Digital Commons Network^™

Quantifying Thresholds Of Barrier Geomorphic Change In A Cross-Shore Sediment-Partitioning Model, Daniel J. Ciarletta, Jennifer L. Miselis, Justin L. Shawler, Christopher J. Hein

VIMS Articles

Barrier coasts, including barrier islands, beach-ridge plains, and associated landforms, can assume a broad spectrum of morphologies over multi-decadal scales that reflect conditions of sediment availability, accommodation, and relative sea-level rise. However, the quantitative thresholds of these controls on barrier-system behavior remain largely unexplored, even as modern sea-level rise and anthropogenic modification of sediment availability increasingly reshape the world's sandy coastlines. In this study, we conceptualize barrier coasts as sediment-partitioning frameworks, distributing sand delivered from the shoreface to the subaqueous and subaerial components of the coastal system. Using an idealized morphodynamic model, we explore thresholds of behavioral and morphologic change …

Biophysical Controls Of Marsh Soil Shear Strength Along An Estuarine Salinity Gradient, Megan N. Gillen, Tyler C. Messerschmidt, Matthew L. Kirwan

VIMS Articles

Sea-level rise, saltwater intrusion, and wave erosion threaten coastal marshes, but the influence of salinity on marsh erodibility remains poorly understood. We measured the shear strength of marsh soils along a salinity and biodiversity gradient in the York River estuary in Virginia to assess the direct and indirect im-pacts of salinity on potential marsh erodibility. We found that soil shear strength was higher in monospecific salt marshes (5–36 kPa) than in biodiverse freshwater marshes (4–8 kPa), likely driven by differences in below ground biomass. However, we also found that shear strength at the marsh edge was controlled by sediment characteristics, …

How Old Are Marshes On The East Coast, Usa? Complex Patterns In Wetland Age Within And Among Regions, Anna E. Braswell, James B. Heffernan, Matthew L. Kirwan

VIMS Articles

Sea‐level dynamics, sediment availability, and marine energy are critical drivers of coastal wetland formation and persistence, but their roles as continental‐scale drivers remain unknown. We evaluated the timing and spatial variability of wetland formation from new and existing cores collected along the Atlantic and Gulf coasts of the United States. Most basal peat ages occurred after sea‐level rise slowed (after ~4,000 years before present), but predominance of sea‐level rise studies may skew age estimates toward older sites. Near‐coastal sites tended to be younger, indicating creation of wetlands through basin infilling and overwash events. Age distributions differed among regions, with younger …

Shoreline Dynamics Along A Developed River Mouth Barrier Island: Multi-Decadal Cycles Of Erosion And Event-Driven Mitigation, Christopher J. Hein, Andrrew R. Fallon, Peter Rosen, Et Al

VIMS Articles

Human modifications in response to erosion have altered the natural transport of sediment to and across the coastal zone, thereby potentially exacerbating the impacts of future erosive events. Using a combination of historical shoreline-change mapping, sediment sampling, three-dimensional beach surveys, and hydrodynamic modeling of nearshore and inlet processes, this study explored the feedbacks between periodic coastal erosion patterns and associated mitigation responses, focusing on the open-ocean and inner-inlet beaches of Plum Island and the Merrimack River Inlet, Massachusetts, United States. Installation of river-mouth jetties in the early 20th century stabilized the inlet, allowing residential development in northern Plum Island, but …

Reconstructing Coastal Sediment Budgets From Beach‐ And Foredune‐Ridge Morphology: A Coupled Field And Modeling Approach, Dj Ciarletta, Jl Shawler, C Tenebruso, Christopher J. Hein, J Lorenzo‐Trueba

VIMS Articles

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 …

Sea-Level And Crustal Movements Along The New England-Acadian Shore, 4,500-3,000 B.P, W. Harrison, C. J. Lyon

VIMS Articles

Remains of three drowned forests have been investigated at Odiorne Point, New Hampshire, and Fort Lawrence and Grand Pre, west-central Nova Scotia. Carbon-14 ages and altitudes below mean tide levels were determined for four in-place stumps of white pine at each locality. Assuming that each dated stump was killed by rising salt water, and that its C14 age represented its true age at death, it was possible to construct curves showing the sequence of submergence and emergence at each site.

A continuous transgression of the sea, approximating 0.31 foot per century, is indicated for the period 4,500-3,200 B.P. This rate …