Dynamic allometry in coastal overwash morphology

Allometry refers to a physical principle in which geometric (and/or metabolic) characteristics of an object or organism are correlated to its size. Allometric scaling relationships typically manifest as power laws. In geomorphic contexts, scaling relationships are a quantitative signature of organization, structure, or regularity in a landscape, even if the mechanistic processes responsible for creating such a pattern are unclear. Despite the ubiquity and variety of scaling relationships in physical landscapes, the emergence and development of these relationships tend to be difficult to observe - either because the spatial and/or temporal scales over which they evolve are so great or because the conditions that drive them are so dangerous (e.g. an extreme hazard event). Here, we use a physical experiment to examine dynamic allometry in overwash morphology along a model coastal barrier. We document the emergence of a canonical scaling law for length versus area in overwash deposits (washover). Comparing the experimental features, formed during a single forcing event, to 5 decades of change in real washover morphology from the Ria Formosa barrier system, in southern Portugal, we find differences between patterns of morphometric change at the event scale versus longer timescales. Our results may help inform and test process-based coastal morphodynamic models, which typically use statistical distributions and scaling laws to underpin empirical or semi-empirical parameters at fundamental levels of model architecture. More broadly, this work dovetails with theory for landscape evolution more commonly associated with fluvial and alluvial terrain, offering new evidence from a coastal setting that a landscape may reflect characteristics associated with an equilibrium or steady-state condition even when features within that landscape do not.Funding Agency NERC Natural Environment Research Council NE/N015665/2 Leverhulme Trust RPG-2018-282info:eu-repo/semantics/publishedVersio

Response of wave-dominated and mixed-energy barriers to storms

EPSRC funded EP/I035390/1 The full text is under embargo until 15.05.15

Quantifying overwash flux in barrier systems : an example from Martha’s Vineyard, Massachusetts, USA

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2011Coastal barriers are particularly susceptible to the predicted effects of accelerated of sea-level rise and the potential for increased impacts of intense storms. Over centennial scales, barriers are maintained via overtopping during storms, causing deposition of washover fans on their landward sides. This study examines three washover fans on the south shore of Martha’s Vineyard using a suite of data including vibracores, ground penetrating radar, high resolution dGPS, and LiDAR data. From these data, the volumes of the deposits were determined and range from 2.1—2.4 x 104 m3. Two overwashes occurred during Hurricane Bob in 1991. The water levels produced by this storm have a return interval of ~28 years, resulting in an onshore sediment flux of 2.4—3.4 m3/m/yr. The third washover was deposited by a nor’easter in January 1997, which has a water level return interval of ~6 years, resulting in a flux of 8.5 m3/m/yr. These fluxes are smaller than the flux of sediment needed to maintain a geometrically stable barrier estimated from shoreline retreat rates, suggesting that the barrier is not in long-term equilibrium, a result supported by the thinning of the barrier over this time interval.Funding for this research was provided by an Emery Fellowship through the Woods Hole Oceanographic Institution Academic Programs Office, the National Science Foundation (grants NSF-GEO-0815875 and NSF-OCE-0840894), and the Department of Defense Strategic Environmental Research and Development Program (contract W912HQ-09-C-0043)

Environmental Factors Affecting Hatch Success in the Loggerhead Sea Turtle (Caretta caretta)

The loggerhead turtle (Caretta caretta) is a species federally listed as “threatened” whose global populations are declining. Georgia Department of Natural Resources conservation protocols for this species require the daily monitoring of nesting activity and permit physical relocation of nests which are at risk of being eroded or flooded by storms and high tides in order to increase hatch success--the proportion of hatched to unhatched eggs. Relocated nests are moved to an area with higher elevation in order to avoid flooding, but other variables such as increased temperature and decreased moisture are introduced when relocating. For years temperature and moisture have been regarded as the most important factors that contribute to hatch success but these variables are not always directly considered when relocating nests. It is likely that other environmental variables have an effect on hatch success and influence temperature and moisture. The hypothesis that a combination of geological and biological factors better predicts hatch success compared to temperature and/or moisture alone was tested. Secondly the environmental variables which influence temperature, moisture, and likelihood of tidal washover were also examined to evaluate their impact on hatch success. Loggerhead nests on Ossabaw Island, Georgia were monitored throughout incubation; upon incubation completion, hatch success was calculated. For all nests, temperature, moisture, vegetation cover and composition, elevation, dune morphology, and tidal washovers were recorded. These variables were analyzed to assess their individual and combined influences on nest conditions and ultimately on hatch success. In addition to number of washover events, temperature, and moisture, nest vegetation and elevation were important predictors of hatch success in loggerhead sea turtle nests and should be considered when nest relocation is required

Southern North Sea storm surge event of 5 December 2013: Water levels, waves and coastal impacts

The storm surge event that affected the coastal margins of the southern North Sea on 5–6 December 2013 produced the highest still water levels on record at several tide gauges on the UK east coast. On east-facing coasts south of the Humber estuary and north-facing Norfolk, water levels were higher than in the twentieth century benchmark surge event of 31 January–1 February 1953. Maximum significant wave heights were highest off the North Norfolk coast (peak Hs = 3.8 m offshore, 2.9 m inshore) and lowest off the Suffolk coast (Hs = 1.5–1.8 m inshore); comparable offshore wave heights in 1953 were 7–8 m and ca. 3 m. The lower wave heights, and their short duration, in 2013 explain both localised breaching, overtopping, and back-barrier flooding associated with gravel ridges and relatively low earthen banks as well as the lack of failure in more highly-engineered coastal defences. On barrier coasts and within estuaries, the signal of maximum runup was highly variable, reflecting the modification of the tide–surge–wave signal by inshore bathymetry and the presence of a range of coastal ecosystems. The landscape impacts of the December 2013 surge included the notching of soft rock cliffs and cliffline retreat; erosion of coastal dunes; and the augmentation or re-activation of barrier island washover deposits. Whilst surge event-related cliff retreat on the rapidly eroding cliffs of the Suffolk coast lay within the natural variability in inter-annual rates of retreat, the impact of the surge on upper beach/sand dune margins produced a pulse of shoreline translation landwards equivalent to about 10 years of ‘normal’ shoreline retreat. The study of east coast surges over the last 60 years, and the identification of significant phases of landscape change — such as periods of rapid soft rock cliff retreat and the formation of new gravel washovers on barrier islands — points to the importance of high water levels being accompanied by high wave activity. Future developments in early warning systems and evacuation planning require information on the variable impacts of such extreme events.This paper is a contribution to NERC BESS Consortium grant A hierarchical approach to the examination of the relationship between biodiversity and ecosystem service flows across coastal margins (grant reference NE/J015423/1). Table 5 incorporates information gathered as part of an EU FP7 Collaborative Project Resilience-Increasing Strategies for Coasts — toolkit (RISC_KIT).This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0012825215000628#

Land and water resources, historical changes, and dune criticality : Mustang and North Padre Islands, Texas

Accompanied by 1 foldout plate -- Plate 1 : Land and water resources, Mustang and north Padre Islands, TexasUT Librarie

Piping plovers demonstrate regional differences in nesting habitat selection patterns along the U. S. Atlantic coast

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zeigler, S. L., Gutierrez, B. T., Hecht, A., Plant, N. G., & Sturdivant, E. J. Piping plovers demonstrate regional differences in nesting habitat selection patterns along the U. S. Atlantic coast. Ecosphere, 12(3), (2021): e03418, https://doi.org/10.1002/ecs2.3418.Habitat studies that encompass a large portion of a species’ geographic distribution can explain characteristics that are either consistent or variable, further informing inference from more localized studies and improving management successes throughout the range. We identified landscape characteristics at Piping Plover nests at 21 sites distributed from Massachusetts to North Carolina and compared habitat selection patterns among the three designated U.S. recovery units (New England, New York–New Jersey, and Southern). Geomorphic setting, substrate type, and vegetation type and density were determined in situ at 928 Piping Plover nests (hereafter, used resource units) and 641 random points (available resource units). Elevation, beach width, Euclidean distance to ocean shoreline, and least-cost path distance to low-energy shorelines with moist substrates (commonly used as foraging habitat) were associated with used and available resource units using remotely sensed spatial data. We evaluated multivariate differences in habitat selection patterns by comparing recovery unit-specific Bayesian networks. We then further explored individual variables that drove disparities among Bayesian networks using resource selection ratios for categorical variables and Welch’s unequal variances t-tests for continuous variables. We found that relationships among variables and their connections to habitat selection were similar among recovery units, as seen in commonalities in Bayesian network structures. Furthermore, nesting Piping Plovers consistently selected mixed sand and shell, gravel, or cobble substrates as well as areas with sparse or no vegetation, irrespective of recovery unit. However, we observed significant differences among recovery units in the elevations, distances to ocean, and distances to low-energy shorelines of used resource units. Birds also exhibited increased selectivity for overwash habitats and for areas with access to low-energy shorelines along a latitudinal gradient from north to south. These results have important implications for conservation and management, including assessment of shoreline stabilization and habitat restoration planning as well as forecasting effects of climate change.Funding for this work was provided by the North Atlantic Landscape Conservation Cooperative and U.S. Fish and Wildlife Service through a U.S. Geological Survey Mendenhall Fellowship to Zeigler. All other funding was through the U.S. Geological Survey (Zeigler, Gutierrez, Plant, and Sturdivant) and the U.S. Fish and Wildlife Service (Hecht). Zeigler, Plant, and Hecht conceived and designed the study and secured funding

A Geospatial Analysis: Impacts of Hurricane Matthew, St. Catherines Island, Georgia

The purposes of this study were to evaluate the shoreline dynamics and environmental change of St. Catherines Island shoreline through the application of an updated shoreline model (1859-2017). Efforts were completed to document and quantify the impacts to the nearshore environments of the island from Hurricane Matthew (07-08 October 2016). This was accomplished through the measurement of Net Shoreline Movement (NSM) that was performed along the shoreface at 200-meter spacings by using aerial imagery and ground-collected GPS data. The Hurricane Matthew NSM data along with the short-term shoreline rates were used to calculate the years of change along the shoreline in response to the storm, indicating that the storm represented an average of 3.7 years of average erosion. A spatial analysis of impacts conducted along the shoreline revealed major habitat losses within the study area of 66.5 acres and the limited accretion of 3.7 acres

Coastal sensitivity/vulnerability characterization and adaptation strategies: A review

Coastal area constitutes a vulnerable environment and requires special attention to preserve ecosystems and human activities therein. To this aim, many studies have been devoted both in past and recent years to analyzing the main factors affecting coastal vulnerability and susceptibility. Among the most used approaches, the Coastal Vulnerability Index (CVI) accounts for all relevant variables that characterize the coastal environment dealing with: (i) forcing actions (waves, tidal range, sea-level rise, etc.), (ii) morphological characteristics (geomorphology, foreshore slope, dune features, etc.), (iii) socio-economic, ecological and cultural aspects (tourism activities, natural habitats, etc.). Each variable is evaluated at each portion of the investigated coast, and associated with a vulnerability level which usually ranges from 1 (very low vulnerability), to 5 (very high vulnerability). Following a susceptibility/vulnerability analysis of a coastal stretch, specific strategies must be chosen and implemented to favor coastal resilience and adaptation, spanning from hard solutions (e.g., groins, breakwaters, etc.) to soft solutions (e.g., beach and dune nourishment projects), to the relocation option and the establishment of accommodation strategies (e.g., emergency preparedness)

A 5000-year history of Caribbean environmental change and hurricane activity reconstructed from coastal lake sediments of the West Indies

A ~5000 yr history of modern and prehistoric hurricane landfall and environmental change has been reconstructed from coastal lake sediments of the northern West Indies. Hurricane overwash layers and environmental shifts were identified by changes in biological and sedimentary stratigraphies, core lithology, and loss-on-ignition techniques. 14C and 137Cs were used to establish a chronology of events. Many hurricane-induced overwash layers were identified within the lake sediments. Evidence indicates distinct periods of temporal shifts in hurricane activity for the Northern Caribbean islands of Anguilla, Barbuda, and Acklins Island, Bahamas, providing the first paleotempestological records for the region. The northern Caribbean record appears to exhibit an anti-phase relationship with the results from the U.S. Gulf coast, in apparent agreement with the Bermuda High hypothesis. Comparison with studies basin-wide indicates three temporal shifts in basin-wide activity occurring at ~1000, 2500, and 3500 yr BP