Coastal compartments: the role of sediment supply and morphodynamics in a beach management context

Abstract

Coastal compartments provide a hierarchical framework to manage beaches and coastal ecosystems in Australia. This study examines the individual behaviour of three adjacent beaches within Shoalhaven Bight, a secondary compartment on the south coast of New South Wales (NSW). The Shoalhaven River discharges intermittently into the northernmost of the beaches, and a fluvial component is detectable within beach and foredune sands. The distribution and orientation of headlands constrains dispersal of fluvial sediments, and results in lower wave-energy conditions further south, implying limited sand transport from one beach, or tertiary compartment, to another. Two years of monthly subaerial surveys across ten different profiles and modelled storm-wave conditions during the major storms, were used to compare the response of beach volume and shoreline position. The greatest changes in volume were observed near Shoalhaven Heads and the northern ends of Culburra and Warrain-Currarong beaches. Results indicate the distinct individual response of neighbouring beaches over the two-year period, in contrast to general trends in beach behavior that might be inferred from long-term regional monitoring programs. However, they also demonstrate the limitations of short-term observations in comparison to those longer-term studies. The NSW beach systems of are some of the best understood in the world in terms of regional behaviour, as a consequence of several decades of surveys on key beaches. However, more focused local monitoring programs may be needed to establish detailed coastal sand transport, and an understanding of intermittent delivery of fluvial sand and longshore inputs and outputs, within and between different compartments.

Geoformas litorales como indicadores del estado morfodinámico de las playas arenosas del litoral nororiental de Cubao indicadores del estado morfodinámico modal de las playas arenosas del litoral nororiental de Cuba

“…Este comportamiento de las playas permitió la formulación de modelos de clasificación de las playas que reconocen la existencia de distintos estados morfológicos en respuesta a las condiciones ambientales predominantes. A partir de esto se han establecido las bases teóricas sobre los modelos de perfil de equilibrio y en planta de una playa y sus diversas aplicaciones, tanto en la ecología de playa (McLachlan y Defeo, 2017;McLachlan et al, 2018), la gestión de la seguridad de los bañistas (Scott et al, 2009, Scott et al, 2011, Scott et al, 2016, Gadkari y Das, 2023, así como el comportamiento dinámico, respuesta y efectividad de los proyectos de regeneración de playas (González et al, 2010;Yoshida et al, 2014;Ludka et al, 2018;Pranzini et al, 2018;Carvalho y Woodroffe, 2023;Zhou et al, 2023). Wright y Short (1984) desarrollaron un modelo de morfología de la playa como una función del oleaje y del tamaño del grano del sedimento, que define el modo en que la energía del oleaje incidente se distribuye a lo largo del perfil y permite clasificar las playas en disipativas, reflejantes y cuatro estadios intermedios.…”