Climate Change Adaptation

Coastal Zone Climate Change Impacts

Several notable climate scientists have indicated that Western Australia, and in particular the Mandurah area, may be at considerable risk to these projected impacts. Particularly relevant for the Mandurah area will be the likely rise in mean sea level and elevated storms surges. These changes will be superimposed on a naturally variable coastal system adding to the current effects of winter storms and coastal flooding. In the face of this predicted global climate change and the strong development pressures in the area, the City will be presented with multiple challenges relating to the management and maintenance of our valuable coastal resources and infrastructure.

In an effort to better understand the issues, in August 2007 the City, along with Coastal Zone Management, convened a conference - ‘Climate Change and the Coast – Think Globally, Act Locally’ and community forum to gather relevant experts who were able to provide latest information and insights into this complex issue. A summary of the conference can be found here.

Recognising that there was a need to better identify and assess the risks posed by sea level rise the City applied for and was successful in gaining Australian Government funding under the Local Adaptation Pathways Program, which was matched by City of Mandurah funding.

The assessment identified a range of potential climate change impacts, which the Mandurah coastal zone may be susceptible. These include:

• Sea level rise increasing rates of erosion of the open ocean coast
• Changes in the movement of sand leading to increased erosion in known coastal environments, such as in lee of groynes and on rock platforms
• Increased water levels within the estuary leading to increased overtopping stress on canal and channel walls and decreased bank stability
• Decline in freshwater entering the estuarine system leading to change in salt/freshwater interface and consequently change in species composition.

Results of the strategic risk assessment indicated that the highest priority risk for the City of Mandurah coastal zone is uncertainty in long-term landuse planning and infrastructure design. Other high priority risks include impacts on infrastructure (private, local government and recreational) through coastal erosion and inundation. At a site-specific level, the areas identified as subject to extreme climate change risk within the coastal zone were Halls Head Beach and Falcon Beach.

The risk assessment adopted the Intergovernmental Panel on Climate Change (IPCC) A1FI scenario, which is the most pessimistic scenario. The timeframe selected was 2070 as this is the longest timeframe of available data and is ideal for strategic assessment of risk. It is important to note that all risks are based on this scenario and timeframe and that these projected changes will put additional pressures on the coastal zone which is already naturally variable and subject to winter storms and coastal flooding.

Overall, the work conducted highlighted the fact that the City of Mandurah is vulnerable to the impacts of Climate Change. Strategic and adaptive responses are required to address identified risks. In light of this, the key outcome of the Project was an adaptation plan to deal with strategic and site-specific risks to ensure the Mandurah community is resilient to these risks. This plan will be implementing over the coming years.

The Coastal Zone Climate Change Risk Assessment and Adaptation Plan Report can be found below.