Sea Level Rise Scenarios

On March 9th  I attended a  workshop held to inform community groups of the latest research and information on the likely impacts of sea level rise on the erosion and recession of sandy and “soft” coastlines.  (Soft coastlines consist of clay, gravel, peat or other unconsolidated material.) This is particularly important to Bruny Island because of the high proportion of these coastline types around the Island.
The natural processes of shoreline erosion and recession were described by Chris Sharples (a consultant geomorphologist working out of the University of Tasmania). Research and observation shows that sandy shorelines are inherently unstable, subject to constant change and experience both retreat and advance.  Other soft shorelines, however, usually are subject to retreat.

There are many causes of coastal erosion other than sea level rise, including:

• the cut and fill cycle (beaches come and go - Neck Beach, Cloudy Bay beach (eastern end)
• progressive beach migration (sand moves along the beach shoreline - movement of sand from the south to the north along the Neck Beach and at Mabel bay)
• coastal evolution (ongoing adjustment since the end of the last ice age - Cloudy Lagoon
• land subsidence (e.g. when groundwater is removed)
• artificial interference (structures or activities that interfere with natural processes) - mouth of Captain Cook Creek
  
  Except for land subsidence, these are all evident on Bruny.