LAND AND GEOGRAPHY OF BANGLADESH: RIVERS, DELTAS, EROSION AND ACCRETION

GEOGRAPHY OF BANGLADESH

Situated between India and Southeast Asia, Bangladesh is almost completely surrounded by India. Bangladesh is 148,460 square kilometers in area (57,321 square miles), which is roughly the size of Wisconsin or Nepal, and extends about 580 kilometers (360 miles) from north to south, and 420 kilometers (260 miles) from east to west. About 70 percent of the country is good for agriculture (compared to 21 percent in the U.S.), 4.6 percent is covered by pasture land and 11 percent by forests and woods. The remaining 18 percent of the country is swamps, marshes and a few mountains.

Bangladesh is a densely populated rural country with the world’s largest river delta and the world’s largest mangrove forest and very lush and green landscape and often full of water. Encompassing eight divisions (states) and about 85,000 villages, Bangladesh is essentially a huge delta and alluvial plain of the Padma River (a combination of the Ganges and Brahmaputra River) and Meghna Rivers. The average elevation of the huge alluvial plain created by these and other rivers averages less than 10 meters (33 feet). There are few areas are above 100 meters (330 feet).

About 59 percent of Bangladesh's nonurban land is arable. Permanent crops cover only 6.5 percent of the country. Bangladesh produces large quantities of quality timber, bamboo, and sugarcane. Bamboo grows in almost all areas, but high-quality timber grows mostly in the highland valleys. Rubber planting in the hilly regions of the country was undertaken in the 1980s, and rubber extraction had started by the end of the decade. A variety of wild animals are found in the forest areas, such as in the Sundarbans on the southwest coast, which is the home of the worldfamous Royal Bengal Tiger. The alluvial soils in the Bangladesh Plain are generally fertile and are enriched with heavy silt deposits carried downstream during the rainy season. [Source: James Heitzman and Robert Worden, Library of Congress, 1989 *]

Of the total area of Bangladesh — 148,460 square kilometers (57,321 square miles) — is comprised of 130,170 square kilometers (50,259 square miles) of land and 18,290 square kilometers (7062 square miles) of water. Compared with other countries in the world in terms of size, Bangladesh ranks 95th. It is slightly larger than Pennsylvania and New Jersey combined; slightly smaller than Iowa. It is about about 16,00 square kilometers larger than Greece. [Source: CIA World Factbook, 2020]

Bangladesh is situated in the delta of the two largest rivers on the Indian subcontinent and two of the largest in the world — the Ganges and Jamuna (Brahmaputra). Bangladesh's capital city, Dhaka, is located in the central part of the country. Bangladesh occupies the eastern part of the Bengal region (the western part of the region is occupied by the Indian state of West Bengal). Before it became an independent state in 1971, Bangladesh was the eastern part of Pakistan. In the British colonial era, it was known as East Bengal. When Pakistan became independent in 1947, present-day Bangladesh was East Pakistan. [Source: “Worldmark Encyclopedia of Nations”, Thomson Gale, 2007]

Borders of Bangladesh

Located in south Asia on the northern edge of the Bay of Bengal, Bangladesh is almost completely surrounded by India (on the east, north and west). In the southeast in the Chittagong hill region it shares a small border with Myanmar (Burma). The Bay of Bengal, which connects to the Indian Ocean is to the south.

Bangladesh has a total land border length of 4,413 kilometers (2,742 miles): 4142 kilometers (2,574 miles) with India and 271 kilometers (168 miles) with Myanmar. The coastline on the Bay of Bengal is 580 kilometers (360 miles). Maritime claims: territorial sea: 12 nautical miles out from the coast; exclusive economic zone: 200 nautical miles from the coast; contiguous zone: 18 nautical miles; continental shelf: to the outer limits of the continental margin. The Geographic coordinates for the country are 24 00 N, 90 00 E. [Source: CIA World Factbook, 2020]

Located south of the Himalayan foothills. Bangladesh borders the Indian states of West Bengal in the west and north, Assam and Meghalaya in the northeast, and Tripura and Mizoram in the east. Meghalaya and northern Bangladesh is one of the rainiest regions in the world. The longest distances are 767 kilometers (477 miles) from south-southeast to north-northwest and 429 kilometers (267 miles) from east-northeast to west-southwest. [Source: Junior Worldmark Encyclopedia of Physical Geography, The Gale Group, Inc., 2003]

The 4,414-kilometer India-Bangladesh border is regarded as one of the most porous in the world. The demarcation line divides several villages and some people eat lunch in their kitchen in India and then retire to their bedroom in Bangladesh for a nap. Towns on the Indian side of the border or noticeable better off than those on the Bangladeshi side. So many Bangladeshis migrate into India in search of jobs and food that the Indian government wants to erect a fence along the entire border. A fence that covers less than a fourth of frontier has done little to slow migration or smuggling.

In 2001, New Delhi approved a $304 million project to fence much of the border of Bangladesh. The India–Bangladesh barrier is 3,406-kilometers (2,116 miles) long. It is a fence of made barbed wire and concrete just under three meters (9.8 feet) high. Of this, 500 kilometers (310 miles) was completed at the cost of US$400 million in 2007. The deadline for project completion was set to be 2009. As of that time about 2,649 kilometers (1,646 miles) of fencing along with about 3,326 kilometers (2,067 miles) of border roads were completed. As of 2011, 2,735 kilometers (1,699 miles) of fencing was completed and the deadline was revised to March 2012.

A border demarcation agreement was signed with Myanmar in May 1979. Due in part to Rohingya crisis, Burmese border authorities are constructing a 200-kilometer (124 mile) wire fence designed to deter illegal cross-border transit and tensions from the military build-up along border

Bangladesh has referred its maritime boundary claims with Burma and India to the International Tribunal on the Law of the Sea; Indian Prime Minister Singh's September 2011 visit to Bangladesh resulted in the signing of a Protocol to the 1974 Land Boundary Agreement between India and Bangladesh, which had called for the settlement of longstanding boundary disputes over undemarcated areas and the exchange of territorial enclaves, but which had never been implemented;

Topography of Bangladesh

A watery, alluvial region, Bangladesh consists primarily of low-lying plains that never rise more than 10 meters (33 feet) above sea level. The majority of the country is engulfed by the delta region of 144,000 square kilometers (55,600 square miles) is formed by the Ganges (Padma), Brahmaputra (Jamuna) and Meghna Rivers and smaller tributary rivers. Changes in topography occur only in the northeastern hilly tea-growing regions of Sylhet and the southeastern forest regions of the Chittagong Hill Tracts. The capital, Dhaka, is less than eight meters (25 feet) above sea level.

Bangladesh is crisscrossed by 250 rivers and numerous tributaries, streams, canals, and tidal creeks. Bangladesh has been built up from alluvial deposits and silt from the Himalayas carried downstream by the countries great rivers. This explains why the soil is so fertile and the land is flooded during the monsoon season. Much of the land is cultivated. Interspersed with the small peasant farms and large plantations are jungles, wooded marshlands, lakes and forests. The coastal area is marshy and jungly. The Chittagong coastal region in the southeast has a narrow connection to the rest of the country.

Most of the country is no more than 90 meters (300 feet) above sea level. The mean elevation for the entire country is 85 meters. The flat landscape is broken only hills in the eastern and southeastern parts of country. Chittagong Hills (near the Burmese border) is the highest region of Bangladesh. The average elevation here is 610 meters (2,000 feet). The highest peak, Keokradong, is 1230 meters (4034 feet high). It is near the Myanmar border in the extreme southeast.

The Bengal region of India and Bangladesh consist large of a vast alluvial, deltaic plain built up by the Ganges and Brahmaputra Rivers. The total Bengal region covers 233,000 square kilometers. Of this 89,000 square kilometers (38 percent) is in India and 144,00 square kilometers (62 percent) is in Bangladesh. The northwestern section of the country, drained by the Tista (Teesta) River, is somewhat higher and less flat. There are dense forest along the eastern frontier with Mynamar and Assam (India).

About half of the total area of Bangladesh is actively deltaic and is prone to flooding in the monsoon season from May through September. The land is suitable for rice cultivation. In the north and the southeast, where the land is more hilly and dry, tea is grown. The Chittagong Hill Tracts have extensive hardwood forests. The vast river delta area is home to the dominant plains culture. The hilly areas of the northeast and southeast are occupied by much smaller tribal groups. [Source: “Countries and Their Cultures”, The Gale Group Inc., 2001]

Plains and Delta Area of Bangladesh

About half of the total area of Bangladesh is comprised of actively-deltaic, alluvial plains that is prone to flooding in the monsoon season from May through September. Much of land is utilized for rice cultivation. The Bengal region consist largely of the vast alluvial, deltaic plain built up by the Ganges and Brahmaputra Rivers. The delta region formed by the Ganges (Padma), Brahmaputra (Jamuna) and Meghna Rivers and smaller tributary rivers covers 144,000 square kilometers (55,600 square miles). The total Bengal region covers 233,000 square kilometers. Of this 89,000 square kilometers (38 percent) is in India and 144,00 square kilometers (62 percent) is in Bangladesh.

Bangladesh's alluvial soil is highly fertile and intensively farmed but vulnerable to flood and drought. The delta area and plains contain deposits of clay, silt, sand, or gravel deposited by running water. Mineral deposits are minimal. During the monsoon season floodwater covers much of the land area, sometimes damaging crops and hurting the economy. Since most of the region is at most a few meters above sea level, there are worries that the region will become permanently is sea levels rises as predicted by climate change.

The broad deltaic plain is fissured by many rivers and streams flowing into the Bay of Bengal. The highly irregular deltaic coastline runs for about 600 kilometers. Roughly 80 percent of Bangladesh is made up of fertile, alluvial Bangladesh Plain. The plain is part of the larger Plain of Bengal, which is sometimes called the Lower Gangetic Plain. Although altitudes up to 105 meters above sea level occur in the northern part of the plain, most elevations are less than 10 meters above sea level; elevations decrease in the coastal south, where the terrain is generally at sea level. With such low elevations and numerous rivers, water — and concomitant flooding — is a predominant physical feature. About 10,000 square kilometers of the total area of Bangladesh is covered with water, and larger areas are routinely flooded during the monsoon season. [Source: James Heitzman and Robert Worden, Library of Congress, 1989 *]

Ganges-Brahmaputra Delta

According to the Guinness Book of Records, the 77,700-square-kilometer (30,000-square-mile) delta created by the Ganges and Brahmaputra rivers in Bangladesh and West Bengal, India is the world's largest delta. Ever year the Brahmaputra and Ganges system carries two billion tons of sediment out to sea. More than any other river system, even the Amazon. The sediment creates islands known as chars, which are utilized for farming but are vulnerable to floods.

The Brahmaputra enters Bangladesh as the Jamuna, joins the Ganges to form the Padma and ends as the Meghna, which splits into a massive delta that empties into the Bay of Bengal at a rate of 2.3 million cubic feet of water a second.

In the Ganges Delta many large rivers come together, both merging and bifurcating in a complicated network of channels. The two largest rivers, the Ganges and Brahmaputra, both split into distributary channels, the largest of which merge with other large rivers before themselves joining. This current channel pattern was not always the case. Over time the rivers in Ganges Delta have changed course, sometimes altering the network of channels in significant ways.

Hilly Areas of Bangladesh

The only exceptions to Bangladesh's low elevations are the Chittagong Hills in the southeast, the Low Hills of Sylhet in the northeast, and highlands in the north and northwest. The Chittagong Hills constitute the only significant hill system in the country and, in effect, are the western fringe of the northsouth mountain ranges of Burma and eastern India. [Source: James Heitzman and Robert Worden, Library of Congress, 1989 *]

The Chittagong Hills rise steeply to narrow ridge lines, generally no wider than 36 meters, 600 to 900 meters above sea level. At 1,230 meters (4034 feet), the highest elevation in Bangladesh is found at Keokradong, also called Reng Mountain, in the southeastern part of the hills near where Myanmar, India, and Bangladesh all come together.. West of the Chittagong Hills is a broad plain, cut by rivers draining into the Bay of Bengal, that rises to a final chain of low coastal hills, mostly below 200 meters, that attain a maximum elevation of 350 meters. West of these hills is a narrow, wet coastal plain located between the cities of Chittagong in the north and Cox's Bazar in the south.*

The small hilly regions of Bangladesh are crossed by swiftly flowing rivers. The Chittagong and Bandarban Hill Tracts are a series of ridges along the Myanmar border. Fertile valleys lie between the hill lines, which generally run north-south. Sylhet District features sedimentary hills, some of which exceed 90 meters (300 feet) in elevation. Near Sylhet, south of the Kusiyara River, six hill ranges connect to the Tripura Hills of India. The maximum elevation of these ranges, near the Bangladesh-Indian border, is about 335 meters (1,100 feet). [Source: Geo-Data: The World Geographical Encyclopedia, The Gale Group Inc., 2003]

Land Divisions and Cities in Bangladesh

Bangladesh encompasses eight divisions (states) and about 85,000 villages. At the local government level, Bangladesh country is divided into (from largest to smallest): divisions, districts (regions), subdistricts (thanas), union parishads (unions) and villages. There are eight divisions: Barishal, Chattogram, Dhaka, Khulna, Mymensingh, Rajshahi, Rangpur, Sylhet. There used to be six divisions: Dhaka, Chittagong, Rajshahi, Barisal and Khulna. These in turn were divided into 64 districts and 495 thanas. In 1997, Bangladesh reorganized its local divisions. It do so again later. At one time there were five divisions and before that four.

Urban population: 38.2 percent of total population in 2020 (compared to 83 percent in Great Britain and 21 percent in Ethiopia). There are four major municipal corporations (Dhaka, Chittagong, Khulna and Rajshahi).
rate of urbanization: 3.17 percent annual rate of change (2015-20 estimated)
Major urban areas: Dhaka (capital): 21.006 million; Chittagong: , 5.020 million; Khulna: , 954,000; Rajshahi: 908,000; Sylhet: 852,000 (2020) [Source: CIA World Factbook, 2020]

Dhaka is located in the central part of the country. It is located near the point where the Ganges (Padma) and Brahmaputra (Jamuna) river systems meet. The Ganges River flows into the country from the northwest, while the Brahmaputra enters from the north. Bangladesh’s other major city is Chittagong. It lies on the Bay of Bengal in the southeast part of Bangladesh. [Source: Columbia Encyclopedia, 6th ed., The Columbia University Press]

Water in Bangladesh

Bangladesh contains over 2,590 square kilometers (1,000 square miles) of permanent waterways. One third of the country is flooded in the monsoon season. Bangladesh's coast along the the Bay of Bengal is made up of delta and coastal islands, mangrove swamps and marshy waterways. Dense mangroves cover much of the fingers of land that extended into the Bay of Bengal. The coast is prone to flooding during Bay of Bengal storms.

The delta area Bangladesh is a maze of streams, tidal creeks and distributaries that form an intricate network of waterways that make up the country's main transportation system. Distributaries are river branches that do not return to the main stream after leaving it. They are most commonly associated with deltas. The Sundarbans, a vast mangrove swamp area along the southwestern coast, contains many low islands. The longest river is the Brahmaputra River., It’s total length is 2,900 kilometers (1,700 miles). Of this about 330 kilometers (200 miles) is in Bangladesh. [Sources: Columbia Encyclopedia, 6th ed., The Columbia University Press] [Source: Geo-Data: The World Geographical Encyclopedia, The Gale Group Inc., 2003 |+|]

During the annual monsoon period, the rivers of Bangladesh flow at about 140,000 cubic meters per second, but during the dry period they diminish to 7,000 cubic meters per second. Because water is so vital to agriculture, more than 60 percent of the net arable land, some 9.1 million hectares, is cultivated in the rainy season despite the possibility of severe flooding, and nearly 40 percent of the land is cultivated during the dry winter months. Water resources development has responded to this "dual water regime" by providing flood protection, drainage to prevent overflooding and waterlogging, and irrigation facilities for the expansion of winter cultivation. Major water control projects have been developed by the national government to provide irrigation, flood control, drainage facilities, aids to river navigation and road construction, and hydroelectric power. In addition, thousands of tube wells and electric pumps are used for local irrigation. Despite severe resource constraints, the government of Bangladesh has made it a policy to try to bring additional areas under irrigation without salinity intrusion.*

The largest lake is artificial Kaptai Lake (Karnaphuli Reservoir). It covers 655 square kilometers (253 square miles) in the Chittagong Hill Tracts. The lake was created by a dam built on the Karnaphuli River in 1963 to generate hydroelectric power. The dam was controversial. The man-made lake submerges villages and farmland of tribal people that launched an insurgency over the issue.. Smaller lakes, called "mils" or "haors," are formed within the network of rivers that meander through Bangladesh's plains. Some of these are like oxbow lakes (U-shaped lakes formed when a wide meander of a river is cut off). The large number of these lakes in the Meghna and Surma river plains causes frequent flooding there. The Sylhet Plain, or the Surma River Plain, around Sylhet and the upper Meghna-Surma drainage area in the northeast are home to a number of large and small lakes. This area is more prone to flooding than the other parts of the country. [Source: Junior Worldmark Encyclopedia of Physical Geography, The Gale Group, Inc., 2003]

Under normal conditions about 10,000 square kilometers (3,861 square miles) of Bangladesh, excluding coastal areas, is covered with water . The rivers flowing though Bangladesh often silt up to form wetlands, islands and new land. Mangrove forests — a brackish tidal wetland environment of low trees, mangrive shrubs and bogs — occupy large swaths of the coast. About two thirds of Kulna Division in western Bangladesh is marsh and mangrove forest. The delta area and islands here along the coast from the Padma-Meghna estuary into India and extending inland. are called the Sundarbans. This forested, tidal-flushed, saltmarsh region is so swampy and flood-prone few people live there. Rajshahi Division, the northwest area of the Bangladesh Plain between the Padma and Jamuna rivers is another extensive wetlands area. Known geographers as the “Paradelta", it is embraces a plain that drops in elevation from about 90 to 105 meters (300 to 350 feet) in the north to about 30 meters (100 feet) in the middle down to about 9 meters (30 feet) in the south. The area is laced with many many old river courses and lakes and contains newer, active rivers and experiences relatively frequent flooding. |+|

Rivers in Bangladesh

There are 700 or so rivers in Bangladesh. These rivers provide a huge transportation network with over 8,370 kilometers (5,200 miles) of waterways in Bangladesh. In the monsoons season you can travel by boat over rice paddies and roads and past half-submerged telephone poles and trees. Even the rivers became submerged and transformed into huge lakes. The river system of Bangladesh's plain is a complex network feeder and effluent streams, that are like capillaries to the nation, generally flowing east, west, southeast, and southwest. The riverine maze is an constant process of flux, changing, shifting and modifying their channels.

The rivers of Bangladesh mark both the physiography of the nation and the life of the people. These rivers generally flow south. The larger rivers serve as the main source of water for cultivation and as the principal arteries of commercial transportation. Rivers also provide fish, an important source of protein. Flooding of the rivers during the monsoon season causes enormous hardship and hinders development, but fresh deposits of rich silt replenish the fertile but overworked soil. The rivers also drain excess monsoon rainfall into the Bay of Bengal. Thus, the great river system is at the same time the country's principal resource and its greatest hazard. [Source: James Heitzman and Robert Worden, Library of Congress, 1989 *]

The largest rivers are the Ganges (Padma), Brahmaputra (Jamuna) and Meghna. The Ganges enter the country in the northwest, while the Brahmaputra flows in from the north. Dhaka, the capital of Bangladesh, is near the point where those river systems meet. Most of the country is situated on deltas of these large rivers which originate in the Himalayas. The Ganges unites with the Jamuna (main channel of the Brahmaputra) and later joins the Meghna to eventually empty into the Bay of Bengal. Offshoots of the Ganges-Padma, including the Burishwar, Garai, Kobadak, and Madhumati, also flow south to the Bay of Bengal. [Source: Junior Worldmark Encyclopedia of the Nations, Thomson Gale, 2007]

The Brahmaputra River starts in the Himalayas and flows through Tibet in China and India before reaching Bangladesh. It is 2,900 kilometers (1,700 miles) long. The section that in Bangladesh is only 337 kilometers (209 miles) long. Branches of the Barak River — the Surma and the Kusiyara — enter Bangladesh from the northeast. They meet to form the Kalni River, which not long after that widens into the Meghna River. The Brahmaputra, Ganges and Meghna all joing together before emptying into the Bay of Bengal. [Source: Junior Worldmark Encyclopedia of Physical Geography, The Gale Group, Inc., 2003 |+|]

In addition to seasonal flooding, the rivers also cause a great deal of erosion that washes away farmland and eats away at villages. The rivers often silt up to form marshlands. The rivers are at their highest in the spring after the snow-melt of the Himalayas and during the summer monsoons. Rich soil is brought in by the rivers and old soil is carried away. The rivers reduce land that is already settled but also produce new land for settlement. The balance between water and land inputs and outputs is vital to Bangladesh's existence. Water policies in upstream in India can have huge impact on Bangladesh.

Main Rivers in Bangladesh

According to Geo-Data “The Ganges River of India, flowing southeastward, comes to the boundary of Bangladesh in the northwest of the country. For about 90 miles (145 kilometers) the Ganges is the boundary between India and Bangladesh; it then continues to the southeast across the alluvial plain. In Bangladesh the Ganges is commonly called the Padma. The area south of the Padma is of very low elevation, and the hundreds of rivers and streams in this true delta segment of the plain are virtually all distributary from the Padma. Principal among them are the Madhumati River and the Arial Khan (also known as the Bhubanswar). Most flow south, and many of them reach the Indian Ocean. The result is a network of channels entering the Bay of Bengal through a crumbled seacoast that stretches for hundreds of miles, including part of India. It is often referred to as "the many mouths of the Ganges." [Source: Geo-Data: The World Geographical Encyclopedia, The Gale Group Inc., 2003]

“Like the Ganges, the Brahmaputra River rises in the high Himalayas. It flows east across Tibet and the Assam Valley of India. Upon reaching the northern border of Bangladesh, the Brahmaputra turns south and enters the country in multiple, narrowly separated channels and then becomes known as the Jamuna River. The wide Jamuna flows south, joining with the Karatoya River and the Atrai River. Near the center of the country, it merges with the Padma. After junction, the combined waters of the Brahmaputra-Jamuna and Ganges-Padma continue southeast for about 60 miles (96 kilometers) to the even wider junction with a third great river, the Meghna.

“The Dhaleswari River, a distributary of the Brahmaputra-Jamuna, leaves the parent river above its junction with the Padma. It flows southeast, below Dhaka and roughly parallel to the lower Padma, receives the Lakhya River, and then joins the Meghna a few miles above its junction with the Padma. This is only one of the largest of the countless distributary streams and rivers that branch off from or into the Padma, Jamuna, and Meghna.

“In the northeast corner of Bangladesh, two branches of the Barak River, the Surma and the Kusiyara, enter the country from India. These rivers, with smaller tributaries, form the Kalni River, which soon becomes the upper Meghna and is then reinforced by a major tributary from the north, the Baulai. From this point the Meghna continues southwest in a twisting, multi-channeled course to the junction with the lower Padma about 65 miles (105 kilometers) away, south of Dhaka.

“From the wide Padma-Meghna junction, the three combined rivers, here called the Meghna, move south in an S-shaped stem channel for about 40 miles (64 kilometers) and then spread out into the Bay of Bengal through one of the largest estuaries in the world, roughly 100 miles (160 kilometers) across, from Khulna to Chittagong.”

Five River Systems of Bangladesh

Bangladesh is defined by five major river systems: 1) the Brahmaputra (Jamuna) and its adjoining channels; 2) the Ganges (Padma) and the united streams of the Ganges and Brahmaputra and its deltaic regions; 3) The Meghna and Surma river systems; 4) the North Bengal Rivers; and 5) the rivers in the Chittagong Hill Tracts. The Brahmaputra is fed by the Himalayas and enters the country the north, the Ganges enters from the west. The rivers join near Dhaka and form a huge delta which extends into the Bay of Bengal in the east. In all 54 major rivers flow into Bangladesh from India, which includes the rainiest place in the world.

The first system, the Jamuna-Brahmaputra, is about 330 kilometers (200 miles) long and extends from northern Bangladesh to its confluence with the Padma. Originating as the Yarlung Zangbo Jiang in China's Xizang Autonomous Region (Tibet) and flowing through India's state of Arunachal Pradesh, where it becomes known as the Brahmaputra ("Son of Brahma"), it receives waters from five major tributaries that total some 740 kilometers in length. At the point where the Brahmaputra meets the Tista River in Bangladesh, it becomes known as the Jamuna. The Jamuna is notorious for its shifting subchannels and for the formation of fertile silt islands (chars). No permanent settlements can exist along its banks. [Source: James Heitzman and Robert Worden, Library of Congress, 1989 *]

The second system is the Padma-Ganges, which is divided into two sections: a 258-kilometer segment, the Ganges, which extends from the western border with India to its confluence with the Jamuna some 72 kilometers west of Dhaka, and a 126-kilometer segment, the Padma, which runs from the Ganges-Jamuna confluence to where it joins the Meghna River at Chandpur. The Padma-Ganges is the central part of a deltaic river system with hundreds of rivers and streams — some 2,100 kilometers in length — flowing generally east or west into the Padma.*

The third network is the Surma-Meghna system, which courses from the northeastern border with India to Chandpur, where it joins the Padma. The Surma-Meghna, at 669 kilometers by itself the longest river in Bangladesh, is formed by the union of six lesser rivers. Below the city of Kalipur it is known as the Meghna. When the Padma and Meghna join together, they form the fourth river system — the Padma-Meghna — which flows 145 kilometers to the Bay of Bengal.*

This mighty network of four river systems flowing through the Bangladesh Plain drains an area of some 1.5 million square kilometers. The numerous channels of the Padma-Meghna, its distributaries, and smaller parallel rivers that flow into the Bay of Bengal are referred to as the Mouths of the Ganges. Like the Jamuna, the Padma-Meghna and other estuaries on the Bay of Bengal are also known for their many chars.*

A fifth river system, unconnected to the other four, is the Karnaphuli. Flowing through the region of Chittagong and the Chittagong Hills, it cuts across the hills and runs rapidly downhill to the west and southwest and then to the sea. The Feni, Karnaphuli, Sangu, and Matamuhari — an aggregate of some 420 kilometers — are the main rivers in the region. The port of Chittagong is situated on the banks of the Karnaphuli. The Karnaphuli Reservoir and Karnaphuli Dam are located in this area. The dam impounds the Karnaphuli River's waters in the reservoir for the generation of hydroelectric power.*

River Erosion in Bangladesh

The landscape of Bangladesh is constantly being changed by floods and erosion: villages, farmland and roads are washed away; rivers carve out new channels; new land is created where soil is deposited downstream; and create fish-filled oxbow lakes. Villagers construct embankments to protect their land and put up sand bags during the monsoon season. Areas near rivers not protected by embankments and are extremely vulnerable to erosion. Many parts of the earthen embankments are eroded away anyway. People living behind the embankments fear they will not hold up sustain them for long. Satellite images show the natural process of erosion and accretion. In some places it is speeded up by man-made dams and channels. But overall, due at least in part to land reclamation projects— Bangladesh has actually gained land in recent decades. But global warming may reverse this trend.

Reporting from Shariatpur, about 240 kilometers (145 miles) south of Dhaka, Azad Majumder of Reuters wrote: “The mighty rivers that give Bangladesh life are slowly taking it back again. With the monsoon rains yet to start, hundreds of families living along the banks of the Padma and other rivers are having to uproot themselves as the powerful waters erode their homes and land from almost under their feet. In Shariatpur, villagers were seen fleeing their homes on the banks of Padma, one of dozens of major rivers that meander through the country. “No one can assure us of a safe living as the Padma often turns treacherous and can take away everything we have,” said villager Tara Miah. [Source: Azad Majumder, Reuters, June 23, 2008]

“Rivers that offer millions of Bangladeshis a living as fishermen and merchandise carriers also pose a great danger, especially during the monsoon season and the onrush of floodwaters from their source, upstream in India. Thousands of villagers are forced each year to migrate to higher ground or overcrowded cities after losing their homes and farms to erosion or floodwaters. Government officials and non-governmental organizations (NGOs) estimate at least 10 million people have been displaced in the past decade.

“But worse may be yet to come. Experts say a third of Bangladesh’s coastline could be flooded if the seas rise one meter in the next 50 years, creating an additional 20 million displaced Bangladeshis — about the population of Australia. “It seems the erosion will not spare anyone this year,” said Humayun Kabir, Miah’s neighbor in Shariatpur. Kabir has been forced to move home twice in the last few years before finally taking shelter in a century-old Muslim shrine, which also has also become vulnerable to heavy erosion. A part of shrine has already been devoured by the Padma and local residents said they feared the whole structure would be lost during this year’s monsoon.

The monsoon starts in Bangladesh in middle of June and lasts until the end of September, flooding large parts of the country almost every year and killing hundreds of people. Villagers near the Padma said they sometimes couldn’t sleep at night as huge chunks of the banks fell into the river with giant splashes. Officials with the Bangladesh Water Development Board said they had tried to tame flooded rivers by dumping stones and sandbags every year, but they proved mostly futile. “The rivers’ fury is too strong to control. Often we just look helpless,” said one Shariatpur official, who asked not to be named.

According to Human Rights Watch river erosion in linked to child marriages in Bangladesh. “Whatever land my father had and the house he had went under the water in the river erosion and that’s why my parents decided to get me married” said Sultana M., who married at age 14 and was 16 years old and 7 months pregnant when she .talked to Human Rights Watch. “This is a place affected by river erosion,” Azima B.’s parents told her, explaining why she had to marry at age 13. “If the river takes our house it will be hard for you to get married so it’s better if you get married now.” [Source: Human Rights Watch, June 9, 2015]

Coastline, the Sea and Islands in Bangladesh

The Bangladesh coastline lies at the northern end of the Bay of Bengal, an extension of the Indian Ocean and sided by Sri Lanka and India to the west and Myanmar and Thailand to the the east. The Bay of Bengal is about 2,090 kilometers (1,300 miles) long and 1,610 kilometers (1,000 miles) wide. Ocean. Despite its location on the Bay of Bengal, Bangladesh is a riverine nation rather than a sea-oriented one. Its ports, including the largest, Chittagong, which is on the sea, are mostly river ports. [Source: Junior Worldmark Encyclopedia of Physical Geography, The Gale Group, Inc., 2003; “Geo-Data: The World Geographical Encyclopedia”, The Gale Group Inc., 2003]

Bangladesh is infamous for its destructive cyclones (hurricane-like storms) and tidal bores. A tidal bore is a wave that sweeps up a shallow river or estuary on the incoming tide but against the river's current. Conditions have to be just right for them to occur. Bangladesh is of the few places in the world they take place. Tidal bores tend to form high waves with abrupt fronts when an incoming surge of water during flood tide encounters an obstacle such as a sandbar. The funnel shape of the Padma-Meghna River estuary and the many channels between the islands are highly favorable to bore formation. A typical tidal bore rushes in with thunderous noise and a wall of water. Velocity and height are magnified if the tidal bore is backed by strong winds from the south, as occurs during cyclonic storms.

Bangladesh is filled with numerous, often changing islands. Several flat islands lie just offshore in the Bay of Bengal. Many have villages inhabited by fishing communities. The largest of the permanent islands are Shahbazpur, North Hatia, South Hatia, and Sandwīp. Along the Chittagong coast in the south lie Kutubdia and Maiskhal islands. In the Padma-Meghna estuary triangle there are a number of permanent islands, including many that rise out of water only at low tide. There are also temporary "chars," land forms built up by silting that may either become permanent or erode. In the Padma-Meghna estuary triangle there are many "chars.""Chars" occur in many places along the larger rivers and their ownership if often subject of disputes.

Rivers and streams break Bangladesh's coastline in the delta region. In contrast, the coastline in the southeast Chittagong region embraces one of the longest beaches in the world, an uninterrupted stretch of sand at Cox's Bazar that is about 120 kilometers (75 miles) long. The section of the Kulna delta that covers the coastline area from the Padma-Meghna estuary into India is called the Sundarbans. This is a jungly, tidal-flushed, salt marsh region

Image Sources: Wikimedia Commons

Text Sources: New York Times, Washington Post, Los Angeles Times, Lonely Planet Guides, Library of Congress, Bangladesh Tourism Board, Bangladesh National Portal (www.bangladesh.gov.bd), The Guardian, National Geographic, Smithsonian magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Wikipedia and various books, websites and other publications.

Last updated February 2022


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