<p>Coral reefs act as natural breakwaters that significantly reduce coastal wave energy, erosion, and coastal flooding risks. Yet, future projections suggest that accelerating sea-level rise and widespread coral degradation driven by climate change and human activities will compromise their protective function. A phase-averaged wave energy model was calibrated on the SW barrier reef of Mayotte, Indian Ocean, to compute the key drivers of wave dissipation from the open ocean to the inner lagoon, namely friction, depth-induced breaking, and nonlinear energy transfers. This model was used to further infer the capacity of the barrier to dissipate waves under projected climate change effects. A literature review has allowed to classify the hydraulic roughness <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${\varvec{k}}_{{\varvec{s}}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mi mathvariant="bold-italic">k</mi> </mrow> <mrow> <mi mathvariant="bold-italic">s</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> value into health categories. This study is the first to establish a correspondence between changes in bottom roughness and IPCC scenarios. We showed that a significant loss of wave reduction is expected for the future (currently a 60.5% reduction in average wave height, compared to 31.6% in the worst-case scenario), with an associated combined decrease in breaking and friction. This study has highlighted the need to maintain complex and thriving reef systems to mitigate climate change issues: With a sea-level rise of +0.7 m (SSP5-8.5 scenario by 2100 in the Mozambique Channel), a major increase in reef roughness (+223% on <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${\varvec{k}}_{{\varvec{s}}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mi mathvariant="bold-italic">k</mi> </mrow> <mrow> <mi mathvariant="bold-italic">s</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>) would be necessary to maintain wave attenuation close to the current state, shifting corals from degraded to intermediate up to very complex ranges.</p>

Past, present, and future drivers of wave attenuation by a barrier reef

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发表日期：

2026年6月1日

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Mila Geindre,
Héloïse Michaud,
Damien Sous,
France Floc’h,
Matthieu Jeanson,
Aline Aubry

摘要

Coral reefs act as natural breakwaters that significantly reduce coastal wave energy, erosion, and coastal flooding risks. Yet, future projections suggest that accelerating sea-level rise and widespread coral degradation driven by climate change and human activities will compromise their protective function. A phase-averaged wave energy model was calibrated on the SW barrier reef of Mayotte, Indian Ocean, to compute the key drivers of wave dissipation from the open ocean to the inner lagoon, namely friction, depth-induced breaking, and nonlinear energy transfers. This model was used to further infer the capacity of the barrier to dissipate waves under projected climate change effects. A literature review has allowed to classify the hydraulic roughness ${\varvec{k}}_{{\varvec{s}}}$ $k_{s}$ value into health categories. This study is the first to establish a correspondence between changes in bottom roughness and IPCC scenarios. We showed that a significant loss of wave reduction is expected for the future (currently a 60.5% reduction in average wave height, compared to 31.6% in the worst-case scenario), with an associated combined decrease in breaking and friction. This study has highlighted the need to maintain complex and thriving reef systems to mitigate climate change issues: With a sea-level rise of +0.7 m (SSP5-8.5 scenario by 2100 in the Mozambique Channel), a major increase in reef roughness (+223% on ${\varvec{k}}_{{\varvec{s}}}$ $k_{s}$ ) would be necessary to maintain wave attenuation close to the current state, shifting corals from degraded to intermediate up to very complex ranges.