2022 – Giving More Weight to Severity of Damage and Loss

Mardi Medwell-Squier – GHD Pty Ltd, Technical Director – Flood Hydrology and Hydraulics, Elise McQuilten – GHD Pty Ltd, Senior Engineer – Dams

Potential Loss of Life and Severity of Damage and Loss jointly determine the Consequence Category of a dam under ANCOLD (2012), however risk- based approaches largely focus on Consequences such as Potential Loss of Life and Monetary Consequences.

This paper presents a project case study for a proposed new dam in an urban environment. A dam failure would lead to significant consequences that are captured under the Severity of Damage and Loss ratings. The potential impacts on assets downstream, loss of community amenity, urban stormwater and transport functions required careful review.

This project demonstrates the application of risk-based consideration in evaluating Severity of Damage and Loss, for example considering the likelihood of failure of downstream assets in the inundation zone. For on-stream storages in urban environments, downstream assets are likely to include stream crossings such as, pedestrian bridges, road bridges and utility bridges. Therefore, the consideration of the likelihood of dam failure and subsequent downstream asset failure in a dambreak scenario may be appropriate in some cases, rather than considering the asset failure and dam failure as absolute.

It highlights the various considerations required when setting design criteria for a new dam, that are beyond potential loss of life and fallback criteria and also takes are realistic view of loss of amenity in an urban environment.