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Responding to climate change

We are already seeing localised effects of climate change:

  • average annual surface temperatures have increased approximately 0.6ºC from 1900 to 1990
  • an increase in storm surge activity has been observed since 1990 - this is reflected in elevated maximum water levels recorded in 2003 and 2004
  • Fremantle sea level records indicate average sea level has risen at a rate of 1.54mm a year between 1897 and 2007
  • autumn and winter rainfall and the frequency of large winter storms has steeply decreased since the early 1970s
  • river flow has decreased as a result of lower rainfall
  • marine water moves further upstream in summer and autumn

The Swan Canning river system is responding and will continue to respond to a series of drivers:

  • increased atmospheric and water temperatures
  • more frequent warm spells and heat waves potentially leading to more algal blooms
  • accelerated sea and estuary water level rise
  • decreased winter rainfall and streamflow
  • decreased groundwater levels leading to reduced flows to drains and streams

The Technical Advisory panel has predicted the changes that might occur in the river system:

  • Water, sediment, salt loads and nutrients from the Avon Catchment to the Swan River are expected to reduce with a drier climate.
  • Community use and perception of the rivers may change if loss of beaches, wetlands and vegetation reduces recreational facilities, changed aesthetic values or public perception of the health of the system if algal blooms and fish kills increase, and increased development of infrastructure to mitigate sea level rise
  • Sea level rise and decreased streamflow will impact the river’s ecology. This is predicted to:
    - increase stratification of saline water and penetration of marine water upstream
    - affect biological processes such as oxygen demand, nutrient cycling and sediment retention
    - alter distribution and abundance of species along with seasonal patterns of productivity and food-web dynamics
    - cause ongoing problems associated with eutrophication such as algal blooms and fish kills, particularly in the upper Swan River 

Parks and Wildlife’s response to climate change effects is based on an adaptive management approach. This is a systematic process of continually improving management policies and practices to reduce or accommodate the adverse impacts of climate change.

Adaption and mitigation strategies identified for the Swan Canning Riverpark include:

  • assessing foreshore vulnerability (vegetation and shoreline)
  • improving water quality through oxygenating water, trapping nutrients and ensuring adequate river flow
  • using monitoring and modelling to predict future changes
  • managing biodiversity
  • protecting infrastructure