How "Critical" is Critical Duration?

The accurate assessment of flood risk and flood damages in any catchment relies on the best possible calculations of peak flood discharges, stages, and maximum runoff volumes. Each of these fundamental parameters is affected by the nature of the particular location being investigated and importantly how it is connected to upstream catchments and downstream drainage infrastructure. TUFLOW GPU has been used in our UK office for whole-of-catchment surface water flood modelling as an alternative to using conventional hydrological models (which are often constrained as they cannot properly simulate the hydraulics of drainage infrastructure) to determine the critical duration storms specific to each study reach across/within a catchment.

The substantial parallel computing ability of TUFLOW GPU means that we can now quickly model multiple storm durations to identify how critical duration events vary within a catchment by simulating both the hydrology (through the distributed direct rainfall runoff capability of TUFLOW GPU) and the hydraulics of the major drainage infrastructure within the catchment (which are directly simulated within TUFLOW GPU).

The analysis above shows such an application and illustrates that, even within a small urban area, modelling more than one critical duration storm is necessary to produce the most accurate representations (i.e. the highest) flood discharges and stages.

How “Critical” is Critical Duration