LOWER CLARENCE FLOOD STUDY UPDATE

Predicted flood heights evolves with changing climate

The updated Lower Clarence Flood Model accounts for notable changes to the floodplain including the Pacific Highway upgrade and second Clarence River crossing at Grafton. The model which predicts future flood heights also incorporates the latest available datasets after the February/March 2022 flood event.

Since the model was last revised in 2013, there have been improvements in modelling software, significant infrastructure developments within the floodplain and updates to flood study guidelines.

This model updates the Clarence Flood Model with higher resolution outputs to provide improved understanding of floodplain behaviour within the Lower Clarence Valley.

Two climate change scenarios have been modelled representing an intermediate and a worst-case scenario. The differences between the scenarios relate to the sea level rise allowances.

– Lower Clarence Flood Model Update 2022

In addition to 20%, 5%, 2% and 1% annual exceedance probability (AEP) flood events, it now includes models for 0.5% and 0.2% flood events, and two climate change scenarios.

PICTURED: Above; extent of inundation during a 0.2% AEP flood event at peak water flow. Red lines indicate existing levees.