Impact of Sea Level Rise on Overtopping, Wave Load, and Erosional Power:
The Case of The Glass Window Bridge, Eleuthera, The Bahamas
Abstract
The Glass Window Bridge Located in Eleuthera, The Bahamas, is the only
bridge connecting Eleuthera’s northern and southern mainland, facing the
Atlantic Ocean to the east and the Great Bahama Bank to the west. This
bridge is under constant threat from hurricanes and large swells in the
Atlantic Ocean. The existing bridge has been subject to severe damage
arising from wave impact forces since its construction. In addition,
severe overtopping of the cliffs near the Glass Window Bridge causes
damage to the roads and severe erosion, that over the years has created
unique geologic features. As the global climate warms and sea level
rises (SLR), coastal areas will be subject to more extreme flooding and
intense hurricanes. Therefore, assessing the impact of potential SLR on
the GW bridge and guiding bridge wave mitigation measures are of crucial
need. A 3D Digital Terrain Model (DTM) of the bridge site and adjacent
ocean bathymetry is constructed from satellite data. This study develops
a multiphase computational fluid dynamics (CFD) model based on the DTM
to study the impact of wave-breaking for three major historical storm
events, and for three different estimates of SLR for the year 2100. Our
results suggest that, due to SLR, the islands are subjected to increased
overtopping, which occurs even during normal wave conditions. Notably,
nonlinear increases in wave splash extent and wave-induced bridge loads
are observed as SLR increases. Our results indicate that SLR
additionally magnifies the erosional energy, accelerating further
changes in the geological features of the island.