Characterization of vegetated and ponded wetlands with implications towards coastal wetland marsh collapse

Cadigan, Jack A.; Jafari, Navid H.; Stagg, Camille L.; Laurenzano, Claudia; Harris, Brian D.; Meselhe, Amina E.; Dugas, Jason L.; Couvillion, Brady R.

doi:10.1016/j.catena.2022.106547

Cited by 6 publications

(17 citation statements)

References 56 publications

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“…The furthest inland tests, Figure 14C, display similar resistance curves with depth, and a single, sharp peak in the upper soil column. The shape of the resistance with depth curve is similar to other Louisiana wetlands, where the vegetative root depth extends to depths of approximately 20-30 cm (Jafari et al, 2019a;Jafari et al, 2019b;Harris B. D. et al, 2020;Cadigan et al, 2020). The identical profiles, and singular-peaks of the resistance curves, indicate that the furthest inland sites are likely unaffected by the storms to a significant degree as compared to the sites closer to the shoreline.…”

Section: Wetland Strengthsupporting

confidence: 67%

“…Between 2009 and 2019, the shoreline experienced approximately 170 m of retreat (Figure 2C) as evidenced by the transition of the offshore monitoring station from wetland to open-water. No significant pond expansion is visible inland, suggesting that wetland elevation and vegetation health in the saltmarsh in this system are relatively stable until directly affected by processes such as shoreline retreat (Cadigan et al, 2020). The location of the edge of the breakwater noted in Figure 2D corresponds to the progress made towards construction of the breakwater system between 2019-2020 prior to the 2020 hurricane season.…”

Section: Instrumentation and Data Collection Planmentioning

confidence: 94%

“…The resulting NDVI maps were compared to NDVI values calculated from Sentinel-2 satellite imagery retrieved and processed using Google Earth Engine (Gorelick et al, 2017). Cone penetrometer tests (CPT) were performed using a modified sleeve designed to better capture the effects of vegetation in the soil column after Hurricane Delta on 26 October 2020 along both transects to measure sediment shear strength and to identify any stratigraphic changes (Jafari et al, 2019a;Harris B. D. et al, 2020;Cadigan et al, 2020;Harris et al, 2021). Multispectral imagery at both transects was collected through DJI Matrice 210 surveys on 4 September 2020 and 26 October 2020 and true-color aerial imagery at both transects was captured via DJI Mavic Pro 2 surveys after Hurricane Delta on 26 October 2020.…”

Section: Instrumentation and Data Collection Planmentioning

confidence: 99%

“…The storm driven sediment deposition on the interior of the wetlands (Figures 8, 9) is also of great interest as wetland elevation is strongly tied to vegetative health and wetland stability (Cahoon et al, 2006;Chambers et al, 2019;Cadigan et al, 2020). The highest accretion values in RWR by far were found at the mouth of Rollover Bayou, which experienced a major depositional event consisting of a very large lens (in the order of 2.5 km 2 ) of fine grained mud deposit with a thickness of approximately 1800 mm (1.8 m or 6 ft) in the middle and tapering off towards the edges.…”

Section: Observations Of the Mud Deposit At Rollover Bayoumentioning

confidence: 99%

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Impacts of Coastal Infrastructure on Shoreline Response to Major Hurricanes in Southwest Louisiana

Cadigan

Bekkaye

Jafari

et al. 2022

Front. Built Environ.

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The Rockefeller Wildlife Refuge, located along the Chenier Plain in Southwest Louisiana, was the location of the sequential landfall of two major hurricanes in the 2020 hurricane season. To protect the rapidly retreating coastline along the Refuge, a system of breakwaters was constructed, which was partially completed by the 2020 hurricane season. Multi-institutional, multi-disciplinary rapid response deployments of wave gauges, piezometers, geotechnical measurements, vegetation sampling, and drone surveys were conducted before and after Hurricanes Laura and Delta along two transects in the Refuge; one protected by a breakwater system and one which was the natural, unprotected shoreline. Geomorphological changes were similar on both transects after Hurricane Laura, while after Delta there was higher inland sediment deposition on the natural shoreline. Floodwaters drained from the transect with breakwater protection more slowly than the natural shoreline, though topography profiles are similar, indicating a potential dampening or complex hydrodynamic interactions between the sediment—wetland—breakwater system. In addition, observations of a fluidized mud deposit in Rollover Bayou in the Refuge are presented and discussed in context of the maintenance of wetland elevation and stability in the sediment starved Chenier Plain.

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Section: Wetland Strengthsupporting

confidence: 67%

Section: Instrumentation and Data Collection Planmentioning

confidence: 94%

Section: Instrumentation and Data Collection Planmentioning

confidence: 99%

Section: Observations Of the Mud Deposit At Rollover Bayoumentioning

confidence: 99%

See 2 more Smart Citations

Impacts of Coastal Infrastructure on Shoreline Response to Major Hurricanes in Southwest Louisiana

Cadigan

Bekkaye

Jafari

et al. 2022

Front. Built Environ.

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“…1981; Wasson et al., 2019; Wells, 1996). The salt marsh resistance to these external factors is linked to sediment dynamics, with a major emphasis placed on vertical accretion and relative sea‐level rise that links to interior marsh ponding (Cadigan et al., 2022; Day et al, 1998; FitzGerald et al, 2008; Kirwan et al, 2016; Pethick, 1993; Priestas et al, 2015; Temmerman & Kirwan, 2015; Temmerman et al, 2005). However, salt marshes are also inherently weak and vulnerable to shoreline retreat (i.e., marsh edge erosion) caused by waves from hurricanes and storms (Barras et al, 1994; Cadigan et al, 2022; Day et al, 2007; Jadhav et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Near‐continuous monitoring of a coastal salt marsh margin: Implications for predicting marsh edge erosion

Cadigan

Jafari

Wang

et al. 2023

Earth Surf Processes Landf

Self Cite

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Mechanisms that control marsh edge erosion include wind‐generated waves, vegetation productivity, land use and land change, and geotechnical properties of sediments. However, existing models for predicting marsh edge evolution focus primarily on edge retreat rates as a function of wave energy while accounting for other controlling factors as empirical constants. This simplification arises from a lack of high‐frequency monitoring of marsh evolutions. In particular, marsh erosion is timescale dependent, and conducting field observations on short temporal and spatial scales could elucidate the progression of erosion, which may improve marsh erosion predictive models. This study developed and validated a near‐continuous camera and erosion pin monitoring system to document marsh edge erosion at a high frequency (i.e., daily) in Terrebonne Bay, Louisiana. This was supplemented with daily wave power to explore the relationships between daily erosion and wave power. Long‐term average erosion rates derived from satellite and aerial imagery from 1989 through 2019 compare similarly to rates derived from longer‐term site visits (i.e., monthly) at approximately 2.2 m/yr. High‐magnitude erosion events (>20 cm/day) are driven by a buildup in wave energy over a 7‐day time period coupled with a strong 1‐day wave event, indicating a gradual reduction in marsh edge resistance with continued wave attack. Long‐term erosion monitoring methods, including monthly field visits, provide results that align well with previously reported relationships between wave power and erosion. High‐frequency measurements, however, illustrate that the previously published trends smooth over the large‐magnitude short‐term erosion events, potentially obscuring the physical processes of marsh edge erosion. For example, satellite and aerial imagery provide a long period of record, but they may underestimate the average annual erosion rate in the region, the effect of which may become exasperated over the varying temporal scales considered in coastal planning efforts across the USA and worldwide.

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Evaluating Hydrogeomorphic Condition Across Ecosystem States in a Non-tidal, Brackish Peat Marsh of the Florida Coastal Everglades, USA

Lamb-Wotton,

Troxler,

Coronado-Molina

et al. 2024

Estuaries and Coasts

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Emergent marsh and open water have been identified as alternate stable states in tidal marshes with large, relative differences in hydrogeomorphic conditions. In the Florida coastal Everglades, concern has been raised regarding the loss of non-tidal, coastal peat marsh via dieback of emergent vegetation and peat collapse. To aid in the identification of alternate stable states, our objective was to characterize the variability of hydrogeomorphic and biologic conditions using a field survey and long-term monitoring of hydrologic and geomorphic conditions across a range of vegetated (emergent, submerged) and unvegetated (open water) communities, which we refer to as “ecosystem states,” in a non-tidal, brackish peat marsh of the coastal Everglades. Results show (1) linear relationships among field-surveyed geomorphic, hydrologic, and biologic variables, with a 35-cm mean difference in soil surface elevation between emergent and open water states, (2) an overall decline in soil elevation in the submerged state that was related to cumulative dry days, and (3) a 2× increase in porewater salinity during the dry season in the emergent state that was also related to the number of dry days. Coupled with findings from previous experiments, we propose a conceptual model that describes how seasonal hydrologic variability may lead to ecosystem state transitions between emergent and open water alternate states. Since vegetative states are only moderately salt tolerant, as sea-level rise pushes the saltwater front inland, the importance of continued progress on Everglades restoration projects, with an aim to increase the volume of freshwater being delivered to coastal wetlands, is the primary management intervention available to mitigate salinization and slow ecosystem state shifts in non-tidal, brackish peat marshes.

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Characterization of vegetated and ponded wetlands with implications towards coastal wetland marsh collapse

Cited by 6 publications

References 56 publications

Impacts of Coastal Infrastructure on Shoreline Response to Major Hurricanes in Southwest Louisiana

Impacts of Coastal Infrastructure on Shoreline Response to Major Hurricanes in Southwest Louisiana

Near‐continuous monitoring of a coastal salt marsh margin: Implications for predicting marsh edge erosion

Evaluating Hydrogeomorphic Condition Across Ecosystem States in a Non-tidal, Brackish Peat Marsh of the Florida Coastal Everglades, USA

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