River - a watercourse of significant size, fed by precipitation from its catchment area and having a clearly defined channel formed by the flow itself. The flow is constant throughout the year. Rivers are considered to be watercourses with a catchment area of at least 50 km 2 . Canals, fjords and bays are not considered rivers. An important factor in landscape formation and the presence species diversity living forms.
Stock– the process of water draining from a catchment area along with the substances and heat it contains. River flow is an important geological and geomorphological factor.
All rivers simultaneously contain 2000 km 3 of water. The largest basin is the Amazon, 6.9 million km 2. It is the most water-bearing 16% of river flow. The longest is the Nile 6670 km. Large: Congo, Mississippi, La Plata, Yangtze, Lena, Mackenzie, Niger. In the CIS: Lena, Ob, Yenisei, Amur, Volga. In Crimea: 1675 small rivers with a total length of 5996 km. 30 of them are small, the rest are temporary and drying up. The average flow in Crimea is 04 l/s per km 2. The annual local flow of Crimean rivers is 450 million km 3 /year.
Types of rivers
To size: large (50 thousand km 2) Ob, Yenisei; medium (2-50 thousand km 2); small (50 km 2 – 2 thousand km 2).
According to the flow conditions: flat (slow flow, small slopes, wide valleys, well-developed floodplain), mountain (fast flow, significant slopes, narrow valleys), semi-mountain transitional (have transitional features).
By nutrition: rain, snow, soil, glacial.
According to water regime: with spring floods, with floods in the warm part of the year, with flood conditions.
By ice regime : freezing and non-freezing.
Morphology and morphometry of the river and its basin.
Morphology:
catchment area- part of the earth's surface and soil thickness from which a given river receives its nutrition. There are: surface and underground catchment areas.
Pool- a part of land that includes a given river system and is limited by watersheds. River basins are combined into basins of seas and oceans into which they flow.
Pool characteristics:
Average height H cp =(h 1 +h 2 +h n)/n
The slope is the same.
Physiographic characteristics of the basin: geoposition (natural zone), geological structure and relief, climate, soil and vegetation cover, coefficients of lake content, swampiness, forest cover, degree of transformation of the basin by economic activity.
Watershed– a line on the earth’s surface dividing the runoff of precipitation along 2 oppositely directed slopes. 2 types: river basins, seas and oceans.
Earth's main watershed: Cape Horn-Andes-Rocky Mountains-Bering Strait-Kolyma Highlands-Aldan Highlands-Pamir-Tien Shan-Hindu Kush-Arabia-mountains of East Africa-shore of the Indian Ocean.
Morphometry: area of the basin, length of the basin (from the mouth of the river to a point on the watershed near the source), maximum width (perpendicular to the length at the widest point), average width (ratio of area to length), length of the watershed line, average height, average slope.
River network and river.
Hydrographic network of the basin– a set of watercourses, reservoirs and special water bodies(swamps, glaciers).
River network- the totality of the main river with all its tributaries discharging their waters through main river into the receiving reservoir.
Main elements of the river: source (spring, spring, spring, lake, swamp, glacier, etc.), mouth (place of confluence with a receiving reservoir or another river), river length (distance along the channel from source to mouth), tortuosity coefficient k inv = l/where is a straight line from source to mouth, the density of the river network (the ratio of the total length of all watercourses to the basin area g=L/S [m/km 2 ].
Straer's scheme.
River (tributary) 1st order - a river that has no tributary. River 2nd order - confluence of two rivers 1st order, etc. If a tributary of a lower order flows into a river, the order of the main river does not increase. An increase in order occurs only when two rivers of the same order merge. This is important for hydraulic zoning of the river network within the basin, as well as determining the age of rivers: those with a small order are younger, those that are ancient are those with a higher order.
Hydrographic network drawing:
1. Parallel - rivers and tributaries of the same order in neighboring basins have the same direction.
2. Peristy - one main river with many tributaries.
3. Centripetal - rivers flow in the center into one river or receiving endorheic basin (indicator of tectonic depressions).
4. Centrifugal - rivers flow from one place - the center. Indicator of tectonic uplifts.
Valley and river bed:
river valley- a narrow concave negative form of relief, developed by a river, having a set of river terraces, floodplains, and a channel, having a general slope of its bed that provides drainage.
In the cross section, the slopes and the bottom of the valley are distinguished. Bottom: channel and floodplain. Slopes: river terraces.
Low floodplain– flooded annually during floods and floods.
High floodplain– flooded once every few years by maximum floods. It is overgrown with meadows.
River terraces: accumulative (alluvium, sandstone, pebbles), erosive basement (in hard rocks).
The terraces can be used to determine the activity of the river in paleotime.
Korninsky and Golovkinsky: river terraces correspond to tectonic calm, and terraces correspond to tectonic active movement.
By the nature of alluvium, it is possible to determine the flow rates at different times - active and passive phases.
Osovy- shallow circus-shaped dents on steep slopes of valleys and gullies; are formed as a result of surface displacements of loamy masses, abundantly moistened by ground and surface waters, especially with the slow melting of snow on shady slopes.
River beds (according to plan form):
1. Straightforward.
2. Meandering.
3. Channels divided into branches.
4. Wandering (scattered) channels.
Morphological elements of the channel:
1. Meanders– a sign of typical lowland rivers (small slopes and low current speeds). We need a diagram for the formation of meanders and oxbow lakes.
2. Middles– flooded moving elevations of the bottom, separated from the shores by water.
3. Islands– high stable medians fixed by vegetation, as well as wedged areas of the floodplain.
4. Sleeves– large parts of the channel separated by islands.
5. Channels– short and small branches of the channel, separated by medians.
6. Plyosy- the deepest place of the river. In a meander opposite the beach.
Roll- shallow section of the river bed.
7. Bottom ridges: bottom dunes, sand waves, ribbon ridges, riffles (small bottom ridges).
8. Fairway– line of depths favorable for navigation.
Morphometric characteristics:
Isobaths– lines of equal depths measured from the surface.
Water section– cross section of the flow in a plane perpendicular to its flow. Live and dead sections.
1. Cross-sectional area (trapezoidal method) S= S triangle + S trap.
2. The width of the channel is the shortest distance between the edges of the banks along the surface of the water.
3. Maximum depth(echo sounder).
4. Average depth - the ratio of the cross-sectional area to the width.
5. Wetted perimeter - the shortest distance between the edges of the banks, taken along the bottom.
6. Hydraulic radius is the ratio of the cross-sectional area to the wetted perimeter.
Genesis of river valleys: erosion, tectonic, glacial, karst.
Cross profile of the valley: trough-shaped (plains), box-shaped (middle reaches of rivers), trapezoidal (for the same areas), v-shaped (foothills and low mountain rivers), canyons, gorge gorge (mountain).
Longitudinal profile of the valley is a graph of changes in bottom and water surface elevations along the riverbed. 3 types: smoothly concave (tect. resting), straight, convex (tect. active).
Within any profile there are geomorphological anomalies - sharp increases in slope downstream, which exceed the slope at the overlying level (cascades). Their reasons: a sharp increase in the water content of the stream, a change in the forest cover of the basin, the replacement of resistant race rocks with pliable ones, the presence of tectonic faults, anthropological activity (dams, dams).
Classification of rivers by types of food:
Voeykova: 1) Rivers arising from the melting of seasonal snowfields and glaciers, 2) Rivers arising as a result of rainfall, 3) Regions where there is no constant surface flow. Lvovich: exceptional (type of nutrition provides more than 80% of the runoff), dominant (50-80%), mixed (all types provide less than 50%).
Water regime of rivers.
Water mode– regular changes in flow speed, runoff, water levels and slopes of the water surface over time and along the river, depending on meteorological and climatic factors.
River water content– an instantaneous snapshot of the river flow over a certain period of time.
Water content of the river– absolute average long-term runoff value.
River hydrograph– graph of changes in water content (discharge) in this place during a year.
Fluctuations in water content: 1. Century-old. Global cosmic causes. 2. Perennial. Causes of meteorological nature. 3. Seasonal. Annual changes in the components of the water balance. 4. Short-term. Showers + diurnal changes.
Phases of river water regime.
1. High water. Annual. Highest water content, rising levels, flooding of low floodplains. Types: spring (melting), summer (glaciers), spring-summer (monsoons), winter (Mediterranean).
2. Flood. Repeated many times. Intensive and short-term increase in water level and water content (rainfall).
3. Low water. Low water content and low level. Winter and summer.
Hydrological year– a period covering all phases of the water regime.
Levels mode.
Depends on the water regime and water content phases. A change in level is associated with a change in the indicators of the open cross-sectional area, flow rate, and flow rate.
Thermal regime of rivers.
Depends on weather factors (radical balance, temperature). There are: seasonal changes and daily.
Thermal regime factors: active vertical circulation of water, heat exchange with underlying rock, heat exchange with thermal waters, thermal discharges from hydroelectric power stations and nuclear power plants, dynamic polynyas.
Ice regime of rivers.
Freezing.Salo– floating pieces of ice film and needle-shaped crystals. Take care– narrow strips of motionless ice off the coast. Sn e zhura - lumpy, loose, non-freezing masses. Suga– lumpy accumulations of inland ice floating on the surface. Zazhory occur during the autumn ice drift, when the channel under the ice is filled with snow, lard and slush. Piatra- ice islands in the form of a cap or cone, the thin base of which is attached to the bottom.
Freeze-up.Polynyas– unfrozen areas on the ice surface. Naledi– re-frozen effluent waters.
Opening.Edges– stripes of free water off the coast without ice. Ice movements are the movement of individual ice fields. Their collision forms congestion.
thin autumn ice that floats and crumbles during the winter in the sea and at river mouths.
Nilas- thin autumn ice that floats and crumbles during the winter in the sea and at river mouths.
Riverdrain.
Runoff is the main element of the continental link in the global cycle of water and energy on earth. Surface runoff consists of river and glacier runoff. River flow is the flow of all watercourses.
Quantitative characteristics of runoff.
1. Water consumption– the amount of water flowing through the outlet gate per unit of time. 2. Drain volume– the amount of water flowing through the site per year. W=QT 3. Drain layer– a layer of water that is evenly distributed over the surface of the catchment area and flows down from it over the course of a year. A=W/F4. Drain module– the amount of water flowing from a unit area per unit time. M=Q/F5. Runoff coefficient L=A/xх-amount of precipitation. 6. Average long-term consumption Y=AF/T
Movementwater.
The movement of water in a river is determined by its speed.
Isotachy– lines of equal flow velocities.
Hydrodynamic flow axis– areas in the river plan with the highest current speeds.
Classifications of water movement.
Depends on the nature of the movement of water, the state of the water surface, and the acting force.
By nature of movement: laminar (movement of particles along parallel trajectories), turbulent (chaotic).
Reynolds number:
Re=Vh/Dwhere V is the flow speed, h is the depth, D is the kinematic indicator of water viscosity. If Re is less than 300 – laminar, 300-3000 – transitional, more than 3000 – turbulent.
According to the state of the water surface: calm streams, stormy.
Froude number:
Fr=V 2 /ghwhere g is the acceleration of free fall. If less than 1 – calm, 1 – critical condition, more than 1 – stormy.
According to the acting force: Coriolis force, transverse circulation (centrifugal force and gravity).
Coriolis force:
Fk=2mVSinφω where m is the mass of water, V is the current speed, ω is the angular velocity of the earth’s rotation, Sinφ is the geographic latitude.
The speed of water is calculated using elliptical formulas:
Chezy formula:
V=c*koreniz(h cp Y) wherec is the Chezy coefficient (depth), Y is the hydraulic slope.
Manning formula:
C=h cp 1/6 /wwhere w is the roughness coefficient.
Channel processes– these are constantly occurring changes in the morphological structure of the channel and floodplain, caused by the action of flowing water. Causes– disturbance of the sediment balance in the river due to: an increase in sediment flow along the river - erosion of the riverbed occurs, with a decrease - accumulation; change in the relationship between the actual sediment flow and the transport capacity of the channel. Channel processes are reversible and irreversible. If the process is irreversible, then it is the evolution of the channel. The stability of a river bed shows the degree to which it can withstand destruction.
Movement of river sediments.
River sediment– solid mineral particles transported by flow and forming channel, floodplain and bottom sediments.
2 types of erosion: 1) On the surface of catchment areas and slopes of the basin. Depends on the intensity of rain, the nature of snowmelt, relief, looseness of soil. 2) Channel erosion. Depends on the speed of the current and on the stability of the soils of the bottom and banks.
Sediment characteristics: 1. Geometric size (diameter). 2. Hydraulic fineness (the rate of sedimentation of particles in still water). 3. Particle density (concentration of particles in a given volume). 4. Water turbidity. 5. Sediment discharge (the amount of sediment passed by a river through a cross section per unit time).
2 types of sediment: transported and suspended.
Movement of traction sediments.
Dragged - sediments that are transported by a river flow in the bottom layer and move due to sliding, rolling, and saltation.
Boulders, pebbles, gravel, sand.
2 forces: a) the force of frontal water pressure, b) the force of friction.
Movement begins when a is greater than b. and depends on the flow speed.
There is a relationship between the mass of the particle and the flow speed:
Erie Formula:
W=aV 6 where W is the weight of the particle, a is the prop. coefficient, V is the flow velocity.
Increasing the flow speed by three times will increase the weight of the particle by 729 times.
Movement of suspended sediment.
Suspended - particles suspended in the thickness of a river flow due to its turbulence and unevenness, and causing the turbidity of the flow.
There is less turbidity in the upper part than in the lower part.
R=SQ where R is the suspended sediment flow rate, S is the water turbidity, Q is the water flow rate.
Sediment runoff.
This is the total amount of transported and suspended sediment carried by a river through a cross section per unit time. Annual flow:W=RT. Drain module sediment load characterizes the sediment runoff in tons per km 2 of the catchment area.
Ion drain.
Main ions. The ion flow is determined by water salinity and water flow. R=AQC where R is ion sink, A is prop. coefficient, Q is water flow, C is salinity.
Mouth of the river- a special geographical object that covers the area where a river flows into a receiving reservoir, and has a natural complex that is regulated by estuarine processes (mixing of sea and fresh waters, deposition of sea and river sediments).
Delta– a low-lying, periodically flooded surface with a complex multi-branch channel, a network of reservoirs and watercourses with thickets of water-loving vegetation.
Estuary- relatively narrow and deep funnel-shaped bays or estuaries, which are flooded low sections of rivers when land subsides and the sea advances.
Mouth area – sea water can penetrate. The estuary region goes through three stages of formation: deltaless, delta formation, and extension to the open sea coast.
Protrusion deltas: lobed, beak-shaped (current), complex, bay.
Bay- Not most of seas, bays, lakes, reservoirs, separated from open waters by parts of land (shore protrusions, rocks and nearby islands) and protected by them from waves and wind.
Lip- a sea bay or bay protruding far into the land, into which large rivers usually flow.
Inland waters - lakes, swamps, rivers, reservoirs, groundwater and glaciers - are the main source fresh water on the planet. They are very important for us, since people mainly use this type of water for their needs.
Inland waters are also a component of the landscape and are interconnected with its other components. In addition, they themselves can influence the landscape. Groundwater, for example, gradually erodes the soil and directly changes the surface topography; groundwater affects the formation of soils and vegetation. Rivers gradually wash away their bottoms and deepen, washing stones and making intricate patterns on the surface.
River Basins
Russia is very rich in river systems. They are very important for the economy. They are used for fishing, navigation, field irrigation, energy supply and water supply to populated areas.
The rivers are distributed unevenly, since their life sums up climate regime, relief features and other important features of nature. They carry their waters to 14 seas washing the territory of our Motherland: 13 three seas oceans (Pacific, Atlantic and Arctic) and into the drainless Aral-Caspian basin, the boundaries of which run along plateaus, mountain systems, hills, among forests, swamps, steppes and semi-deserts.
The largest area of Russia occupies Arctic Ocean basin. Its area reaches 11.7 million m^2. It receives water from the rivers of the Urals, the East European Plain and Siberia. The largest rivers of Russia flow into it - Indigirka, Ob, Pechora, Yenisei, Lena, Northern Dvina, Kolyma. The longest river flowing into the basin is the Lena (4,400 km), the largest catchment area is the Ob River, 2,990 thousand square meters. km; The largest average annual flow at the mouth of the Yenisei is 630 cubic meters. km.
The eastern part of Russia is occupied by Pacific Ocean basin, with an area of 3.3 million km^2. From afar, the Amur carries water into the Tatar Strait, whose length reaches 2820 km. The remaining rivers are relatively short in length, since the watershed passes through the mountains and is close to the shores of the Pacific Ocean.
In the west is Atlantic Ocean basin. The rivers in this area flow into 3 different seas- Black, Azov and Baltic. The river systems of this basin have one peculiarity: they are located close enough to build canals.
In the northern part of the huge endorheic basin of Eurasia there is Endorheic Aral-Caspian basin, with an area of 4.9 million km^2. It, in turn, consists of three basins: Balkhash, Aral and Caspian. Largest area occupies the Caspian basin (3 million km^2, which is 60% of the total area). The largest rivers of the world flow into this basin from the north and south: the Volga (3530 km), Syr Darya (2660 km), Amu Darya (2540 km), Ural (2430 km), Kama (1805 km) and Kura (1360 km).
Nutrition of Russian rivers
Russian rivers receive water from rains, glaciers, groundwater drainage and melting snow. Based on the sources of nutrition, there are several types: rain, snow and mixed with a predominance of snow, rain, ground and glaciers.
Most common snow food, or mixed with a predominance of snow. This type includes the rivers of the Black Sea and Caspian lowlands (80% of the annual flow), as well as the Volga, Yenisei, Ob, etc.
Rivers of this type are divided into 3 groups: with spring floods, with spring-summer and summer floods, and with flood regime. The most common rivers are those with spring floods, since Russia is covered with a stable snow cover. Less common are rivers with spring-summer and summer floods.
Floods in warm periods of the year are caused by rains and melting glaciers in mountainous areas. The least common are rivers with flood conditions. They are characterized by a sharp rise in water during heavy rains. In the areas of the Black Sea slope of the Caucasus, the climate is warm and there is a lot of moisture, so floods on the rivers occur throughout the year.
The rain feeds the rivers with a monsoon climate, such as Amur. Mountain rivers are fed by glaciers modern glaciation. Absolutely all rivers receive a share of groundwater.
Thermal regime of rivers
The thermal regime of rivers depends on climate, temperature, groundwater that feeds the river, and the presence of permafrost, glaciers and lakes. On the Kola Peninsula and Karelia, the average temperature of river water in summer is +14 C0, and in the south in the lower reaches of the Volga, it reaches +24 C0. In the North-Eastern part of Siberia, the temperature of rivers in summer does not rise above +6 C0. Very low temperature(+1+2С0) water at the sources of rivers that flow from under glaciers.
In winter, almost all Russian rivers freeze. On the Taimyr Peninsula, rivers are covered with ice already at the beginning of September, and by the end of September they already take on an icy appearance. The rivers in southwestern Russia are the last to become covered with ice.
According to the ice regime, rivers are divided into 4 groups. Most rivers have stable annual ice composition with varying durations; slightly fewer have unstable ice composition, which is not observed annually. There are also rivers where ice phenomena are observed, but there is no ice composition and absolutely no ice formations (places where winter time the air temperature is above 0).
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Rivers, characteristics and types of rivers Water that falls in the form of rain immediately after it falls, and that falls in the form of snow, cereals, and hail after they melt, partly flows along the surface of the soil, partly seeps into the soil and comes out in the form of springs (springs, springs). Both are collected first into small watercourses - streams, then into larger ones - rivers, which finally reach the sea or a stagnant lake, for example the Volga - Caspian Sea, the Amu Darya - Aral Sea, or, finally, like the rivers of very dry countries, get lost in the sand or reeds, like Bolshoy and Maly Uzeni. R. carries, therefore, into the sea or lake excess precipitation, water that fell in the form of rain, and water obtained from the melting of precipitation that fell in solid form (snow, hail, graupel), or the water of these precipitation minus evaporation. It is clear from this that the amount of river water flowing in a given area depends largely on the climate. Of course, for comparison you need to take the same areas. The big river, in its lower course, is the result climatic influences, acting on its entire basin. Since over large areas the climate is rarely uniform, in the lower reaches big river a known average value will be expressed, but it is useful to know its components. It is necessary to take into account the speed of the flow and the length of the river in order to judge how long, for example, it will take for water to flow in a given place of the river after rain or melting of snow in one or another part of its basin. With a current speed of 3 versts per hour, water falling 3000 versts from the river mouth will reach it only on the 42nd day. Part of the water coming from rain and melting snow flows along the surface of the soil and quite soon reaches rivers, while the other is absorbed by the soil and rocks permeable to water and comes to the surface in the form of sources (springs, springs). The underground flow of water can continue for a very long time. The more permeable the rocks, the more water is absorbed by the springs and the quieter the water reaches the rivers. But even in such countries, the regulating effect of groundwater has limits: after very constant and heavy rains, the underground layers become saturated, and if the rains continue, then more and more of the fallen water will flow over the surface of the soil and, therefore, quickly reach P. Lakes have big influence on the river, contributing to the constancy of their flow, especially in the case when the lake is very large in comparison with the river flowing from it; for example, Lake Ladoga contains approximately 11 times more water than flows through its source, the Neva, during the year. Therefore, the water level of typical lake rivers fluctuates very little throughout the year due to rain or melting snow. The most significant Rivers are found in North America, especially the St. Lawrence River, into which the waters of lakes Superior, Michigan, Huron, Erie and Ontario flow, of which the first is the largest freshwater lake on earth. The Asian and African continents each have only one large lake river; in Asia, the Angara-Yenisei flows from Lake Baikal; in Africa, the Nile flows from Lake Ukereve or Victoria Nyanza. Both of these rivers are complex in the sense that, after leaving the lakes, they flow for several thousand miles, gradually losing their lake character. In Europe, the largest lake river is the Neva, which collects the waters of Ladoga, Onega, Saimaa and many other lakes. Lake rivers are also remarkable for the transparency of the water and the small amount of turbidity suspended in them, which settles in the lakes. It is enough to point out the transparency of the water of the Neva near St. Petersburg, the Angara near Irkutsk, the Rhone near Geneva and compare them with the muddy waters of the Mississippi, Volga, Danube and especially the Po, Rhone, Terek, and Yellow Rivers. Rivers flowing from relatively small and shallow lakes have a less constant level. Best examples of this kind are the Sukhona, the source of Lake Kubenskoye, the Volkhov, the source of Ilmen, and the Sheksna, the source of White Lake. The spring water supply in them is large, especially after a snowy winter, so they constitute a transition from more typical lake rivers - the Neva, Svir, most of the rivers of Finland - to the rest of the rivers of Russia. Evaporation from the surface of soil and water varies greatly depending on the temperature, and increases very quickly as it rises. Plant evaporation is also very important in relation to water consumption. Exact numbers regarding evaporation cannot be obtained, since it varies greatly depending on many reasons, but this does not prevent it from being taken into account in its main features. Due to large evaporation, rains in the warm season do not have the same effect on the rise of water in rivers as rains in the cold season. This has long been known and taken into account by hydraulic engineers; Belgran even believed that summer rains could not produce floods. Regarding the Seine basin near Paris, this is true, since there the summer rains are not particularly abundant, and heavy downpours are limited to small areas, while in autumn and winter the rains spread over a large area at once and, with little evaporation, can cause floods. The floods of tropical and monsoon countries show that the rains of the warm season are capable of causing floods; 200-400 mm of water per month outside the mountains - these are the quantities falling in rainy time years in many tropical countries. Despite the evaporation of soil and water, despite the amount of water evaporated by luxurious vegetation, this amount of water causes a noticeable rise in river levels. In addition, especially in monsoon countries, once a rainy season has established itself, the cloud cover is very large, the sun appears rarely and for a short time, and at the same time the dampness of the air is great: all this greatly moderates evaporation. The amount of turbidity or particles suspended in water was often determined in different R., both in relation to the volume and weight of water. Below are the figures for some R. by weight. For Mississippi the average, according to Humphreys and Abbott, is 1/1500. This river annually carries about 6 billion tons into the sea solid precipitation. For the Ganges 1/510 (average for the year). For the Irrawaddy, 1/1700 during high water and 1/5725 during low water. The influence of vegetation is reflected in these figures: the Ganges passes through fields almost along its entire length, the soil surface remains bare for a long time and therefore flowing waters carry away a lot of solid sediment, especially after heavy rains. The Irrawaddy basin, on the other hand, is covered over a large area with forest, where living and dead covers significantly interfere with the flow of particles, so the Irrawaddy, even in floods after heavy rains, carries less suspended particles than the Ganges on average per year. In the basins of other rivers carrying very muddy water - the Po, Rhone, Yellow R. - there are also very few forests, most of the space is under fields. The rivers, which flow entirely through dense forests and swamps, are sometimes almost completely devoid of solid sediments; they are painted brown with solutions organic matter. These are many of the “black rivers” of our north and the rivers and rivers in the Amazon basin (the name of the main left tributary of the Amazon, Rio Negro, literally means “black river”). Analyzes various waters showed that they not only contain less different salts than the water of the seas and almost all stagnant lakes, but also the composition of the salts is very different. In the seas and the largest salt lakes, sodium chloride NaCl predominates ( salt), and there are very few carbonated salts, and in river water carbonated salts make up half or more than half of all substances dissolved in water. Thus, according to Bischof’s analyses, river waters contain on average 21 hundred thousandths of salts dissolved in water, including 11.3 hundred thousandths of carbon dioxide salts. The amount of dissolved salts ranged from 2.61 hundred thousandths in the water of a mountain Alpine stream to 54.5 in the water of the Beuvronne river, a tributary of the Loire. The latter was more than 20 times richer in salts than the first. If there is a fairly accurate concept of the amount of water that a river carries throughout the whole year and of the average amount of precipitation (rain and snow) in its basin, then, knowing the area of the basin, it is possible to express the amount of precipitation water in the same cubic measures in which The amount of water flowing in the river is determined. If, for example, the area of the river basin is 10,000 square meters. km and the average amount of falling water is 800 mm per year, then a total of 8 cubic meters will accumulate per year in the basin space. km ( D). If the river carries an average of 2 cubic meters. km per year ( A), then module ( M) or the ratio of precipitation to river runoff will be M=D/A=0.25, i.e. 1/4 of the water that falls in the pool ends up in the river. Since the first determinations of the amount of water carried by rivers were made in Western Europe and gave modulus = 0.30 to 0.33, the concept of what the ratio of runoff to precipitation is ( M) exists everywhere. But with low precipitation and strong evaporation, no large rivers are formed at all; with heavy precipitation and low evaporation, the ratio of runoff to precipitation is very high. According to the studies of Humphreys and Abbott over the Mississippi and its tributaries (Humphreys and Abbott, “Physics a. Hydraulics of Mississipi-river”), the value M For different parts basin of this river: Ohio 0.24, Missouri 0.15, Upper Mississippi 0.24, Arkansas and White 0.15, Red River 0.20, Yazoo and St. Francis 0.90. The entire Mississippi Basin is 0.25. Consequently, the lowest ratios are found in Arkansas and Missouri. Coming out of the mountains, these rivers, over a large area of dry steppes and deserts, lose a lot of water by evaporation. In contrast, the Yazoo and S. Francis basins are in very wet areas, and the amount of precipitation may not be fully determined. For Russian rivers there are still no such precise definitions of the ratio of precipitation to runoff as for Western Europe and the Mississippi basin. We know that highest value for our R. it is snowy, not rainwater. So, for the Moscow River M turned out to be equal to 0.72 for falling snow water and 0.19 for rain water, and the average for the year is 0.40. For the Volga basin above the Syzran Alexander Bridge, where all its significant tributaries have already flowed into the Volga, M=0.44; therefore, for these two Russian R. M more than for the rivers of Western Europe and the Mississippi basin [See. Climates of the globe.], which is explained by our long winter and the fact that then the water falls in the form of snow, evaporation is small and in the spring the melting occurs quickly and the rivers quickly fill up. Depending on the time of precipitation and the type of precipitation (rain or snow), the following types of P can be established. Type I.R., receiving water from rains and having floods in the summer. This is a type of R., corresponding to tropical rains and monsoon rains. Since precipitation is unevenly distributed in such countries and in winter there is little or no precipitation, at this time the rivers have relatively little water and are fed exclusively or almost exclusively by springs. On the contrary, during rainy times, which generally coincide with summer time, and for some time after it, the rivers are filled with water. Obviously, the longer the river, the quieter its flow, the more time it takes for the high water to reach its lower reaches, and this must be taken into account if we want to judge from the time of the flood the time when the heaviest rains fall. Type I is observed in a completely pure form in many rivers, especially in the tropical zone, since the basins of many rivers are entirely at a temperature at which snow never falls. Other rivers in the tropical zone receive part of their water from snow melting in the mountains, but the latter has only a very minor effect on the amount of water and on changes in river levels. This depends on two reasons: 1) the space occupied by the snow cover is very small even in the cold season, since it only contains heights significantly higher than 4000 m, and a large space of such heights in tropical zone It is found only in Bolivia and southern Peru and, moreover, it is generally dry. 2) Since the temperature of the seasons varies little in the tropical zone, especially near the equator, there is no time when large masses of snow immediately melt, as happens in the middle latitudes. So, the first reason explains why in tropical countries the influx of snow water is generally small, and the second why it changes little throughout the year. It should also be added that more abundant snow in high mountains occur at the same time as heavy rains for more low levels, and some of the snow that has fallen will soon melt. Of the very large rivers, the Congo and Orinoco are entirely Type I. The Amazon receives only very little water from the melting of the snow in the mountains, so that, of course, no less than 99/100 of its water comes from rain. In the upper Amazon, near the city of Ega, the R level varies by 15 m (45 ft) throughout the year. It should be noted that the terrain is completely flat, so that during floods the river spills over a huge area. Of the rivers, the floods of which depend on monsoon rains, mention should be made of the Nile. Starting from 17° northern latitude, it does not receive a single influx, however, the water level varies to a very large extent even in Egypt. After the discovery of the large lakes from which the Nile and its tributaries originate, it was thought that the flood of the Nile depended on the rains in these countries. However, it has now been positively shown that this is not true and that the lakes and surrounding countries maintain the level of the Nile in winter, preventing it from falling too low. This is because: 1) in general, lakes can be called regulators of the river water flowing from them; Lake Ukerewe (Victoria-Nyanza) is very large and deep, and the Nile, upon leaving it, can be called a typical lake river; 2) near the equator and near the large lakes of Africa it rains throughout the whole year, and the heaviest and longest falls in September and November. Taking into account the time required for water to reach Egypt from under the equator, it is clear that these rains cannot be the cause of the Nile flood. On the contrary, between 5°-15° northern latitude from June to September the rains are very heavy, while in winter there is complete drought, and there is no doubt that the flood of the Nile downstream depends on these rains. Already in these latitudes, the Nile loses the character of a typical lake river. Regarding the most important rivers of India, especially the Ganges and Brahmaputra, it is known that the floods in them depend on monsoon rains. Melting snow in the Himalayan mountains also does not provide much water. The same can be said about the large rivers of China, i.e., that the highest water in them depends on the rains that fall in the warm season (rainy monsoon), and the melting of snow in the mountains provides little water, mainly in the spring: in the mountains Western China receives little snow. The Chinese themselves consider rains to be the reason for the high summer floods of their large rivers. The Amur generally belongs to the same type. In winter there is quite a bit of snow (except in areas along the lower reaches of the river), so that usually in the spring after the snow melts, the river does not overflow, but in the summer there are destructive floods, which did a lot of harm to the Russian settlers until they became familiar with the nature of the river and began to build higher. Even the Selenga floods not in the spring, but in the summer, so that Baikal serves as an approximate climatic boundary between two types of rivers: to the east of it, the rivers of the monsoon region, which flood from summer rains, to the west, type IV already appears. Type II. Water is supplied by rain; it is higher in the cold season than in summer, and the difference is significant. This type predominates in southern Europe. As you approach the south, less and less rain falls in the summer, while a lot of it evaporates. Rivers that do not receive water from melting snow in the mountains have very little water in the summer, and some even dry up. On the contrary, during the rainy season, in autumn or winter, the rivers are filled with water. This is predominantly a flood area. To the natural climatic causes that cause floods, human influence, direct and indirect (deforestation, destruction of grass by livestock), was added, which greatly increased the evil. Since most of these countries are more or less mountainous, their rivers partly belong to type V (that is, receiving water from the melting of mountain snows and glaciers); for example, in southern France many rivers flow from the Alps and Pyrenees, in Spain from the Pyrenees and Sierra Nevada. Outside Europe, type II, partly with an admixture of type V, includes: some rainier parts of Turkestan, eastern Transcaucasia and Persia, part of Asia Minor and Syria, the northern coast of Africa from Tunisia to Morocco, California, Oregon, Chile, the northern island of New Zealand, southern and western Australia. Type III. Water is supplied by rain; it is higher in the colder months of the year, but the regular periodic change is not great. This type predominates in central and western Europe. It includes: the basins of the Weser, Meuse, Scheldt, Seine, partly the Loire, R. England (except for the northwestern ones) and the lower part of the Rhine and Elbe basins. In the more continental parts of these countries, summer precipitation predominates, but not particularly much, and the excess water falls far from covering the excess evaporation. Therefore, in general, rivers carry more water in the cold season than in the summer. But since here more or less heavy precipitation falls at all times of the year, there is no time when the rivers have so little water as in tropical countries in winter, and in countries near Mediterranean Sea in summer. The Elbe and especially the Rhine belong to types III and V. In the upper reaches of the Rhine, type V predominates, i.e. it receives more water from melting glaciers and snow in the mountains than from rain. The further downstream, the more pronounced type III is, but even where most of the water comes from rain, the melting of snow and glaciers produces an annual flood in the summer. This is noticeable even in Strasbourg. But already in Cologne the water is higher in autumn and winter than in summer. Type IV, that is, flood due to snow melting in the spring or early summer, and, however, a significant part of the river's water is delivered by rain. This is a type of country with harsh, snowy winters. There is, of course, no shortage of rains in summer and autumn, but in general they are not so abundant and long lasting as to cause flooding in large rivers. Summer rains coincide with the time of greatest evaporation. On the contrary, snow accumulated during a long winter melts very quickly and water fills the river. In addition, especially at the beginning of the snow melting, the ground is frozen, so water cannot seep in and flows along the surface. This type includes the Northern and Western Siberia, all of European Russia, except Crimea, Scandinavia, eastern Germany, Northern part United States and part of the North American continent to the north. In many places in this strip there are so many lakes and they are so vast that they have a very great influence on the character of the rivers. This type is not found in the southern hemisphere. Type IV is most common within Russia, European and Asian, and therefore is of particular importance to us. Largest quantity water falls in our summer, but this amount is still not large, rarely exceeding, in the long-term average, up to 90 mm per month. In some places especially rainy month up to 250 mm falls, but usually such heavy rains do not immediately spread over a large area, therefore the large rivers of Russia (with the exception of the Amur) generally do not have floods that depend on summer rains. The amount of water falling as snow in central Russia is only 1/4 of the annual amount, or approximately 10-15 cm, but this snow melts quickly, with the rapid rise in temperature in spring characteristic of a continental climate. Type V.P. get water from melting snow in the mountains. It does not exist in a completely pure form; appears most clearly in the western parts of the mountain ranges occupying the middle of Asia. The Amu and Syr Darya, Tarim, and upper Indus undoubtedly receive most of their water from melting snow in the mountains. In the low valleys and plains of these countries there is very little precipitation, so there is no river, except for those that flow from the mountains. Because annual course temperature is quite correct, then the summer flood in these rivers is very regular, at least the time of its onset, while the height of the water varies greatly, depending on the amount of snow that fell in winter. They took advantage of this summer flood in Central Asia, East Turkestan, Punjab, etc. - for an extensive field irrigation system, without which agriculture would be impossible. Type VI and VII. R. receive water from melting snow on the plains and on low mountains up to 1000 m. In its pure form, this type does not exist anywhere. The closest approach to it is in the northern part of Siberia and the North American continent, where snow cover lasts 8-10 months and most of the water in the river comes from snow melting. A special position is occupied by countries covered with snow and glaciers (with the exception of a few places along the coast and some steep mountains); here rivers are replaced by glaciers, with their subglacial watercourses; they carry excess precipitation over evaporation to the sea or to lower valleys. This can be called type VII. In the northern hemisphere the only extensive country of this kind is Greenland, but there is reason to suppose that most of the high latitudes are in the same condition southern hemisphere, beyond 70° south latitude. This is the so-called south polar continent, the central part of which is near the south pole. Type VIII. The absence of rivers and permanent watercourses in general, due to the dry climate. There is probably no area on the globe where there is no precipitation at all, but there are, however, vast areas where it falls in small quantities and irregularly. After a particularly heavy rain, the ravines are filled with water, which reaches the sea, a salt lake or some depression, where it stagnates and finally disappears, seeping and evaporating. In some places, rivers flow through such countries, originating in damper places, but they not only do not receive an influx of water, but lose a lot of it through seepage and evaporation from the surface of water and aquatic plants (reeds, etc.). The best examples of this kind are: the Nile from the confluence of the Atbara to the Mediterranean Sea (17°-31° north latitude), the Volga from Sarepta to the mouth, the Indus from the confluence of the Sutlej to the mouth, the Colorado in the lower reaches from approximately 35° north latitude to the confluence of the Gila River. Countries without R. include: the Sahara, most of Arabia, part of the Aral-Caspian lowland, most of the central highlands of Asia, vast highlands North America on both sides Rocky Mountains, Atacama and the coastal strip from 18° to 30° south latitude in South America, Kalahari and neighboring coastal areas in south africa, finally, most of inland Australia. The transition to type VIII consists of countries where the rainy season is short and the rivers have water only then and for some time after, and the rest of the time they dry out or turn into a series of puddles with an underground flow in between. In countries with harsh winter Rivers often have water only after the snow melts in the spring. In general, in the countries named above, on the borders with more abundant precipitation, similar transitional areas are found. These include, for example, the northern steppe part of Crimea, part of the Kyrgyz steppes, steppes along the lower reaches of the Kura and Araks, part of Mongolia, along the border of China, the strip between 13°-18° northern latitude (depending on the meridians) in northern Africa, where the rains of the African monsoon are already falling, but where they are short and not abundant, many areas of North America and Australia. Man has a great influence on rivers, even beyond engineering work to regulate them. By cutting down forests, draining swamps, replacing them, as well as meadows and steppes with fields, people allow water to flow faster and destroy obstacles that previously hindered him. Where snow lies for a long time, forests, especially coniferous ones, slow down its melting in the spring and also prevent water from reaching the river as quickly as if there are no forests. Therefore, human activity in this direction, accelerating the flow of water, increases the danger of floods after rainfall and melting snow and reduces the amount of water stored in soil and waters (swamps, lakes) and serving to feed the river. dry time of the year. The increase in the network of mountain ravines and ravines acts in the same direction: it in itself promotes faster flow of water, and in addition, in some places ravines, cutting through the upper or less permeable layers of the subsoil, expose more permeable layers, for example sands, fractured limestones, etc. d. In more densely populated countries, river regulation and drainage also contribute to faster water flow. Reducing the quantity different waters, in some cases very significant, is facilitated by irrigation work, for example, canals drawn from the Amu and Syr Darya, from many rivers of India, etc. But in the named cases, the main expenditure of water for irrigation occurs at a time when the rivers are rich by it: in Turkestan from the melting of mountain snows, in India partly from the same, but even more from the rains of the summer monsoon. In these cases, irrigation, therefore, reduces the size of the river's flood. In other cases, human activity results in more proper nutrition of the river and rivers; In part, the latter is directly meant - these are reservoirs (beyshlots) or dams to assist navigation, for example, in Russia, dams in the upper reaches of the Vyshnevolotsk water system, the Upper Volga beyshlot. In part, more proper nutrition is achieved along the way in the case of dams for factories and factories.
Nobody knows the exact number of rivers. It all depends on what exactly is considered a river and what is just a stream.
For example, in Russia there are 130 thousand rivers whose length exceeds 10 km. If we count water streams less than 10 km long as rivers, then there are over 3 million of them in Russia!
There are more than 50 large rivers with a channel length of over 1000 km on the entire planet. And their total length is 180 thousand km.
Geographical feature (meaning)
R eka - a stream of fresh water flowing in a relatively fixed channel and replenished mainly by precipitation.
First, you need to remember a few terms:
.bed- a depression through which water flows. The channel is usually fixed, has a winding shape with alternating shallow places (rifts) and deeper places (reaches). Due to geological changes, natural phenomena a river can change its course, leaving holes and depressions - meanders. For example, the Kosi River in India carves a new channel for itself every year, washing away villages and villages along its path.
The meanders of the riverbed are called bends, and in deep-water rivers the channel line is called a fairway. By the way, the Piana River is considered the most winding river in the world. It flows through Nizhny Novgorod region in Russia. The length of the river is 400 km, while the distance from source to mouth in a straight line is only 30 km.
. Source- the beginning of the river. The source can be a spring, a melting glacier, another body of water (swamp, sea, lake) or the confluence of two rivers.
. Estuary- the end of a river, the place where it flows into the sea, ocean or other river.
. River system- a river with all its tributaries.
. River basin- the area from which a river and its tributaries collect water. River basins are separated by watersheds. Most often, mountains and hills play the role of watersheds.
Characteristics of rivers
The most important characteristics of a river are its size, fall, flow speed, water flow, flow, and type of nutrition.
By falling rivers are called the difference in height between the source and the mouth. The higher the fall, the higher the flow speed, and therefore the greater the possibility of obtaining energy.
Current speed rivers are measured in m/sec. In different parts of the river, the speed can be different, it depends on the terrain and the slope of the riverbed.
Water consumption shows how much cubic meters water passes through the cross section of the channel in 1 second. Water consumption over a long period of time (six months, a year) is called runoff. The Amazon is considered the most abundant river in the world. In Russia, these are the Yenisei and Lena.
Nutrition rivers occur in different ways. There are 4 groups of rivers based on this criterion: rain, snow, underground and glacial. Rain power rivers of the tropics receive snow, rivers temperate zones and northern, glacial - mountain rivers. But most rivers have mixed type nutrition, replenishing water supplies from several sources at once.
Types of river mouths
An estuary is a place where a river flows into another body of water. Depending on the shape of this part of the river, two types of mouths are distinguished: delta and estuary (estuary, lip).
(The image shows a model of the river mouth)
Delta formed by a branched system of branches and ducts. Rivers flowing into calm bodies of water form deltas of gigantic size. The largest delta is near the Ganges, it covers an area of 105.6 thousand square meters. km.
Estuary- this is the mouth of the river in the shape of a funnel, expanding towards the sea. Estuaries are formed. If the part of the sea adjacent to the mouth has greater depth. In Russia, the largest estuaries are the Gulf of Ob (Ob River) and the Yenisei Bay (Yenisei River).
The longest rivers in the world
(Amazon river)
The longest river in the world - Amazon(6800km). Located in South America. Its origins are in the Andes. The Amazon crosses the entire continent from west to east and flows into the Atlantic Ocean.
Almost the entire course of the Amazon and its tributaries is located in latitudes where tropical rainforests are common, so this river is also the deepest in the world.
The second longest river is Nile(6695km), located in Africa. The sources of the Nile are in the mountains, the river flows into the Mediterranean Sea. The Nile is famous for its floods.
The largest river in North America is Mississippi with a tributary of the Missouri (6400 km). The sources are in the mountains and flow into the Gulf of Mexico.
The longest rivers in Asia - Yangtze(5800km) and Yellow River (4845km). Both flow through China from west to east and empty into the Pacific Ocean.
The widest rivers in the world
A river is considered wide if the width of its bed is more than 150 meters.
(River La Plata, on the horizon the city of the same name La Plata)
The widest river in the world is considered La Plata, or Silver River. It flows on the border of Uruguay and Argentina. The width of the channel is 220 km! But with such width, La Plata has little depth. This river is home to turtles and one of the rarest species of dolphins, which is called La Plata.
The widest river in Russia is Ob. The width of its channel is 60 km. Amur is in second place (50 km), Lena is in third (30 km). Volga takes only 4th place (27.5 km).
The longest river in Russia
(Ice drift on the Lena River, Yakutia)
The longest river in Russia is Lena(4400km). The source is a swamp located near Lake Baikal. The Lena flows through Siberia and flows into the Laptev Sea. Tributaries: Vitim, Vilyui, Olekma and Aldan.
Today, no one can say for sure how many rivers there are in the world. After all, everything also depends on what can be considered a river and what can be considered a stream. So, for example, if you add up the length of all the rivers in Russia, you get more than 8 million kilometers. Their total number, if you count large and small, is close to 2.5 million. There are no more than 50 largest rivers on the entire globe, and their total length is about 200,000 km. But what does the source and mouth of the river consist of?
Geographical significance of the river
A river is a stream of fresh water that moves in a fixed channel and is replenished mainly by precipitation. Before you understand the characteristics of freshwater streams, you need to remember a few key terms:
- A channel is a depression along which the flow of water from a river follows. It is usually fixed, sinuous in shape with alternating shallow and deep places. Due to geographical changes or other factors, it may change, leaving behind holes and depressions. So, for example, in India there is the Kosi River, which makes its way almost every year. new way, washing away everything that comes in its way.
- The source is the beginning of the river. It could be a spring, a melting glacier, any other body of water, or the confluence of two water streams.
- The mouth is the place where a river ends, whether it flows into the sea, ocean or other water stream.
- A river system is not only the river itself, but also its tributaries.
- A river basin is a defined area from which all the water is collected. All basins are separated by watersheds, and their role is played by hills.
Main parameters of river characteristics
The main characteristics of rivers are their size, flow speed, flow, fall and type of food.
The difference between the heights of the source and the mouth is called the fall. The higher the fall, the greater the speed of flow in the river.
Current speed is measured in m/sec. It will not be the same everywhere; the areas have different terrain and the slope of the riverbed is different.
Water flow shows how many cubic meters passed in 1 second through the cross section of the riverbed.
The river is fed in several ways: by rainwater, after melting ice, from underground springs and glaciers. Rivers located in the tropics are fed by rain. Rivers in temperate zones and those located in the northern hemisphere are fed by snow, while mountain rivers are fed by glaciers. There are several main rivers:
- Equatorial - only rains all year round.
- Subequatorial - the river is fed by rain, but it is uneven and seasonal.
- Subtropical - rain with a rise in river level in winter and shallowing in summer.
- Subarctic is snow feeding, which ensures a rise in water levels in summer and a sharp shallowing in winter, when most of the rivers freeze over.
- Ozerny - the river is fully nourished all year round and does not depend in any way on other types of nutrition.
- Mountain - in high mountains at night the rivers become shallow, and during the day they are replenished due to the melting of glaciers and snow.
You can also very often hear about the river regime. But not everyone knows what a river regime is. What does it depend on? The answer is very simple, the river regime is the course of long-term, seasonal and daily changes in the river flow in the channel. Changes can happen very quickly, depending on where and under what conditions the river flows.
Rivers flow through the plains, flow down from the mountains, and during their entire life they can change their path several thousand times, become shallower or, conversely, become more full-flowing.
Features of river flow
And the mouth of the river is already known, but what are the features of the water flow in each of them? After all, it is known that there are rivers with standing water and a quiet current, but there are those where the water runs at such a speed that it can demolish any, even the largest, obstacle in its path.
The nature of the flow and speed of the river depend on the topography, slope and fall of the water. On the plains, river flows are wide, calm, and their fall slope is small. Such rivers include the Volga, Danube, Dnieper, Neman. But there are also those that flow among the mountainous heights. They are distinguished by turbulent and strong streams; on their way there are many rapids and sometimes high waterfalls. Such rivers have a huge fall, which means that their flow pattern is completely different. Such streams include the Terek, Rioni, Tigris and Yangtze.
The full flow, regime, and sometimes nutrition of rivers depend on the climate. In wet conditions rivers remain full at any time of the year, but in a dry climate they very often dry up and are fed only by precipitation, and there is not very much of it in a year.
Mountain rivers are cold because they are fed by melting glaciers located on the peaks. But if you walk along the entire riverbed, then at the very end the water can be very warm, since during its journey it heats up under the scorching rays of the sun.
What is a mountain and lowland river?
We have already managed to figure out what a river regime is, but what type of rivers are there? After all, they can simply run among the plains or descend from high mountains.
Lowland rivers are water streams passing through flat terrain with small slopes and flow rates. Such rivers flow in developed valleys with a winding bed, where reaches and rifts alternate.
Mountain rivers originate in the mountains or foothills. They have steep slopes and rocky riverbeds cluttered with debris rocks. Such rivers are characterized by large slopes and flow speeds, and shallow depths. Often along the path of these rivers there are waterfalls and rapids, and erosion processes also predominate.
There is also mountain-plain rivers, which begin far in the mountains, then gradually turn into a quiet lowland river.
5 largest rivers in the world
Every person knows the name of the largest rivers in the world. The list of the 5 largest and deepest rivers in the world is headed by the Amazon, which is considered the heart of South America. More recently, it was considered 2nd on the list of the largest after the Nile. But after scientists accepted the small source of the Ucayali as the true beginning of the river, it began to be considered the longest. Its length is more than 7 thousand km.
In second place was the African Nile River. It is considered a sacred river, since only thanks to it can people living in the harsh and very dry climate of Africa survive. During the rainy season, the river floods, allowing the population of Africa to engage in agriculture; rice is grown on its banks. The length of the second largest river in the world is just over 6800 km, and the river basin has an area of more than 3 million square meters. km.
The Yangtze is another large river in the world, which is considered the main deep-water stream of Eurasia. This river can be considered a mountain-plain river, since it originates in the Tibetan Plateau, then passes through the Sino-Tibetan Mountains and then flows into the Sichuan Basin. The length of this very deep river is about 6.3 thousand km, and the basin area is about 1.8 million square meters. km.
The Yellow River, or Yellow River, is another major river in the world, with its source in the mountains of Tibet. Its length is about 5 thousand km, and the basin area is 700 thousand square meters. km.
The names of rivers located in Russia can be found on the map. Among them there is one that is included in the list of the 5 largest - this is the Ob. Its length is a little more than 5,400 km, and the basin area is almost the same as that of the Nile - 3 million square meters. km. This water flow originates in Russia, and then passes through Kazakhstan and ends its path in China.
The world's major rivers have great importance for industrial and economic development states in whose territory they flow. Rivers give life-giving moisture to people. In addition, there are a lot of fish in the rivers, which feed not only animals, but also humans.
List of the smallest rivers in the world
But there are not only large rivers on the planet. There are also the smallest ones, which have their own significance for the people living on its banks. The smallest rivers:
- Reprua - this river flows in Abkhazia, and its length is only 18 meters. In addition, it is considered the coldest river on the Black Sea coast.
- Kovasselva - this water stream is located on the Norwegian island of Hitra, and its length is no more than 20 meters.
Amazing rivers of the world
The characteristics of rivers are not only information about whether they are large or small in size. There are also unusual and amazing water streams on the planet that attract attention with their originality.
Caño Cristales is the most colorful river located in Colombia. Most often, locals call it the river of five colors. The river acquires such a bright and unusual variety of colors thanks to the algae living in its water. If you look at the water in it, you might think that a rainbow fell into the water.
Citarum is the most dirty river on the planet. It is located in Indonesia, and is dirty because more than 5 million people live in its basin. People dump all their waste into its waters. If you look at the river from afar, you won’t even immediately understand what it is; you get the feeling that you’re looking at a landfill.
Congo is the most deep river on the planet. It flows in Central Africa, in some places its depth reaches 230 meters, and perhaps even more.
El Rio Vinegre is the most acidic river. It flows past the Purace volcano in Colombia. Its water contains more than 11 parts of sulfuric acid and 9 parts of hydrochloric acid. There can be no living creatures in this river.
Life in rivers: plants
The characteristics of rivers are not only nutrition, length and other parameters, but also animals and plants. After all, in every water flow, whether it is the largest or the smallest, has its own life. In every quick or quiet river Many plants have found their home that adapt to life in a particular stream, with its flow characteristics, water temperature and other parameters.
River plants can be divided into 5 main groups:
- Plants found in water and on land. They begin their growth at the bottom of the river, and their upper part rises above the water. These include reed, reed, horsetail, cattail and arrowhead.
- Plants whose roots are attached to the bottom and whose leaves float on the surface of the water. Such plants are floating pondweed.
- Plants with roots at the bottom, whose leaves remain in the water, are urut and common pondweed.
- Plants are floating and have no roots at the bottom. One such plant is duckweed.
- Plants that live in the middle layer of water - hornwort, filamentous algae and elodea.
River life: fauna
Characteristics of rivers are also animals that cannot exist anywhere except in water. Not only does it live in rivers a large number of species of fish, but also other living organisms:
- Plankton are living organisms that live in the water column; they seem to float in a body of water and surrender to the power of the current. Plankton is the main food for many fish.
- Benthos. This group includes bottom organisms.
- Nekton are actively moving animals that can overcome currents. Today, there are more than 20 thousand species of nekton, these include fish, squid, cetaceans, pinnipeds, turtles and others.
- Neuston - animals and plant organisms, living on the surface of water bordering the atmosphere.
- Pleiston is animal and plant organisms that are semi-submerged in water, i.e., capable of living simultaneously in both aquatic and air environments.
- Epineuston includes organisms that live on the surface film.
- Hyponeuston - organisms associated with the surface film, but living underneath it.
- Periphyton are organisms that live on the surface of objects submerged in water.
Mammals also live in the rivers: beavers, otters, muskrats, and reptiles: turtles, snakes, crocodiles.
How are rivers used?
Even in ancient times, people believed that water is life. They often built houses on the banks of rivers and reservoirs to make it easier for them to carry out everyday life. Using the river helps not only to do household chores, but also to run your household. Water from rivers is used for drinking, having been purified beforehand, used to prepare food for themselves and animals, and used for watering plants.
Today, water from rivers is purified at special stations and supplied through pipes to homes in large cities. Rivers are also often used for timber rafting, as a way to travel over long distances. They swim and fish in the rivers. Rivers are also very beautiful landscapes, because it’s nice to sit on the shore and enjoy the fresh, humid air, admiring the surroundings.
How much water is needed for industrial enterprises that also build closer to rivers?! Thanks to this proximity, any enterprise will be able to draw water from the reservoir. In distant countries - Africa or South America - where the climate is very dry and rivers often dry up, the main source of drinking for wild animals is these rivers, even if they are dry in some places. But during the rainy season they become full again.
Without rivers, our planet would not be as beautiful and real. They, like water sleeves, weave around the globe and give life-giving moisture, but the task of humanity is to make every effort to preserve their purity and beauty.
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