A Numerical Study of Geomorphic and Oceanographic Controls on Wave-Driven Runup on Fringing Reefs with Shore-Normal Channels

Many populated, tropical coastlines fronted by fringing coral reefs are exposed to wave-driven marine flooding that is exacerbated by sea-level rise. Most fringing coral reefs are not alongshore uniform, but bisected by shore-normal channels; however, little is known about the influence of such chan...

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Bibliographic Details
Published in:Journal of marine science and engineering 2022-06, Vol.10 (6), p.828
Main Authors: Storlazzi, Curt D., Rey, Annouk E., van Dongeren, Ap R.
Format: Article
Language:English
Subjects:
channel
Channels
Coasts
Coral reefs
Flooding
Fringing reefs
Geomorphology
Incident waves
Investigations
Marine invertebrates
Morphology
Offshore
Population
reef
runup
Sea level changes
Shoreline protection
Simulation
Slopes
Tropical climate
Variation
Very Low Frequencies
water level
Water levels
wave
Wave runup
Wave slope
Waves
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Summary:Many populated, tropical coastlines fronted by fringing coral reefs are exposed to wave-driven marine flooding that is exacerbated by sea-level rise. Most fringing coral reefs are not alongshore uniform, but bisected by shore-normal channels; however, little is known about the influence of such channels on alongshore variations on runup and flooding of the adjacent coastline. We conducted a parametric study using the numeric model XBeach that demonstrates that a shore-normal channel results in substantial alongshore variations in waves, wave-driven water levels, and the resulting runup. Depending on the geometry and forcing, runup is greater either on the coastline adjacent to the channel terminus or at locations near the alongshore extent of the channel. The impact of channels on runup increases for higher incident waves, lower incident wave steepness, wider channels, a narrower reef, and shorter channel spacing. Alongshore variation of infragravity waves is predominantly responsible for large-scale variations in runup outside the channel, whereas setup, sea-swell waves, and very-low frequency waves mainly increase runup inside the channel. These results provide insight into which coastal locations adjacent to shore-normal channels are most vulnerable to high runup events, using only widely available data such as reef geometry and offshore wave conditions.
ISSN:2077-1312
2077-1312
DOI:10.3390/jmse10060828