Frictional Dissipation of Incident Waves Over a Spatially-Varying Rough Barrier Reef in Mayotte, Indian Ocean

Abstract Coral reefs serve as a highly effective natural barrier against incoming ocean waves. However, climate change and human-induced degradations are threatening reefs, reducing their capacity to protect coastal populations by diminishing the frictional processes that dissipate wave energy. The most common approach to represent wave energy dissipation through bottom friction relies on the estimation of a representative roughness length, whose definition on coral environments remains to be elucidated. As a consequence, a generic parametrization for friction processes on coral reef systems is still lacking. In this study, high-resolution hydrodynamical and topographical data collected at the South-West barrier reef of Mayotte, Indian Ocean, were used to perform an estimation of wave friction. The hydraulic roughness estimated across the reef varies spatially, and attempts are made to connect this information with the diverse bed morphologies observed in the field.