Impact Assessment of Coastal Hazards due to Typhoons in the Marshall Islands

Climate change and sea level rise are a global threat to coastal areas and, in particular, to small island states. Future projections indicate that sea levels are expected to rise in the next century, at different rates in different regions around the world. On top of that, the intensity and frequency of extreme events such as typhoons may vary. In this study, the impacts in terms of inundation of different typhoon conditions will be assessed in the present situation as well as accounting for climate change effects. In particular, the assessment was carried out for the island of Ebeye, located on Kwajalein Atoll (Republic of Marshall Islands).

The results presented herein show that coastal engineering experiences at traditional coasts cannot be applied one-on-one to small islands states in the Pacific, because the relevant hydrodynamic processes offshore and on the reef are fundamentally different. These processes can be examined using a modeling approach combining parametric wind models, as well as process based models such as Delft3D and XBeach. The model results suggest that offshore extreme wave and storm surge levels may increase up to 6-8% as a result of higher typhoon winds. Nevertheless, the projected sea level rise is by far the dominant process in relation to increase in flooding levels, accounting for about 90% of the total increase in flooding impacts.