Course of the Meghna in Bangladesh ( headwaters Barak only partially )
View of the Upper Meghna from the bridge at Gazaria
Meghna ( Bengali: Meghana মেঘনা ) is the common name of two successive sections of the river system in the great rivers of Bengal, which also Brahmaputra and Ganges include. They lie within the boundaries of Bangladesh. Both sections of the river are often treated as two separate rivers. The Lower Meghna ( Lower Meghna ) is 36,500 m³ / s the most powerful power in Asia and the third largest in the world. It is produced by the union of Upper Meghna ( Upper Meghna ) with the nearly 8 - fold greater Padma, which arises in turn about 100 kilometers above the confluence of the main strands of the Ganges and Jamuna (lower Brahmaputra ). The Lower Meghna flows after 130 kilometers in the Indian Ocean.
The area around Cherrapunji, one of the wettest regions in the world, drains into the Meghna.
The Upper Meghna arises under the name Barak in Patkai Mountains (about 25 km south-east of the mountain Japvo ) in northeastern India. The source is located in the state of Manipur, in the further course of the river running through parts of the states of Nagaland, Mizoram and Assam. In the area of the border between India and Bangladesh, the sediment- rich Barak leaves the mountains and splits after his up here about 610 kilometer race in two main arms, in Surma (15 % of the water supply ) and Kushiyara ( 85%). Both creeks are embedded in a network of meandering watercourses that are subject to constant change and were only selectively fixed and regulated by human intervention. Although they do remove up to 45 kilometers apart, can form a contiguous surface water to the monsoonal floods. Since the main waterways took other paths repeatedly in the past, the nomenclature is not uniform small scale changing and today.
South arm Kushiyara
The southwestward flowing Kushiyara was still in the 19th century, when this part of Bengal to Assam belonged, like the upper reaches called Barak. Today this name still leads one branching below the confluence of the Manu small side arm. From this branch of the main stream Bibiyana is called and a little later, after confluence of the Surma ( today only a small tributary of the later again leading- Surma main line ), Kalni. Prior to the unification of the two major branches of the river north of Bhairab Bazar in the district Kishorganj the south arm has a length of about 290 kilometers. From here, the river carries the name Meghna.
North Arm Surma
The first relatively small Surma arm gets on his way to the west in rapid succession -watered tributaries from the mountains in the north, which is considered to stimulate the richest area in the world, known by weather records of the town of Cherrapunji. The handsome become main stream does not flow like today, still Surma called small tributary to the south, but as Dhanu further west to the mouth of Shomeshwari, then as Baulai to the south and recording of the coming of the West Kangsa Ghorautra. The Surma and the many waterways connected to it to flow through a subsidence area in which form extensive marsh and water areas between the dam banks of the rivers. The windungsreiche north arm has to union with the south arm has a length of approximately 380 kilometers. At the point of its reunification, the water levels of both arms is not substantially different.
At Bhairab Bazar named flows after the former main branch of the Brahmaputra in the Meghna, which only leads to full-length, probably due to tectonic uplift, a little water. Today, it opens only a minor tributary of the Old Brahmaputra; whose main branch opens under other names only 80 km further downstream in the Meghna. Here also flow more from the Jamuna (name of the Brahmaputra in Bangladesh) at diverted waters. Their united in broad Dhaleshvari brown water are still far downriver to differ from the gray - green waters of the Meghna. In Chandpur, after almost another 40 miles, joins the. Between one and two kilometers wide Upper Meghna with the far larger Padma
The entire course of the river Barak - Kushiyara - Upper Meghna has a length of about 1040 km, of which as Meghna about 140 kilometers. The water flow before the confluence with the Padma is approximately 3,610 m³ / s
The lower Meghna essentially represents the continuation of the Padma, which is the largest river in Asia already with over 32,000 m³ / s. Although the Padma is named after the lower reaches of the Ganges, in terms of volume but the lower reaches of the larger Brahmaputra. Off the west displacement of the Brahmaputra in the Eighteenth Century met its water masses, today's running of the Upper Meghna vorzeichnend, only here on the Ganges. The discharge flow of the combined flow varies greatly between the rainy and dry seasons and is in Chandpur 10000-160000 m³ / s; annual average over 36,000 m³ / s The high water phase of the Padma and Lower Meghna takes several months, since the peak discharge of the Brahmaputra is in July and August and the Ganges in September. The Upper Meghna does not cause a significant shift in the hydrograph.
The currents are dangerous especially at the throat of Chandpur, especially the tidal range in the eastern Bay of Bengal with three to seven meters is quite high and far enough upstream. The 3 to 10 kilometers wide stream bifurcates before it flows into two main channels. Numerous small tributaries join the main stream on both sides.
The Lower Meghna is currently the most active morphodynamically part of the Ganges-Brahmaputra - Meghna delta of großflächigsten river deltas in the world. Although large by the annual floods soil fertility allows for an extremely high rural population density along the Meghna and their hinterland, yet provide the power of the monsoonal floods and flash floods, as well as the threat of rising sea levels and direct danger to millions of people dar. One tries the coastal shorelines to stabilize by planting of mangrove forests, which, however, can not counter any shift trends of the main streams.