WATER SUPPLY RISK ASSESSMENTS USING STOCHASTIC PEAKING FACTORS
A method for sizing back-up provisions to match probable water supply failures
Publication Date (Web): 30 August 2018
In Australia the national water supply design guidelines, Water Supply Code of Australia, recommend that risk assessments are undertaken as part of the process of sizing reservoirs and pump stations, and the determination of system configurations. The guidelines refer to AS/NZS ISO 31000:2009 Risk Management – Principles and Guidelines which outlines a risk/consequence matrix approach for determining risks, and the most appropriate risk mitigation actions.
Such matrices can identify the relative need for back-up provisions to cope with identified failure events. Unfortunately, while water supply failure risks can be well assessed, the consequences are much more difficult to evaluate. This is primarily because it is usually not possible to know whether the failure event would be most likely to occur during a minimum day, maximum day or some other value demand event. The size of the back-up provisions therefore cannot be determined with any certainty and it is usual for water supply practitioners to have to make an “educated guess” about the required provisions.