Coffs Harbour City Council's latest climate change impact assessment for coastal zone

Snapshot of report cover page

In September 2010 BMT WBM Pty Ltd completed what appears to be a final revision of its Coffs Harbour Coastal Processes and Hazards Definition Study commissioned by Coffs Harbour City Council and this final draft has now entered the public domain courtesy of the Northern Beaches Alliance and the Environmental Defender's Office.

In The Coffs Coast Advocate on March 18, 2011:

Commissioned by Coffs Harbour City Council, the Coastal Processes and Hazard Definition Study was completed by world-renowned engineering and environmental consultants BMT WBM.

The water levels illustrated on the maps assume beaches will recede, creeks and lakes will swell and tides, storm surges and waves heights will rise – all of which are predicted by the best available environmental science on offer in NSW.

The most prominent examples of predicted inundation under a one-in-100-year storm event include the Jetty Foreshores, Hogbin Dr, parts of Boambee East and properties near the Woolgoolga and Hearnes lakes, Arrawarra Creek and Corindi River at Red Rock.

The floodplains of Darkum, Fiddaman's, Moonee, Coffs, Boambee, Bonville, Pine and Bundageree creeks would also expand vastly.

Quotes from the Coffs Harbour Coastal Processes and Hazards Definition Study Final Draft Report :

This Coffs Coastal Processes and Hazards Definition Study Report presents a summary of coastal processes (from the Coffs Coastal Processes Draft Progress Report), and then provides the methodology and outcomes for the definition of the eight coastal hazards on the Coffs regional coastline. The likelihood ('almost certain', 'unlikely' and 'rare') of beach erosion and shoreline recession, and separately, coastal inundation have been mapped for the immediate, 2050 and 2100 horizons. Detailed hazard maps are contained in the Figures section at the end of this report.

The Coffs regional geomorphology is therefore summarised:
a multiple sand barrier and estuary type coastline with extensive outcrops of rock reef offshore from the headlands between Bundagen Headland and Coffs Harbour;
smaller pocket or embayed beaches, with an increase in offshore rock reefs north from Coffs Harbour to Arrawarra Headland; and
between Arrawarra Headland and Station Creek, the longer sand barrier and estuary type coastline is again dominant.

It is widely acknowledged that sea level rise will result in the recession (or transgression) of sandy shorelines, such as described by the Bruun Rule (1962). This assessment utilises world's best practice Shoreline Evolution Modelling to determine the extent of recession due to sea level rise in the Coffs region,……

Oceanic inundation of low lying and back beach areas may also increase in frequency with sea level rise.

This report supports the general scientific consensus on global warming and previous state and federal reports concerning future beach recession and land loss on the Australian east coast.

The full 204 page report can be downloaded as a PDF file here. Predicted water level mapping is here and here.