Ganges Delta

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Ganges Delta Gangesdelta klein.jpg
Ganges Delta

The Ganges-Brahmaputra Delta (also known as the Brahmaputra Delta, [1] the Sundarbans Delta or the Bengal Delta [2] ) is a river delta in the Bengal region of the Indian subcontinent, consisting of Bangladesh and the Indian state of West Bengal. It is the world's largest delta [3] and empties into the Bay of Bengal the combined waters of several river systems, mainly those of the Brahmaputra river and the Ganges river. It is also one of the most fertile regions in the world, thus earning the nickname the Green Delta. The delta stretches from the Hooghly River east as far as the Meghna River.

River delta Silt deposition landform at the mouth of a river

A river delta is a landform that forms from deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide coastline defense and can impact drinking water supply. They are also ecologically important, with different species' assemblages depending on their landscape position.

Bengal Region in Asia

Bengal is a geopolitical, cultural and historical region in South Asia, specifically in the eastern part of the Indian subcontinent at the apex of the Bay of Bengal. Geographically, it is made up by the Ganges-Brahmaputra delta system, the largest such formation in the world; along with mountains in its north bordering the Himalayan states of Nepal and Bhutan and east bordering Burma.

Indian subcontinent Peninsular region in south-central Asia south of the Himalayas

The Indian subcontinent, also known as the Asian subcontinent and Indo subcontinent, is a southern region and peninsula of Asia, mostly situated on the Indian Plate and projecting southwards into the Indian Ocean from the Himalayas. Geologically, the Indian subcontinent is related to the land mass that rifted from Gondwana and merged with the Eurasian plate nearly 55 million years ago. Geographically, it is the peninsular region in south-central Asia delineated by the Himalayas in the north, the Hindu Kush in the west, and the Arakanese in the east. Politically, the Indian subcontinent includes Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka.

Contents

Geography

A typical landscape in the Delta with palms, rice, flat, green and ponds SunderbanFarmHouse.JPG
A typical landscape in the Delta with palms, rice, flat, green and ponds
Delta of Ganges from the map of surveyor James Rennell (1778) The delta of Ganges by J. Rennel.jpg
Delta of Ganges from the map of surveyor James Rennell (1778)

The Ganges Delta has the shape of a triangle and is considered to be an "arcuate" (arc-shaped) delta. It covers more than 105,000 km2 (41,000 sq mi), and although the delta lies mostly in Bangladesh and India, rivers from Bhutan, Tibet, India, and Nepal drain into it from the north. Approximately 60% of the delta is in Bangladesh and, 40% in West Bengal, India. Most of the delta is composed of alluvial soils made up by small sediment particles that finally settle down as river currents slow down in the estuary. Rivers carry these fine particles with them, even from their sources at glaciers as fluvio-glacial. Red and red-yellow laterite soils are found as one heads farther east. The soil has large amounts of minerals and nutrients, which is good for agriculture.

Bhutan Landlocked kingdom in Eastern Himalayas

Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia. Located in the Eastern Himalayas, it is bordered by Tibet Autonomous Region of China in the north, the Sikkim state of India and the Chumbi Valley of Tibet in the west, the Arunachal Pradesh state of India in the east, and the states of Assam and West Bengal in the south. Bhutan is geopolitically in South Asia and is the region's second least populous nation after the Maldives. Thimphu is its capital and largest city, while Phuntsholing is its financial center.

Nepal country in South Asia

Nepal, officially the Federal Democratic Republic of Nepal, is a landlocked country in South Asia. It is located mainly in the Himalayas but also includes parts of the Indo-Gangetic Plain. With an estimated population of 26.4 million, it is 48th largest country by population and 93rd largest country by area. It borders China in the north and India in the south, east, and west while Bangladesh is located within only 27 km (17 mi) of its southeastern tip and Bhutan is separated from it by the Indian state of Sikkim. Nepal has a diverse geography, including fertile plains, subalpine forested hills, and eight of the world's ten tallest mountains, including Mount Everest, the highest point on Earth. Kathmandu is the nation's capital and largest city. Nepal is a multiethnic nation with Nepali as the official language.

Bangladesh Country in South Asia

Bangladesh, officially the People's Republic of Bangladesh, is a sovereign country in South Asia. It shares land borders with India and Myanmar (Burma). The country's maritime territory in the Bay of Bengal is roughly equal to the size of its land area. Bangladesh is the world's eighth most populous country as well as its most densely-populated, to the exclusion of small island nations and city-states. Dhaka is its capital and largest city, followed by Chittagong, which has the country's largest port. Bangladesh forms the largest and easternmost part of the Bengal region. Bangladeshis include people from a range of ethnic groups and religions. Bengalis, who speak the official Bengali language, make up 98% of the population. The politically dominant Bengali Muslims make the nation the world's third largest Muslim-majority country. Islam is the official religion of Bangladesh.

It is composed of a labyrinth of channels, swamps, lakes, and flood plain sediments (chars). The Gorai-Madhumati River, one of the distributaries of the Ganges, divides the Ganges Delta into two parts: the geologically young, active, eastern delta, and the older, less active, western delta. [2]

Channel (geography) A type of landform in which part of a body of water is confined to a relatively narrow but long region

In physical geography, a channel is a type of landform consisting of the outline of a path of relatively shallow and narrow body of fluid, most commonly the confine of a river, river delta or strait. The word is cognate to canal, and sometimes shows in this form, e.g. the Hood Canal.

Swamp A forested wetland

A swamp is a wetland that is forested. Many swamps occur along large rivers where they are critically dependent upon natural water level fluctuations. Other swamps occur on the shores of large lakes. Some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation or soil saturation. The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps. In the boreal regions of Canada, the word swamp is colloquially used for what is more correctly termed a bog, fen, or muskeg. The water of a swamp may be fresh water, brackish water or seawater. Some of the world's largest swamps are found along major rivers such as the Amazon, the Mississippi, and the Congo.

Gorai-Madhumati River river in Bangladesh

The Gorai-Madhumati River is one of the longest rivers in Bangladesh and a distributary of the Ganges. In the upper reaches it is called the Gorai, and the name changes to Madhumati. Madhumati continuous stream through Kushtia, Jessore, Faridpur, Khulna, Pirojpur and Barguna districts in Bangladesh.

Population

Between 125 and 143 million people live on the delta,[ citation needed ] despite risks from floods caused by monsoons, heavy runoff from the melting snows of the Himalayas, and North Indian Ocean tropical cyclones. A large part of the nation of Bangladesh lies in the Ganges Delta, and many of the country's people depend on the delta for survival. [4]

Monsoon seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea

Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is sometimes incorrectly used for locally heavy but short-term rains, although these rains meet the dictionary definition of monsoon.

Himalayas mountain range in Central Asia

The Himalayas, or Himalaya, form a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has many of the Earth's highest peaks, including the highest, Mount Everest. The Himalayas include over fifty mountains exceeding 7,200 m (23,600 ft) in elevation, including ten of the fourteen 8,000-metre peaks. By contrast, the highest peak outside Asia is 6,961 m (22,838 ft) tall.

It is believed that upwards of 300 million people are supported by the Ganges Delta, and approximately 400 million people live in the Ganges River Basin, making it the most populous river basin in the world. Most of the Ganges Delta has a population density of more than 200 people per km2 (520 people per square mile)[ citation needed ], making it one of the most densely populated regions in the world.

Wildlife

Bengal tiger Panthera tigris.jpg
Bengal tiger

Three terrestrial ecoregions cover the delta. The Lower Gangetic plains moist deciduous forests ecoregion covers most of the delta region, although the forests have mostly been cleared for agriculture and only small enclaves remain. Thick stands of tall grass, known as canebrakes, grow in wetter areas. The Sundarbans freshwater swamp forests ecoregion lies closer to the Bay of Bengal; this ecoregion is flooded with slightly brackish water during the dry season, and fresh water during the monsoon season. These forests, too, have been almost completely converted to intensive agriculture, with only 130 square kilometres (50 sq mi) of the ecoregion's 14,600 square kilometres (5,600 sq mi) protected. Where the delta meets the Bay of Bengal, Sundarbans mangroves form the world's largest mangrove ecoregion, covering an area of 20,400 square kilometres (7,900 sq mi) in a chain of 54 islands. They derive their name from the predominant mangrove species, Heritiera fomes, which are known locally as sundri or sundari.

The Lower Gangetic plains moist deciduous forests is a tropical moist broadleaf forest ecoregion of Bangladesh and eastern India. The ecoregion covers an area of 254,100 square kilometres (98,100 sq mi), covering most of Bangladesh and the Indian states of West Bengal, Bihar and Tripura, and extending into adjacent portions of Assam, Uttar Pradesh and Orissa states.

Mangrove A shrub or small tree that grows in coastal saline or brackish water

A mangrove is a shrub or small tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves occur worldwide in the tropics and subtropics, mainly between latitudes 25° N and 25° S. The total mangrove forest area of the world in 2000 was 137,800 square kilometres (53,200 sq mi), spanning 118 countries and territories.

<i>Heritiera</i> genus of plants

Heritiera is a genus of flowering plants in the family Malvaceae, subfamily Sterculioideae. They are most dominant tropical forest trees in several areas in eastern Africa and India to the Pacific. Some are mangroves. Several are valuable for their timber and are over-exploited.

Animals in the delta include the Indian python ( Python molurus ), clouded leopard ( Neofelis nebulosa ), Indian elephant (Elephas maximus indicus) and crocodiles, which live in the Sundarbans. Approximately 1,020 endangered Bengal tigers (Panthera tigris tigris) are believed to inhabit the Sundarbans. The Ganges–Brahmaputra basin has tropical deciduous forests that yield valuable timber: sal, teak, and peepal trees are found in these areas. The delta region has mangrove trees.

It is estimated that 30,000 chital (Axis axis) are in the Sundarbans part of the delta. Birds found in the delta include kingfishers, eagles, woodpeckers, the shalik ( Acridotheres tristis ), the swamp francolin (Francolinus gularis), and the doel ( Copsychus saularis ). Two species of dolphin can be found in the delta: the Irrawaddy dolphin (Orcaella brevirostris) and the Ganges river dolphin (Platanista gangetica gangetica). The Irrawaddy dolphin is an oceanic dolphin which enters the delta from the Bay of Bengal. The Ganges river dolphin is a true river dolphin, but is extremely rare and considered endangered.

Trees found in the delta include sundari, garjan ( Rhizophora spp.), bamboo, mangrove palm ( Nypa fruticans ), and mangrove date palm ( Phoenix paludosa ). Many endangered species live here.

Geology

The Ganges Delta lies at the junction of three tectonic plates: the Indian Plate, the Eurasian Plate, and the Burma Plate. [5] The edge of the Eocene paleoshelf runs approximately from Kolkata to the edge of the Shillong Plateau. The edge of the paleoshelf marks the transition from the thick continental crust in the northwest to the thin continental or oceanic crust in the southeast. The enormous sediment supply from the Himalayan collision has extended the delta about 400 kilometres (250 mi) seaward since the Eocene. The sediment thickness southeast of the edge of the paleoshelf beneath the Ganges Delta can exceed 16 km (10 miles). [6]

Economy

Rice, cattle and fishing in rivers and ponds are important sources of food. CowShed.JPG
Rice, cattle and fishing in rivers and ponds are important sources of food.

Approximately two-thirds of the Bangladesh people work in agriculture, and grow crops on the fertile floodplains of the delta. The major crops that are grown in the Ganges Delta are jute, tea, and rice. [4] Fishing is also an important activity in the delta region, with fish being a major source of food for many of the people in the area. [7]

In recent years,[ when? ] scientists have been helping the poor people of the delta to improve fish farming methods. By turning unused ponds into viable fish farms, and improving methods of raising fish in existing ponds, many people can now earn a living raising and selling fish. Using new systems, fish production in existing ponds has increased 800%. [8] Shrimp are farmed in containers or cages that are submerged in open water. Most are exported. [7]

A lot of bustle at a ferry pier HasnabadFerryPier.JPG
A lot of bustle at a ferry pier
The Vidyasagar Setu which spans the Hoogli River in Kolkata Vidyasagar setu.jpg
The Vidyasagar Setu which spans the Hoogli River in Kolkata

As there is a maze of many river branches, the area is difficult to pass. Most islands are only connected with the mainland by simple wooden ferryboats. Bridges are rare. Some islands are not yet connected to the electric grid, so island residents tend to use solar cells for a bit of electric supply.

Arsenic pollution

Arsenic is a naturally occurring substance in the Ganga Delta that has detrimental affects on health, and may enter the food chain, especially in key crops such as rice.

Climate

The Ganges Delta lies mostly in the tropical wet climate zone, and receives between 1,500 to 2,000 mm (59 to 79 in) of rainfall each year in the western part, and 2,000 to 3,000 mm (79 to 118 in) in the eastern part.[ citation needed ]. Hot, dry summers and cool, dry winters make the climate suitable for agriculture.

Cyclones and flooding

In November 1970, the deadliest tropical cyclone of the twentieth century hit the Ganges Delta region. The 1970 Bhola cyclone killed 500,000 people (official death toll), with another 100,000 missing. The Guinness Book of World Records estimated the total loss of human life from the Bhola cyclone at 1,000,000. [9]

Another cyclone hit the delta in 1991, killing about 139,000 people. [10]

People have to be careful on the river delta as severe flooding also occurs. In 1998, the Ganges flooded the delta, killing about 1,000 people and leaving more than 30 million people homeless. The Bangladesh government asked for $900 million to help feed the people of the region, as the entire rice crop was lost. [11]

Future of the delta

One of the greatest challenges people living on the Ganges Delta may face in coming years is the threat of rising sea levels caused by climate change. An increase in sea level of 0.5 metres (1 ft 8 in) could result in six million people losing their homes in Bangladesh. [12]

Important gas reserves have been discovered in the delta, such as in the Titas and Bakhrabad gas fields. Several major oil companies have invested in exploration of the Ganges Delta region. [13] [14]

View

Brahmaputra River from Space Bangladesh tmo 2011313.jpg
Brahmaputra River from Space

See also

Notes

  1. Merriam-Webster 1997, p. 412.
  2. 1 2 Chowdhury, Sifatul Quader; Hassan, M Qumrul (2012). "Bengal Delta". In Islam, Sirajul; Jamal, Ahmed A. Banglapedia: National Encyclopedia of Bangladesh (Second ed.). Asiatic Society of Bangladesh.
  3. https://www.worldatlas.com/articles/which-is-the-largest-delta-in-the-world.html
  4. 1 2 Bowden 2003, p. 39: "Many of [Bangladesh's] people depend on the delta for their survival. Two-thirds of Bangladeshis work in agriculture and grow crops on the fertile delta floodplains. Jute fiber, used to make twine and sacking, is Bangladeh's main export crop. Tea, wheat, rice, beans, sugarcane, and fruits are grown."
  5. "Tectonics & Geophysics". BanglaPIRE. Retrieved 13 June 2017. The Ganges Brahmaputra Delta lies at the junction of three plates: the Indian Plate, the Eurasian Plate and the Burma Platelet.
  6. Steckler, Michael S.; Humayun, S. Akhter; Seeber, Leonardo (15 September 2008). "Collision of the Ganges-Brahmaputra Delta with the Burma Arc". Earth and Planetary Science Letters. Elsevier. 273 (3–4). doi:10.1016/j.epsl.2008.07.009 . Retrieved 22 April 2013. The edge of the pre-delta Eocene paleoshelf is marked by the shallow-water Sylhet Limestone, which runs NNE from near Calcutta to the edge of the Shillong Plateau ... The Sylhet Limestone drops ... indicating the presence of thick continental crust. East of the hinge zone the great thickness of sediments indicates that the crust is greatly thinned or oceanic ... The enormous supply of sediments provided by the Himalayan collision fed the [Ganges-Brahmaputra Delta (GBD)] and has produced ~400 km of progradation of the shelf edge since the Eocene ... Total sediment thickness beneath the GBD southeast of the hinge zone exceeds 16 km.
  7. 1 2 Bowden 2003, p. 44: "Fishing has played a part in the lives of Bangladeshi people for a long time ... Fish is particularly important in Bangladesh, where it provides the main source of protein in the diet of many people ... Shrimp are farmed in large containers or cages that are submerged in the open water. They are mainly sold for export."
  8. "Global Demand for Fish Rising—Fish Farming is the Fastest Growing Field of Agriculture". Future Harvest. Archived from the original on 5 October 2006. In Bangladesh, scientists are turning unused ponds into viable fish farms and improving fish raising in the existing ones. The project has led to a new way for the rural poor to earn an income ... Using new systems developed through research, fish production in existing ponds has increased eightfold.
  9. "History and Society/Disasters/Cyclone Deaths". Guinness World Records. Archived from the original on 19 November 2005. Retrieved 12 July 2013.
  10. Bowden 2003, p. 43: "In 1970 Bangladesh suffered the world's worst recorded cyclone, when about 500,000 people were killed. The last bad cyclone to strike Bangladesh was in 1991. It killed 139,000 people."
  11. Bowden 2003, p. 40: "In 1998 ... About one thousand people were killed, and more than 30 million were left homeless by floods ... The entire rice crop was ruined, and the government asked for almost $900 million dollars of aid to help it feed and rehouse its people."
  12. Bowden 2003, p. 44-45: "The greatest change Bangladesh and its people may face in the coming years will probably be the threat of global warming ... One of the likely results of global warming is a gradual rise in sea levels. This could be 1.6 feet (.5 meters) by 2100. That might not sound like very much, but it would mean that 6 million Bangladeshis would lose their homes."
  13. USGS-Bangladesh Gas Assessment Team (2001). U.S. Geological Survey—PetroBangla Cooperative Assessment of Undiscovered Natural Gas Resources of Bangladesh. DIANE Publishing. ISBN   978-1428917972.
  14. Bowden 2003, p. 41: "Gas reserves ... lie under the delta region and offshore in the Bay of Bengal. Important discoveries were made during the 1990s, and several major oil companies have invested in gas exploration in Bangladesh."

Related Research Articles

Geography of India geography of the country of India

India lies on the Indian Plate, the northern portion of the Indo-Australian Plate, whose continental crust forms the Indian subcontinent. The country is situated north of the equator between 8°04' to 37°06' north latitude and 68°07' to 97°25' east longitude. It is the seventh-largest country in the world, with a total area of 3,287,263 square kilometres (1,269,219 sq mi). India measures 3,214 km (1,997 mi) from north to south and 2,933 km (1,822 mi) from east to west. It has a land frontier of 15,200 km (9,445 mi) and a coastline of 7,516.6 km (4,671 mi).

Bay of Bengal Northeastern part of the Indian Ocean between India and the Andaman and Nicobar Islands

The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India on the north by Bangladesh, and on the east by Myanmar and the Andaman Islands of India and Myanmar and the Nicobar Islands of India. Its southern limit is a line between Sri Lanka and the northwesternmost point of Sumatra (Indonesia). It is the largest water region called a bay in the world. There are Countries dependent on the Bay of Bengal in South Asia and Southeast Asia. The Bay of Bengal was also called the Chola Lake.

Geography of Bangladesh

Bangladesh is a densely-populated, low-lying, mainly riverine country located in South Asia with a coastline of 580 km (360 mi) on the northern littoral of the Bay of Bengal. The delta plain of the Ganges (Padma), Brahmaputra (Jamuna), and Meghna Rivers and their tributaries occupy 79 percent of the country. Four uplifted blocks occupy 9 percent, and steep hill ranges up to ca 1,000 m high occupy 12 percent in the southeast and in the northeast. Straddling the Tropic of Cancer, Bangladesh has a tropical monsoon climate characterised by heavy seasonal rainfall, high temperatures, and high humidity. Natural disasters such as floods and cyclones accompanied by storm surges periodically affect the country. Most of the country is intensively farmed, with rice the main crop, grown in three seasons. Rapid urbanisation is taking place with associated industrial and commercial development. Exports of garments and shrimp plus remittances from Bangladeshis working abroad provide the country's three main sources of foreign exchange income.

Brahmaputra River River in China, India, and Bangladesh

The Brahmaputra is one of the major rivers of Asia, a trans-boundary river which flows through China, India and Bangladesh. As such, it is known by various names in the region: Assamese: লুইত luit[luɪt], ব্ৰহ্মপুত্ৰ নৈ Brohmoputro noi, ব্ৰহ্মপুত্ৰ নদ Brohmoputro[bɹɔɦmɔputɹɔ]; Sanskrit: ब्रह्मपुत्र, IAST: Brahmaputra; Tibetan: ཡར་ཀླུངས་གཙང་པོ་, Wylie: yar klung gtsang po Yarlung Tsangpo; simplified Chinese: 布拉马普特拉河; traditional Chinese: 布拉馬普特拉河; pinyin: Bùlāmǎpǔtèlā Hé. It is also called Tsangpo-Brahmaputra. The Manas River, which runs through Bhutan, joins it at Jogighopa, in India. It is the ninth largest river in the world by discharge, and the 15th longest.

Indo-Gangetic Plain plain

The Indo-Gangetic Plain, also known as the Indus-Ganga Plain and the North Indian River Plain, is a 630-million-acre (2.5-million km2) fertile plain encompassing Northern regions of the Indian subcontinent, including most of northern and eastern India, the eastern parts of Pakistan, virtually all of Bangladesh and southern plains of Nepal. The region is named after the Indus and the Ganges rivers and encompasses a number of large urban areas. The plain is bound on the north by the Himalayas, which feed its numerous rivers and are the source of the fertile alluvium deposited across the region by the two river systems. The southern edge of the plain is marked by the Chota Nagpur Plateau. On the west rises the Iranian Plateau.

Sundarbans National Park A National Park, Tiger Reserve, and a Biosphere Reserve in West Bengal, India.

The Sundarbans National Park is a National Park, Tiger Reserve, and a Biosphere Reserve in West Bengal, India. It is part of the Sundarbans on the Ganges Delta, and adjacent to the Sundarban Reserve Forest in Bangladesh. The delta is densely covered by mangrove forests, and is one of the largest reserves for the Bengal tiger. It is also home to a variety of bird, reptile and invertebrate species, including the salt-water crocodile. The present Sundarban National Park was declared as the core area of Sundarban Tiger Reserve in 1973 and a wildlife sanctuary in 1977. On 4 May 1984 it was declared a National Park. It is a UNESCO world heritage site inscribed in 1987, and it has been designated as a Ramsar site since 2019. It is considered as a World Network of Biosphere Reserve from 2001.

Sundarbans The worlds largest mangrove forest located in the delta of Ganges, Meghna and Brahmaputra rivers in the Bay of Bengal

The Sundarbans is a mangrove area in the delta formed by the confluence of Ganges, Brahmaputra and Meghna Rivers in the Bay of Bengal. It spans from the Hooghly River in India's state of West Bengal to the Baleswar River in Bangladesh. It comprises closed and open mangrove forests, agriculturally used land, mudflats and barren land, and is intersected by multiple tidal streams and channels. Four protected areas in the Sundarbans are enlisted as UNESCO World Heritage Sites, viz Sundarbans National Park, Sundarbans West, Sundarbans South and Sundarbans East Wildlife Sanctuaries.

The Bengal Fan, also known as the Ganges Fan, is the largest submarine fan on Earth. The fan is about 3,000 km (1,900 mi) long, 1,430 km (890 mi) wide with a maximum thickness of 16.5 km (10.3 mi). The fan resulted from the uplift and erosion of the Himalayas and the Tibetan Plateau produced by the collision between the Indian Plate and the Eurasian Plate. Most of the sediment is supplied by the Ganges and Brahmaputra rivers which supply the Lower Meghna delta in Bangladesh and the Hoogly delta in West Bengal (India). Several other large rivers in Bangladesh and India provide smaller contributions. Turbidity currents have transported the sediment through a series of submarine canyons, some of which are more than 1,500 miles (2,414 km) in length, to be deposited in the Bay of Bengal up to 30 degrees latitude from where it began. To date, the oldest sediments recovered from the Bengal fan are from Early Miocene age. Their mineralogical and geochemical characteristics allow to identify their Himalayan origin and demonstrate that the Himalaya was already a major mountain range 20 million years ago.

Baleshwari River river in India

The Baleshwari River is located in Bangladesh, forming part of the eastern border of Bagerhat District and the western border of Barguna District. It borders on the east the largest mangrove forest in the world, in the Ganges-Brahmaputra delta, the Bangladesh part of which is set aside as the Sundarbans Reserve Forest. The Baleshwar River flows south into the Haringhata River, which flows into the Bay of Bengal.

Floods in Bangladesh

Bangladesh is prone to flooding due to being situated on the Ganges Delta and the many distributaries flowing into the Bay of Bengal. Coastal flooding, combined with the bursting of river banks is common, and severely affects the landscape and society of Bangladesh. 80% of Bangladesh is floodplain, and it has an extensive sea coastline, rendering the nation very much at risk of periodic widespread damage. Whilst more permanent defences, strengthened with reinforced concrete, are being built, many embankments are composed purely of soil and turf and made by local farmers. Flooding normally occurs during the monsoon season from June to September. The convectional rainfall of the monsoon is added to by relief rainfall caused by the Himalayas. Meltwater from the Himalayas is also a significant input.

Lohachara Island island in West Bengal, India

Lohachara Island was an islet which was permanently flooded in the 1980s. It was located in the Hooghly River as part of the Sundarban delta in the Sundarban National Park, located near the Indian state of West Bengal. The definite disappearance of the island was reported by Indian researchers in December 2006, which led to international press coverage. No specific study was ever done to prove that the island was permanently inundated because of sea level rise.

Geology of Bangladesh

The Geology of Bangladesh is affected by the country's location, as Bangladesh is mainly a riverine country. It is the eastern two-thirds of the Ganges and Brahmaputra river delta plain stretching to the north from the Bay of Bengal. There are two small areas of slightly higher land in the north-centre and north-west composed of old alluvium called the Madhupur Tract and the Barind Tract, and steep, folded, hill ranges of older (Tertiary) rocks along the eastern border.

Sundarbans usually refers to the Sundarbans freshwater swamp forests, the term applying generally to a tropical moist broadleaf forest ecoregion of India and Bangladesh. It may specifically refer to:

Sundarbans East Wildlife Sanctuary

Sundarbans East Wildlife Sanctuary, a protected forest in Bangladesh, extends over an area of 31,227 ha. of mangrove forest. It was established in 1977 under the Bangladesh Wildlife (Preservation) (Amendment) Act, 1974, having previously been a forest reserve. It is the most fertile of the three, non-adjoining wildlife sanctuaries established in the Sundarbans at that time, the others being the Sundarbans West Wildlife Sanctuary and the Sundarbans South Wildlife Sanctuary. The dominant mangrove species is "sundri" from which the Sundarbans region gets its name.

Sundarbans West Wildlife Sanctuary

Sundarbans West Wildlife Sanctuary is a UNESCO World Heritage Site and animal sanctuary in Bangladesh. The area of the reserve covers 715 km2. It is part of the larger Sundarbans region, one of the largest mangroveforests in the world. It is formed at the unified delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal. The total area of the entire Sundarbans is about one million ha, 60% of which is found in Bangladesh, with the remainder in India. The region is divided by the Raimangal River. Within the Bangladeshi area of Sundarbans, there are three wildlife sanctuaries: Sundarbans East, Sundarbans South, and Sundarbans West.

Climate change in Bangladesh is a pressing issue. According to National Geographic, Bangladesh is one the most vulnerable nations to the impacts of climate change. Bangladesh being located on the Tropic of Cancer receives fairly direct radiation throughout the year & maintains relatively high temperature.

Top dying disease is a disease that affects Heritiera fomes, a species of mangrove tree known as "sundri", a characteristic tree of the estuarine complex of the Ganges–Brahmaputra Delta in Bangladesh and West Bengal. Although an increase in certain trace elements in the sediment deposited where these trees grow may be a factor in the incidence of the disease, its cause has not been fully established.

Environmental issues in Bangladesh

Bangladesh, with an area of 144,000 km2, features a flood plain landscape and several river systems throughout the country. This landscape provides the major natural resources of water, land, fisheries, forests, and wildlife. The country currently faces several environmental issues which threaten these resources, including groundwater metal contamination, increased groundwater salinity, cyclones and flooding, and sedimentation and changing patterns of stream flow due to watershed mismanagement. Some of these, such as the changing patterns of stream flow and presence of lead in groundwater, can be directly correlated with human activity and industrial processes, while others, such as cyclones and flooding are naturally occurring issues. Many of these issues are further exacerbated by climate change, which causes increased occurrence of storms and cyclones and rising sea levels. According to the Notre Dame Global Adaptation Index, Bangladesh is the 43rd most vulnerable country to the effects of climate change, and the 37th least prepared country to address these effects. There has been some government actions taken to address these issues.

Environmental impact of development in the Sundarbans, is the study of environmental impact on Sundarban, the largest single tract mangrove forest. It consist of a geographical area of 9,629 square kilometres (3,718 sq mi), including 4,185 square kilometres (1,616 sq mi) of reserve forest land, and is a natural region located partly in southern Bangladesh and partly in the Indian state of West Bengal. It is ecologically a southern part of the Gangetic delta between the Hooghly river in India on the west and the Meghna river in Bangladesh on the east and is bounded by the Ganga-Padma, the Padma-Meghna on the north and by the Bay of Bengal on the south. The area that is not reserve forest land is inhabited by human settlements with a total population around 4 million (2003).

References

Coordinates: 22°42′N89°40′E / 22.700°N 89.667°E / 22.700; 89.667