Water Accounting System for Strategic Resource Management

This paper describes a water accounting system (WAS) that provides a strategic long-term water management tool. The WAS integrates water use and availability, provides a comprehensive and consistent historical database, and allows exploration of scenarios. The WAS has spatial, temporal and sectoral resolution and has been established and tested for the state of Victoria in Australia, and can be extended to cover other or all regions of Australia. It is part of a larger stocks and flows framework covering key drivers such as demography, land-use and electricity production. The WAS has features in common with system dynamics, such as the evolution of stocks (with age profiles), linking of stock and flow variables in causal chains of influence, and the use of a diagrammatic interface and time series output. However, an innovative difference of the present work with system dynamics is the deliberate removal from within the model code of feedback loops that involve choices belonging to the social or economic domain. This has particular importance for stimulating and exploring the many behavioural, technological and engineering options that are possible for resolving tensions between, in this case, water supply and demand. In particular, it is possible to arrange the information flows, as shown in Figure 1, which allows influence chains to be traced so that the main causes of tensions can be readily identified. This paper demonstrates the advantage of taking this "design approach" implemented in the whatIf software environment for understanding the complex interactions in, for example, the water system and identifying key drivers of long-term (50+ years) sustainable futures. For example, Figure 2 shows the river flow in the catchment that supplies the majority of water to Melbourne. Both historical data and two scenarios are shown. The scenarios are for a high climate change environment (average global temperature increase of 2.2 degrees C in 2050). River flow drops rapidly and flow are diverted to maintain the Thomson Reservoir at about 50% capacity. Less pressure is placed on the river if extra proportions are not diverted, but the Reservoir fails in about 2040. [GRAPHICS] Many other water management options and scenarios can be created and explored in the WAS. Ideally, this would occur with the engagement of key stakeholders. It is beyond the scope of this paper to document this process or a range of scenarios.