The role of beach and sand dune vegetation in mediating wave run up erosion

Feagin, Rusty A.; Furman, M.; Salgado, Karla; Martínez, M. Luisa; Innocenti, Rachel A.; Eubanks, K. E.; Figlus, Jens; Huff, Thomas P.; Sigren, Jake; Silva, R.

doi:10.1016/j.ecss.2019.01.018

Cited by 98 publications

(69 citation statements)

References 39 publications

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“…Lack of data in dune vegetation did not allow considering the effect of dune vegetation in attenuating the wave run up and overtopping, although recent research shows that it can provide a reduction of wave-run up erosion of 40% (Feagin et al, 2019). Erosion of dunes under large storms was also not considered although it could reduce the effectiveness of dunes should they breach.…”

Section: The Effect Of Dunes In Coastal Riskmentioning

confidence: 99%

The Risk Reduction Benefits of the Mesoamerican Reef in Mexico

Reguero

Secaira²,

Toimil

et al. 2019

Front. Earth Sci.

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Coastal development and climate change are dramatically increasing the risks of flooding, erosion, and extreme weather events. Coral reefs and other coastal ecosystems act as natural defenses against coastal hazards, but their degradation increases risk to people and property. Environmental degradation, however, has rarely been quantified as a driver of coastal risk. In Quintana Roo, Mexico, a region on the Mexican Caribbean coast with an annual tourism economy of 10 billion USD, coral reefs constitute a natural barrier against flooding from hurricanes. This study spatially quantifies the risk reduction benefits of the Mesoamerican Reef in Quintana Roo for people, buildings, and hotel infrastructure. The risk reduction benefits are substantial. For example, the reefs prevented 43% additional damage during Hurricane Dean in (2007) and provide nowadays hazard risk reduction for 4.3% of the people, 1.9% of the built capital, and 2.4% of the hotel infrastructure, per year. The annual benefits are estimated in 4,600 people, 42 million USD damage prevention for buildings, and 20.8 million USD for hotel infrastructure. The study also compares the risk reduction of coral reefs with (i) the protection offered by dunes and (ii) the increase in coastal risk from sealevel rise (SLR). The risk reduction of dunes is more critical where there are no coral reefs offshore and for small return-periods storms. Sea-level rise, however, will make the more frequent storms more impactful and will drive significant increases in annual expected damages across the region. However, we demonstrate that, in coral reef environments, the contribution of reef degradation to coastal risk is larger than the expected increase in risk from SLR. However, the spatial distribution of the risk reduction benefits from reefs differs for people and infrastructure, and in particular for hotels, which receive the most protection from reefs. Furthermore, many sections present larger benefits than the typical costs of restoration. This valuation makes a compelling case for protecting and maintaining this natural infrastructure for its risk reduction service, but also allows the development of piloting innovative strategies, such as risk finance and insurance strategies, that can align environmental and risk management goals.

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Section: The Effect Of Dunes In Coastal Riskmentioning

confidence: 99%

The Risk Reduction Benefits of the Mesoamerican Reef in Mexico

Reguero

Secaira²,

Toimil

et al. 2019

Front. Earth Sci.

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“…In addition, dune crest erosion is also expected if the storm duration is long enough to produce erosion to the point where a dune is lowered leading to a shift in the storm impact regime (e.g., dune erosion and slumping leading to overwash; Stockdon et al, ), which surrogate models do not capture skillfully. As the duration of the storm is included in our surrogate models, this finding suggests that other processes not explicitly included here, such as the presence of vegetation which stabilizes dunes, may have a larger influence on dune erosion during the collision regime (Charbonneau et al, ; Feagin et al, ).…”

Section: Discussionmentioning

confidence: 98%

Combining Numerical and Statistical Models to Predict Storm‐Induced Dune Erosion

et al. 2019

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Dune erosion is an important aspect to consider when assessing coastal flood risk, as dune elevation loss makes the protected areas more susceptible to flooding. However, most advanced dune erosion numerical models are computationally expensive, which hinders their application in early-warning systems. Based on a combination of probabilistic and process-based numerical modeling, we develop an efficient statistical tool to predict dune erosion during storms. The analysis focuses on Dauphin Island, AL, in the northern Gulf of Mexico, where we combine synthetic sea storms with a calibrated and validated XBeach model to develop and test a range of different surrogate models for their ability to predict barrier island geometric parameters under storm conditions. Surrogate models are developed by combining the oceanographic forcing from 100 optimally sampled sea storm events covering the entire multivariate parameter space (used as XBeach input) and associated changes in the dune system (XBeach output). We test four surrogate models using a k-fold approach for validation. All models perform well in predicting changes in dune elevation, barrier island area, and width but are less accurate in predicting alterations in the cross-shore locations of dune morphological features. Multivariate adaptive regression splines is identified as the best surrogate model based on its fast development and good performance, attaining a modified Mielke index of 0.81 for dune crest height. As demonstrated at Dauphin Island, our approach shows potential to be used in an operational framework to predict dune response (in particular crest elevation change) when water level and wave forecasts are available. Key Points: • Surrogate models of XBeach are developed and tested, showing that multivariate adaptive regression splines exhibits the best performance • Carefully trained statistical and machine-learning models predict changes in barrier island geometric parameters at low computational cost • The highest performance is attained for the most extreme dune impact regimes, allowing fast and accurate dune height change predictions Correspondence to:Here, surrogate models are designed to predict coastal dune erosion by addressing issues related to computational performance and absence of sufficient forcing data. Our main goal is to understand complex morphological interactions through simulation of a wide range of realistic scenarios. To accomplish this, we develop and test surrogate models for XBeach that are trained with simulated, physically consistent oceanographic variables and associated dune response. This includes the following steps: (1) select a subset of synthetic multivariate sea storm events from Wahl et al. (2016) and consider time-dependent evolution of the oceanographic variables, (2) use XBeach to predict morphological response parameters for the selected sea storms, and (3) develop and test a range of different surrogate models to mimic XBeach at low computational cost. The different analysis steps are summarized in Figure 1. In...

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“…Furthermore, little consideration is being given to concerns arising from dune rejuvenation leading to increased coastal erosion (Lindell et al 2017). Vegetation reduces wave run up dune erosion by approximately 40% (Feagin et al 2019), with vegetated foredunes having poststorm sediment volumes that are larger than dunes with no vegetation (Maximiliano-Córdova et al 2019). The presence of plants decreases scarp retreat by over 30%, and mature roots double the time for dune structural failure and increase the shear required to erode sediment by 180% (Sigren et al 2014).…”

Section: Shift In Paradigm and Critical Examination Of Dune Rejuvenatmentioning

confidence: 99%

Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary

2019

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Coastal dunes are experiencing increases in vegetation cover and reduced mobility levels in many sites around the world. Ecology-led approaches to coastal dune management perceive this change as 'undesirable' because the increase in plant cover leads to a reduction in partially vegetated to bare sand habitats and the species depending on them. This has generated a shift in the management paradigm where the objective is to revert this trend by intervening in the landscape, with actions ranging from reintroducing grazing and mowing, to mechanical removal of dune form and vegetation (dune 'rejuvenation'). In some cases, such as many coastal dunes in Britain, this has also led to low controls on visitor pressure and allowing/promoting human trampling as a 'natural' way to free up areas of bare sand. This commentary critically analyses the main principles (and terminology) underlying this relatively recent shift in management paradigm, and questions assumptions such as 'bare sand is good' and/or 'mobility is natural' in the context of dune evolutionary cycles and responses to abiotic and biotic drivers. We review the limitations and dangers of this approach and argue that it is not sustainable given the current climatic and environmental conditions, and that it can increase the risk of coastal erosion and force dune systems to deviate from adapting and changing to direct/indirect drivers. Finally, we present the benefits of a management approach that focuses on minimizing human impacts so that natural processes continue to occur.

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The role of beach and sand dune vegetation in mediating wave run up erosion

Cited by 98 publications

References 39 publications

The Risk Reduction Benefits of the Mesoamerican Reef in Mexico

The Risk Reduction Benefits of the Mesoamerican Reef in Mexico

Combining Numerical and Statistical Models to Predict Storm‐Induced Dune Erosion

Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary

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