Effects of Roughness Loss on Reef Hydrodynamics and Coastal Protection: Approaches in Latin America

Osorio-Cano, Juan D.; Alcérreca‐Huerta, Juan Carlos; Mariño‐Tapia, Ismael; Osorio, Andrés F.; Acevedo-Ramirez, César A.; Enríquez, Cecilia; Costa, Mirella Borba Santos Ferreira; Pereira, Pedro; Mendoza, Edgar; Escudero, Mireille; Astorga-Moar, Alejandro; López-González, José; Appendini, Christian M.; Silva, Rodolfo; Oumeraci, Hocine

doi:10.1007/s12237-019-00584-4

Cited by 23 publications

(13 citation statements)

References 67 publications

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“…Although the fw value agreed with previous findings, the cf value was lower than expected when comparing to similar studies (e.g., Péquignet et al, 2011). It is well documented that small changes in reef composition can have large effects on the bottom roughness and, in turn, change the nearshore hydrodynamics (e.g., Osorio-Cano et al, 2019;Reguero et al, 2019). Fiji, like many Pacific Island countries has reported coastal degradation over recent years.…”

Section: Numerical Model (Xbeach)supporting

confidence: 86%

“…Another possible solution to improve the model could be to apply a varying friction coefficient depending on marine habitat across the model domain (Passeri et al, 2018). Coral reefs are complex systems in terms of geometry and bottom roughness; hence, incorporating this complexity into the numerical model might improve the results (e.g., Osorio-Cano et al, 2019;Reguero et al, 2019;Silva et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

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Distant-Source Swells Cause Coastal Inundation on Fiji’s Coral Coast

et al. 2020

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Distant-source swells are known to regularly inundate low-lying Pacific Island communities. Here we examine extreme total water level (TWL) and inundation driven by a distant-source swell on Fiji's Coral Coast using observations and a phase-resolving wave model (XBeach). The objective of this study is to increase understanding of swell-driven hazards in fringing reef environments to identify the contribution of wave setup and infragravity waves to extreme TWL and to investigate coastal flooding during present and future sea levels. The maximum TWL near the shore was caused by compounding mechanisms, where tides, wave setup, infragravity waves, and waves in the sea swell frequencies contributed to the TWL. Waves and wave setup on the reef were modulated by offshore wave heights and tides with increased setup during low tide and increased wave heights during high tide. Numerical simulations were able to reproduce the mechanisms contributing to the extreme TWL and allowed an estimation of the inundation extent. Simulations of the same swell under the RCP8.5 sea-level rise scenario suggest the area of inundation would increase by 97% by 2100. A comparison between the numerical model, a multiple linear regression model, and two commonly used parametric models reveals that both XBeach and the linear regression model are better suited to reproduce the nearshore wave setup and TWL than the empirical equations. The results highlight the need for customized, site-specific coastal hazard assessments and inundation forecast systems in the South Pacific.

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Section: Numerical Model (Xbeach)supporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Distant-Source Swells Cause Coastal Inundation on Fiji’s Coral Coast

et al. 2020

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“…Quataert et al [19] and Lowe et al [51] reported friction coefficients of 0.3 from field data from reefs in the Marshall Islands and Hawaii respectively. Osorio-Cano et al [17] claim that friction factors are within the range of 0.2-0.3 for healthy coral reefs. Nevertheless, some studies report higher friction coefficients in reefs of higher complexity such as 0.6 and 0.8 at the Ningaloo reef [29] and 1.8 at the structurally complex forereef at Palmyra Atoll [52].…”

Section: Modeling Approach and Input Parametersmentioning

confidence: 99%

“…In addition to natural and anthropogenic impacts, these unique ecosystems are threatened by diverse processes derived from climate change, as sea-level rise (SLR) and changes in pH and water temperature. For example, coral bleaching events and ocean acidification threaten reef ecosystems reducing bottom friction [17]. Reef degradation reduces their ability to mitigate the effects of coastal hazards and modifies nearshore dynamics, increasing the vulnerability of the coast to erosion and flooding events [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Impact of Climate Change on Nearshore Waves at a Beach Protected by a Barrier Reef

Lalouvière

Gràcia

Sierra

et al. 2020

Water

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Barrier reefs dissipate most incoming wind-generated waves and, as a consequence, regulate the morphodynamics of its inbounded shorelines. The coastal protective capacity of reefs may nevertheless be compromised by climate change effects, such as reef degradation and sea-level rise. To assess the magnitude of these climate change effects, an analysis of the waves propagating across the barrier reef is carried out in Flic-en-Flac beach, Mauritius, based on scenarios of future sea levels and predicted coral reef condition. In the study, both the mean wave climate and extreme event conditions are considered. The results show that lower coral structure complexity jointly with higher water levels allow for higher waves to pass over the reef and, therefore, to reach the shoreline. In addition, modeling for cyclonic conditions showed that nearshore waves would also increase in height, which could lead to major coastal morphodynamic changes. Measures aimed at preserving the coral reef may allow the system to accommodate for the gradual climatic changes forecasted while keeping its coastal protective function.

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“…The presented methodology has been demonstrated with many coral reef properties set as constant. It is well-established that changes in the roughness and friction (Lowe et al, 2005;Pomeroy et al, 2012;Monismith et al, 2015;Buckley et al, 2016;Rogers et al, 2017Rogers et al, , 2018Osorio-Cano et al, 2019;Reguero et al, 2019), porosity (Lowe et al, 2008;Asher et al, 2016;Asher and Shavit, 2019;Zhu et al, 2019), and storm surge (Hoeke et al, 2013;Smithers and Hoeke, 2014;Tajima et al, 2016) will affect the hydrodynamics over a coral reef, and in turn the resulting wave runup at the shoreline. Therefore, the RCPs as they are currently do provide a means to estimate wave runup based on reef morphology, although the estimate is limited to coral reefs with similar properties used in this study.…”

Section: Application Of the Methodologymentioning

confidence: 99%

Hydro-Morphological Characterization of Coral Reefs for Wave Runup Prediction

et al. 2020

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Many coral reef-lined coasts are low-lying with elevations <4 m above mean sea level. Climate-change-driven sea-level rise, coral reef degradation, and changes in storm wave climate will lead to greater occurrence and impacts of wave-driven flooding. This poses a significant threat to their coastal communities. While greatly at risk, the complex hydrodynamics and bathymetry of reef-lined coasts make flood risk assessment and prediction costly and difficult. Here we use a large (>30,000) dataset of measured coral reef topobathymetric cross-shore profiles, statistics, machine learning, and numerical modeling to develop a set of representative cluster profiles (RCPs) that can be used to accurately represent the shoreline hydrodynamics of a large variety of coral reef-lined coasts around the globe. In two stages, the large dataset is reduced by clustering cross-shore profiles based on morphology and hydrodynamic response to typical wind and swell wave conditions. By representing a large variety of coral reef morphologies with a reduced number of RCPs, a computationally feasible number of numerical model simulations can be done to obtain wave runup estimates, including setup at the shoreline and swash separated into infragravity and sea-swell components, of the entire dataset. The predictive capability of the RCPs is tested against 5,000 profiles from the dataset. The wave runup is predicted with a mean error of 9.7-13.1%, depending on the number of cluster profiles used, ranging from 312 to 50. The RCPs identified here can be combined with probabilistic tools that can provide an enhanced prediction given a multivariate wave and water level climate and reef ecology state. Such a tool can be used for climate change impact assessments and studying the effectiveness of reef restoration projects, as well as for the provision of coastal flood predictions in a simplified (global) early warning system.

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Effects of Roughness Loss on Reef Hydrodynamics and Coastal Protection: Approaches in Latin America

Cited by 23 publications

References 67 publications

Distant-Source Swells Cause Coastal Inundation on Fiji’s Coral Coast

Distant-Source Swells Cause Coastal Inundation on Fiji’s Coral Coast

Impact of Climate Change on Nearshore Waves at a Beach Protected by a Barrier Reef

Hydro-Morphological Characterization of Coral Reefs for Wave Runup Prediction

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