Development and use of a decision support tool for supporting the operation of Melbourne Water's drinking water reservoirs, Victoria, Australia

Operators and managers of water resources have a responsibility to make reliable decisions in response to a broad range of drivers, from strategic planning requirements to unforeseen or unusual events. These decisions are made with varying levels of uncertainty. To increase their certainty in the management of its drinking water reservoirs Melbourne Water (MW) have implemented a real-time decision support tool. The Aquatic Real-time Management System (ARMS) utilises historical and real-time field data and numerical models for reporting, analysing and assessing reservoir conditions with improved certainty. The three-dimensional hydrodynamic model ELCOM is configured for six of MW's nine major drinking water reservoirs, and each reservoir model has undergone performance checks commensurate with the available field data. Field instruments record up-to-the-minute observations that are remotely acquired by ARMS and automatically applied to the models to execute real-time simulations and scenario forecasting. The ability to run models in real-time allows the user to forecast a range of scenarios and compare possible outcomes, thereby reducing uncertainty in decisions relating to the operational management of reservoirs. The ARMS Graphic User Interface (GUI) was tailor-made to MW's specific needs. Time series of an observed or modelled variable may be plotted against reporting criteria and presented to the operator for quick assessment. Customisation of ARMS is a major advantage. All MW's discrete and continuous data sources may be imported, configured and analysed, streamlining use and interrogation of data. Custom plotting allows efficient communication of key information and model output to operators and managers. Data gaps are filled using basic algorithms there-by minimising downtime. The on-going integration of field data, model output, reporting criteria, error analysis and gap identification in ARMS has been applied successfully at MW to investigate the fate and transport of post-fire debris flow in Upper Yarra Reservoir, and to conduct scenario analysis for complex operational decision-making, for example, assessing the dilution rate of desalinated water in Cardinia Reservoir. The components of MW ARMS are continually improved and updated, such as improving model performance and customising GUI functions. In-house capability is built through training in the use of MW ARMS and interpretation of output.