A Framework for Modelling Shoreline Response to Clustered Storm Events: Case Studies from Southeast Australia
Authors / CoAuthors
Coastal communities in Australia are particularly exposed to coincident natural hazards, whereby tropical cyclones and extra-tropical storms cause damage to infrastructure and shorelines from severe wind, flood and storm surge. Because the climatic drivers of severe storms are stronger under certain conditions (e.g. during La Ni±a periods for tropical cyclones), these events can repeatedly impact the coast over periods of weeks to months. Historically, major episodes of beach erosion along southeast Australia have occurred during every decade over the last century, with the most severe in 1974 resulting from two extra-tropical storms in two months.
<p>While the process of beach erosion is well understood in general terms, the response of a specific sector of coast to clustered storms may not be. For effective coastal management, this site specific knowledge becomes essential. Here we present a framework for integrating coastal geomorphology and coastal engineering approaches to model shoreline response to clustered storms at a spatial scale that can directly inform management agencies. We focus on two case study areas in southeast Australia, the beaches of the Adelaide metropolitan coast (South Australia) and Old Bar beach (central New South Wales) where erosion is a management priority.
<p>For each site we adopt the coastal sediment compartment as the functional management unit, mapped for the Australian continent at multiple spatial scales, and use sub-surface information (boreholes, ground penetrating radar profiles) to estimate sediment volumes in the upper beach to foredune. These data are then used to inform shoreline response modelling linked to an event time series (observed and hind cast) as a separate project component. Future work includes assessment of `at-risk infrastructure at each site. This paper is a contribution to the Bushfire and Natural Hazard Cooperative Research Centre project Storm surge: Resilience to clustered disaster events on the coast.