Coastal Climate Change impacts in South Australia

1
Coastal Climate Change impacts in South Australia
Department of Environment, Water and Natural
Resources
Murray TownsendManager, Public Land and Coastal
Conservation
2
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

3
2100 sea level rise projections (USACE 2011)
4
(No Transcript)
5
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 Centres SEAFRAME project has been
  using a network of satellite calibrated tidal
  stations to accurately measure SLR since early
  1990s.

6
Net relative sea level trend at SEAFRAME sites in
Australia (mm/yr) July 1992 to June 2011
7
Current average sea level (2009)
North Glenelg
8
Projected average sea level (2100)
North Glenelg
9
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

10
Port Adelaide Seawater Stormwater flood
mapping 100 year ARI storm, 50cm SLR,21cm
subsidence
11
Marion Bay 100 year ARI storm, current sea
level
Yorke Peninsula Sea Flood Risk Mapping
12
Marion Bay 100 year ARI storm, 1.0m sea level
rise
13
Storm Damage - erosion
North Glenelg, 1964
14
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.

15
Port Wakefield
16
Rising groundwater
17
Wave Overtopping
The Broadway, Glenelg South
18
Coast Protection Board

• The Boards strategic direction
• Ensure that new development is not placed at risk
  from coastal hazards (including climate change
  impacts)
• Develop and act on strategies to protect existing
  at-risk development
• Allow coastal ecosystems to adapt to the impacts
  of climate change (retreat, migration)

19
Coastal Development Policy

• The Boards 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.

20
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.

21
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.

22
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 Boards or Departments advice.
• The Board considers it beneficial to retain the
  nexus between authority for approving coastal
  development and responsibility for the
  consequences of decisions made.

23
Existing Coastal Development

• Boards 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 Cwealth funds, e.g. NDRGS.

24
Hazard assessment

• Previous and current work informs coastal zoning
  to identify areas subject to current and future
  hazards
• In these zones, the Boards policies should apply
• Need high resolution flood mapping (digital
  elevation models and bathymetry) to better define
  hazards and guide responses.

25
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.

26
Questions