Salt marsh resilience to sea-level rise and increased storm intensity

Pannozzo, Natascia; Leonardi, Nicoletta; Carnacina, Iacopo; Smedley, Rachel

doi:10.1016/j.geomorph.2021.107825

Cited by 21 publications

(5 citation statements)

References 61 publications

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“…In this study, we addressed the issue by simulating a prescribed set of storm surges and combining them to produce a realistic forecast that accounts for both magnitude and frequency of storms. This approach differs from the more traditional methodology of running a limited number of fictional scenarios in which a set of parameters such as surge, relative sea level, and wind speed are changed (e.g., Mariotti et al., 2010; Pannozzo et al., 2021). Note that our simulations are short, lasting 8 days, while the inorganic mass accumulation rates are measured in years.…”

Section: Discussionmentioning

confidence: 99%

“…Sediments that are brought over the marsh during a storm can originate from rivers or the bottom of nearby bays, channels, and mudflats. In addition, during storms, marshes themselves can act as a source of material (Pannozzo et al., 2023). In this case, the lateral erosion generated by waves impacting marsh edges provides additional material to the system (Hopkinson et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

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Storm Impacts on Mineral Mass Accumulation Rates of Coastal Marshes

Cortese,

Zhang,

Simard

et al. 2024

JGR Earth Surface

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Coastal marsh survival may be compromised by sea‐level rise, limited sediment supply, and subsidence. Storms represent a fundamental forcing for sediment accumulation in starving marshes because they resuspend bottom material in channels and tidal flats and transport it to the marsh surface. However, it is unrealistic to simulate at high resolution all storms that occurred in the past decades to obtain reliable sediment accumulation rates. Similarly, it is difficult to cover all possible combinations of water levels and wind conditions in fictional scenarios. Thus, we developed a new method that derives long‐term deposition rates from short‐term deposition generated by a finite number of storms. Twelve storms with different intensity and frequency were selected in Terrebonne Bay, Louisiana, USA and simulated with the 2D Delft3D‐FLOW model coupled with the Simulating Waves Nearshore (SWAN) module. Storm impact was analyzed in terms of geomorphic work, namely the product of deposition and frequency. To derive the long‐term inorganic mass accumulation rates, the new method generates every possible combination of the 12 chosen storms and uses a linear model to fit modeled inorganic deposition with measured inorganic mass accumulation rates. The linear model with the best fit (highest R2) was used to derive a map of inorganic mass accumulation rates. Results show that a storm with 1.7 ± 1.6 years return period provides the largest geomorphic work, suggesting that the most impactful storms are those that balance intensity with frequency. Model results show higher accumulation rates in marshes facing open areas where waves can develop and resuspend sediments. This method has the advantage of considering only a few real scenarios and can be applied in any marsh‐bay system.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Storm Impacts on Mineral Mass Accumulation Rates of Coastal Marshes

Cortese,

Zhang,

Simard

et al. 2024

JGR Earth Surface

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“…When mudflat platforms reach an elevation which is above sea-level, tidal creeks form and become the main mean through which marine sediments can reach the marsh platform and deposit; they transport silt-sized sediments to the marsh areas of higher elevation during flood tide and deposit them during ebb tide (Reed et al, 1999). The sandy layers that punctuate the upper 100 cm of the core are instead likely to be caused by infilling of fine sand through load traction during occasional flooding of the marsh platform owed to spring tide high waters or storm surges (Pannozzo et al, 2021a(Pannozzo et al, , 2021b). Accordingly, the numerical simulations show that the sediment budget of Hesketh Out Marsh decreases toward present day both for embankments and no-embankments scenarios (Figure 8a).…”

Section: Natural Accretion Of the Marshmentioning

confidence: 99%

An Integration of Numerical Modeling and Paleoenvironmental Analysis Reveals the Effects of Embankment Construction on Long‐Term Salt Marsh Accretion

et al. 2022

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Salt marshes are ecosystems of high environmental and economic value that provide a variety of services, including nutrient removal, habitat provision and high rates of carbon sequestration at geological time scales (Barbier et al., 2011;Zedler & Kercher, 2005). As a result of their ability to buffer storm waves, they also provide coastal protection against flooding (e.g., Leonardi et al., 2018;Moller et al., 1999), which led to a worldwide effort to create new salt marshes and/or restore salt marshes that were previously reclaimed for anthropogenic activities to provide long-term and low-cost coastal protection (Temmerman et al., 2013).Salt marshes form when tidal flats increase in elevation with respect to sea-level, through the delivery of fine sediment from rivers and the sea to estuarine accommodation space, which creates newly exposed surfaces that

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“…Our goal is to utilize high‐spatial resolution, remotely sensed maps of water‐level change beneath the vegetation canopy to determine the factors influencing water movement in marshes during a falling tide. This analysis is particularly important for quantifying the resilience of marshes (e.g., French & Spencer, 1993; Pannozzo et al., 2021; Sullivan et al., 2019). In fact, when water drains back to the ocean, nutrients and sediments are released within the surrounding environment, which has consequences for the long‐term evolution of these vegetated ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Spatial Variability in Salt Marsh Drainage Controlled by Small Scale Topography

Donatelli,

Passalacqua,

Jensen

et al. 2023

JGR Earth Surface

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Water movement in coastal wetlands is affected by spatial differences in topography and vegetation characteristics as well as by complex hydrological processes operating at different time scales. Traditionally, numerical models have been used to explore the hydrodynamics of these valuable ecosystems. However, we still do not know how well such models simulate water‐level fluctuations beneath the vegetation canopy since we lack extensive field data to test the model results against observations. This study utilizes remotely sensed images of sub‐canopy water‐level change to understand how marshes drain water during falling tides. We employ rapid repeat interferometric observations from the NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar instrument to analyze the spatial variability in water‐level change within a complex of marshes in Terrebonne Bay, Louisiana. We also used maps of herbaceous aboveground biomass derived from the Airborne Visible/Infrared Imaging Spectrometer‐Next Generation to evaluate vegetation contribution to such variability. This study reveals that the distribution of water‐level change under salt marsh canopies is strongly influenced by the presence of small geomorphic features (<10 m) in the marsh landscape (i.e., levees, tidal channels), whereas vegetation plays a minor role in retaining water on the platform. This new type of high‐resolution remote sensing data offers the opportunity to study the feedback between hydrodynamics, topography and biology throughout wetlands at an unprecedented spatial resolution and test the capability of numerical models to reproduce such patterns. Our results are essential for predicting the vulnerability of these delicate environments to climate change.

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Salt marsh resilience to sea-level rise and increased storm intensity

Cited by 21 publications

References 61 publications

Storm Impacts on Mineral Mass Accumulation Rates of Coastal Marshes

Storm Impacts on Mineral Mass Accumulation Rates of Coastal Marshes

An Integration of Numerical Modeling and Paleoenvironmental Analysis Reveals the Effects of Embankment Construction on Long‐Term Salt Marsh Accretion

Spatial Variability in Salt Marsh Drainage Controlled by Small Scale Topography

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