Ganges Delta
Encyclopedia
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...
in the South Asia region of Bengal
Bengal
Bengal is a historical and geographical region in the northeast region of the Indian Subcontinent at the apex of the Bay of Bengal. Today, it is mainly divided between the sovereign land of People's Republic of Bangladesh and the Indian state of West Bengal, although some regions of the previous...
, consisting of Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
and the state of West Bengal
West Bengal
West Bengal is a state in the eastern region of India and is the nation's fourth-most populous. It is also the seventh-most populous sub-national entity in the world, with over 91 million inhabitants. A major agricultural producer, West Bengal is the sixth-largest contributor to India's GDP...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. It is the world's largest delta, and empties into the Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...
. 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 on the west to the Meghna River
Meghna River
The Meghna River is an important river in Bangladesh, one of the three that forms the Ganges Delta, the largest on earth fanning out to the Bay of Bengal. Being a part of the Surma-Meghna River System, Meghna is formed inside Bangladesh by the joining of different rivers originaing from the hilly...
on the east. It is approximately 350 km (217.5 mi) across at the Bay of Bengal. Kolkata
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...
(formerly Calcutta) and Haldia
Haldia
Haldia has a typical moderate climate with winter temperatures ranging from a low of around 7 degrees Celsius to a high of 22 degrees Celsius. Winters are chilly and is when the residents hold the Haldia Utsav festival. Summers can be very hot and humid. Usual summer temperatures in May, the...
in India and Mongla
Port of Mongla
- Overview :It was formerly located at Chalna, about 11 miles upstream on the Pusur River, but it is now located 48 km south of Khulna city, as established in 1954. The port is situated at the confluence of the Pashur River and the Mongla River...
and Chittagong
Chittagong
Chittagong ) is a city in southeastern Bangladesh and the capital of an eponymous district and division. Built on the banks of the Karnaphuli River, the city is home to Bangladesh's busiest seaport and has a population of over 4.5 million, making it the second largest city in the country.A trading...
in Bangladesh are the principal seaports on the delta.
A number of large rivers flow through the Ganges Delta, including the Padma
Padma River
The Padma is a major trans-boundary river in Bangladesh. It is the main distributary of the Ganges , which originates in the Himalayas. The Padma enters Bangladesh from India near Chapai Nababganj...
(main distributary
Distributary
A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. They are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a tributary...
of the Ganges) and the Jamuna (main distributary of the Brahmaputra
Brahmaputra River
The Brahmaputra , also called Tsangpo-Brahmaputra, is a trans-boundary river and one of the major rivers of Asia. It is the only Indian river that is attributed the masculine gender and thus referred to as a in Indo-Aryan languages and languages with Indo-Aryan influence...
), which merge and then join the Meghna before entering the sea.
Shape and composition
It covers more than 105000 km² (40,540.7 sq mi), and although the delta lies mostly in Bangladesh and India, rivers from Bhutan
Bhutan
Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
, India, and Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
drain into it from the north. Approximately two-thirds of the delta is in Bangladesh. 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
Fluvio-glacial
Fluvio-glacial is the water created by the melting of glaciers. It literally means "Water Glacier." It is also commonly called melt water.Fluvio-glacial can also mean sediments deposited by the glacier meltwater....
. Red and red-yellow laterite
Laterite
Laterites are soil types rich in iron and aluminium, formed in hot and wet tropical areas. Nearly all laterites are rusty-red because of iron oxides. They develop by intensive and long-lasting weathering of the underlying parent rock...
soils are found as one heads farther east. The soil has large amounts of minerals and nutrients, which is good for agriculture.
It is composed of a labyrinth of channels
Channel (geography)
In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...
, swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
s, lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s, and flood plain sediments (Chars). The Ganges Delta is separated into two parts: eastern (active), and the western (less active).
Geology
The Ganges Delta lies at the junction of three tectonic plates: the Indian Plate, the Eurasian PlateEurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
, and the Burma Plate
Burma Plate
The Burma Plate is a small tectonic plate or microplate located in Southeast Asia, often considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate...
. Enormous sediment supply since the Himalayan collision made ~400 km progragation of the shelf edge since Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
. The edge of the paleoshelf in Eocene runs approximately from Calcutta to the edge of the Shilong Plateau. The edge of the paleoshelf marks the transition from the thick continental crust in the northwest to the thin continental and oceanic crust in the southeast. The sediment thickness southeast of the edge of the paleoshelf beneath the Ganges Delta can exceed 16 km.
Population
Between 125 and 143 million people live on the delta, despite risks from floodFlood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
s caused by monsoon
Monsoon
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...
s, heavy runoff from the melting snows of the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
, and tropical cyclone
Cyclone
In meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. This is usually characterized by inward spiraling winds that rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth. Most large-scale...
s. 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.
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), making it one of the most densely populated regions on earth.
Agriculture and fishing
Jute
Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, which has been classified in the family Tiliaceae, or more recently in Malvaceae....
, tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
, and rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
. 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.
In recent years, 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%. Shrimp and salmon are farmed in containers or cages that are submerged in open water—most of these fish are exported.
Infrastructure
Climate
The Ganges Delta lies mostly in the tropical wet climateClimate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
zone, and receives between 1500 to 2000 mm (59.1 to 78.7 in) of rainfall each year in the western part, and 2000 to 3000 mm (78.7 to 118.1 in) in the eastern part. The coolest month of the year, on average, is January, with April and May being the warmest months. Average temperatures in January range from 14 to 25 °C (57.2 to 77 F), and average temperatures in April range from 25 to 35 °C (77 to 95 F).
July is the wettest month, on average, when over 330 mm (13 in) of rain falls on the delta (temperature averages from Kolkata).
Cyclones and flooding
In November 1970, the deadliest tropical cyclone of the twentieth century hit the Ganges Delta region. The 1970 Bhola cyclone1970 Bhola cyclone
The 1970 Bhola cyclone was a devastating tropical cyclone that struck East Pakistan and India's West Bengal on November 12, 1970. It was the deadliest tropical cyclone ever recorded, and one of the deadliest natural disasters in modern times...
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 -
Another cyclone hit the delta in 1991, killing about 138,000 people—see 1991 Bangladesh Cyclone
1991 Bangladesh cyclone
-External links:** from NIRAPAD disaster response organisation.**...
.
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
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
crop was lost.
Flora and fauna
Lower Gangetic plains moist deciduous forests
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 , covering most of Bangladesh and the Indian states of West Bengal, Bihar, and Tripura, and extending into adjacent portions of Assam,...
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 (50.2 sq mi) of the ecoregion's 14600 square kilometres (5,637.1 sq mi) protected. Where the delta meets the Bay of Bengal, Sundarbans mangroves form the world's largest mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
ecoregion, covering an area of 20400 square kilometres (7,876.5 sq mi) in a chain of 54 islands. They derive their name from the predominant mangrove species, Heritiera
Heritiera
Heritiera is a genus of flowering plants in the mallow family, Malvaceae family.-Selected species:* Heritiera aurea* Heritiera borneensis* Heritiera fomes* Heritiera globosa* Heritiera javanica* Heritiera littoralis...
fomes, which are known locally as sundri or sundari.
Animals in the delta include the Indian Python (Python molurus), Clouded Leopard (Neofelis nebulosa) , Indian Elephant
Indian Elephant
The Indian Elephant is one of three recognized subspecies of the Asian elephant, and native to mainland Asia. Since 1986, Elephas maximus has been listed as endangered by IUCN as the population has declined by at least 50% over the last three generations, estimated to be 60–75 years...
(Elephas maximus indicus) and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s, which live in the Sundarbans. Approximately 1,020 endangered Bengal tiger
Bengal Tiger
The Bengal tiger is a tiger subspecies native to the Indian subcontinent that in 2010 has been classified as endangered by IUCN...
s (Panthera tigris tigris) are believed to inhabit the Sundarbans.
It is estimated that 30,000 chital
Chital
The chital or cheetal , also known as chital deer, spotted deer or axis deer is a deer which commonly inhabits wooded regions of Sri Lanka, Nepal, Bangladesh, Bhutan, India, and in small numbers in Pakistan...
(Axis axis) are in the Sundarbans part of the delta. Birds found in the delta include kingfisher
Kingfisher
Kingfishers are a group of small to medium sized brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species being found in the Old World and Australia...
s, eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
s, woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s, the shalik (Acridotheres tristis
Common Myna
The Common Myna or Indian Myna also sometimes spelled Mynah, is a member of family Sturnidae native to Asia. An omnivorous open woodland bird with a strong territorial instinct, the Myna has adapted extremely well to urban environments...
), the Swamp Francolin
Swamp Francolin
The Swamp Partridge or Swamp Francolin is a species of partridge found in parts of India, Nepal and Bangladesh mostly in the Ganges and Brahmaputra valleys.-Description:From Frank Finn's The Game Birds of India & Asia :...
(Francolinus gularis), and the doel (Copsychus saularis
Oriental Magpie Robin
The Oriental Magpie Robin is a small passerine bird that was formerly classed as a member of the thrush family Turdidae, but now considered an Old World flycatcher. They are distinctive black and white birds with a long tail that is held upright as they forage on the ground or perch conspicuously...
). Two species of dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
can be found in the delta: the Irrawaddy Dolphin
Irrawaddy dolphin
The Irrawaddy dolphin is a euryhaline species of oceanic dolphin found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia.-Etymology and taxonomic history:...
(Orcaella brevirostris) and the Ganges River Dolphin
Ganges and Indus River Dolphin
The South Asian River Dolphin is a freshwater or river dolphin found in India, Nepal and Pakistan which is split into two sub-species, the Ganges River Dolphin and Indus River Dolphin...
(Platanista gangetica gangetica). The Irrawaddy Dolphin is an oceanic dolphin
Oceanic dolphin
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
that enters the delta from the Bay of Bengal. The Ganges River Dolphin is a true river dolphin
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...
, but is extremely rare and considered endangered.
Trees found in the delta include sundari, garjan (Rhizophora
Rhizophora
Rhizophora is a genus of tropical mangrove trees, sometimes collectively called true mangroves. The most notable species is the Red Mangrove but some other species and a few natural hybrids are known. Rhizophora species generally live in intertidal zones which are indundated daily by the ocean...
spp.), bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
, mangrove palm (Nypa fruticans
Nypa fruticans
Nypa fruticans, known as the attap palm , nipa palm , and mangrove palm or buah atap , buah nipah , dừa nước , Ging Pol in Sinhala in Sri Lanka and gol pata , dani . It is the only palm considered a mangrove in the Mangroves Biome...
), and mangrove date palm (Phoenix paludosa
Phoenix paludosa
Phoenix paludosa or Mangrove Date Palm is a species of flowering plant in the palm family, indigenous to coastal regions of India, Bangladesh, Myanmar, Thailand and peninsular Malaysia. Clustering, to 5 m high, usually forming dense thickets, the leaves are 2 to 3 m long and...
).
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 levelSea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
s caused mostly by subsidence
Subsidence
Subsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation...
in the region and partly by climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
. An increase of half a meter could result in six million people losing their homes in Bangladesh.
Important gas reserves have been discovered in the delta. Several major oil companies have invested in exploration of the Ganges delta region.
External links
- NASA (Johnson Space Center) : Ganges-Brahmaputra River Delta
- The Golden Fibre Trade Centre: Ganges Delta: Most Fertile Land for Growing Raw Jute
- Banglapedia: Ganges-Padma River System
- Bibliography on Water Resources and International Law. Peace Palace Library