A sea level rise of between 0.8-1.1 metres by 2100, hotter temperatures, and reduction in rainfall and an increase in extreme natural events e.g. flooding, are all expected to impact the ecology and dynamics of estuaries. Existing threats, such as changes to natural estuary openings and increases in nutrient levels may also be exacerbated by the indirect impacts of climate change, in particular through sea level rise and increases in storm surges. Existing threats, such as acidification, changes to natural estuary openings and nutrient levels may also be exaggerated by the indirect impacts of climate change.

The region’s estuaries are normally quite resilient to coastal processes such as tidal exchanges, shoreline recession and natural estuary openings. However, with sea levels projected to rise on average by 0.8–1.1 metres by 2100, combined with an increase in storm surge events and reduced inflows, climate change is expected to greatly impact all estuaries in the region, as the figure below illustrates.

Climate change impact is expected to be higher in the estuaries of the Curdies, Gellibrand, Aire and Anglesea rivers. It is also expected to have a major impact on the Barwon River estuary, especially in the upper reaches of the estuary into Lake Connewarre.

It is expected sea level rise will have less of an impact on the Hovells Creek estuary. This estuary is located in Corio Bay and is not as exposed to the increase in projected storm surge events expected in the more exposed areas of the region’s coastline.