Meghna

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Upper Meghna
Barak, Surma, Kushiyara
Course of the Meghna in Bangladesh (Upper Barak only partially)

Course of the Meghna in Bangladesh (Upper Barak only partially)

Data
location India , Bangladesh
River system Meghna
Drain over Lower Meghna → Bay of Bengal
source as Barak in Northeast India
25 ° 28 ′ 21 ″  N , 94 ° 17 ′ 17 ″  E
Association with Padma to Lower Meghna Coordinates: 23 ° 14 ′ 20 ″  N , 90 ° 37 ′ 40 ″  E 23 ° 14 ′ 20 ″  N , 90 ° 37 ′ 40 ″  E
Mouth height 0.5  m

length 1040 km
Catchment area 82,000 km²
Drain MQ
3600 m³ / s
Left tributaries Dhaleshwari, Langai, Manu, Gumti
Right tributaries Shomeshwari, Kangsa, Old Brahmaputra , Dhaleshwari
Big cities Silchar , Sylhet , Bhairab Bazar
Medium-sized cities Chhatak, Munsiganj
View of the Upper Meghna from the bridge at Gazaria

View of the Upper Meghna from the bridge at Gazaria

Meghna ( Bengali : মেঘনা Meghanā ) is the common name of two successive river sections in the system of the great rivers of Bengal, which also includes Brahmaputra and Ganges . Both river sections are often treated as two separate rivers. The Lower Meghna ( Lower Meghna ) is the most powerful river in Asia with 36,500 m³ / s and the third largest in the world. It arises from the union of the Upper Meghna ( Upper Meghna ) with the almost 8 times larger Padma , which in turn arises a good 100 kilometers above from the confluence of the main lines of the Ganges and Jamuna (lower Brahmaputra). The Lower Meghna flows into the Indian Ocean after 130 kilometers .

The stretches of river known as Meghna are within the borders of Bangladesh , but the system also drains large parts of northeast India . The area around Cherrapunji , which is one of the rainiest regions in the world, drains into the Meghna.

Upper Meghna

Upper course (Barak) in Manipur
Barak

Upper Barak

The Upper Meghna rises under the name Barak in the Patkai Mountains (approx. 25 km southeast of the Japvo Mountain ) in northeast India . The source is in the state of Manipur , in the further course the river crosses parts of the states of Nagaland , Mizoram and Assam . In the area of ​​the state border between India and Bangladesh, the sediment-rich Barak leaves the mountainous country and splits after about 610 kilometers to this point. long course in two main arms, in Surma (15% of the water flow ) and Kushiyara (85%). Both river arms are embedded in a network of meandering watercourses that are subject to constant change and were only fixed and regulated selectively by human intervention. Although they are up to 45 kilometers apart, monsoonal floods can form a continuous body of water. Since the main waterways always took different courses in the past, the naming changes in small areas and remains inconsistent to this day.

South arm of Kushiyara

The southwest flowing Kushiyara was still in the 19th century, when this part of Bengal belonged to Assam, like the upper reaches as Barak . Today this name still bears a small branch branching off below the confluence of the Manu. From this junction the main stream is called Bibiyana and a little later, after the confluence of the Surma (today only a small branch of the Surma main line, which only later joins again), Kalni . Up to the union of the two large river arms north of Bhairab in the Kishoreganj district , the south arm is a good 290 kilometers long. From here the river bears the name Meghna .

The Surma

Northern arm of Surma

The initially relatively small Surma arm receives on its way west in rapid succession water-rich tributaries from the mountainous region in the north, which is considered the rainiest area in the world, known for the weather records of the city of Cherrapunji . The main stream, which has become stately, does not flow to the south like today's small tributary , still called Surma , but as Dhanu further west to the mouth of the Shomeshwari, then as Baulai to the south and, after the Kangsa coming from the west, as Ghorautra . The Surma and the many watercourses connected to it flow through a subsidence area in which extensive swamp and water areas form between the banks of the rivers. The winding north arm has a length of around 380 kilometers until it joins the south arm. At the point of their reunification, the water flow of both arms does not differ significantly.

Lower course

At Bhairab Bazar, the name of the former main arm of the Brahmaputra flows into the Meghna, which has little water along its entire length, probably as a result of tectonic uplift . Today only an insignificant branch of the Old Brahmaputra flows here; its main line flows under a different name 80 kilometers further downstream into the Meghna. Other waters branched off from the Jamuna (name of the Brahmaputra in Bangladesh) also flow here. Their brown waters, united in the broad Dhaleshvari, can still be distinguished far downstream from the gray-green waters of the Meghna. At Chandpur , after a further 40 kilometers, the Upper Meghna, between one and two kilometers wide, unites with the much larger Padma .

The entire course of the Barak-Kushiyara-Upper Meghna river is about 1040 km long, including about 140 kilometers as Meghna. The water flow before the confluence with the Padma is around 3,610 m³ / s.

Lower Meghna
location Bangladesh
River system Meghna
Confluence of Padma and Upper Meghna
23 ° 14 ′ 20 ″  N , 90 ° 37 ′ 40 ″  E
Source height 0.5  m
muzzle Bay of Bengal , Indian Ocean
22 ° 22 ′ 30 ″  N , 91 ° 11 ′ 20 ″  E
Mouth height m
Height difference 0.5 m
Bottom slope 0 ‰
length 130 km as Meghna , river system with Brahmaputra: 3,450 km
Catchment area 1,722,300 km²
Drain
at the mouth
MQ
36,500 m³ / s
Medium-sized cities Chandpur

Lower Meghna

Ganges (left), Brahmaputra (center, top) and Meghna (center, right) during the monsoon season. The river arms Surma and Kushiyara (upper center) form a continuous water surface

The Lower Meghna is essentially the continuation of the Padma, which is already the largest river in Asia with around 32,000 m³ / s. The Padma is, according to its name, the lower course of the Ganges, but according to its volume it is the lower course of the greater Brahmaputra. Before the westward shift of the Brahmaputra in the eighteenth century, its water masses, marking the current course of the Upper Meghna, first met that of the Ganges here. The flow rate of the combined river varies greatly between the rainy and dry seasons and is between 10,000 and 160,000 m³ / s at Chandpur; annual average over 36,000 m³ / s. The flood phase of the Padma and the Lower Meghna lasts several months, as the drainage point of the Brahmaputra is in July and August and that of the Ganges in September. The Upper Meghna does not cause any significant shift in the discharge hydrograph .

The currents are particularly dangerous at the Chandpur narrow point , especially since the tidal range in the eastern Bay of Bengal is quite high at three to seven meters and extends far upstream. The 3 to 10 kilometer wide river forks into two main gullies in front of the mouth. Numerous small branches accompany the main stream on both sides.

The Lower Meghna is currently the morphodynamically most active part of the Ganges-Brahmaputra-Meghna delta , the largest river delta in the world. The high fertility of the soil due to the annual floods allows an extremely high rural population density along the Meghna and in its hinterland, but the violence of the monsoonal floods and spring tides as well as the threat of sea level rise pose immediate dangers for many millions of people to stabilize coastal shorelines by planting mangrove forests , which, however, cannot counter any shifting tendencies of the main streams.

Web links

Commons : Meghna  - collection of pictures, videos and audio files

Individual evidence

  1. a b Joint Rivers Commission Bangladesh, Ministry of Water Resources: Basin Map of the Ganges, the Brahmaputra and the Meghna River ( Memento of the original of July 6, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , supplemented by the approximately 1000 km² catchment area of ​​the lower Meghna, which was not taken into account there @1@ 2Template: Webachiv / IABot / www.jrcb.gov.bd
  2. a b P.K. Parua: Flood Management in Ganga-Brahmaputra-Meghna-Basin: Some Aspects of Regional Co-operation ( Memento of the original from June 20, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ( MS Word ; 71 kB) @1@ 2Template: Webachiv / IABot / www.unescap.org
  3. Meghna River of Banglapedia
  4. The Amazon with 209,000 m³ / s and the Congo with 41,000 m³ / s are richer in water , only slightly smaller is the discharge of the Orinoco with almost 35,000 m³ / s.
  5. ^ Surma-Meghna River System at Banglapedia
  6. Kushiara River at Banglapedia
  7. ^ Surma River at Banglapedia
  8. In contrast to the Ganges, the length information for Brahmaputra that is common in the literature is shortened in such a way that it can be reproduced with a measuring polygon of a good 200 km mean length. Therefore, the rounded own measurement in aerial photo material (google earth) is shown here for the time being.
  9. M. Monirul Qader Mirza, Ema. Manirula Kādera Mirjā, Ajaya Dixit, Ainun Nishat: Flood Problem and Management in South Asia, Dordrecht 2002 ISBN 1-4020-1068-0