A beel or a bheel is a term for a pond (wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

) with static water (as opposed to moving water in rivers and canals - typically called khaals), in the Ganges - Brahmaputra flood plain

Indo-Gangetic plain

The northern Plains also known as the Indo - Gangetic Plain and The North Indian River Plain is a large and fertile plain encompassing most of northern and eastern India, the most populous parts of Pakistan, parts of southern Nepal and virtually all of Bangladesh...

s of the Eastern 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...

n states 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...

, and Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

 and in the country 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...

. The term owes its origins to the word of the same pronunciation meaning "pond" in the Bengali

Bengali language

Bengali or Bangla is an eastern Indo-Aryan language. It is native to the region of eastern South Asia known as Bengal, which comprises present day Bangladesh, the Indian state of West Bengal, and parts of the Indian states of Tripura and Assam. It is written with the Bengali script...

 and Assamese

Assamese language

Assamese is the easternmost Indo-Aryan language. It is used mainly in the state of Assam in North-East India. It is also the official language of Assam. It is also spoken in parts of Arunachal Pradesh and other northeast Indian states. Nagamese, an Assamese-based Creole language is widely used in...

 languages.

Formation

Typically, beels are formed by inundation of low lying lands during flood

Flood

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...

ing, where some water gets trapped even after flood waters recede back from the flood plains. Beels may also be caused by filling up of low lying areas during rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

s, specially during the 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...

 season.

There are different causes for the formation of beels. A string of beels is indicative of their being the remains of some great river, which deserted its channel in favour of a new one somewhere else. In other cases, they are probably because of silt deposits, which have raised their beds and marginal banks so high that they flow above the level of the surrounding area. The land between a pair of parallel rivers thus forms a kind of trough in between. The rivers, on the other hand, cannot overflow their banks into these depressions as they are locked within their channels by high levees.

Haor, baor

In north eastern Bangladesh there are large water bodies called haor

Haor

A haor is a wetland ecosystem in the north eastern part of Bangladesh which physically is a bowl or saucer shaped shallow depression, also known as a backswamp...

s. A haor is a bowl shaped depression

Depression (geology)

A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...

 which is flooded every year during 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...

. Throughout the rainy season a haor is such a vast stretch of turbulent water that it is thought of as a sea, within which the villages appear as islands. It remains under water for seven months of the year. During the dry season, most of the water drains out leaving small shallow lakes or completely dry out by the end of dry season exposing rich alluvial soil extensively cultivated for rice. In the central part Bangladesh, important beels are Katla, Chatal, Nagarkanda, and Chanda. In greater Comilla, Faridpur, Dhaka and Pabna districts the beel is sometimes referred to as baor.

Bangladesh

In Bangladesh, there are thousands of beels of different sizes. Some of the most common names are Chalan Beel

Chalan Beel

Chalan Beel is a wetland in Bangladesh. It is a large inland depression, marshy in character, with rich flora and fauna. Forty-seven rivers and other waterways flow into the Chalan Beel...

, Gopalganj-Khulna Beel, Meda Beel, Aila beel, Dekhar beel, Kuri beel, Erali beel and Arial Beel. Most of these large beels have shrunk quite considerably in recent decades. Regionwise, in the northwest of Bangladesh some of the larger beels are Bara Beel in Pirganj, Tagrai Beel in Kurigram

Kurigram District

Kurigram is a district in Northern Bangladesh. It is located in the Rangpur Division.-Geography:Kurigram District is located in the northern region of Bangladesh along the border of India. The area of this district is 2,296.10 km² and population is 1,782,277...

, Lunipukur in Rangpur

Rangpur District

The district of Rangpur have 4924 mosques, 480 temples, 43 churches and six tombs.In an anthropologic view most people of Rangpur are having Rajbagshi blood in their veins...

, Bara Mirzapur Beel in Narail

Narail District

Narail is a district in South-western in Bangladesh. It is a part of the Khulna Division.-Geography:Narail District with an area of 990.23 km², is bounded by Magura District on the north, Khulna District on the south, Faridpur District and Gopalganj District on the east, and by Jessore...

 and Keshpathar in Bogra

Bogra District

Bogra is a northern district of Bangladesh, in the Rajshahi Division. It is called the gateway to the north Bengal. It is an industrial city where many small and mid sized industries are housed. Bogra district was a part of the ancient Pundravardhana territory and Bogra was the capital of...

. The old river course of Atrai

Atrai River

Atrai River flows in West Bengal and northern parts of Bangladesh.In ancient times the river was called Atrei and finds a mention in the Mahabharata. It is linked with Karatoya River. It originates in West Bengal and then after flowing through Dinajpur District of Bangladesh, it enters India again...

 is marked by some beels. In the southern region of Bangladesh, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur.

Assam

In Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

, Deepor Beel is a permanent, freshwater lake, in a former channel of the Brahmaputra river, to the south of the main river south-west of Guwahati

Guwahati

Guwahati, Pragjyotishpura in ancient Assam formerly known as Gauhati is a metropolis,the largest city of Assam in India and ancient urban area in North East India, with a population of 963,429. It is also the largest metropolitan area in north-eastern India...

. It has great biological and environmental importance besides being the only major storm water storage basin for the Guwahati city. The beel is endowed with rich floral and faunal diversity. In addition to huge congregation of residential water birds, the Deepor ecosystem harbours large number of migratory waterfowl each year. Deepor Beel has been designated as a Ramsar

Ramsar Convention

The Ramsar Convention is an international treaty for the conservation and sustainable utilization of wetlands, i.e., to stem the progressive encroachment on and loss of wetlands now and in the future, recognizing the fundamental ecological functions of wetlands and their economic, cultural,...

site in November 2002.