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Coastal Climate Change impacts in South Australia

Coastal Climate Change impacts in South Australia. Department of Environment, Water and Natural Resources. Murray Townsend Manager, Public Land and Coastal Conservation. Global SLR Summary. Increasing evidence that the SLR projections in the IPCC assessments are underestimates.

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Coastal Climate Change impacts in South Australia

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  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. 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.

  5. Net relative sea level trend at SEAFRAME sites in Australia (mm/yr) July 1992 to June 2011

  6. Current average sea level (2009) North Glenelg

  7. Projected average sea level (2100) North Glenelg

  8. 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

  9. Port Adelaide Seawater – Stormwater flood mapping 100 year ARI storm, 50cm SLR,21cm subsidence

  10. Yorke Peninsula Sea Flood Risk Mapping Marion Bay 100 year ARI storm, current sea level

  11. Marion Bay 100 year ARI storm, 1.0m sea level rise

  12. Storm Damage - erosion North Glenelg, 1964

  13. 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.

  14. Port Wakefield

  15. Rising groundwater

  16. Wave Overtopping The Broadway, Glenelg South

  17. Coast Protection Board • The Board’s 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)

  18. 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.

  19. 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”.

  20. 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.

  21. 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.”

  22. 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.

  23. 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.

  24. 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.

  25. Questions

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