Insights into barrier-island stability derived from transgressive/regressive state changes of Parramore Island, Virginia

Raff, Jessica L.; Shawler, Justin L.; Ciarletta, Daniel J.; Hein, Emily A.; Lorenzo‐Trueba, Jorge; Hein, Christopher J.

doi:10.1016/j.margeo.2018.04.007

Cited by 53 publications

(75 citation statements)

References 96 publications

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“…In the context of the Virginia system, where overwash‐driven landward migration and erosion dominates the response of barriers under low shoreface sediment flux conditions, we suggest Parramore Island's marginal rate of progradation (barely maintaining long‐term seaward advance) renders it particularly vulnerable to changes in sediment fluxes consistent with the magnitude of trapping at Fishing Point. Our results support the hypothesis proposed by Raff et al () that the Virginia barriers are subject to rapid state transitions (between net erosion, progradation, and migration) resulting from downdrift‐cascading sediment supply deficits.…”

Section: Discussionsupporting

confidence: 91%

“…Assuming long‐term (multi‐decadal through centennial) shoreface sediment fluxes are primarily derived from sediment delivered through the southerly longshore transport system, then changes in the progradation rate of northern Parramore Island—and by extension, changes in the morphology of associated foredune ridges—reflect changes in the rate of allogenic sediment delivery. Along the Virginia barrier islands, longshore sediment fluxes are controlled by such factors as updrift inlet configurations and sediment‐bypassing processes (FitzGerald, ), sediment trapping in flood‐tidal deltas associated with ephemeral inlets (Seminack & McBride, ), variations in ebb‐tidal delta storage (Fenster et al, ), and disruptions in sediment supply associated with the growth and erosion of updrift spits and islands (McBride et al, ; Raff et al, ). For example, Fishing Point itself—located updrift of the mixed‐energy barrier islands to the south—traps sand at a rate of up to 1.1 × 10 6 m 3 /year (Moffatt and Nichol, Engineers, ), removing it from the longshore transport system.…”

Section: Discussionmentioning

confidence: 99%

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Reconstructing Coastal Sediment Budgets From Beach‐ and Foredune‐Ridge Morphology: A Coupled Field and Modeling Approach

Ciarletta

Shawler²,

Tenebruso

et al. 2019

JGR Earth Surface

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Preserved beach and foredune ridges may serve as proxies for coastal change, reflecting alterations in sea level, wave energy, or past sediment fluxes. In particular, time‐varying shoreface sediment budgets have been inferred from the relative size of foredune ridges through application of radiocarbon and optically stimulated luminescence dating to these systems over the last decades. However, geochronological control requires extensive field investigation and analysis. Purely field‐based studies might also overlook relationships between the mechanics of sediment delivery to the shoreface and foredune ridges, missing insights about sensitivity to changes in sediment budget. We therefore propose a simple geomorphic model of beach/foredune‐ridge and swale morphology to quantify the magnitude of changes in cross‐shore sediment budget, employing field measurements of ridge volume, ridge spacing, elevation, and shoreline progradation. Model behaviors are constrained by the partitioning of sediment fluxes to the shoreface and foredune ridge and can be used to reproduce several cross‐shore patterns observed in nature. These include regularly spaced ridges (“washboards”), large singular ridges, and wide swales with poorly developed ridges. We evaluate our model against well‐preserved ridge and swale systems at two sites along the Virginia Eastern Shore (USA): Fishing Point, for which historical records provide a detailed history of shoreline progradation and ridge growth, and Parramore Island, for which a relatively more complex morphology developed over a poorly constrained period of prehistoric growth. Our results suggest this new model could be used to infer the sensitivity of field sites across the globe to variations in sediment delivery.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Reconstructing Coastal Sediment Budgets From Beach‐ and Foredune‐Ridge Morphology: A Coupled Field and Modeling Approach

Ciarletta

Shawler²,

Tenebruso

et al. 2019

JGR Earth Surface

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“…The progradation and elongation of Chincoteague and Assateague islands from ca. 1000 years ago (a) to present (b), resulted in the trapping of sand in subaerial portions of the these islands equivalent to the volume of the entire southern Virginia barrier-island chain (c), estimated from barrier areas combined with (commonly sparse) sediment core data from Rice et al (1976), Gayes (1983), Finkelstein and Ferland (1987), Byrnes (1988), Oertel et al (1989), and Raff et al (2018).…”

Section: Discussionmentioning

confidence: 99%

The Role of Coastal Sediment Sinks in Modifying Longshore Sand Fluxes: Examples From the Coasts of Southern Brazil and the Mid-Atlantic Usa

Hein

Shawler

Camargo

et al. 2019

Coastal Sediments 2019

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Coastal change fundamentally occurs in response to changes in the balance between accommodation creation and filling, the latter in part reflecting longshore sediment fluxes. In Santa Catarina (southern Brazil), growth of the Jurerê Strandplain trapped 50-110 x 10 6 m 3 of sand, effectively halting longshore transport for 3000 years; re-initiation of headland bypassing in the last 1000 years allowed for formation of the downdrift Daniela Spit. In northern Virginia (U.S. East Coast), elongation of the Assateague Island spit-end during just the last 100 years has sequestered a similar volume of sand (~45 x 10 6 m 3), reducing longshore transport fluxes by at least 25%, and contributing to the erosion and/or landward migration of adjacent, downdrift barrier islands. These findings demonstrate the potential for longshore sediment trapping through natural growth of updrift sediment sinks to control long-term and large-scale downdrift coastal behavior.

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“…They demonstrate highly variable geologic frameworks, sediment flux, subsidence rates and types of evolution, even across relatively small spatial scales (Anderson et al 2004, Otvos 2018. The geologic framework and inherited antecedent topography are critical factors impacting island progradational, retrogradational and or aggradational evolution modes (Raff et al 2018, Timmons et al 2010, paleovalleys anchoring tidal inlets (Mallinson et al 2010) and erosional hotspots (Twichell et al 2013, Hapke et al 2016, Honeycutt and Krantz 2003, Browder and McNich 2006. Stratigraphic framework, antecedent topography and relative sea level rise rates also strongly influences wave ravinement depths, which vary greatly across Texas (8-12m) (Rodriguez et al 2001, Wallace et al 2010Wallace and Anderson, 2013) and Louisiana (10-16m) (List et al 1994).…”

Section: Shorelines Of the Gulf Of Mexico Are Among The Most Vulnerabmentioning

confidence: 99%

“…However, observational data used to constrain models are usually limited to the instrumental record, which do not capture longer-term barrier system geomorphic threshold responses (island formation, stabilization, progradation, transgression, destruction). These geomorphic threshold responses result from forcing mechanisms such as changes in sea level increasing accommodation space by flooding antecedent topography (Rodriguez et al 2004, 2008, Anderson et al 2014 and changes in sediment supply (Raff et al 2018, Rodriguez et al 2018, Odezulu et al 2018. Many studies show the most complete records of coastal evolution are preserved within paleofluvial incised valleys and partially in antecedent shelf deposits (Anderson et al 2014, Mallinson et al 2010, Zaremba et al 2016, Nordfjord et al 2005.…”

mentioning

confidence: 99%

Late Quaternary evolution and stratigraphic framework influence on coastal systems along the north-central Gulf of Mexico, USA

Hollis

Wallace

Miner

et al. 2019

Quaternary Science Reviews

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Coastal systems in the Gulf of Mexico are threatened to reduced sediment supply, storm impacts and relative sea level rise (RSLR). The geologic record can provide insights of geomorphic threshold crossings (formation, progradation, transgression, destruction) to these forcing mechanisms to predict future barrier evolution to climate change. The stratigraphic framework and antecedent topography directly influence coastal evolution over geologic timescales. This study synthesizes ~2100km of geophysical data, 700+ sediment cores, and 63 radiocarbon dates to regionally map two sequence boundaries, multiple ravinement surfaces and fourteen depositional facies. One marine isotope stage (MIS) 6 valley's fill provided up to 300 x10 6 m 3 of sand to modern systems through transgressive ravinement during the Holocene. Repeated storm breaches or tidal inlets correspond to paleotopographic low's in the MIS 2 surface. A Holocene geomorphic evolutionary model was created for Petit Bois and Dauphin Island from available data, highlighting RSLR rates and sediment supply. As the MIS 2 surface was flooded, tidal/wave scour supplied sand to migrating marine shoals. These rapidly transgressing shoals converted drowned paleovalleys to estuaries starting about 9ka. Islands formed in their modern positions about 6ka, when sediment supply was high and RSLR rates were 2mm/yr. Between 4ka-1750 CE. Islands prograded due to RSLR rates of 1-0.4mm/yr and sufficient sand supply from alongshore and inner shelf sources. Currently, the islands experience RSLR rates of 3.61 mm/yr and reduced sediment supply resulting in barrier degradation. This study provides geologic evidence of coastal geomorphic thresholds related to RSLR, sediment supply and antecedent topography. iii ACKNOWLEDGMENTS I would like to thank my advisor, Dr. Davin Wallace for his guidance and great support through this project. I would also like to thank my committee members Dr. Michael Miner and Dr. Jessica Pilarczyk, and lab mates, Clayton Dike, Nina Gal, and Shara Gremillion for their helpful and insightful feedback and guidance. This project was funded by the Bureau of Ocean and Energy Management, as part of a Gulf of Mexico sand resource mapping effort. Thank you to colleagues at the University of Alabama, the Geological Survey of Alabama and USGS for allowing core sampling. The USGS and UTIG shared archive geophysical data. Mollusk bivalve identification was greatly aided by Dr. Jennifer Walker. Dr. John Anderson (Rice) and Dr. Ervin Otvos (USM) also provided valuable insight. iv DEDICATION This thesis is dedicated to friends, family and loved ones especially Bob, Ellen, Joey and Alli. Their love, appreciation and support allowed me to pursue my scientific passion. v

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Insights into barrier-island stability derived from transgressive/regressive state changes of Parramore Island, Virginia

Cited by 53 publications

References 96 publications

Reconstructing Coastal Sediment Budgets From Beach‐ and Foredune‐Ridge Morphology: A Coupled Field and Modeling Approach

Reconstructing Coastal Sediment Budgets From Beach‐ and Foredune‐Ridge Morphology: A Coupled Field and Modeling Approach

The Role of Coastal Sediment Sinks in Modifying Longshore Sand Fluxes: Examples From the Coasts of Southern Brazil and the Mid-Atlantic Usa

Late Quaternary evolution and stratigraphic framework influence on coastal systems along the north-central Gulf of Mexico, USA

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