48
GEBCO (https://www.bodc.ac.uk/) gridded data with spatial resolution 30 seconds (0.008333°) has been used to generate the bathymetry for the study area (longitude from 88.0°E to 89.5°E and latitude from 21.0°N to 22.5°N). For the SWAN
simulations the above bathymetry and constant wind fields have been given as
model inputs. A course SWAN run was also performed for the Indian Ocean region
to generate the boundary conditions. The significant wave heights (SWH) generated
are compared for the Hooghly (88
0
08′ E, 21
0
38′ N) and Matla (88
0
44′ E, 21
0
53′ N)
estuaries.
It is observed that Sonneratia apetala showed better attenuation in Hooghly estuary during July 2018 compared to the Matla estuary (Figs. 2.8 and 2.9). Table 2.10
presents the model computed SWH for the month of July.
In July, the month characterized with considerable monsoon in the study area,
Sonneratia apetala showed maximum attenuation and the wave height has been
reduced by 57%. The attenuation decreased in the month of November (`~31%)
which is a postmonsoon month in the study area (Figs. 2.10 and 2.11). During this
month the wave height is very less compared to the monsoon season (Mitra 2013;
Mitra and Zaman 2015; Mitra and Zaman 2016; Sinha et al. 2019). Table 2.11 highlights the model computed SWH for the month of November.
Fig. 2.6 Density of dominant mangroves in 10 stations of Indian Sundarbans during 2016, 2017
and 2017; the species-wise data for these figures are highlighted in Tables 2.7, 2.8 and 2.9
2 Mangroves: A Shield Against Storms and Wave Actions
GEBCO (https://www.bodc.ac.uk/) gridded data with spatial resolution 30 seconds (0.008333°) has been used to generate the bathymetry for the study area (longitude from 88.0°E to 89.5°E and latitude from 21.0°N to 22.5°N). For the SWAN
simulations the above bathymetry and constant wind fields have been given as
model inputs. A course SWAN run was also performed for the Indian Ocean region
to generate the boundary conditions. The significant wave heights (SWH) generated
are compared for the Hooghly (88
0
08′ E, 21
0
38′ N) and Matla (88
0
44′ E, 21
0
53′ N)
estuaries.
It is observed that Sonneratia apetala showed better attenuation in Hooghly estuary during July 2018 compared to the Matla estuary (Figs. 2.8 and 2.9). Table 2.10
presents the model computed SWH for the month of July.
In July, the month characterized with considerable monsoon in the study area,
Sonneratia apetala showed maximum attenuation and the wave height has been
reduced by 57%. The attenuation decreased in the month of November (`~31%)
which is a postmonsoon month in the study area (Figs. 2.10 and 2.11). During this
month the wave height is very less compared to the monsoon season (Mitra 2013;
Mitra and Zaman 2015; Mitra and Zaman 2016; Sinha et al. 2019). Table 2.11 highlights the model computed SWH for the month of November.
Fig. 2.6 Density of dominant mangroves in 10 stations of Indian Sundarbans during 2016, 2017
and 2017; the species-wise data for these figures are highlighted in Tables 2.7, 2.8 and 2.9
2 Mangroves: A Shield Against Storms and Wave Actions