of the water. This end of the log is invisible, and encountering it while moving, especially against the current, ends in damage to the shell, and sometimes even damage to the frame of the vessel.

Zapani. On the rivers where timber rafting is carried out, all summer long there are dam systems made of narrow, several-log rafts, held by steel cables and blocking individual river channels in order to direct the rafted timber into the main channel. There are also storage pits that block the entire channel in order to accumulate timber for rallying or transshipment to the shore. As an obstacle, a jam is similar to a blockage—a drawing current goes under it, but you can’t get through it.

The trap can be passed under a high bank, where the cable is raised high above the water, and the logs do not reach the shore. You can also, while on the tank, temporarily separate or submerge the links of the tank. Storage areas usually always have a lot of forest, so they need to be surrounded.

Rye walls. On small rafting rivers (this is especially typical for the rivers of the European North and the Carpathians) there are often row walls made of logs, located on the concave outer banks of the channel bends, held from the inside by log cages with stones. The ryazhevy wall as an obstacle is similar to the clamp, but flakes from logs and metal staples holding the logs together often protrude from it.

The last type of artificial obstacles includes the general cluttering of the riverbed with a variety of objects, including sharp ones, within populated areas.

MAIN CHARACTERISTICS OF THE RIVER DETERMINING
COMPLEXITY OF THE ALLOY

Water consumption. An important characteristic of a river for a water tourist is water flow, that is, the volume of water flowing through the cross section of the stream per unit of time (m 3 /s). Water consumption depends on the size of the basin, its water content, the nature of the relief, geological structure, soil cover and vegetation of the territory. Water flow is directly proportional to the area of ​​the basin, therefore, the further downstream, the more water the river has, as more and more tributaries flow into it. The exceptions are rivers flowing through the desert, and rivers, part of the water of which is spent on irrigation, for example, Amu Darya, Syr Darya, Kuban, Terek.

The relief of the basin affects the amount of precipitation - the higher the mountains, the more precipitation, and the rate at which melt and rainwater enters the riverbed - the steeper the mountains, the faster the river collects melt and rainwater, the sharper the peaks of summer rain floods. The rate of entry of melt and rainwater into the river is also influenced by the nature of vegetation. Snow melts more slowly in the forest, the forest retains melt and rainwater longer; The steppe and desert quickly give water to the river.

To compare different drainage basins with respect to the amount of runoff, the value of the runoff module is introduced, that is, the ratio of water flow in a given river section to the area of ​​the basin above this section. The runoff module is the amount of water in liters that the river receives from each square kilometer of the basin in one second, measured in l/km 2 *s. The greatest flow is in the mountains. On the northern slope of the Caucasus it reaches 50, and in Western Transcaucasia 75 l/km 2 *s. Large flowing lakes are among the most powerful flow regulators. If there are many lakes in the river basin, then all flood peaks will be smoothed out, extended in time and small in amplitude.

Water consumption is also influenced by climatic factors: temperature and distribution of precipitation by season.

High water. This is the phase of the highest standing water in the river. On lowland rivers of a temperate climate it is caused by the melting of snow (spring flood), on mountain rivers by the melting of glaciers and snow (summer flood).

Flood. A relatively short-term rise in water in the river as a result of heavy rains. Usually it has a pronounced peak - the highest level, which moves along the river at the average speed of its flow, forming a flood wave. Before the peak passes, the water rises, after passing - it decreases. A flood peak can be caused artificially, for example, by opening a reservoir dam in the upper reaches of a river, or by breaking a dam (ice or ground) holding a lake in the upper reaches of a mountain river.

Flood rise (Fig. 8a) is characterized by a higher water level at the core and its transverse circulation along the surface from the middle to the shores (small debris floats near the shores). The decline of the flood (Fig. 8b) is characterized by a higher water level near the banks and its transverse circulation along the surface from the banks to the middle (small debris floats in the middle of the channel). A flood, and especially a flood, is also characterized by muddy, dirty water. The flood may also be caused by the melting of glaciers in the river basin.

Low level. The summer season in the vast majority of tourist areas of the country corresponds to the low-water level - the lowest water level, when there is no significant influx of snow and rain water into the river. In the highlands and the Far East, the low-water period shifts to autumn. The average low-water level corresponds to the average year for climatic conditions. During low-water periods, the river seems to be in a steady state, channel processes hardly occur, and the channel most fully corresponds to the water flow flowing in it. However, in case of rainier summers, tourists face high water.

This is not a flood, but simply a larger than average influx of water into the river, that is, a higher low-water level. The water, as a rule, is clear, there are no sharp fluctuations in level, it comes close to the coastal bushes, flooding the pebble shallows and almost all the islands.

In a dry summer, a tourist may encounter low water - standing below the average low-water level. A characteristic sign of low water is a significant difference in flow speeds on reaches, rapids and rifts. You can hardly feel the current on the reaches. There are many pebble shallows and islands on the river, steeply plunging into the water. With a steady change in weather, a transition from high or low water to an average low-water level may be observed. Unlike sharp flood declines and rises, this transition lasts for one to two weeks and occurs in clear water.

Slope. A very important characteristic of a river is expressed by the ratio of the difference between the water edges of the beginning and end of a given section of the river to its length (measured in m/km or written as a dimensionless decimal fraction). The slope of the river is a parameter that largely determines the speed of the flow. A river as a whole or a large section of it may be characterized by an average slope, but navigation conditions in small sections will be determined, among other factors, by the local slopes of these small sections.

Longitudinal profile of the river. A graph in which the water edges are plotted along the vertical axis, and the distances of the corresponding points from the source or mouth of the river along the horizontal axis. On the longitudinal profile it is easy to identify areas with different slopes. Typically, a river with a well-developed channel develops a longitudinal profile in the form of a parabola - it is called an equilibrium profile. On average, the slope gradually decreases from source to mouth.

In the upper reaches the slope can be significantly higher than average, but the river is low-water. Water velocities are high, the river often flows in one channel, and erosive (erosive) water activity predominates. In the middle course, the slope is close to average, the water content of the river increases, channels and islands appear, the eroding and accumulating activities of the river are approximately balanced. In the lower reaches, the slope is below average, the water content of the river has increased significantly, there are many channels and islands, the river mainly deposits material washed up higher. But all this is true on average. In practice, in any course of a mountain or mountain-taiga river there may be sections with both a small and a large slope. Some rivers in the upper reaches flow along swampy watershed plateaus and have a small slope, while they have a large slope only in the middle reaches, breaking through the bordering ridges (for example, such Siberian rivers as Tsipa, Temnik).

RIVER PASSABILITY

Water tourists are primarily interested in the river's passability - that basic and not easily perceptible characteristic, which consists of many factors and which is different for different types of rivers and different classes of vessels.

The passability of lowland rivers is determined mainly by sufficient water flow at the starting point of the rafting and the number of long-term impassable blockages on the river. The passability of mountain taiga rivers depends on the water flow at the starting point of the rafting, the slope and speed of the flow, as well as the nature of the valley. The blockage is of secondary importance. When mountain rivers are passable, especially with a predominance of glacial feeding, it is necessary to consider not only the minimum required water flow at the starting point of the rafting, but also the maximum allowable for safe rafting (on medium rivers).

In an average year in terms of climatic conditions, the country’s lowland rivers flowing in the forest zone can be considered accessible for kayaking at a distance of at least 40 km from the source (according to a 1:1,000,000 scale map) or from the source itself, if the river serves as the only drainage lakes with an area of ​​at least 80 km2. This corresponds to a low-water flow rate of 3-6 m 3 /s. On mountain taiga and mountain rivers, the minimum water flow at the starting point of the rafting should be 7-12 m 3 /s, depending on the slope, flow speed, and the nature of the valley. On mountain rivers fed by glaciers, such flow can be reached 10-15 km from the source (on rivers of Central Asia, sometimes directly from the glacier), on most mountain taiga rivers - 20-30 km. The greater the slope and speed of the current, the greater the water consumption required to begin swimming. However, to ensure the proper level of safety, all these characteristics are limited from above, and with the improvement of rafting technology, rafting means and means of insurance, this level is gradually increasing. For the most versatile modern vessels - multi-seat catamarans - rivers are now available with an average slope of up to 20 m/km and maximum slopes of individual short sections (3-5 km) of up to 40 m/km at water flow rates from 10 m 3 /s to 60 m 3 /With. For catamarans with an increased reserve of buoyancy and modern rafts with inflatable elements, these values ​​can be taken higher by 10%, for frame-inflatable kayaks - lower by 20%, for rigid-frame kayaks - lower by 30-40%.

However, the slope itself mainly affects only the speed of the river. To determine its passability, it is much more important to know the degree of development of the channel and valley, which is determined by the slope of the river and water flow taken together, depending on the hardness and heterogeneity of the rocks of the channel and valley. A small stream and a large river, passing through the same level difference, make various jobs Therefore, with the same material, the channels and valleys are eroded differently. Where there is little water, the level difference is hard rocks will be triggered by steps, waterfalls, unsuitable for swimming; where there is more water, one can expect, even in hard rocks, the formation of a more uniform channel, possibly suitable for swimming. Therefore, from the point of view of cross-country ability, it is important to know the material and degree of development of the river bed and valley.

Rivers with poorly developed canyon-like gorges are less accessible for navigation. A poorly developed gorge indicates the hardness of the rocks or insufficient flow power: in both cases, in a poorly developed gorge one can expect difficult or impassable obstacles in the form of waterfalls and steep, high drainages. In a poorly developed gorge, it is also difficult to organize reconnaissance and insurance; the passage of rivers with such gorges is only possible for well-prepared and specially equipped groups.

Various forces act on a river flow, primarily gravity. The magnitude of its component affecting the water in the direction of flow depends on the slope of the river. The greater the slope, the greater this component, the higher the water speed. The speed of the current is ultimately the main factor determining the complexity and danger of the river for tourists. The gravity component is opposed by the friction force of water on the banks and bottom of the river and the force of internal friction between layers of water. These forces are determined by the degree of roughness of the material of the river bottom and banks, the depth and width of the riverbed. The larger the particles that make up the bottom and shores, the greater the friction force.

The water in the river is also affected by centrifugal force (at turns in the riverbed) and the Coriolis force caused by the rotation of the Earth. The centrifugal force acts from the center along the radius of rotation; the Coriolis force in the northern hemisphere is always directed to the right along the flow. These forces cause transverse currents in the river (the current caused by the Coriolis force can be ignored in tourist practice). There is a certain average flow velocity and local velocity. The local velocity is zero at the bottom and shores and is maximum at a certain line below the water surface (the corresponding line on the water surface is called the core).

According to the distribution of velocities in the flow cross-section, flows are distinguished as laminar, turbulent and with a spatial regime. Laminar flows, characterized by parallel movement of layers of liquid, are rarely encountered in tourist practice: they can only exist at very low depths, water velocities and channel slopes. Thus, with a river depth of 20 cm, laminar flow can exist at a flow speed of no more than 1 cm/s. A tourist almost always deals with a turbulent flow, characterized by the formation of vortices in the flow volume, that is, by the fact that different parts of the fluid have not only longitudinal, but also transverse velocity components. The vortices that arise at the bottom and shores break off and move toward the center of the flow. In a turbulent flow, the line of maximum local speeds is also below the flow surface, but the speed increases unevenly with distance from the bottom. At the very bottom there is a very thin layer of zero and low velocities, and then the velocities quickly increase and can reach, for example, already at a depth of one tenth 40-50% of the maximum speed, and at half the depth - 80-90% of the maximum speed. For turbulent flow, the maximum speed can be calculated. It is directly proportional to the slope and depth of the river and inversely proportional to the bottom roughness (the half-diameter of the particles that make up the bottom) to varying degrees. Below are graphs of the dependence of the maximum speed v on the slope i at various depths H and channel roughness D (Fig. 9) and on the depth at various slopes (Fig. 10) provided that the channel is assumed to be rectangular.

In Fig. 11 shows a graph of constant speeds with changes in slope, river depth, and constant channel roughness. If we take some kind of limit speed, for example 2 m/s, then we can determine at what combinations of slope, depth and bottom roughness the current speed will be higher or lower than the limit speed. Knowing that the flow speed largely determines the complexity and danger of the river, it is possible, by setting certain boundary speeds, for example 1.5 m/s, 3 m/s, to obtain from this graph approximate data on the slopes and depths at which the river will be uncomplicated , complex and very complex.

If the obstacle is underwater and has a smooth ridge (a large stone, an underwater ridge, a channel ledge, a dam), then the disruption of the flow structure occurs mainly in the vertical plane. Depending on the speed of the current and the relative (to the depth of the river) height of the obstacle behind it, either a system of standing waves is formed, parallel to the crest of the obstacle, or a vertical whirlpool zone with the movement of the surface layer of water opposite to the flow (a water hole, or a barrel - Fig. 5). Sometimes in tourist reports the complexity and danger of a river are assessed by such a parameter as the product of water flow and slope. This parameter to some extent gives an idea of ​​​​the maximum speed of the river, since it is proportional to the slope to the power of one-half, and the water flow is proportional to the speed of the current. The attractiveness of this parameter is that both the slope and water flow can be obtained from tables of the main hydrological characteristics of the river. But it must be used carefully. More accurate results are obtained by calculating the maximum speed of the river. The maximum river speed during low-water periods is also shown on topographic maps. The speed of the current is affected by obstacles in the riverbed. The extent of their influence can be calculated. For example, massive protrusions in a channel with a diameter of 1 m, following each other at intervals of 5 m, reduce the flow speed by approximately 1.8 times, and dense aquatic vegetation from the bottom to the surface of the water by up to 10 times.

The river bed is designed in such a way that the least amount of energy is expended to move water. This condition is usually met on rivers with a well-developed channel and during low water periods. Rivers with insufficiently developed channels (in young mountainous regions), as well as during floods, carry many particles of different sizes, and the patterns indicated above do not always apply (so-called channel processes take place, that is, the formation of a channel). These patterns do not apply in places where the river narrows. In such cases, a completely different type of flow with a spatial structure can be observed, characterized by a strong displacement of the line maximum speeds in depth, as well as the presence of a stable cross-flow along the surface of the river from the banks to the middle of the channel and along the bottom from the middle to the banks. This structure has no visible distinctive features and can be found in rapids, canyons, cheeks, and generally in poorly developed channels with high water flow. The tourist recognizes this flow structure when the ship is strongly pulled into the stream, when exiting the stream requires significant effort from the crew. The spatial flow regime is one of the cases of stable transverse velocity of water flow in the channel. Transverse velocities, reaching 30-40% of the maximum current speed and directed from the shore to the middle of the river, also arise due to vortex formation near the banks of the turbulent flow. These speeds have a random distribution in time and space.

A stable transverse velocity occurs at a river bend due to centrifugal force. There is always a circulation flow at a turn. On the surface, water shifts from the inner bank of the bend to the outer bank. At the outer bank, the water velocity is directed from the surface to the bottom, and along the bottom the water moves from the outer bank of the turn to the inner bank (Fig. 8c). The maximum value of the transverse speed is quite high (it can reach 30-50% of the average flow speed) and this must be taken into account when negotiating turns. The transverse velocity leads to a displacement of the flow core towards the outer bank of the turn.

The circulation current at the bends causes erosion of the outer bank and the formation of shoals near the inner bank. On mountain rivers with high flow speeds at sharp turns, the circulation current causes water to pile up on the outer rocky bank (pressure). Due to the circulation flow at sharp turns of high-speed rivers, a noticeable transverse slope of the water surface is formed. Noticeable transverse velocities also occur during rapid flood rise or fall of water. When the water rises, the river seems to swell, the middle of the flow rises, and the transverse flow along the surface is directed from the middle of the channel to the banks. When the water recedes, the middle of the flow collapses, the transverse flow along the surface is directed from the banks to the middle of the river (Fig. 8 a, b).

When flowing around obstacles in the channel, areas of transverse and even reverse flows are also formed. Flow around obstacles, like flow in a channel, can be laminar or turbulent. Laminar flow without disturbing the flow structure with smooth expansion and closure of the jets is observed either at very low flow velocities or with an ideally streamlined obstacle shape. Both cases are almost never encountered in tourist practice. Turbulent flow around obstacles is characterized by disruption of the flow structure.

If an obstacle protrudes above the water (a rock, a shore ledge), then the flow structure is disrupted mainly in the horizontal plane. A zone of high pressure is formed in front of the obstacle, due to which a water “cushion” appears (the water rises and a transverse flow is created along the frontal part of the obstacle). A zone of low pressure (the so-called whirlpool zone) appears behind the obstacle due to the fact that the jet breaks away from the obstacle. Depending on the flow speed, shape and size of the obstacle, the jet is disrupted from the side or almost from the frontal surface of the obstacle. The length of the whirlpool zone can exceed the diameter of the obstacle by 10 times. Behind large protrusions of the coast, the whirlpool zone sometimes forms an area with regular circular movement of water - a catch already familiar to us (Fig. 7). When the jet stalls early, oblique standing shafts appear near the frontal part of the obstacle, diverging to the sides from it. The area of ​​standing water behind an above-water rock is often called the high-velocity area, or simply the “shadow” of the rock.

Reverse currents can also occur under the influence of external forces, such as wind or tide. There is a known wind surge of water at the mouth of the Neva, causing floods, as well as tidal waves that turn the rivers back at the mouth for 30-50 km (on some rivers of the European North, flowing into the White and Barents Seas). Such features of rivers should be clarified when preparing a trip.

A river flowing in its channel, on the one hand, erodes it, and on the other, deposits erosion material in places where the flow slows down. The greater the slope, the higher the flow speed, the more the erosive activity of the river during a flood prevails over the accumulating activity. We can assume that for a certain section of the river, where the slope is greater than the average, erosive activity predominates, and where the slope is less than the average, accumulative activity predominates. Areas with a predominance of erosive activity are characterized by thresholds, cheeks, and shivers. Areas with a predominance of accumulative activity are characterized by rifts, alluvial rifts and especially blockages. This is not a mandatory rule, but the prevailing trend.

When a river breaks through a mass of homogeneous rocks, cheeks are formed, not only in soft rocks, but also in fairly hard ones. There are known shale cheek canyons in the Eastern Caucasus, cheeks of the Tuvan Ka-Khem river in a lava massif and others. Usually the cheeks are replete with rapids, because in the mass of one rock there are many heterogeneities. In addition, there are frequent collapses in the cheeks, which also contribute to the appearance of thresholds. Rapids, cheeks and rifts found in sections of the river with a large slope have an individual character, and the line of movement in them should be determined depending on the structure of each obstacle after its reconnaissance.

In areas with a lower slope, with a predominance of the accumulating activity of the river, it is already possible to identify some patterns of the formation and structure of obstacles that clearly determine the choice of the route of movement. The river transports material of various sizes - from sand suspended in the water to the so-called transportable sediment (stones up to 1-2 m in diameter). The patterns of deposition of such sediments are similar: they are all deposited in places where flow slowdowns occur.

Where are these places in the riverbed? If there is an island on the river, then the current slows down when the channels separate and the streams from the channels are knocked together, that is, at the head and tail of the island, where elongated sandbanks are formed. If two channels are of unequal length, then the flow in the longer one is slower, because it has less slope. This means that it is more clogged with sediment, and there should be less water in it, since the river gradually clogged it. It can be expected that the outlet of the longer channel will be the most clogged: it is at the outlet that its water is strongly inhibited by the backwater of a longer channel. fast water short duct. Often, especially on mountain rivers, a longer channel ends in a steep and very shallow decline of pebbles deposited by water. A lot of sediment is carried by tributaries, especially steeply falling ones, and this sediment falls at the mouth of the tributary - where its flow is slowed down by the backwater of the main river. Alluvial rifts or shoals are usually created at the confluence of tributaries.

The areas noted above with a large slope (predominance of erosive activity) and with a smaller slope (predominance of accumulating activity) are clearly distinguishable on the map and on the ground. They differ primarily in the character of the valley. In areas with a large slope, the valley is narrow, like a gorge, and there is usually only one channel, without channels. In areas with a lower slope, the valley is wide, and the river is often divided into channels. The places of transition from one area to another and the place where the profile breaks are also clearly visible on the ground. At the point of transition from a higher slope to a smaller one, the flow slows down, so at the end of a difficult section with a high slope you can expect a long drift. Slowing down of water before a threshold such as a simple step can also lead to the formation of a pre-threshold alluvial rift.

IMPACT OF FLOW ON A FLOATING VESSEL

Let us briefly consider the effect of flow on a sailing ship. The influence of the flow on a floating object occurs within the depth of its immersion. Any free-floating object moves at the speed of flowing water or faster. The greater the mass of an object, the slope of the river and the smaller the area of ​​contact of its surface with water, the more its speed differs from the speed of water.

The most interesting for a tourist are the effects on a single-hull vessel of the already mentioned oppositely directed currents (the boundary of the catch and the stream, currents in standing waves, etc.). The general rule is that the smaller the vessel’s draft and the larger its size, the weaker the impact of local currents on it. In the region of standing waves, this effect is expressed in the appearance (due to different directions surface currents on the slopes of standing waves) a torque tending to place the vessel across the current (lag), that is, in the position of least stability for a single-hull vessel. Similar forces arise when the stern and bow enter areas of currents with different or even opposite velocities. In this case, the moment of forces acting oppositely on the bow and stern may be sufficient not only to turn with the lag, but also to overturn a narrow and long low-stability vessel, such as a kayak. Double-hulled (catamarans) and multi-hulled (rafts) vessels are much more stable in these cases. The vertical components of the current, for example in whirlpools, submerge and heel ships depending on which part of them is affected by the vertical current. Very large eddies can capsize small boats. In flows with a spatial structure, the vessel is drawn into the region of maximum speeds (into the jet) under the influence of the transverse component of the current speed.

A river is a natural stream of water that flows in the same place constantly or intermittently during the dry season (drying rivers). The place where a river begins is called its source. The source can be lakes, springs, glaciers. The place where a river flows into a sea, lake or other river is called an estuary. A river flowing into another river is called a tributary.

River mouths can be deltas and estuaries. Deltas arise in shallow areas of the sea or lake as a result of the accumulation of river sediments and have a triangle shape in plan. The river bed here branches into many branches and channels, usually arranged in a fan-shape. Estuaries are single-arm, funnel-shaped river mouths, expanding towards the sea (the mouths of the Thames, Seine,). Usually the part of the sea adjacent to the estuary has great depths, and river sediments are removed sea ​​currents. Low-water rivers sometimes end in blind mouths, i.e. do not reach the reservoir (Murgab, Tedzhent, Coopers Creek).

The main river with all its tributaries forms a river system. The territory from which the river collects surface water is called a basin. Each river has its own pool. The largest basins have rivers (more than 7 million km2), Congo (about 4 million km2), and Russia (about 3 million km2). The boundary between river basins is called a watershed.

The flowing water of the river over a long period of time produces long and complex river valleys. A river valley is a concave, winding landform that stretches from source to mouth and slopes toward the mouth. It consists of a channel, floodplain, and terraces.

A channel is a depression in a river valley through which river waters constantly flow. A floodplain is a part of a river valley that fills with water during flood periods. The slopes of the valley usually rise above the floodplain, often in a stepped shape. These steps are called terraces. They arise as a result of the eroding activity of the river. The river bed usually has a sinuous shape in plan and is characterized by alternating deeper sections (reaches) with shallower ones (rifts). The meanders of the river are called bends, or meanders, and the lines of greatest depth are called fairways.

All the given characteristics of the river are its natural characteristics. In addition to them - and no less important - is a set of calculated characteristics that are closely related, and sometimes interspersed with natural ones.

Important characteristics of a river are its fall, slope, flow speed, flow and discharge. The fall of a river is the excess of its source above its mouth (the difference in heights of two points). Channel slope is the ratio of the fall to the length of the river. For example, the height of the source is 226 m, the mouth is 28 m, and the length is 3530 km. Then its slope will be equal to: 226 - (-28) / 3530 = = 7.2 cm/km. The falls and slopes of individual sections of the river are also calculated if their height and length are known. The fall and slopes, as a rule, decrease from the sources to the mouth; the flow speed depends on their magnitude; they characterize the energy of the flow.

Each river has middle and lower reaches. The upper reaches are characterized by significant slopes and high erosive activity, the lower reaches have the largest mass of water and lower speed.

The speed of a water stream is measured in meters per second (m/s) and is not the same in different parts of it. It consistently increases from the bottom and walls of the channel to the middle part of the stream. Speed ​​is measured in various ways, for example, by hydrological floats or hydrometric meters.

The water regime of a river is characterized by water flow and runoff. Discharge is the amount of water passing along a river bed in one second, or the volume of water flowing through a cross-section of a stream in a unit of time. Typically, flow rate is expressed in cubic meters per second (m 3 /s). It is equal to the cross-sectional area of ​​the flow multiplied by the average flow velocity. Water consumption over a long period of time—a month, a season, a year—is called runoff. The amount of water that rivers carry on average per year is called water content.

The most abundant river in the world is the Amazon. Her average consumption- 20 thousand m 3 /s, about 7 thousand km 3. In its lower reaches, the width of the Amazon in some places reaches 80 km. In second place in terms of water content is the Congo River (flow - 46 thousand m 3 / s), then the Ganges. In Russia, the most water-rich (discharge 19.8 thousand m 3 /s) and Lena (17 thousand m 3 /s). The most in the world is the Nile (with Kagera) - 6671 km, in Russia - the Amur (with Argun) - 4440 km.

Depending on the rivers, they are divided into two large groups: lowland and mountainous. Many rivers in the upper reaches are mountainous, while in the middle and lower reaches they are flat. Mountain rivers have significant falls and slopes (up to 2.4 and even up to 10 m/km), fast flow (3-6 m/s), and usually flow in narrow valleys. Sections of rivers with a rapid flow, confined to places where difficult-to-erode waters come to the surface, are called rapids. The fall of water from a steep ledge in a river bed is called a waterfall. The highest waterfall on Earth is (1054 m) on the Caroni River (a tributary of the Orinoco); Victoria on the Zambezi River (Africa) has a height of 120 m and a width of 1800 m. Plain rivers are characterized by slight falls and slopes (10-110 cm/km), slow flow (0.3-0.5 m/s), usually flow in wide valleys.

A significant portion of the water flow consists of dissolved salts and solids. All solid material carried by a river is called . It is expressed by the mass or volume of material that the river carries over a certain time (season, year). This is an extremely large river work. The average annual solid runoff, for example, of the Amu Darya is about 100 million tons of solid material. River sediments clog, fill reservoirs, and impede the operation of hydraulic turbines. The turbidity of the water depends on the volume of solid waste, which is measured in grams of the substance contained in 1 m 3 of water. The turbidity of river waters is the lowest (up to 20 g/m3), and the highest (500 - 1000 g/m3).

The most important characteristic of rivers is their nutrition. There are four sources of nutrition: snow, rain, glaciers, underground. The role of each of them is different in different seasons of the year and in different places. Most rivers have mixed feeding. Rain is typical for rivers in equatorial and monsoon regions. Snow feeding is observed near rivers at latitudes with cold, snowy winters. Glacially fed rivers originate in high, covered mountains. Almost all rivers are fed to one degree or another. Thanks to them, the rivers do not dry out in the summer and do not dry up under the ice.

The regime of rivers largely depends on nutrition. River regime is a change in the amount of water flow according to the seasons of the year, fluctuations in level, and changes in water. In the annual water regime of rivers, periods with typically repeating levels are distinguished, which are called low water, high water, and flood.

Low water - the most low level water in the river. During low water periods, the flow and flow of rivers are insignificant; the main source of nutrition is groundwater. In temperate and high latitudes there is summer and winter low water. Summer low water occurs as a result of the absorption of precipitation and strong evaporation, while winter low water occurs as a result of the lack of surface nutrition.

Flood is a high and prolonged rise in the water level in the river, accompanied by flooding of the floodplain. It is observed annually in the same season. During high water, rivers have the highest water content; this period accounts for most of the annual flow (up to 60-80%). Floods are caused by spring melting of snow on the plains or summer melting of snow and ice in the mountains and polar regions. Floods often cause long and heavy rains during the warm season.

Flood is a rapid but short-term rise in the water level in a river. Unlike a flood, a flood occurs irregularly. It is usually formed from rain, sometimes from rapid melting of snow or discharge of water from. Down the river, the flood spreads as a wave, which gradually fades.

Floods are the highest rises of water that inundate areas located in a river valley and adjacent low-lying areas. Floods are formed as a result of an abundant influx of water during the period of snowmelt or rainfall, as well as due to the blockage of the riverbed with ice during the period of ice drift. In the Kaliningrad region (Pregolya river) and (Neva river) they are also associated with the wind surge of water from the sea and the backwater of the river flow. Floods are common on rivers ( monsoon rains), on, Ohio, Ganges, etc. They cause great harm.

Rivers of cold and temperate latitudes in the cold season they freeze and become covered with ice. The thickness of the ice cover can reach 2 m or more. However, some sections of rivers do not freeze, for example, in a shallow area with a fast current, or when rivers emerge from a deep lake, or at the site of a large number of springs. These areas are called polynyas.

The opening of a river in the spring, during which the movement of broken ice floes downstream the river is observed, is called ice drift. Ice drift is often accompanied by jams and jams. - accumulation of floating ice caused by any obstacles. Jams are accumulations of inland ice. Both cause a sharp rise in the water level, and when a breakthrough occurs, its rapid movement along with the ice.