38
Md. A. Sattar and K. K. W. Cheung
3.1 Introduction
Tropical cyclone (TC) is a well-known natural disaster that can devastate much
of a society, environment, economy and result in people’s deaths. The North Indian
Ocean (NIO) is one ocean basin that is very prone to TC. TCs often cause huge human
casualties in densely populated communities like Bangladesh, India and Myanmar
around the Bay of Bengal (BoB) region of the NIO. Most of the population resides
in low-lying coastal areas and most settlement areas are formed by riverine sedimentation. These areas suddenly and excessively inundate due to TC landfall along
the Bangladeshi coast of the BoB, which causes massive flooding and immense
damage and losses in material goods and people’s lives. Jisan et al. (2018) applied
the hydrodynamic model Delft3D in their study and reported that if TC activity over
the Bangladeshi coast remains the same as what is currently happening, there will
still be an increase in surge height and inundation areas due to sea-level rise (SLR).
In an another study, Woodruff et al. (2013) reported that for the densely populated
coastal areas, global impacts from flooding due to TC activity may even be larger
than that from SLR. The issue is complicated by the fact that TC impacts are not
only concentrated within inundated areas but can extend beyond those areas that vary
with wind speed.
It is known that several factors are responsible for coastal inundation that could
make the coast more vulnerable (Gayathri et al. 2017). For example, sea-level rise
(SLR), coastal erosion, changes of geomorphology and man-made disturbances will
cause permanent flooding, while TC, tsunami and tide strikes will trigger short-term
flooding. When a TC approaches the coast, it brings an enormous amount of water
with it and subsequently increases the sea level. In addition, landfall of TC brings
excessive rainfall together with windy to wild weather conditions. Numerical models
play a vital role in predicting storm surges and their associated flooding outcomes.
Storm surge modelling research began in the 1970s for the BoB basin since most
TCs formed there. Das (1972) took the first attempt to develop a numerical storm
surge model for the BoB region, especially the east coast of India and Bangladesh. In
general, this model simulated surge height as being too high compared with observed
values by the tide gauges. Since then, several initiatives have been taken by other
modellers. The study by Gayathri et al. (2017) argued that although remarkable
achievements have been reported in terms of storm surge and inundation forecasting,
it is still critical to investigate the coastal risk associated with TC landfall because
SLR is expected to increase in the future.
Past studies mainly focused on predicting peak surge height. For instance, the
SPLASH (Special Programme to List Amplitudes of Surges from Hurricanes) model
(Jelesnianski 1972), the FVCOM (Finite-volume coastal ocean) model (Chen et al.
2006), the SLOSH (NOAA) and ADCIRC (Luettich et al. 1992) were developed for
storm surge forecasting. Recently, several attempts have been made to address coastal
area inundation caused by TC and a few other studies developed tools and models
for the assessment of coastal inundation and their associated impacts worldwide
(Cheung et al. 2003; Graeme and Kathleen 1999; Lian et al. 2004).
Md. A. Sattar and K. K. W. Cheung
3.1 Introduction
Tropical cyclone (TC) is a well-known natural disaster that can devastate much
of a society, environment, economy and result in people’s deaths. The North Indian
Ocean (NIO) is one ocean basin that is very prone to TC. TCs often cause huge human
casualties in densely populated communities like Bangladesh, India and Myanmar
around the Bay of Bengal (BoB) region of the NIO. Most of the population resides
in low-lying coastal areas and most settlement areas are formed by riverine sedimentation. These areas suddenly and excessively inundate due to TC landfall along
the Bangladeshi coast of the BoB, which causes massive flooding and immense
damage and losses in material goods and people’s lives. Jisan et al. (2018) applied
the hydrodynamic model Delft3D in their study and reported that if TC activity over
the Bangladeshi coast remains the same as what is currently happening, there will
still be an increase in surge height and inundation areas due to sea-level rise (SLR).
In an another study, Woodruff et al. (2013) reported that for the densely populated
coastal areas, global impacts from flooding due to TC activity may even be larger
than that from SLR. The issue is complicated by the fact that TC impacts are not
only concentrated within inundated areas but can extend beyond those areas that vary
with wind speed.
It is known that several factors are responsible for coastal inundation that could
make the coast more vulnerable (Gayathri et al. 2017). For example, sea-level rise
(SLR), coastal erosion, changes of geomorphology and man-made disturbances will
cause permanent flooding, while TC, tsunami and tide strikes will trigger short-term
flooding. When a TC approaches the coast, it brings an enormous amount of water
with it and subsequently increases the sea level. In addition, landfall of TC brings
excessive rainfall together with windy to wild weather conditions. Numerical models
play a vital role in predicting storm surges and their associated flooding outcomes.
Storm surge modelling research began in the 1970s for the BoB basin since most
TCs formed there. Das (1972) took the first attempt to develop a numerical storm
surge model for the BoB region, especially the east coast of India and Bangladesh. In
general, this model simulated surge height as being too high compared with observed
values by the tide gauges. Since then, several initiatives have been taken by other
modellers. The study by Gayathri et al. (2017) argued that although remarkable
achievements have been reported in terms of storm surge and inundation forecasting,
it is still critical to investigate the coastal risk associated with TC landfall because
SLR is expected to increase in the future.
Past studies mainly focused on predicting peak surge height. For instance, the
SPLASH (Special Programme to List Amplitudes of Surges from Hurricanes) model
(Jelesnianski 1972), the FVCOM (Finite-volume coastal ocean) model (Chen et al.
2006), the SLOSH (NOAA) and ADCIRC (Luettich et al. 1992) were developed for
storm surge forecasting. Recently, several attempts have been made to address coastal
area inundation caused by TC and a few other studies developed tools and models
for the assessment of coastal inundation and their associated impacts worldwide
(Cheung et al. 2003; Graeme and Kathleen 1999; Lian et al. 2004).