Impacts on Aquatic Systems

Waterways - Rivers and Inland Wetlands

The projected decreases in average rainfall and runoff is likely to have direct impacts on the hydrology of waterways and wetlands, with consequent impacts for vegetation and fauna (Wallis et al., 2015). For wetlands, these changes combined with increased temperatures could cause a shift in wetting and drying regimes, with the impact likely to be greatest on those that require frequent wetting or permanent inundation.

Existing threats including flooding, erosion and sedimentation are likely to be exacerbated by increased frequency and intensity of rainfall events, whilst poor water quality will also be influenced by increased temperatures and low flow conditions in summer and autumn (Hobday & Lough, 2011).

Coasts, Estuaries and Coastal Wetlands

Coastal areas including estuaries and wetlands are subject to a range of hazards including inundation, erosion and flooding, which are likely to increase in frequency and extent in the coastal areas of the region under future climate scenarios. The drivers of these include changes in sea level, storm surge, tides and rainfall. Transition and migration of coastal habitats is possible where there are no barriers such as infrastructure or other built assets, but there are potential impacts to agriculture from inundation of low-lying land. Loss of habitat is possible where coastal habitats become trapped between landward boundaries and rising sea level.

Estuaries and coastal wetlands are likely to be highly vulnerable to the effects of climate change, including from changes to catchment inflows, storm surge and sea level rise, with associated impacts including shoreline erosion and changes to salinity and water quality (Gillanders et al., 2011).