Numerical modelling for the extreme flood event in the Fitzroy Basin, Queensland, Australia

Fitzroy Basin is the second largest catchment that drains to the coast in Australia. Fitzroy Basin is capable of producing severe flooding from tropical cyclone with heavy rainfall due its immense size and fan-like shape. Analysis shows that the historical peaks of different tributaries in different sub-basins of the Fitzroy River occurred in different years and their contributions are different for each flood event. However a scenario might happen when the flood peaks of different tributaries would synchronize and its consequence will be mass devastation indeed. The impact of combination of extreme flood peaks of different tributaries in different sub-basins to the total flood magnitude of the Fitzroy river is presented in this study using an integrated hydrological and hydrodynamic model. The discharge found from the synchronized extreme flood event was about 36% higher than the most severe historical flood that occurred in 1918.