Abstract:
The Port-Bouët Bay shoreline is threatened by extreme sea level (ESL) events, which result
from the combination of storm tide, wave run-up, and sea level rise (SLR). This study provides
comprehensive scenarios of current and future ESLs at the local scale along the bay to understand the
evolution of the phenomenon and promote local adaptation. The methodological steps involve first
reconstructing historical storm tide and wave run-up data using a hydrodynamic model (D-flow FM)
and the empirical model of Stockdon et al. Second, the Generalized Pareto Distribution (GPD) model
fitted to the Peaks-Over-Thresholds (POT) method is applied to the data to calculate extreme return
levels. Third, we combine the extreme storm tide and wave run-up using the joint probability method
to obtain the current ESLs. Finally, the current ESLs are integrated with recent SLR projections to
provide future ESL estimates. The results show that the current ESLs are relatively high, with 100-year
return levels of 4.37 m 0.51, 4.97 m 0.57, and 4.48 m 0.5 at Vridi, Petit-Bassam, and Sogefiha
respectively. By end-century, under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios, the future SLR is
expected to increase the current ESLs by 0.49 m, 0.62 m, and 0.84 m, respectively. This could lead
to a more frequent occurrence of the current 100-year return period, happening once every 2 years
by 2100, especially under SSP5-8.5. The developed SLR scenarios can be used to assess the potential
coastal flood risk in the study area for sustainable and effective coastal management and planning.
Description:
A publication submitted to the West African Science Service Centre on Climate Change and Adapted Land Use, the Université de Lomé, Togo in partial fulfillment of the requirements for the requirements for the degree of Doctor of Philosophy Degree in Climate Change and Disaster Risk Management
