Coastal erosion… A “Shore” Thing? A study into the Erosion, Coastal Processes and Management occurring at Kiama’s beach-dune systems.

There is a growing need for coastal managers to understand the factors affecting their coastal zones and the effectiveness of current management strategies, especially in view of the highly dynamic characteristics of the coastal environment, human impact and the predicted effects of a changing climate. It was recognised in the Fifth Assessment Report by the IPCC, that coastal monitoring needs to integrate a broad range of spatial and temporal scales to more effectively understand the likely impacts of climate change. A research project was undertaken within the Kiama Local Government Area (LGA), south-eastern Australia, which summarised key baseline information for the coastal zone; and attempted to integrate several methodologies that operate at differing spatial and temporal scales. This will assist the Kiama Municipal Council to assess the effectiveness of current management regimes and develop ongoing management strategies for the future. There are 13 beach systems within the Kiama LGA that all predominantly possess an easterly aspect, and range from the large prograding Seven Mile beach, to intermediate embayed beaches to finally the small pocket beach compartments. The 13 beaches were classified in terms of their morphological characteristics (i.e. barrier form and compartment nature), and surveyed noting vegetation structure and composition. This was done using Real Time Kinematic (RTK) GPS profiling, and field observations. Two beaches of similar size and aspect (Bombo and Werri) were examined in more detail due to their differing management histories. Changes over long and short time scales, as well as subaerial beach and dune morphology at Bombo Beach were compared with Werri Beach, using aerial photography, geospatial analyses and GPS surveying. A Time-lapse camera was also installed at both ends of Bombo Beach, to evaluate a low cost method for assessing and forecasting short-term beach change (hourly change). The short-term study found that the two study beaches were highly dynamic and are prone to significant storm impact. A maximum sand volume of 60m3 at Bombo and 70m3 at Werri was lost during the June storm, 2013. When compared with previous storm activity, a full recovery is anticipated to take over 5 years to reach. The long-term study suggested Kiama’s beach systems as oscillating, with periods of clear erosion (1974, 1996) and accretion (1971, 2012) occurring. This study provides baseline knowledge for further coastal hazard assessment and will help better understand the relationship between climate, coastal processes and human behaviour on our coast. More importantly, it indicates the types of data that can be acquired by coastal land managers and illustrate cost-effective methodologies for monitoring and managing beach-dun