Coral Reef Geometry and Hydrodynamics in Beach Erosion Control in North Quintana Roo, Mexico

Mireille Escudero,Borja G. Reguero,Edgar Mendoza,Fernando Secaira,Rodolfo Silva

doi:10.3389/fmars.2021.684732

Abstract

Coral reefs are increasingly recognized for their shoreline protection services. The hydrodynamic performance of this ecosystem is comparable to artificial low-crested structures often used in coastal protection, whose objective is to emulate the former. Coral reefs also provide other important environmental services (e.g., food production, habitat provision, maintenance of biodiversity and social and cultural services) and leave almost no ecological footprint when conservation and restoration actions are conducted to maintain their coastal protection service. However, studies have focused on their flood protection service, but few have evaluated the morphological effects of coral reefs through their ability to avoid or mitigate coastal erosion. In this paper, we investigate the relation between shoreline change, reefs’ geometry and hydrodynamic parameters to elucidate the physics related to how the Mesoamerican Reef in Mexico protects sandy coastlines from erosion. Using numerical wave propagation and historical shoreline change calculated from satellite imagery, a direct correlation was found between shoreline movement, the depths and widths of reef flats, changes in the wave energy flux, and the radiation stresses of breaking waves. The findings indicate that the most remarkable efficacy in preventing beach erosion is due to reefs with shallow crests, wide reef flats, a dissipative lagoon seabed, located at ∼300 m from the coastline. The results provide essential insights for reef restoration projects focused on erosion mitigation and designing artificial reefs in microtidal sandy beaches. Results are limited to wave-dominated coasts.

Highlights

Over the last decade, scientific and engineering interest in determining how coastal ecosystems reduce the vulnerability of coastlines to erosion and flooding has increased
Reef hydrodynamics have been found to be as efficient as those of artificial low-crested breakwaters in decreasing the wave energy that reaches the coast by breaking the waves and by frictional dissipation (Lowe et al, 2005; Monismith et al, 2015)
We provide new insights into the role of reefs in beach morphodynamics at local and regional scales using wave modeling and historic shoreline changes near the Mesoamerican Reef at Puerto Morelos, Mexico

Summary

Introduction

Scientific and engineering interest in determining how coastal ecosystems reduce the vulnerability of coastlines to erosion and flooding has increased. Reef hydrodynamics have been found to be as efficient as those of artificial low-crested breakwaters in decreasing the wave energy that reaches the coast by breaking the waves and by frictional dissipation (Lowe et al, 2005; Monismith et al, 2015) This prevents flood damage and provide important risk reduction services to many reef-lined coasts (Beck et al, 2019; Reguero et al, 2019; Zhao et al, 2019). As biodiversity and ecosystem services continue to be lost on tropical coastlines, nature-based approaches are increasingly proposed as a solution to protect communities These alternatives, focus on imitating the performance of natural ecosystems and their ecological functions, unlike more traditional coastal structures such as breakwaters (Cardenas-Rojas et al, 2021). Reef-building species such as Acropora palmata are considered to provide fast and effective reef restoration, given their significant coral cover and the complex topography they provide (Bruckner et al, 2002; Alvarez-Filip et al, 2009)

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Results

Conclusion