@article {bnh-2333, title = {Resilience to clustered disaster events on the coast: storm surge - Annual project report 2014-2015}, number = {122}, year = {2015}, month = {02/11/2015}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

What is the problem?

Coastal communities in Australia are particularly exposed to clustered disaster events, due to the impact of cyclones and extra-tropical storms when there can be coincidence of severe wind damage, storm surge, coastal flooding and shoreline erosion. Because the climatic drivers of cyclones and severe storms are stronger during or across specific years (e.g. during La Ni{\~n}a periods), these events often repeatedly impact the coast over periods of weeks to months. The consequences of individual events are therefore exacerbated with little or no opportunity for recovery of natural systems or communities.

The storm events that occurred on the southeast coast of Australia during 1974 are the most significant and recent in memory in terms of coastal impact associated with clustered events. Traditional wisdom indicated that there were two storms that led to the coastal impact (May and June). However, the reanalysis data sets indicate that between January and June of 1974, there were at least 10 events but not all of these events led to coastal erorion. These prior events would have played some role in setting the pre-conditions of the beach that ultimately led to the erosion towards the end of this six month period. The question therefore is to determine the beach response to clustered event sets and the nature of how those events ultimately lead to erosion.

The problem is complex as the response to the forcing will vary {\textendash} there will be a spectrum from inundation to erosion, and further, there will be varying factors that drive the erosion (e.g. long-shore, cross-shore) that are functions of the location and the event.

Why it is important?

Australia{\textquoteright}s population is concentrated along the coastline, with over 85\% within 50 km of the coastline (Australian Bureau of Statistics 2001). In New South Wales for example, the NSW Government has identified 15 erosional hotspots (Kinsela and Hanslow 2013), along its 2000 km of coastline. Of the approximately 1000 km of erodible sandy beaches (open coast only), 28\% is within 220 m of property.

How are you going to solve it?

The study will quantify the risk of these clustered events by determining the nature of the hazard, the elements that are exposed to this hazard and their resultant vulnerability. Combining the frequency of the hazard with its impact will enable the risk to be quantified. This risk can then be managed through the coastal and disaster management processes of all stakeholders.

The study will focus on two case studies determined in consultation with the project end-users. Defining the hazard is non-trivial as it may be difficult to identify clustered events in the historical record. Determining the impact from a clustered event set will need to take into account the beach recovery time for the two sites. The coastal compartment framework provides the functional unit for understanding the shoreline response at a range of spatial scales, and detailed geomorphological site investigations will be undertaken and analysed within this framework for input to the beach response modelling.

The risk and coastal compartments framework are powerful in terms of situating the assessment at local, regional and national scales.

}, issn = {122}, author = {Scott Nichol} }