2024 – Exploring the Order of Magnitude Impact to Potential Loss of Life from the Distribution of Rainfall Downstream of a Dam

E. Funnell, R. Jensen

A vital component of assessing the incremental potential loss of life (PLL) associated with dam failure is the derivation of flooding in the coincident catchment downstream of a dam. The flooding behaviour of the coincident catchment can be significantly influenced by the temporal and spatial distribution of rainfall. As the industry moves away from the assessment of PLL using static dambreak flood surfaces of peak depth and velocity and moves towards dynamic simulation of evacuation, the need to consider at least the temporal variability of rainfall distribution and hence flows becomes paramount.

This paper presents methods for accounting for the underlying variability of PLL to spatial and temporal distributions of rainfall for the dam and coincident catchments. It also presents the findings of a worked example where two full sets of space-time patterns (20 in total) were simulated in dambreak and LifeSim models. The results show that the variability in incremental PLL across the 10 space-time patterns was 3.0 to 3.5 times the median incremental PLL. This illustrates that selecting a single space-time/temporal pattern could be masking a very significant amount of variability in incremental PLL.