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Greenwich Dunes, Prince Edward Island National Park, is a sandy mainland and barrier spit beach–dune complex stretching for about 10 km along the northeast shore of Prince Edward Island, Canada. In October 1923, surge associated with an intense storm produced catastrophic overwash along the whole length of the study area. Subsequent evolution of the system was quantified from historic aerial photographs taken in 1936, 1953, 1971, 1997, and 2005. Orthophoto mosaics were generated for each photo set using PCI Geomatica OrthoEngine, a digital photogrammetric software. Linear changes in shoreline position and areal changes in geomorphic units were evaluated for each photo set. In addition, digital elevation models (DEMs) were extracted from the 1953, 1971, and 1997 aerial photos, enabling analysis of topographic and volumetric changes. The 1936 photos show complete destruction of all foredunes, with overwash and transgressive dunes extending 300 to 600 m inland. A descriptive model of the stages of evolution of the system is proposed based on the processes controlling overwash healing and dune stabilization. Detailed topographic and volumetric changes associated with the development of an extensive transgressive dunefield and subsequent stabilization as a result of reduced sand supply due to the growth of a new vegetated foredune complex and vegetation colonization are doccumented for each stage. It was nearly 40 years before a continuous foredune system was re-established and a further 30 years before the inland transgressive dunes became completely stabilized. Les dunes Greenwich du Parc national de l’Île-du-Prince-Édouard forment un complexe de région continentale et de barre–dunes qui s’étend sur une dizaine de kilomètres le long de la côte nord-est de l’Île-du-Prince-Édouard, Canada. En octobre 1923, une vague de grosse tempête a causé un débordement catastrophique tout le long du secteur à l’étude. L’évolution subséquente du système a été quantifiée à partir de photographies aériennes historiques prises en 1936, 1953, 1971, 1997 et 2005. Des mosaïques orthophotographiques ont été générées pour chaque ensemble de photos au moyen du logiciel numérique de photogrammétrie OrthoEngine de PCI Geomatica. Les changements de position de la ligne de rivage et les changements de superficie des unités géomorphologiques ont été évalués pour chaque ensemble de photos. De plus, des modèles numériques et d’élévation ont été extraits des photographies aériennes prises en 1953, 1971 et 1997, permettant d’analyser les changements topographiques et volumétriques. Les photos de 1936 montrent la destruction complète de toutes les avant-dunes; elles montrent aussi du matériau de débordement et des dunes transgressives s’étendant de 300 à 600 m à l’intérieur des terres. Un modèle descriptif des étapes de l’évolution du système est proposé basé sur les processus contrôlant le rétablissement à la suite du débordement et la stabilisation des dunes. Les changements topographiques et volumétriques détaillés associés au développement d’un grand champ de dunes transgressives et la stabilisation subséquente résultant d’un apport moindre en sable en raison du développement d’un nouveau complexe d’avant-dunes végétalisé et la colonisation par la végétation sont documentés pour chaque étape. Une période de près de 40 ans a été nécessaire pour que se rétablisse un système continu d’avant-dures et 30 autres années avant que les dunes transgressives à l’intérieur des terres ne soient complètement stabilisées. [ABSTRACT FROM AUTHOR]

A simple technique for rapid measurement of moisture content at a point on a beach with a Delta-T moisture probe is described. The sensing elements of the probe consist of four stainless steel rods (6 cm long) which, when inserted into the beach sediments, measure the impedance introduced by the presence of moisture. To provide a realistic measure of surface moisture content, the effective length of the probe was shortened from 6 to 2 centimeters by inserting the rods through a cube 14 centimeters thick) of dielectric foam. Laboratory tests comparing the output voltage of the probe with gravimetric moisture content in sand taken from a field site at Greenwich Dunes, Prince Edward Island, Canada, produced linear best-fit lines (R² 0.971). The tests showed no appreciable difference between the short probe and the original long probe for moisture content of 0-10% and for differing salt content. A calibration produced from 150 measurements in the field over 4 weeks with the short probe and gravimetric moisture content of core samples (2 centimeters thick) was the same as the laboratory calibration, though with more scatter. Field tests within plots (1 meter square) show that surface moisture content can vary by more than 3% within this small area. Measurements within a rectangular grid 50 meters alongshore and 25 meters cross-shore show spatial patterns related to wave run-up and tidal cycles and seepage from the dune, as well as temporal fluctuation related to precipitation events and drying by sun and wind. [ABSTRACT FROM AUTHOR]

A field experiment was carried out over a period of five weeks on an intertidal ridge and runnel system on the Northumberland Strait coast of Nova Scotia, Canada. The area is microtidal with a spring tidal range of just under 2 m. The main purpose of the research was to examine the effects of changing water depth and bar emergence on the morphodynamics of the system and to determine the controls on the stability of the ridges during non-storm conditions. The system is developed on a gently sloping platform over 300 m wide at spring low tide with an average gradient of 0.004. It is characterised by the presence of 5 or 6 ridges in the intertidal zone and 2 bars in the subaqueous zone. The ridges are 0.35-0.50 m in height, 50-60 m in wave length, and the continuity of the ridges alongshore is broken by drainage channels. The system at Linden Beach is similar to others that have developed in a number of areas along this coast on platforms resulting from recession of relatively weak sandstone cliffs. Topographic surveys were carried out along 10 profiles spaced 25 m apart using a total station and the position of the ridge crests and troughs was also mapped using a GPS system. Measurements of wave transformation, water motion and suspended sediment concentration over individual tidal cycles were carried out along a profile across the second ridge and associated troughs using electromagnetic current meters, resistance wave staffs and OBS nephelometers. There were no major storms during the monitoring period but there were a number of days with significant wave heights >0.4 m and the measurements spanned the full range from neap to spring tides. During the five week period the ridge crests exhibited a high degree of stability with maximum movement <5 m. The effects of tidal currents were isolated through measurements made during calm conditions with light winds. Measurements indicate that wave shoaling and breaking across the ridge crest at mid to high tide have the potential to transport large quantities of sediment landward and thus to induce landward migration under non-storm conditions. The stability of the bars appears to be controlled by a combination of offshore flows across the bar crests due to undertow and tidal currents near high tide, and through the transport of sediment alongshore in the troughs and offshore in the drainage channels on the ebb tide. The dynamics of the system more closely resembles that of sub-tidal multiple parallel bars than that of intertidal swash bars. [ABSTRACT FROM AUTHOR]

Beaches and dunes are one of the most heavily used environments on Earth, with tourism and residential uses leading to ecosystem loss and dune degradation. Many coastal dune fields also host a range of economic activities such as farming, mining, and animal grazing, which can affect their evolution. The second half of the 20th century has seen an increase of dune vegetation cover in many dunes around the world, with climatic forcing often cited as a driver for this. However, identification of the relative contributions to landscape change due to climate vs. natural and/or artificial disturbances remains unclear. This poses a problem for managers seeking to maintain some 'desirable' landscape characteristics, because understanding the reasons for dune field change is essential prior to implementing interventions, as is differentiating what is natural from what is not. This study proposes a systematic approach to identifying dune disturbances and isolating them from the effect of climate. The approach assumes that it is possible to measure dune disturbances by comparing observed vegetation cover with that expected due to climate. A semi-quantitative procedure is proposed to explore the existence of disturbance, its significance, and the causes for it. The procedure can also be used in reverse to explore the effect of variables driving disturbance and the likely landscape trajectory if the driver is removed. The approach is tested with a case study of the Sefton dunes in NW England, a large dune field subject to multiple interventions and degrees of human impact. The discussion focuses on the importance of disturbance location and the range of variables involved in changes to vegetation cover at this and other locations. In natural dune fields, it is recommended as best practice to managers that artificial stressors and human-led disturbances are minimized to allow coastal dune systems to evolve naturally., (Crown Copyright © 2019. Published by Elsevier B.V. All rights reserved.)