Coast & Estuaries
Page 235
Climate Change
Coastal systems are highly vulnerable to sea level rise and the changing storm
and wave energy regimes predicted as a result of climate change. In the
Intergovernmental Panel on Climate Change (IPCC) 2007 report for sea level
rise, a reasonable figure on how much sea level rise could be expected from
Greenland and Antarctic icesheets could not be determined.. Extensive work
has been undertaken since then, and the estimates for sea level rise globally by
2100 are now 80cm to 1.2m or possibly up to 2m (Rahmstorf. S, 2010).
The 2009 Commonwealth Parliamentary Report ‘
Managing our coastal zone in
a changing climate’
provided a full outline of the issues facing all coastal
environments in Australia, particularly in relation to potential climate change
impacts, and included a focus on the Lefevre Peninsula area. (Council provided
a submission to the Committee to highlight the particular issues in this area).
There are potentially significant flooding impacts for coastal regions, particularly
in low lying areas, due to an increase in height of storm surges associated with
sea-level rise, more intensive storm events and increase in stormwater runoff
linked to rainfall events. Tidal, estuarine and dune coastal systems are highly
dependant on sea-level, tidal range and flooding regimes. There is a high risk of
potential damage to beaches, estuaries, mangroves, salt marshes and
important biodiversity, recreational and industry assets. The impact on the coast
is exacerbated by previous degradation and removal of sand dunes.
The City of Port Adelaide Enfield commissioned a report titled ‘Flood Risk
Management Study 2005’. This study aimed to identify the risks and develop
and implement a strategy to protect the vulnerable areas of the City from the
risk of seawater rise and stormwater flooding, taking into account the possible
sea level rise and known land subsidence over the next hundred years.
The study included floodplain mapping and damage estimates for a range of
future sea level rise scenarios of inundation combined with a 100 year storm
event. These estimates predict that the damages associated with a 100 year
storm event will increase dramatically from existing conditions (from $8 million
to $28 million) to future scenarios associated with 500-880mm of sea level rise
(an increase from $180 million to $310 million) within the City of Port Adelaide
Enfield.
In South Australia, the Coast Protection Board (DENR) developed a policy
regarding how coastal development should consider the potential for sea level
rise, and to minimise flooding in the future. Their 1992 policy regarding this is
still current, and Development Plans of all Councils have incorporated the
Policy’s requirements into standard planning provisions for coastal
development. The CPB Policy has been recently reviewed by the State
Government (2010), and has considered the updated research, but is still to be
formally published and adopted.
