2023 – The Application of Ensemble Approach in Hydraulic Modelling on Dambreak Consequence Studies

Albert Shen, Tim Craig

With the popularity of using LifeSim for potential life loss estimation on dambreak consequence studies, understanding the impact of storm variability on the warning evacuation time becomes more and more important. However, it is difficult to understand the wide variability of individual flood outcomes by
adopting a “representative flood” approach.

Running an ensemble of storms or temporal patterns in hydraulic models is a commonly adopted approach in flood plain modelling to understand the influence of storm variability in the hydrological model. For dambreak consequence assessment this has been more challenging, as the high flows and large flood plains typically associated with dambreak modelling meant this isn’t a viable strategy. With the increasing computational power of the graphic cards and the advancement of sub-grid sampling (SGS), the application of an ensemble approach in dambreak hydraulic modelling becomes a more feasible option for modellers.

This paper explores a practical way of applying an ensemble approach in dambreak hydraulic modelling to help flood modellers notice and understand the potential impact of the variability characterised in the hydrological model on the outcomes of a consequence assessment and how that variability can be efficiently considered without significant impacts to project timelines and budgets.