Implications of Sea Level Rise on Coastal Hazards and Adaptation Options in Western Port
Tim Womersley is presenting at the CSIRO run Climate Adaptation Engineering for cities and coasts symposium http://wp.csiro.au/icae/
Authors: Tim Womersley, Water Technology, ; Christine Lauchlan Arrowsmith, Water Technology, ; Josh Mawer, Water Technology, ;
Western Port contains an unusually high diversity of coastal and backshore environments due to the complicated interaction of a wide range of processes. These include tectonics, exposure of a large variety of different lithologies, extensive development of coastal wetland plant communities and modifications to shorelines associated with agricultural production, shoreline protection works and Port and Harbour infrastructure.
Projected 21st century sea level rise could be expected to result in the development of a wide range of coastal hazard impacts to the varying shorelines and backshore environments in Western Port.
Water Technology was commissioned by Melbourne Water to undertake the Western Port Local Coastal Hazard Assessment in order to identify the extent and nature of the potential coastal hazard impacts that could be expected due to 21st century sea level rise in Western Port.
In order to provide an assessment of the potential extent of the shoreline response that may occur due to sea level rise and/or climate change and associated coastal hazard impacts around such a diverse variety of shorelines, the shorelines of Western Port were characterised into seven major geomorphic shoreline classes.
Conceptual shoreline models were developed for each shoreline class to develop an understanding of the geology, processes and dynamics that characterise each shoreline type. This approach provided the basis for understanding the key response mechanisms of the shorelines to sea level rise and/or climate change and the relationship between these response mechanisms and potential rates of shoreline change and associated coastal hazard impacts in Western Port. Figure 1 displays an example of the conceptual model of shoreline change due to sea level rise for the low earth cliffed shoreline class in Western Port.
A key finding of the coastal hazard assessment was that a significant extent of the shorelines of Western Port (approx. 20%) are backed by networks of levees, constructed by landholders to prevent coastal inundation of agricultural land. The future maintenance and adaptation of these levees will significantly influence the extents of coastal inundation hazards with sea level rise in Western Port. In addition, the South Gippsland Highway and associated causeway were identified as forming a significant control on potential tidal encroachment onto low lying backshore environments in the north western section of Western Port.
The adaptation response of coastal infrastructure including coastal levees and the South Gippsland Highway will significantly influence the potential extents of the inundation hazards due to sea level rise in Western Port.
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