2020 – Estimation of consequences for WaterNSW’s diverse portfolio of Greater Sydney dams

Andrew Northfield, Peter Hill, Muhammad Hameed, Hench Wang, Sam Banzi

In 2018 WaterNSW undertook a Portfolio Risk Assessment (PRA) for 20 dams across the greater Sydney area.

This paper describes the estimation of consequences for this large and diverse portfolio of dams. For some dams the population at risk were greater than 100,000 people whereas for others there were no permanent PAR which required the careful consideration of itinerants. This diversity of the dams required that the approach for estimating the consequences be tailored to the specific characteristics. For example, the approaches for estimating the potential loss of life (PLL) varied from a detailed simulation model (HECLifeSim) to a simpler empirical approach (Reclamation Consequence Estimation Methodology (USBR, 2014) to bespoke consideration of itinerant campers and users of walking tracks. For some dams the economic costs were driven by direct infrastructure costs whereas for other the indirect costs dominated the total economic cost for failure.