Wave Energy Dissipation in a Shallow Coral Reef Lagoon Using Marine X-Band Radar Data

Abstract

A novel approach for estimating wave energy dissipation on a coral reef barrier is studied using X-Band radar technology. The prominent features of coral reefs, including the delineation of reef morphological structure, wave energy dissipation and wave transformation processes are obtained in a reef lagoon in San Andres Island, Colombia. Results show that reef attenuates incident waves by approximately 75% due to both frictional processes and wave breaking, with an equivalent bottom roughness of 0.20 m and a wave friction factor of 0.18. These parameters are comparable with estimates reported in other shallow coral reef lagoons as well as at seagrass meadows obtained using in-situ measurements. Also, the mean height of the reef elements Hbed and its standard deviation σb are also estimated in the entire radar coverage area. Hbed and σb (0.5 and 7.66 cm respectively) are in the same order of magnitude of measured data reported by previous studies and in good agreement with the geometric parameters proposed by in-canopy flow models for branched species, such as Stylophora and Pocillopora, which are also common in the coral carpets of San Andres Island. This work proposes a completely novel use for X-Band radars by describing prominent features in barrier-reef systems including the delineation of the reef structure and wave energy dissipation.