Coasts

23 pages, 2281 KiB

Open AccessArticle

Documenting the Evolution of a Southern California Coastal Lagoon during the Late Holocene

by Sarah Dickson, Joseph Carlin, Nicole Bonuso and Matthew E. Kirby

Coasts 2022, 2(2), 102-124; https://doi.org/10.3390/coasts2020007 - 24 May 2022

Viewed by 2453

Coastal wetlands are declining globally, and although wetland restoration looks to offset these losses, its success relies on anticipating environmental response to external forces. The purpose of this study is to investigate the sedimentological record of Los Peñasquitos Lagoon to determine the processes that drive environmental transitions in a Southern California coastal wetland. For this project, we analyze three sediment cores from the wetland for grain size, total organic matter, and shell assemblages to reconstruct environmental change over the past ~4000 years. From the results, we find that the lagoon was initially an open embayment that persisted for >2000 years; however, at ~1000 cal yrs BP, a short-lived wet climatic period triggered a fluvial deltaic progradation at the head of the lagoon. As the wet period ended and drier conditions returned, the delta began to retreat, and the lagoon infilled as the estuarine mouth bar was permanently established. The permanent establishment of the mouth bar resulted in a transition to a marsh-dominated environment throughout the wetland. Ultimately, these environmental transitions were driven by climate variability, although evidence of human impacts was observed more recently in the record. Therefore, future restoration efforts must consider both natural climatic variability and anthropogenic influences if they intend to sustain coastal wetlands. Full article

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9 pages, 2142 KiB

Open AccessArticle

Thermal Metrics to Identify Canadian Coastal Environments

by William A. Gough

Coasts 2022, 2(2), 93-101; https://doi.org/10.3390/coasts2020006 - 19 Apr 2022

Cited by 6 | Viewed by 1956

Abstract

A thermal metric developed using the day-to-day temperature variability framework that was previously applied to the east coast of China has been adapted for Canadian climate station data. The same metric, based on the variability of the minimum temperature of the day, was able to distinguish between coastal and inland stations, especially when the winter months of December, January and February, were removed from the analysis. While the threshold of the metric that distinguished between the two groups was different than that developed for the east coast of China, it was nonetheless unambiguous. The range of latitudes in the Canadian setting was sufficiently narrow that a latitude correction, as was performed for the China climate stations, was not required. A comparison with a more traditional measure of continentality suggests that the thermal variability measure performs better at identifying the coastal/continental nature of the climate station data. This work also suggests that a more nuanced treatment of winter months should be considered for all such measures in colder climates. Full article

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23 pages, 13236 KiB

Open AccessArticle

Time-Lapse Camera Monitoring and Study of Recurrent Breaching Flow Slides in Cap Ferret, France

by Yves Nédélec, Philippe Fouine, Cyrille Gayer and Florent Collin

Coasts 2022, 2(2), 70-92; https://doi.org/10.3390/coasts2020005 - 9 Apr 2022

Cited by 2 | Viewed by 2216

Abstract

In this paper, we present a low-cost method designed to monitor recurrent breaching flow slides that impact the security of a beach. This beach, located in France at the inlet of Arcachon Bay, connects a sand spit to a tidal channel while ending at the toe of a coastal defense. Monitoring is based on capturing images and intends to add continuous information to intermittent direct observations so that triggering and influencing factors can be assessed more precisely. The method is based on time-lapse picture collection and processing. The field of view shows successive emerged manifestations of flow slide phenomena, as well as some possibly related environmental elements. On-site application for 576 days provides important indications and details on flow slide event progress and beach recovery. A simple but quantitative analysis of the influence of sand spit topographic changes is proposed as a preliminary approach of the method’s suitability for studies of environmental processes in conjunction with coast protection. Full article

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19 pages, 27676 KiB

Open AccessArticle

Variability of the Spreading of the Patos Lagoon Plume Using Numerical Drifters

by Douglas Vieira da Silva, Phelype Haron Oleinik, Juliana Costi, Eduardo de Paula Kirinus, Wiliam Correa Marques and Osmar Olinto Moller

Coasts 2022, 2(2), 51-69; https://doi.org/10.3390/coasts2020004 - 6 Apr 2022

Cited by 5 | Viewed by 2427

Abstract

The Patos Lagoon coastal plume is a small-scale outflow that is strongly controlled by meteorological tides. However, the riverine discharge of the lagoon is subject to high decadal variability. Hence, the discharge amount alters the scale of this coastal plume and its effects over the inner shelf environment. This study uses hydrodynamic simulations and a Lagrangian model to estimate the spreading of the plume under two different discharge conditions.Through scale parameters, we characterized the contrasts of the plume structure between high discharge and low discharge conditions. During a strong discharge regime, the width and thickness of the plume are enhanced, and the inertial processes increase against the frictional effect of the wind. The consequences of these differences include higher values of alongshore and cross-shore spreading of the drifters for the strong discharge regime. These findings indicate that under similar wind conditions, different amounts of riverine discharges alter the extent to which the material delivered by the plume can spread over the inner continental shelf. Full article

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Coasts, Volume 2, Issue 2 (June 2022) – 4 articles

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