Using high-resolution regional climate projections to investigate the impact of climate change on flood inundation: a case-study from Tasmania

Changes to design flood hydrographs were assessed using projected changes to the magnitude of extreme rainfall events as a result of climate change. The Climate Futures for Tasmania (CFT) project has produced dynamically downscaled high-resolution climate change projections for Tasmania using the CSIRO Conformal Cubic Atmospheric Model (CCAM). The impact of climate change on flood levels was assessed for selected Tasmanian catchments, namely the lower reaches of the Huon River, Derwent River, Forth River and Mersey River. A series of design flood hydrographs for the 1:10, 1:50, 1:100 and 1:200 annual exceedance probability (AEP) events have been produced for the observed 1961-1990 period, then scaled for three future periods (2010-2039, 2040-2069 and 2070-2099) using the CFT projections. MIKE 11 and MIKE 21 hydraulic models were run for each of the selected catchments and each of the design floods. Results from MIKE 11 and MIKE 21 were used to generate flood inundation maps for use by the Tasmanian State Emergency Services (SES).