05 Apr 2022
05 Apr 2022
Status: this preprint is currently under review for the journal NHESS.

Assessing flood hazard changes using climate model forcing

David Patrick Callaghan1 and Michael G. Hughes2,3 David Patrick Callaghan and Michael G. Hughes
  • 1School of Civil Engineering, The University of Queensland, Brisbane, QLD, Australia
  • 2Science Economics and Insights Division, NSW Department of Planning and Environment, Australia
  • 3School of Earth Atmospheric and Life Sciences, University of Wollongong, North Wollongong, NSW, Australia

Abstract. A modelling framework for using regional climate projections to assess flooding hazard has been developed and applied to the Gwydir River (catchment 26,600 km2 and floodplain 8,100 km2), NSW, Australia. The model framework uses NSW and ACT Regional Climate Modelling version 1.5 projections combined with computationally efficient hydrologic and hydraulic models. While requiring model management and high-performance computing resources, the modelling framework successfully processed 18 regional climate projections into flood projections. Specifically, a six-member set of climate model combinations simulating a historical period (1950–2006) and a future period (2006–2100) under two global emission pathways (RCP4.5 and RP8.5) were used to predict flood depth and speed. In total, 1,470 continuous years were simulated at hourly time step. These flood (depth and speed) projections were analysed to assess the flood hazard changes under future climate scenarios by estimating changes in the annual probability of occurrence of a range of flood hazard classes. The six-member ensemble indicates flood hazard in the Gwydir Valley will decrease in the short, medium and long term. There are also cases within the ensemble which includes increases in all non-safe flood hazard classification while decreasing the safe flood hazard classification.

David Patrick Callaghan and Michael G. Hughes

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2022-84', Jesper Neilsen, 09 May 2022
  • RC2: 'Comment on nhess-2022-84', Anonymous Referee #2, 09 May 2022

David Patrick Callaghan and Michael G. Hughes

Data sets

Gwydir River hydraulic model results using regional climate projections Callaghan, David

David Patrick Callaghan and Michael G. Hughes


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Short summary
A new method was developed to estimate changes of flood hazard under climate change. We use climate projections covering New South Wales, Australia, with two emission paths of business as usual and one with reduced emissions. We apply our method on the lower floodplain of the Gwydir Valley with changes of flood hazard provided over the next 90 years compared to the previous 50 years. We find that changes in flood hazard reduces over time within the Gwydir Valley floodplain.