46
tree, diameter of the tree etc. Her study considered the regulatory role of four major
true mangrove floral species (Sonneratia apetala, Avicennia marina, Avicennia alba
and Avicennia officinalis) in two separate estuaries namely Hooghly and Matla having contrasting salinities. This work is the first attempt to evaluate the species-wise
attenuation of waves using SWAN model on the basis of real time data that have
been collected from the mangrove ecosystem of Indian Sundarbans during July and
November, 2018.
In the coastal region, mangrove vegetation has the ability to attenuate wave
which are generated by severe storms and tidal surges. SWAN model helps to determine the effect of vegetation on the wave height. Thus this model is a powerful tool
to evaluate the attenuation of waves by mangrove or any other coastal vegetation.
This model consists of an energy dissipated term due to vegetation. The dissipated
energy is subtracted from the incoming wave energy, which results in less wave
energy behind the vegetation span thus resulting in the lowering of the wave height.
Table 2.6 Sampling stations with salient features
Station
Longitude &
Latitude
Site description
Harinbari
(Stn. 1)
88
°
04′22.88
″ E
21
°
46′53.07
″ N
Situated in the western region of Indian Sundarbans almost
in the middle of the Sagar Island; receives the water of the
Hugli River.
Chemaguri
(Stn. 2)
88
°
08′49.01
″ E
21
°
39′42.88
″ N
Situated on the south-eastern side of Sagar Island and
receives the water of the Mooriganga River.
Sagar south
(Stn. 3)
88
°
04′0.51
″ E
21
°
37′49.90
″ N
Situated on the south-western part of the Sagar Island at the
confluence of the river Hugli and the Bay of Bengal.
Anthropogenically stressed zone due to presence of
passenger jetties, fishing activities and pilgrimage.
Lothian island
(Stn. 4)
88
°
19′8.47
″ E
21
°
39′08.04
″ N
Situated east of Bakkhali island; a wildlife sanctuary; faces
the river Saptamukhi.
Prentice island
(Stn. 5)
88
°
17′3.62
″ E
21
°
42′43.31
″ N
Situated north of Lothian island; receives the water of the
Saptamukhi River.
Canning
(Stn. 6)
88
°
41′04.43
″ E
22
°
19′03.20
″ N
Situated in the central part of the Indian Sundarbans and
faces the mighty river Matla, a tide-fed river. Due to
presence of fish landing stations, passenger jetties and busy
market, the area is anthropogenically stressed.
Sajnekhali
(Stn. 7)
88
°
48′15.78
″ E
22
°
06′34.19
″ N
A Wildlife Sanctuary and a part of Sundarban Tiger
Reserve; adjacent to river Bidhya and Gomor. Tourism
pressure is extremely high in this station particularly during
postmonsoon.
Chotomollakhali
(Stn. 8)
88
°
54′26.71
″ E
22
°
10′40.00
″ N
Situated in the upper portion of Central Indian Sundarban
adjacent to Jhila forest; receives the water of Rangabelia
and Korankhali Rivers.
Satjelia
(Stn. 9)
88
°
52′49.51
″ E
22
°
05′17.86
″ N
Situated adjacent to river Duttar in the upper region of
Central Indian Sundarban facing western part of the Jhilla
forest.
Pakhiralaya
(Stn. 10)
88
°
48′29.00
″ E
22
°
07′07.23
″ N
Situated adjacent to river Gomor; opposite to Sajnekhali
Wild Life Sanctuary.
2 Mangroves: A Shield Against Storms and Wave Actions
tree, diameter of the tree etc. Her study considered the regulatory role of four major
true mangrove floral species (Sonneratia apetala, Avicennia marina, Avicennia alba
and Avicennia officinalis) in two separate estuaries namely Hooghly and Matla having contrasting salinities. This work is the first attempt to evaluate the species-wise
attenuation of waves using SWAN model on the basis of real time data that have
been collected from the mangrove ecosystem of Indian Sundarbans during July and
November, 2018.
In the coastal region, mangrove vegetation has the ability to attenuate wave
which are generated by severe storms and tidal surges. SWAN model helps to determine the effect of vegetation on the wave height. Thus this model is a powerful tool
to evaluate the attenuation of waves by mangrove or any other coastal vegetation.
This model consists of an energy dissipated term due to vegetation. The dissipated
energy is subtracted from the incoming wave energy, which results in less wave
energy behind the vegetation span thus resulting in the lowering of the wave height.
Table 2.6 Sampling stations with salient features
Station
Longitude &
Latitude
Site description
Harinbari
(Stn. 1)
88
°
04′22.88
″ E
21
°
46′53.07
″ N
Situated in the western region of Indian Sundarbans almost
in the middle of the Sagar Island; receives the water of the
Hugli River.
Chemaguri
(Stn. 2)
88
°
08′49.01
″ E
21
°
39′42.88
″ N
Situated on the south-eastern side of Sagar Island and
receives the water of the Mooriganga River.
Sagar south
(Stn. 3)
88
°
04′0.51
″ E
21
°
37′49.90
″ N
Situated on the south-western part of the Sagar Island at the
confluence of the river Hugli and the Bay of Bengal.
Anthropogenically stressed zone due to presence of
passenger jetties, fishing activities and pilgrimage.
Lothian island
(Stn. 4)
88
°
19′8.47
″ E
21
°
39′08.04
″ N
Situated east of Bakkhali island; a wildlife sanctuary; faces
the river Saptamukhi.
Prentice island
(Stn. 5)
88
°
17′3.62
″ E
21
°
42′43.31
″ N
Situated north of Lothian island; receives the water of the
Saptamukhi River.
Canning
(Stn. 6)
88
°
41′04.43
″ E
22
°
19′03.20
″ N
Situated in the central part of the Indian Sundarbans and
faces the mighty river Matla, a tide-fed river. Due to
presence of fish landing stations, passenger jetties and busy
market, the area is anthropogenically stressed.
Sajnekhali
(Stn. 7)
88
°
48′15.78
″ E
22
°
06′34.19
″ N
A Wildlife Sanctuary and a part of Sundarban Tiger
Reserve; adjacent to river Bidhya and Gomor. Tourism
pressure is extremely high in this station particularly during
postmonsoon.
Chotomollakhali
(Stn. 8)
88
°
54′26.71
″ E
22
°
10′40.00
″ N
Situated in the upper portion of Central Indian Sundarban
adjacent to Jhila forest; receives the water of Rangabelia
and Korankhali Rivers.
Satjelia
(Stn. 9)
88
°
52′49.51
″ E
22
°
05′17.86
″ N
Situated adjacent to river Duttar in the upper region of
Central Indian Sundarban facing western part of the Jhilla
forest.
Pakhiralaya
(Stn. 10)
88
°
48′29.00
″ E
22
°
07′07.23
″ N
Situated adjacent to river Gomor; opposite to Sajnekhali
Wild Life Sanctuary.
2 Mangroves: A Shield Against Storms and Wave Actions