Wave energy dissipation in a shallow coral reef lagoon using marine x-band radar data

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.This research has been possible thanks to financial support from Colombian Science and Technology Ministry Projects FP44842-144-2016 (Wave propagation and sediment transport on coral reefs) and 0376-2013 (Developing and modeling of a sea state sensor through the processing of radar signals). Wendy Navarro was supported by Universidad del Norte, COLCIENCIAS (Call 757) and iCOOP+2016 (CSIC) fellowships. Andres Orejarena-Rondon was supported by COLCIENCIAS (Call 727). The authors thank Universidad del Norte for providing equipment and the Colombian Naval Academy Almirante Padilla (Dept. of Oceanography) for field support. Alejandro Orfila acknowledges financial support from the Spanish Government MICINN/FEDER through MOCCA Project (RTI2018-093941-B-C31).Peer reviewe