Regional Scale Assessment of the Sensitivity of Illawarra Indigenous Heritage Sites to Sea Level Rise and Associated Hazards

Climate change and sea level rise are expected to exacerbate existing coastal hazards such as erosion and inundation. As a result many coastal heritage sites around the world are expected to be put at potential risk of damage or destruction. The likely susceptibility of Australia’s Indigenous coastal heritage sites to these hazards is widely recognised but the sensitivity has not been quantified or analysed in detail. In order to assess the sensitivity of Indigenous coastal heritage sites, both coastal and estuarine indices of sensitivity and vulnerability were adapted to be used in a heritage context. The study focused on the coastal Illawarra region of southern NSW. Desk based regional models were produced within the ArcGIS program for both Coastal and Estuarine shorelines in the region with underlying landform sensitivity used as a proxy for heritage site sensitivity. The coastal shoreline was assessed using an adaption of a Coastal Sensitivity Index technique, using Slope, Geology, Shoreline Exposure, Geomorphology, Site Distance to Shoreline, Sea Level Rise, Wave Height and Tidal Range to assess heritage site sensitivity to sea level rise. Indigenous heritage sites on the shoreline around Lake Illawarra estuary were assessed using an adaption of modelling designed to investigate biophysical vulnerability to erosion and flooding hazards using estuarine geomorphic units. The relative effectiveness of the desk based modelling approach was also examined by ground-truthing of a number of sites analysed in the coastal site sensitivity index. The results of the coastal analysis highlighted several sites located near beaches in the region that were estimated to have ‘Very High’ sensitivity to sea level rise and the associated hazards. In the Lake Illawarra estuary heritage sites were estimated to generally have higher sensitivity when located on the coastal barrier. Results of both methods indicated that sites on resilient bedrock landforms were considerably less sensitive than sites on Quaternary sediment. However, ground-truthing at Bass Point suggested in some locations sites may be sensitive to coastal hazards despite being associated with resilient landforms. The study was able to identify Indigenous heritage sites within the coastal Illawarra region that were most sensitive to climatic and sea level rise driven hazards. The ground-truthing of sites identified areas for future research to improve the desk based approach, particularly in regards to including the sensitivity of individual site types to erosion and inundation hazards. Desk based regional modelling was shown to be a useful tool for planning and conservation management, particularly in directing resources to sites of the highest risk, and informing the direction of more in depth studies into the hazards faced by coastal Indigenous heritage sites