The influence of coral reef spur and groove morphology on wave energy
dissipation and wave overtopping under future climate change scenarios
Coral reefs protect coastlines from inundation and flooding, servicing
over 200 million people globally. Wave transformation has previously
been studied on coral reef flats with limited focus on forereef zones
where wave transformation is greatest during high-energy conditions.
This study investigates the role of forereef spur and groove (SaG)
morphology on wave energy dissipation and overtopping on coral reefs.
Using XBeach on LiDAR-derived bathymetry, we reproduced dissipation
rates comparable to SaG field studies. Our results emphasize accurate
bathymetries’ role in forereef wave energy dissipation models by
including morphological features (e.g., groove sinuosity, irregular
forereef slopes) that control the mode of wave energy dissipation
(frictional and breaking). We then investigated changes to wave energy
dissipation and wave overtopping based on IPCC AR5 low and high emission
scenarios (RCP2.6 and RCP8.5) and a total disaster scenario (TD) for the
year 2100 considering changes to SaG morphology, wave power and relative
sea-level rise. For RCP2.6, an increase in wave heights of 0.8 m and an
increase in water level of 0.3 m resulted in a two-fold increase in
dissipation rates. For RCP8.5 and TD, with no increase in incident wave
height, dissipation rates were 29% and 395% lower than RCP2.6. This
resulted in increased overtopping at the reef crest by 1.8 m and 2.7 m
for RCP8.5 and TD scenarios, respectively, when compared to RCP2.6.
Decreased dissipation rates and increased wave overtopping in forecasted
climate conditions suggest the need for strategies to promote coral
growth to facilitate high dissipation rates in the future.