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​Coastal Flood Mapping of Eyre Peninsula and the Limestone Coast

Significant coastal storm events in recent years have highlighted the need for better information to identify areas that may be vulnerable to coastal flooding and prioritise areas that require adaptation strategies. pic1.jpg

Climate change is expected to increase the frequency, intensity and impacts of some weather events, such as coastal storms. Sea level rise leads to increased frequency and depth of flooding in coastal areas. Therefore it is important to identify areas that are likely to be affected by storm events to determine the most appropriate management strategies, such as avoid, retreat, accommodate or do nothing.

This interactive Flood Mapping Tool has been developed as a result of the partnerships between the Limestone Coast Local Government Association, the Eyre Peninsula NRM Board, the Eyre Peninsula Local Government Association, the Coast Protection Board and the Department for Environment and Water. The maps identify areas on Eyre Peninsula and the Limestone Coast that may be vulnerable to coastal flooding due to storm surge and/or sea level rise.

The main goals of the coastal flood maps are to:

  • Identify areas that may be vulnerable to coastal flooding at a regional scale,
  • Visualise the potential impacts from different sea level rise scenario’s through maps, and
  • Inform policy-making and strengthen partnerships in managing coastal hazards.
Spring high tide water level

Spring high tide water level

storm-surge-water-level.jpg

Storm surge water level

As more data become available across the State, this will be incorporated in to the tool, broadening the coverage available to users.

What is bathtub modelling?

This coastal flood mapping uses a ‘bathtub’ model which is a common method for identifying areas potentially at risk from coastal flooding. This is a simple method that identifies any land below a certain elevation as being at risk of flooding, like pouring water into a bathtub. Bathtub flood modelling is a relatively quick and effective method of identifying potential risk at a large or regional scale. There are a number of limitations with this methodology which are identified below.

 

Example of limitation: identified as being at risk of flooding during a 1 in 100 year storm with a 1m sea level rise, but there is no current connection, or pathway, for the sea to reach this area

The coastal flood mapping has limitations which users need to be aware of, including:

  • No allowances for future changes to the landform, through uplifting or movement of tectonic plates or through the installation of man-made structures since the original data were captured.
  • No consideration for hydraulic flow restrictions, such as the width and depth of channel flow paths for flooding (i.e. can enough sea water flow through a restriction to fill the low lying area during the duration of the storm surge event).
  • No consideration of coastal erosion hazard.
  • No allowance for wave run-up.
  • No allowances for future changes to the landform, through uplifting or movement of tectonic plates or through the installation of man-made structures since the original LiDAR was captured.  
  • No coverage of inland coastal areas on Eyre Peninsula and Limestone Coast beyond the extent captured in the project, so any land further in-land will not show in the scenarios.

These limitations may result in an over-estimation of flood risk in some areas and an under-estimation of flood risk in other areas.

These maps are for planning, awareness and educational purposes only and should not be used for site-specific analysis.