Beel - Revision history

Mukbil at 15:38, 8 September 2021

2021-09-08T15:38:19Z

← Older revision		Revision as of 15:38, 8 September 2021
Line 1:		Line 1:
	'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[~~Depressions3~~\|depression]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.		'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[Depression3\|depression]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

	Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.		Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.

Mukbil at 15:38, 8 September 2021

2021-09-08T15:38:08Z

← Older revision		Revision as of 15:38, 8 September 2021
Line 1:		Line 1:
	'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[~~depressions3~~]] are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.		'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[Depressions3\|depression]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

	Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.		Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.

Mukbil at 15:37, 8 September 2021

2021-09-08T15:37:38Z

← Older revision		Revision as of 15:37, 8 September 2021
Line 1:		Line 1:
	'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[~~depression3~~]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.		'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[depressions3]] are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

	Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.		Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.
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	In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.		In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.

	Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[Pirganj Upazila (Thakurgaon District)\|pirganj]], Tagrai Beel at [[Kurigram District\|kurigram]], Lunipukur at [[Rangpur District\|rangpur]], Bara Mirzapur Beel at [[Narail District\|narail]] and Keshpathar at [[Bogra ~~Distrcit~~\|bogra]]. The old river course of [[Atrai River\|atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain]		Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[Pirganj Upazila (Thakurgaon District)\|pirganj]], Tagrai Beel at [[Kurigram District\|kurigram]], Lunipukur at [[Rangpur District\|rangpur]], Bara Mirzapur Beel at [[Narail District\|narail]] and Keshpathar at [[Bogra District\|bogra]]. The old river course of [[Atrai River\|atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain]

	[[Category:natural sciences]]		[[Category:natural sciences]]

	[[bn:বিল]]		[[bn:বিল]]

Mukbil at 15:36, 8 September 2021

2021-09-08T15:36:59Z

← Older revision		Revision as of 15:36, 8 September 2021
Line 1:		Line 1:
	'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[~~depression~~]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.		'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[depression3]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

	Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.		Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.
Line 7:		Line 7:
	In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.		In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.

	Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[Pirganj Upazila (Thakurgaon District)\|pirganj]], Tagrai Beel at [[Kurigram ~~Distrct~~\|kurigram]], Lunipukur at [[Rangpur ~~Distrct~~\|rangpur]], Bara Mirzapur Beel at [[Narail ~~Distrct~~\|narail]] and Keshpathar at [[Bogra ~~Distrct~~\|bogra]]. The old river course of [[Atrai River\|atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain]		Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[Pirganj Upazila (Thakurgaon District)\|pirganj]], Tagrai Beel at [[Kurigram District\|kurigram]], Lunipukur at [[Rangpur District\|rangpur]], Bara Mirzapur Beel at [[Narail District\|narail]] and Keshpathar at [[Bogra Distrcit\|bogra]]. The old river course of [[Atrai River\|atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain]

	[[Category:natural sciences]]		[[Category:natural sciences]]

	[[bn:বিল]]		[[bn:বিল]]

Mukbil at 15:35, 8 September 2021

2021-09-08T15:35:06Z

← Older revision		Revision as of 15:35, 8 September 2021
Line 1:		Line 1:
	'''Beel''' a large surface waterbody that accumulates surface [[runoff water]] through internal drainage [[channel]]s; these [[depression]][[s]] are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[comilla]], [[faridpur]], [[dhaka]] and [[pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.		'''Beel''' a large surface waterbody that accumulates surface [[Runoff Water\|runoff water]] through internal drainage [[channel]]s; these [[depression]]s are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[Comilla District\|comilla]], [[Faridpur District\|faridpur]], [[Dhaka District\|dhaka]] and [[Pabna District\|pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

	Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.		Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.

	In the active [[floodplain]]s of the Surma-Meghna, the Brahmaputra-Jamuna, and the Ganges-Padma river systems, there are several large and small beels. In Bangladesh, there are thousands of beels of different sizes. Some of the most common names are [[chalan beel]], [[gopalganj-khulna beel]] and [[arial beel]]. Most of these large beels have shrunk quite considerably in recent decades. For instance, in the early 19th century Chalan Beel used to cover an area of about 1,085 sq km but it was reduced to 368 sq km in 1909, of which only 85 sq km remains underwater throughout the year. It has since shrunk to only 26 sq km.		In the active [[floodplain]]s of the Surma-Meghna, the Brahmaputra-Jamuna, and the Ganges-Padma river systems, there are several large and small beels. In Bangladesh, there are thousands of beels of different sizes. Some of the most common names are [[Chalan Beel\|chalan beel]], [[Gopalganj-Khulna Beel\|gopalganj-khulna beel]] and [[Arial Beel\|arial beel]]. Most of these large beels have shrunk quite considerably in recent decades. For instance, in the early 19th century Chalan Beel used to cover an area of about 1,085 sq km but it was reduced to 368 sq km in 1909, of which only 85 sq km remains underwater throughout the year. It has since shrunk to only 26 sq km.

	In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.		In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.

	Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[pirganj]], Tagrai Beel at [[kurigram]], Lunipukur at [[rangpur]], Bara Mirzapur Beel at [[narail]] and Keshpathar at [[bogra]]. The old river course of [[atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain~~] [Alam, Mohd Shamsul Professor of Geography and Environment, Jahangirnagar University~~]		Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[Pirganj Upazila (Thakurgaon District)\|pirganj]], Tagrai Beel at [[Kurigram Distrct\|kurigram]], Lunipukur at [[Rangpur Distrct\|rangpur]], Bara Mirzapur Beel at [[Narail Distrct\|narail]] and Keshpathar at [[Bogra Distrct\|bogra]]. The old river course of [[Atrai River\|atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain]

	[[Category:natural sciences]]		[[Category:natural sciences]]

	[[bn:বিল]]		[[bn:বিল]]

0:0:0:0:0:0:0:1: Content Updated.

2021-06-17T19:01:00Z

Content Updated.

New page

'''Beel''' a large surface waterbody that accumulates surface [[runoff water]] through internal drainage [[channel]]s; these [[depression]][[s]] are mostly topographic lows produced by erosions and are seen all over Bangladesh. The term ''beel'' is synonymous to [[baor]], and familiar in greater [[comilla]], [[faridpur]], [[dhaka]] and [[pabna]] districts. Beels are small saucer-like depressions of a marshy character. Many of the beels dry up in the winter but during the rains expand into broad and shallow sheets of water, which may be described as fresh water lagoons.

Beels can be formed due to many causes. In some cases a string of them is found along a line of drainage, suggesting that they are the remains of some great [[river]], which centuries ago deserted its channel in favour of a new one somewhere else. In other cases, they are probably due to the action of rivers, which by centuries of [[silt]] deposits 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 themselves are locked within their channels by high [[levee]]s.

In the active [[floodplain]]s of the Surma-Meghna, the Brahmaputra-Jamuna, and the Ganges-Padma river systems, there are several large and small beels. In Bangladesh, there are thousands of beels of different sizes. Some of the most common names are [[chalan beel]], [[gopalganj-khulna beel]] and [[arial beel]]. Most of these large beels have shrunk quite considerably in recent decades. For instance, in the early 19th century Chalan Beel used to cover an area of about 1,085 sq km but it was reduced to 368 sq km in 1909, of which only 85 sq km remains underwater throughout the year. It has since shrunk to only 26 sq km.

In the deeper beels nothing is to be seen but water, often dotted with [[char]]s or enclosed by high lands with villages and trees on them. Many of the villages are completely isolated during the [[monsoon]], when the only mode of transport is a [[boat]]. Not surprisingly, these beels form a serious obstacle to transport by land as roads can be constructed across them only at a great expense. The roads again have to be strong enough to withstand the pressure of water, which may be as much as 3.05m in depth.

Beels are mainly fed by surface runoff water. A few larger ones are fed by floodwater during the wet season from the parent river channel. Regionwise, in the northwest some beels of considerable sizes are Bara Beel at [[pirganj]], Tagrai Beel at [[kurigram]], Lunipukur at [[rangpur]], Bara Mirzapur Beel at [[narail]] and Keshpathar at [[bogra]]. The old river course of [[atrai]] is marked by some beels, viz Chakchaki, Sabul, Ghugri, Kanchan, Manda, Utrail, Hilna, Kumar and Shona. In the southern region, important beels are Boyra, Dakatia, Bara, Kola, Patla, Chatal and Srirampur. In the central part, Katla, Chatal, Nagarkanda, and Chanda are important beels. In eastern areas, such beels are small in size. In the northeast, beels of Haor Basin (Sylhet Basin) area merge together in the wet season appearing like vast bodies of water. Normally, beels remain deeply flooded for most of the wet season and the rims are primarily used for either boro cultivation or deepwater rice. Like baors, beels are also important [[wetland]]s and regarded as valuable [[fish]] and [[wildlife]] habitat. [Mohd Shamsul Alam and Md Sazzad Hossain] [Alam, Mohd Shamsul Professor of Geography and Environment, Jahangirnagar University]

[[Category:natural sciences]]

[[bn:বিল]]