Ganges Delta
The Ganges Delta (also Sunderban Delta or the Bengal Delta) is a river delta in the South Asia region of Bengal, consisting of Bangladesh and the state of West Bengal, India. It is the world's largest delta, and empties into the Bay of Bengal. It is also one of the most fertile regions in the world, thus earning the nickname The Green Delta. The delta, also known as the Ganges-Brahmaputra Delta, stretches from the Hugli River on the west to the Meghna River on the east. It is approximately 220 miles (350 km) across at the Bay of Bengal. Kolkata (formerly Calcutta) and Haldia in India and Mongla in Bangladesh are the principal seaports on the delta.
The Ganges Delta arises from the confluence of the following rivers:
- Padma (Lower Ganges) (Pôdda)
- Jamuna (Lower Brahmaputra) (Jomuna)
- Meghna
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Shape and composition
The Ganges delta has the shape of a triangle, and is considered to be an "arcuate" delta (arc-shaped). It covers more than 105,000 km², and although the delta lies mostly in Bangladesh and India, rivers from Bhutan, China, India and Nepal drain into it from the north. Approximately two-thirds of the delta is in Bangladesh. Most of the delta is composed of alluvial soils, with red and red-yellow laterite soils 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 waterways, swamps, lakes and flood plain sediments (Chars). The Ganges delta is separated into two parts: the eastern (active), and the western (less active) part.
Population
Between 125 and 143 million people live on the delta, despite risks from floods caused by monsoons, heavy runoff from the melting snows of the Himalayas, and 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.
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 520 people per square mile (200 people per km²), making it one of the most densely populated regions on earth.
Agriculture and fishing
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. 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.
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 The Guinness Book of World Records estimated the total loss of human life from the Bhola cyclone at 1,000,000 - [1] Another cyclone hit the delta in 1991, killing about 138,000 people—see 1991 Bangladesh Cyclone.
People have to be careful building 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.
Climate
The Ganges Delta lies mostly in the tropical wet climate zone, and receives between 60 and 80 inches (1.5 to 2 m) of rainfall each year in the western part, and 80-120 inches (2 to 3 m) 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 57 to 77 °F (14 to 25 °C), and average temperatures in April range from 77 to 95 °F (25 to 35 °C). July is the wettest month, on average, when over 13 inches (330 mm) of rain falls on the delta (temperature averages from Kolkata).
Flora and fauna
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 km² of the ecoregion's 14,600 km² protected. Where the delta meets the Bay of Bengal, Sundarbans mangroves form the world's largest Mangrove ecoregion, covering an area of 20,400 km² 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.
Animals in the delta include the endangered Bengal tiger, the Indian python, Clouded leopard, Asian elephant, and crocodiles, which live in the Sundarbans. Approximately 1,020 Bengal tigers are believed to inhabit the Sundarbans.
It is estimated that 30,000 spotted deer are in the Sundarbans part of the delta. Birds found in the delta include kingfishers, eagles, swamp partridges, woodpeckers, shaliks, and the doel (magpie robin). Two species of dolphins can be found in the delta: the Irrawaddy dolphin, and the Ganges River Dolphin. The Irrawaddy dolphin is not a true river dolphin, but 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, garyan, bamboo, mangrove palm (Nypa fruticans), and mangrove date palm (Phoenix paludosa).
Future of 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 mostly by subsidence in the region and partly by climate change. An increase of half a meter could result in six million people losing their homes in Bangladesh. Higher temperatures related to climate change could also bring about more severe flooding of the delta, because of increased melting of snow and glaciers in the Himalayas.
Important gas reserves have been discovered in the delta, which could play a major role in the future of the region, and hopefully help lift many of the poor people living in the delta out of poverty. Several major oil companies have invested in exploration of the Ganges delta region.
See also
- River delta
- Ganges Fan
- Ganges River
- Mega Delta
References
- A river journey, the Ganges, by Rob Bowden, 2003
- Future Harvest - [2]
- Visible Earth, NASA - [3]
- Water Resources in the Ganges River Basin, Louisiana School for Math, Science, and the Arts - [4]
- The Ganges Delta, by Prof. Kanan Gopal Bagchi, 1944
- Weather.com
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
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