Abstract:
Coastal areas of the world face a range of risk related to climate change. Cyclone and
associated storm surge is the most destructive hazard that frequently occurs in
Bangladesh and causes enormous suffering to the people of the coastal area. This study
has been carried out to assess the hydrological hazard based risk associated with the
storm surge due to increase in Sea Surface Temperature (SST) and Sea Level Rise
(SLR) in the coastal area of Bangladesh. Increase in SST and SLR will increase surge
height which will enlarge the boundary of the Risk Zone (RZ) and High Risk Area
(HRA). The maximum surge height was estimated by using an empirical equation. This
study illustrates that surge height will increase by about 13 and 33% for 2 and 4°C
increase of SST, respectively, for the entire coastal zone of Bangladesh. Increase in
surge height indicates greater intrusion distance and larger RZ and HRA. Intrusion
distance of the surge water was calculated by using another empirical equation. Study
shows intrusion distance will be increased by 6-10 and 18-23% for 2 and 4°C increase
in SST, respectively, in the coastal area of Bangladesh. As RZ depends on the possible
extent of inland intrusion, increasing intrusion distance will increase the boundary of the
RZ as well as HRA. Study demonstrates that RZ will be increased by approximately
16% and 29% for 2 and 4°C increase in SST, respectively. The study also reveals that
the HRA will be increased by approximately 20 and 34% for 2 and 4°C increase in SST,
respectively. Within the RZ, the areas where cyclone shelter/safe haven are present
partially protect the people from the adverse impact of storm surge. It is also found that
at present about 75-99% of the population in the coastal districts of Bangladesh are still
vulnerable to storm surge risk due to unavailability of the cyclone shelters. The situation
will be even worse for the 2°C increase in SST. Residual risk map of the study area
shows that Noakhali Sadar, Lakshmipur, Chakaria, Bhola Sadar, Char Fashion,
Ramgati, Patiya and Mirsharai thana will be highly susceptible to storm surge risk for
the 2°C increase of SST. Moderately vulnerable thanas are Ramgati, Patiya, Mirsharai,
Cox's Bazar Sadar, Sitakundu, Banshkhali, Galachipa, Bauphal, Mehendigonj, Hatiya,
Mathbaria, Barguna Sadar, Amtali, Burhanuddin, Lalmohon, Roypur, Companiganj,
Sonagaji, Sandwip, Chittagong port, Anwara, Maheskhali Teknaf and Ramu. Hence, the
populations of those thanas will be even more vulnerable to cyclones/storm surges as a
result of climate change. This information will help in making decision for providing
safety to coastal population from the adverse impact of climate change.
