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BIFURCATION OF THE PAMIR RIVERS
MAJIDOV ODINABOY SHARIFMURODOVICH
Department of Geography and Remote Sensing of the Earth of the National Academy of Sciences
of Tajikistan. Dushanbe
Annotation: The article provides a brief description of the Pamir relief and data on a rare landscape and hydrographic phenomenon - the bifurcation of the river in the basin of the river. Panj. It is shown that the high-mountainous rivers of the Pamirs are divided into a series of autonomous channels, giving rise to two rivers and sometimes even three rivers in different basins. It is also given some reasons for the appearance of a bifurcation.
Key words: Pamir, river, bifurcation, branch, branch, branch, basin.
Our planet at first glance seems stable, but in fact, complex processes are constantly taking place on Earth, many of which are cyclical, but some are quite rare and inexplicable. One of these phenomena is the natural bifurcation of rivers.
River bifurcation mainly occurs on flat and low watersheds.
About the bifurcation of the rivers of Central Asia (Amu Darya and Syr Darya), which originate high in the mountains and flow into the Aral Sea, much has been written in historical stories [2, 4, 5, 16].
The phenomenon of bifurcation and polyfurcation, which we will consider, manifests itself in the highlands, mainly in the Pamirs.
Before we start discussing the phenomenon of bifurcation of mountain rivers, let us briefly describe the physical geography of the Pamirs.
Pamir is an orographically closed arid high-mountainous country, located at a considerable distance from the oceans and large water bodies and lying in the area of convergence of the largest mountain rises of Asia - the Kunlun, Karakoram, Hindu Kush, Pamir-Alay and Tian Shan. The orographic compactness of the Pamirs is determined by much higher mountain rises on the outskirts of the region than in its deep parts. These are the Trans-Alay Range in the north, the Kashgar Mountains (Western Kunlun) in the east, the Hindu Kush Range in the south, and the Kukhi-Lal Mountains (a spur of the Hindu Kush) in the west. The placement of the maximum heights of the Pamirs coincides with the watershed ridges of these ranges. The largest peaks stand out in the Zaalaysky ridge: the name of Abuali ibn Sino (formerly Lenin Peak 7234 m), Dzerzhinsky (6712 m), Zarya Vostoka (6346 m); in the Kashgar Range - the peaks of Aksai-Bashi (6146 m), Kongur (7719 m), Kongurtyube-Tag (7595 m), Mus-tag-Ata (7546 m); in the Hindu Kush - the peaks Ochil (6523 m), Akashak (6872 m), Iushan (7455 m), Tirich-Mir (7690 m); in the Kukhi-Lal ridge - Vid-Gaz (6010 m), in the ridge of the Academy of Sciences - Istikliyat peak (formerly Revolution peak 6974 m) [9].
The modern relief of the Pamirs was formed as a result of the Alpine movement. As a result of Alpine fold movements, the northwestern and northern part of the Pamirs is rising.
The watershed ridges of these ridges delineate the vast high-mountainous Pamir territory, with a total area of 91945 km2, preserving the internal generic unity of natural outlines. In the complex natural zoning, the Pamirs are divided into 4 districts. Within the accepted internal regional boundaries, these districts occupy the following absolute (km2) and relative (%) parameters (Table 1).
Distribution of parameters of the Pamir territory, according to orographic units.
Table 1 [1 L].
Name of orographic units Territory
km2 %
Western Pamir 29 670 32,7
Central Pamir 27 135 29,8
Wakhan-Hindukush Pamir 13 540 14,3
Kashgar Pamir 21 600 23,2
Total 91945 100
The formation of the relief of the Pamirs has not yet been completed, the rise of the ranges continues. This is evidenced by numerous seismic manifestations, especially in the Western Pamirs. The entire territory of the Pamirs, according to the seismic zoning scheme, is assigned to the 9-point zone. Professor K. V. Stanyukovich believed that the Pamirs have experienced an extremely sharp paroxysm of uplift in recent decades [13].
Shifts of the mountainous country were discovered in the eastern part of the Pamirs. The band of giant Pamir mountain ranges between the Kashmir Klin and the Alai Valley, 300 km wide, is slowly shifting to the north. The researchers determined that over the past millennium the mixing of the Pamirs was 4-5 km, and this hypothesis was confirmed by the expedition of the Geological Institute of the USSR Academy of Sciences [5].
In general, the relief of the Pamirs is a gently concave bowl, the bottom of which is formed by snowless mountain peaks, fluctuating within a relatively narrow interval from 5000 to 6000 m of absolute height [8].
Pamir is located mainly in the upper reaches of the Amu Darya basin, and its eastern territory (Kashgar Pamir) captures the upper part of the river basin. Tarim, in the south directly adjoins the headwaters of the Indus. Pamir is a grandiose watershed of the largest water arteries of Central Asia.
The relief of the Pamir territory differs from the middle mountains and plains. Therefore, the hydrographic network here has its own characteristics, including the branching of rivers.
A river bifurcation (from the Latin furca, fork) occurs when a river flowing in one stream splits into two or more separate streams (called splitters) that continue downstream. Some rivers form complex distributor networks, especially in their deltas. If the streams eventually merge again or empty into the same body of water, then the fork forms a river island.
The main reason for the furcation of the channels is the appearance of middle channels in it or the rejection of side rifts from the banks, which are gradually covered with vegetation and become islands.
Islands form in areas of sediment accumulation or in places where there are several dynamic axes between which alluvium accumulates. From this it follows that the entire phenomenon of bifurcation in lowland rivers is associated with the accumulation of alluvial deposits in river channels.
This process is an extremely interesting phenomenon, which is observed quite rarely. In the history of geographical research and observations, there were not so many descriptions of the bifurcation of rivers.
A similar division of water flows occurred in the past, and they continue to the present. The geography of distribution of the phenomenon is quite wide. The most characteristic and most studied examples are the division of the Orinoco (South America), Niger (Africa), etc.
It is worth noting that these examples have different reasons for the bifurcation of the rivers. What is this phenomenon and why does it happen?
The first about the existence of a natural channel between the Orinoco and Amazon basins was reported in 1641 by the priest-missionary Acuña. But irrefutable evidence of its existence was obtained in 1799-1804. Alexander von Humboldt with his colleague, botanist Aimé Bonpland. Although it can be seen that the phenomenon of bifurcation on historical maps of Central Asian rivers, such as the Amu Darya and Syr Darya, was described by Humboldt.
The reasons for the branching of rivers can be called seasonal floods and floods. The first arises as a result of the intensive growth of water volumes in the river delta. This may be due to heavy continuous rains, sudden melting of snow, water runoff due to precipitation in mountainous areas and it occurs spontaneously, regardless of the time of year. High water occurs at the same time every year, most often as a result of increased water content in the river.
Branches - watercourses of very long length (up to several tens or even hundreds of kilometers) on rivers of various orders. Their channel regime does not depend on the reshaping of the main river channel, and the hydraulic regime of the sources is not related to that at the mouth, where the branches join the main channel. There are two types of branches. The first includes independent large branches of the river, forming a forked channel. The second variety is a system of relatively low-water floodplain channels that divide the floodplain and large island massifs into separate parts, forming together a floodplain multi-branch.
Forked channels are a type of branching in which a river flows over a long area with two, often equivalent branches, separated by a vast array of floodplains, with relatively shallow transverse channels between them, constituting a floodplain multi-branch. The length of river sections with such branches varies from 5 to 50 km, on small and medium-sized rivers, and up to hundreds of kilometers on the largest ones. Examples of a forked channel are the Big (right arm) and Small (left arm) Ob in the lower reaches of the Ob, the Dniester and the Turunchuk channel, the branches of the Argun, Charysh, the sources of the Murgab and Vakhandarya rivers, the tributaries of the Obihingou and Surkhob, etc.
Branches that form a forked channel, separating from the river, pass in opposite parts of the valley floor, often receive and give part of the flow from it along floodplain channels, but, having their own catchment area, along with food from the main river, they are characterized by water and water features that are different from the main river. channel regimes.
The ramifications of river channels into branches are the most complex and diverse manifestations of channel processes, both in morphology and deformation regime (dynamics), and in terms of their management conditions during the development of river resources. It is believed that the branching of channels into branches is mainly the prerogative of large and largest rivers [12], which is reflected in the compiled map of the branching of rivers in the territory of the former USSR countries into branches [11].
But on, there are branches and ramifications. Three main types of river bifurcation are usually distinguished [4, 13]. The last division by N. N. Makkaveev in 1955 into 3 stages; mountainous, foothill and plain [14]. In the article, we consider the territories of mountainous countries, where small and medium-sized rivers mainly flow.
1. Bifurcation with merging. With this type, after the bifurcation, the flows merge into one main channel. For example, a bifurcation on the river. Niger in Africa.
2. Bifurcation with division in one basin. This is a relatively common type. Almost all coastal deltas are of this type.
3. Bifurcation with fully autonomous separation of flows into different basins that do not converge with each other. This type is quite rare.
Of the 11 manifestations of furcations discovered and described by us, 9 are located on the territory of Tajikistan, one phenomenon of polyfurcation occurs on the riverbed. Pyanj (polyfurcations; Panj-Darkad-Kyzylsu, 520 m abs), one in Afghanistan and one in Kyrgyzstan. The
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rest 8 branches, some of which are considered seasonal, occur on the channels of small rivers, at altitudes of more than 3000 m abs.
Of the total number of furcation phenomena, 9 are located on the territory of the Pamirs, and the channels of these rivers after branches flow down into different basins. Seven out of nine furcations eventually merge in the basin of the river. Panj. Two other bifurcations, which belong to the basin of Lake Khovar (Karakul), can also be considered part of the basin of the river. Panj, which we will discuss in detail below.
First, let us consider the manifestation of bifurcation in terms of height increase on some permanent and seasonal rivers and lakes in Tajikistan (Table 2).
Manifestation of bifurcation by increasing height by territory of Tajikistan
Table 2.
№ Point name bifurcations Coordinates: NL and EL Height (m.a.s.l.) Branching angle (O) Mode actions
1 Panj river (Darkad Island) 37°34'45" 520 30 Constantly
69°41'45"
2 Karashura river 39°06 '25" 3270 43 Constantly
72°21'39"
3 Ters-Angar-Suu river. (Kyrgyzstan) 39°14 '26" 3636 45 Constantly
72°15 '15"
4 Kurunkul (Muksu river) 38°46 '49" 3976 25 Seasonally
73°17 '39"
5 Kurunkul (Muzjilga river) 38°45 '02" 3983 28 Constantly
73°15 ' 02"
6 Birgutayi-Jilgachelov (Afghanistan) 37°13'18" 4070 30 Constantly
74°06 '44"
7 Urtabuz pass 37°36 '51" 4246 47 Constantly
74°00 '46"
8 Karadung lake 37°30 '14" 4373 46 Constantly
74°01'00"
9 Aydynkul lake 37°25 '59" 4449 23 Constantly
74°12 '54"
Yangidavan pass 37°30 '48" 4470 58 Seasonally
10 74°02'56"
11 Bandera pass 37°22'15" 4563 180 Constantly
74°14'05"
[Note: those rivers and lakes are seasonal, the waters of which flow under alluvial deposits and in the autumn-winter period water does not drain from them].
Two manifestations of the bifurcation are in the territory; Afghanistan and Kyrgyzstan, but after a branch one of the channels of these rivers flows through the territory of Tajikistan. The manifestation of bifurcation on the territory of neighboring states, we will not consider in the article.
Now let us briefly characterize each of these bifurcations with increasing height separately.
1. Bifurcation r. Panj near the island of Darkad.
Panj river, leaving the narrow valley near the river. Dzhumar (10 km east of Chubek), gradually expands, the width with floodplains in this section of the river reaches more than 500 m. Southeast of the village of Dakhana (Tajikistan), located on the right bank of the river. Panj at an altitude of 550 m abs, the river branches off. Karos. On this segment, where the width of the floodplain is more than 1.7 km. The Panj flows before the fork at an average speed of 4.2 m/s. To the west of this section, the river gradually widens, branching into numerous branches. In this territory, the bulk of the channels flow through the territory of Afghanistan.
Below the village of Chubek, on the border between Tajikistan and Afghanistan, the river. The Panj is divided into several branches, in the center of which an island called Darkad (Urtatugai) has formed. Also, dozens of river channels flow through this island. Panj, one of the largest is called the river. Darkad [6].
The phenomenon of bifurcation in this area is considered the most abundant in water, since the river forks here Panj. In recent years, due to the strengthening of the banks, the channel processes have been disturbed, and the volume of water flowing through the channels has changed.
2. Another phenomenon of bifurcation is fixed at the sources of the Karashur river, on the ridge of Peter the Great, on the western part of the Saidoi Nasafi (Baralmas) glacier. In parallel with the glacier, from the left side of the two streams, a river is formed, which is called Karashura, flowing 3.5 km. merges with the river that flows from the Saidoi Nasafi glacier. Flowing after the confluence of another 1.3 km with an average slope of 98 m/km at an altitude of 3270 m.a.s.l, Karashura river branches out. At this bifurcation point, the branched rivers diverge into two regions of republican subordination (Sangvor and Tojikobod).
The main river with the name Karashura flows first to the west, and then to the south-west, becoming a 4 th-order tributary of the Obihingou river. From the source to the mouth of the river. Karashura changes its name in the following order: Karashura - Obikulik - Shaklysu - Ragnou. R. Ragnou is a tributary of the first order of the Obihingou river.
Another river after a bifurcation (branches from the Karashur river) flows first to the northwest and then, turning smoothly to the northeast, merges with the river. Surkhob. It should be noted that this river with the name Surkhob is a tributary of the 2nd order of the Surkhob river. Surkhob river originates from the Baralmas glacier, then becomes a tributary of the Archakala river, which, in turn, merges with the river. Muksu, forms the river. Surkhob (a tributary of the Vakhsh river). Branched channels flowing down in different basins: 141 km along the riverbed. Surkhob and 162 km along the Obikhingou river, merge at the source of the. Vakhsh river.
The angle between two branched brooks is 43.5°.
Two bifurcation phenomena were revealed on both sides of Kurunkul lake. One is located at an altitude of 3976 m.a.s.l, (38°46 '49" NL, 73°17 '38" EL), northeast of Kurunkul lake, which is seasonal. Kurunkul lake is located 10 km, south- west of Khovarkul lake (Karakul).
This is a very rare and unique bifurcation phenomenon that occurs in nature. The uniqueness of this phenomenon is that the two neighboring rivers Muksu (on the right) and Muzdzhilga (on the left) flow down from the mountains, almost at the same m.a.s.l, (abs. high), branch off. Branching off from the river Muksu, in the flood season, the channel tends to the left and flows into Kurunkul Lake. The main river merges into the endorheic lake Karakul.
In the same way from Muzdzhilga river duct branches off, heading first to the northwest, and then to the northeast, then flowing into lake Kurunkul. The main branch of the Muzjilga river, heading southwest, becomes a tributary of the Kokuibail river. In turn, Kokubeyl river, merging with the Tanymas river, form the Goodara river. Later, this river will be renamed into the Bartang river, one of the main tributaries of the Panj river.
Both branch tributaries from the Muksu (right) and Muzdzhilga (left) rivers flow to Kurunkul Lake, only 1 km long, and sometimes (during low water season) under alluvial deposits. Apparently because of this, Lake Kurunkul is drainless and salty.
Bifurcation near Urtabuz pass. Urtabuz (4235 m.a.s.l., 37°36 ' 51" NL, 74°00 '46" EL) between the Mashale (right) and Irisu (left) rivers at an altitude of 4246 m.a.s.l. - seasonal (Fig. 1).
1 - rivers, 2 - seasonal rivers, 3 - glaciers, 4 - elevation marks, 5 - lakes, 6 - bifurcation points.
Figure 1. Bifurcation at the pass Urtabuz., Karadung and Yangidavan.
On this territory, on both sides of the Urtabuz pass, the Mashale and Irisu rivers are as close as possible, and the distance between them is 1.3 km. From the south of the Urtabuz pass, opposite the highest point (4235 m.a.s.l.), an unnamed seasonal river flows from south to north, which branches into two seasonal streams 420 m from the pass. One of them, turning to the west and flowing 1.1 km, flows into the river with the name Iris, and the other after a branch, turning to the right, flowing 1.1 km, flows into the Mashale river.
The angle between branched brooks is 47°.
Irisu river is a tributary of the 5th order of the river. Gund, and Mashale river is a tributary of the 5th order of the Bartang river.
4. Polyfurcation north of Karadung lake (37°30'14" NL, 74°01'00" EL).
This bifurcation point is located 4.5 km north of Karadung lake, at an altitude of 4373 m.a.s.l.), and is seasonal (Fig. 1).
This polyfurcation can also be considered unique, although it is seasonal, since one river branches into three rivers and they flow into three different basins. The main river, which is seasonal and has no name on topographic maps, flows south from the South Alichur ranges. On the way from the right bank, two seasonal streams merge onto it. After the confluence of these tributaries, the river flows for almost 1 km and then branches again. The length of the river from source to bifurcation is
3.2 km.
The first, upper fork (bifurcation) is observed at an altitude of 4384 m.a.s.l., and the second, lower one on this river, is located at an altitude of 4373 m.a.s.l. The branching angle between the rivers of the upper bifurcation is 44°, and between the rivers of the lower bifurcation -46°.
The first river after the upper bifurcation first turns to the left, to the southeast, flowing for almost 200 m and forks again. The left duct flows to the east, flowing 12 km, flows into the Ystyk river. Another duct flows south towards Karadung lake. This bifurcation phenomenon is seasonal. After the upper bifurcation, the average angle of inclination of the runoff of the main river sharply decreases.
The upper river after a bifurcation, which was formed at an altitude of 4384 m.a.s.l. The distance from the place of bifurcation to Kokdzhigit lake is 6.2 km. After Kokdzhigit lake, the river changes its name to Mukurchiolob and it flows into Zorkul lake, where the river flows from it. Pamir.
The third river branches 200 m below the upper bifurcation point from the left tributary and flows south with a deviation to the east. Near Karadung lake, the river turns left, flowing 7.4 km, merges with the river, which overflows from Karadung lake, and then flows into the Ystyk river. This river, bypassing a small hollow, flows down to the Ystyk river at an altitude of 4256 m.a.s.l. The distance from the point of confluence of the third channel to the point of confluence of the left tributary in the Ystyk river is 12 km.
It should be noted that the rivers up to the point of this branch are seasonal. After the bifurcation point, for some part of the way, some rivers flow under glacial-proluvial-alluvial deposits. In addition to these streams, many other rivers in the Murgab region flow under glacial-proluvial-alluvial deposits.
5. Bifurcation near Yangidavan pass. (37°30'48" NL, 74°02'56" EL).
To the south of the Urtabuz bifurcation, the phenomenon of bifurcation can be observed another seasonal bifurcation, which is located northeast of the Yangidavan pass. The basin of this bifurcation is not very large and both branched rivers are tributaries of theYstyk river. (Fig. 1).
This phenomenon of bifurcation is recorded on the southern slope of the Yuzhnoalichursky ridge. The river flows from the southern slope of the mountains to the southeast and to the abs. at an altitude of 4470 m.a.s.l. from sea level it branches into two branches.
The left stream after the bifurcation is directed to the northeast and tends towards the Ystyk river, where 10.4 km flows to the confluence with it. Another branch after bifurcation flows south,
3.3 km, then merges with another tributary of the Ystyk river. The angle between the branched streams is 58°.
6. Bifurcation near Aydynkul lake. A bifurcation in this area is observed 1.3 km southwest of Aydynkul lake at an altitude of 4449 m abs. (37°25'59" NL, 74°12'54" EL).
At the right tributary Andyminsu. The length of the river Andyminsu, from the source to the bifurcation point - 3 km. The river first flows from south to north, after a branch of which one part of it turns to the left and becomes a tributary of the river. Admynsu, and the other, flowing down to the right, merges into the lake Aydynkul. From Aydynkul lake to the bifurcation point, the river flows
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2.6 km, and then, merging with the river. Admynsu, flows for another 3.6 km. The angle between branched brooks is 23°. Also, lower from this point of the bifurcation at the Aydynkul river observed and other points where the channel forks.
The length of the Aydynkul river from the mouth to the lake -39 km, and the total length from the bifurcation point to the confluence with the lake Aydynkul -44.3 km. After walking the same distance, Aydynkul, on the way it will be renamed into the Beshbulok river, then, taking, on the right, a tributary called the Jamanshura river at an altitude of 3990 m.a.s.l., merges with the Ystyk river.
Another branch after a branch merges with the Andiminsu river, which in turn is a tributary of the Ystyk river.
Bifurcations at the Aydynkul river is not indicated on the topographic maps of the 70-80s of the last century. From this it follows that they appeared recently.
Also, 3.6 km to the north (with a deviation to the west) from Aydynkul lake, there is another lake that does not have a name. 350 m southwest of this lake, another manifestation of the seasonal bifurcation is observed at an altitude of 4355 m.a.s.l. (37°28'43" NL, 74°12'37" EL).
7. Bifurcation at the Bandersky Pass (37°22'15" NL, 74°14'05" EL, 4540. m.a.s.l.). This pass is located on the Wakhan Range and divides the border between the Republic of Tajikistan and Afghanistan. The very phenomenon of bifurcation is fixed on the territory of Tajikistan.
Flowing from south to northeast, on the northwestern slope of the Wakhan Range, the Andymin river, originates on a glacier, which is located on the territory of the Republic of Tajikistan. Having traveled almost 2 km from the source to the bifurcation point, the water at the peak of the Bandera pass first accumulates in the form of a small lake, and then, branching off, flows down into different basins. The branching angle of the bifurcation between the rivers Andymin and Andamin is 180°, i.e. they go in opposite directions (Fig. 2).
Andamin river, after a branch, first heads east, towards Afghanistan and at an altitude of 4468 m.a.s.l., taking a tributary called Kyzyldzhilga on the left, turns southeast and flows into the Aksu river (first-order tributary of the Murghab river). Fig. 2.
Figure 2. Bifurcation at the Bendersky Pass
Andamin river (a tributary of the Aksu river), flowing for more than 112 km, merges with the river. Sulistik at an altitude of 3790 m.a.s.l., south of the village of Tukhtamish, Murgab district. Moreover, from the source to the border of Tajikistan, the Aksu river flows 49.6 km through Afghanistan.
Another river, which branches off from the bifurcation point (from the Bandera pass) flows to the northwest, is called the river. Andymin. After passing 4 km from the source, the river merges with another nameless river, at an altitude of 4417 m.a.s.l., After which the river takes the name Andiminsu. Andiminsu river is a tributary of the first order of the Ystyk river. The Ystyk river changes its name to Suulu-Ystyk, after accepting the tributaries Kastandai-Dzhilga (on the right) and Uch-Dzhilga (on the left), and with this name flows to the village of Tukhtamysh, where it merges into the river. Aksu. The Ystyk river flows more than 95 km from the bifurcation point to the village of Tukhtamysh.
At the beginning of the article, we said that the identified bifurcations are located at altitudes of more than 3000 m.a.s.l., and they are high mountains. On fig. 3 shows a diagram of the location of these furcations in height.
5000
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2500
Bifurcation point height (m.a.s.l.)
♦ ♦
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bifurcation points
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Figure 3. Location of bifurcation points in height.
It is easy to see that the largest bifurcation points are fixed at altitudes above 4000 m.a.s.l.
In the highlands, the channels of mountain rivers branch off to form giant river islands, while in semi-mountain and lowland rivers, islands appear in river channels. Entire mountain ranges become islands here. Examples of such large branches, as we considered above, can be a bifurcation at the sources of the Karashur river, where the ridge of Peter the Great is located between two channels, or a bifurcation at the head of the Burgutai-Dzhilgadzhelav river, where several Pamir mountain systems were between the channels. Alpine rivers differ from lowland rivers in that they have a large slope of the longitudinal profile and, in comparison with lowland rivers, they are very shallow. In addition, in the sources of high-mountain rivers located at altitudes of about 4000 m.a.s.l.. in the autumn-winter period, the waters in these rivers freeze, and no reformation of the river bed is observed. Perhaps for this reason, the phenomenon of bifurcation in high-mountain rivers is longer.
In the sources of mountain rivers, they flow down along the proluvial deposits, where the clastic material is less broken or almost not broken. The flow of water in most cases flows under these deposits.
For the appearance of furcation, there must be some barrier (interference). At the same time, the topographic conditions of the area must be special, the hydrological parameters of the river, the weathering of rocks, and other landscape parameters must be appropriate. According to V.V. Bartold, the necessary conditions for the bifurcation of rivers are an unbalanced distribution of water, a difference in the relative elevations of the receiving streams, and a shift in the main stream [3].
The furcation of the river flow is associated with geological processes. If the catchment area of the river during intensive peneplanation reaches such a state when the bottom of the hollow becomes flat, then the "inversion" of the flow occurs and any characteristics of the relief (or geological structure, for example, the state of soils) can cause a bifurcation of the flow [10].
Have rather wide development usually temporary (seasonal) furcations (the second type). Such a furcation occurs on a sub-plain relief during floods and high waters, where the slow speed of the river flow and the abundance of precipitation cause branching, alluvial islands are formed.
Furcation is especially typical for rivers with unstable and unstable channels; along with this, it develops in areas of accumulation of river sediments (deltas, places where mountain rivers enter the plain, areas of negative local structures). Where accumulation is intense, regressive (upstream) buildup of islands is observed. Incised arms are a much rarer phenomenon than incised meanders. The formation of such branches is observed during the incision of rivers with a complex structure of the bedrock with a predominance of rocks. In rivers flowing from lakes, the existence of such branches is supported by specific conditions created for the ice regime (mass sludge formation, forcing the current to lay and maintain detours) [7].
Another reason for the formation of a bifurcation is the work and retreat of glaciers. Retreating, glaciers leave a certain layer of madder residues in the form of coarse and medium clastic alluvial deposits. These alluvial deposits form an almost flat relief, as a result, the flow of the river breaks through more than one channel.
These bifurcation points can serve as an excellent object for geo and eco tourists. It should be noted that almost all of the above bifurcation points on the territory of Tajikistan can be reached by car (SUV).
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