Date of Award

12-31-2016

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

First Advisor

Shaowu Bao

Second Advisor

Leonard J. Pietrafesa

Third Advisor

Varavut Limpasuvan

Abstract

The hydrodynamic model Delft3D is used to study the impact of Sea Level Rise (SLR) on storm surge and inundation in the coastal region of Bangladesh. To study the present-day inundation scenario, track of two known tropical cyclones (TC) were used: Aila (Category 1; 2009) and Sidr (Category 5; 2007). Model results were validated with the available observations. Future inundation scenarios were generated by using the strength of TC Sidr, TC Aila and an ensemble of historical TC tracks but incorporating the effect of SLR. Since future change in storm surge inundation under SLR impact is a probabilistic incident, that’s why a probable range of future change in inundated area was calculated by taking in to consideration the uncertainties associated with TC tracks, intensities and landfall timing. Along with that, role of topographic slope was investigated to see how they could alter the impact of SLR on storm surge and inundation. The model outputs showed that, the inundated area for TC Sidr, which was calculated as 1860 km2, would become 31% higher than the present-day scenario if a SLR of 0.26 meter occurs during the mid-21st century climate scenario. Similar to that, an increasing trend was found for the end of the 21st century climate scenario. It was found that with a SLR of 0.54 meter, the inundated area would become 53% higher than the present-day case. Along with the inundation area, the impact of SLR was examined for the changes in future storm surge level. A significant increase of 21% was found in storm surge level for the case of TC Sidr in Barisal station if a Sea Level Rise of 0.26 meter occurs at the middle of the 21st century. Similar to that, an increase of 37% was found in storm surge level with a SLR of 0.54 meter in this location for the end of the 21st century climate scenario. Ensemble projections based on uncertainties of future TC events also showed that, for a change of 0.54 meters in SLR, the inundated area would range between 3500-3750 km2 whereas for present day SLR simulations it was found within the range of 1000-1250 km2. Outputs from the topographic slope-storm surge inundation experiments showed that, even coastal areas with a steep topographic slope, inundated area would increase greatly due to the impact of SLR. These results revealed that even if the future TCs remain at the same strength as at present, the projected changes in SLR will generate more severe threats in terms of surge height and extent of inundated area.

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