Department of
Environment, Water
and Natural Resources
Coastal Climate Change impacts in
South Australia
Murray Townsend
Manager, Public Land and Coastal Conservation
www.environment.sa.gov.au
Global SLR Summary
• Increasing evidence that the SLR projections in
the IPCC assessments are underestimates.
• Greatest uncertainty comes from Greenland
and West Antarctic ice sheet contributions.
• Emissions and SLR observations are tracking at,
or above, the ‘worst case’ IPCC scenario.
• SLR will continue to rise for several centuries
after global temperatures have been stabilised
2100 sea level rise projections
(USACE 2011)
The South Australian Perspective
Sea level rise:
• Estimates from tidal records indicate global rate of SLR
in the 20th century was 1.7mm per year.
(South Australia 1.5mm/yr)
• National Tidal Centre’s SEAFRAME project has been
using a network of satellite calibrated tidal stations to
accurately measure SLR since early 1990s.
Net relative sea level trend at SEAFRAME sites in Australia (mm/yr)
July 1992 to June 2011
Current average sea level (2009)
North Glenelg
Projected average sea level (2100)
North Glenelg
Implications for the Coast
Higher sea levels can mean:
• Increased severity and frequency of sea flood
events.
• Increased coastal erosion.
• More difficult to maintain sandy beaches
Port Adelaide Seawater –
Stormwater flood mapping
100 year ARI storm,
50cm SLR,
21cm subsidence
Yorke Peninsula Sea
Flood Risk Mapping
Marion Bay
100 year ARI storm,
current sea level
Marion Bay
100 year ARI storm,
1.0m sea level rise
Storm Damage - erosion
North Glenelg, 1964
Implications for the Coast
Higher sea levels mean:
• Landward migration of intertidal ecosystems
eg. Mangroves, saltmarsh
• Higher groundwater levels.
• Increased wave overtopping of protection
structures.
Port Wakefield
Rising groundwater
Wave Overtopping
The Broadway, Glenelg South
Coast Protection Board
The Board’s strategic direction:
1. Ensure that new development is not placed at risk
from coastal hazards (including climate change
impacts)
2. Develop and act on strategies to protect existing
at-risk development
3. Allow coastal ecosystems to adapt to the impacts
of climate change (retreat, migration)
Coastal Development Policy
• The Board’s “Policy on Coast Protection and New
Coastal Development” requires new development
to allow for SLR.
• The Policy was endorsed by the SA Govt in 1991.
• Relevant provisions were included in Development
Plans state-wide in 1994 by Ministerial DPA.
New Coastal Development
• Must allow for 0.3m of SLR, and able to be protected
“by reasonable means” from a further 0.7m.
• Must allow for erosion, including effects of SLR.
• Should not compromise ability of ecosystems to
adapt to climate change (eg mangrove migration)
• Major developments must consider “full range of
possible climate change and sea level rise effects”.
New Coastal Development
The Board/DENR aims to minimise exposure of
development and communities to coastal hazards
The Board is a referral body for developments in
coastal zones - has power of direction under certain
conditions, advice in others.
In 2010, of the 199 development applications referred
to the Board, 83.5% of decisions were made in
accord with Board advice.
Consequences
In the 1991 SA Government Policy on coast protection and
new coastal development:
• “(The Board) does not consider that State Government
funds should be available for protection of new
development approved unwisely and against the Board’s
or Department’s advice.”
• “The Board considers it beneficial to retain the nexus
between authority for approving coastal development
and responsibility for the consequences of decisions
made.”
Existing Coastal Development
• Board’s role is to coordinate the identification of
areas at risk and the preparation of response
strategies.
• Provides grant funding for investigation of
adaptation strategies and implementation of
protection works.
• Keen to leverage C’wealth funds, e.g. NDRGS.
Hazard assessment
Previous and current work informs coastal zoning to
identify areas subject to current and future hazards
In these zones, the Board’s policies should apply
Need high resolution flood mapping (digital elevation
models and bathymetry) to better define hazards
and guide responses.
The future?
Development of human societies occurred during a
6,000-year period of stable sea level – this is not a
luxury we will enjoy for some centuries.
Demand to protect existing communities might exceed
capacity to do so.
Seek common strategic ground to minimise
occurrences of emergencies – prevention rather
than response.
Questions