Resolving boundary conditions in economic analysis of distributed solutions for water cycle management

Abstract

Over the last 30 years leading thinkers have taken us beyond mechanistic and reductionist analysis into systems theory and the critical boundary judgements that are fundamental to systems analysis. In defining and discussing boundary conditions, we also redefine values and facts imposed on hydrological and economic analysis that underpins decisions about government policy in water resources. The repeal of legislation for distributed interventions (water-efficient appliances and rainwater harvesting) that was previously enacted to improve the security of a regional water supply system is examined as a case study. The results of the analysis were defined by the costs and benefits that are inside or outside of the boundaries of legitimate and recognized consideration. This paper refers to those differences as boundary conditions and considers how those boundary conditions affect the outcome of analysis. Setting of boundary conditions (what is included, what is excluded and assumptions) in engineering and economic analysis dominates outcomes of decisions about government policy. These insights have general application to development of government water policy. The investigations outlined in this paper were combined to create an enhanced version of a systems analysis of a policy for setting targets for water savings on all new dwellings. It was established, using appropriate boundary conditions, that a 40% target for water savings is feasible for South East Queensland (SEQ) and provides a cost-benefit ratio of 2.1. These results indicate that a policy of mandating targets for sustainable buildings would provide substantial benefits to the state of Queensland, water utilities and citizens.

Water in the city: Green open spaces, land use planning and flood management – An Australian case study

“…Major floodway and flood-related development controls in Australian urban centres are principally controlled by state-based legislation (Godden and Kung 2011), and influenced by state and territory guidelines for best practice urban stormwater management (Barton and Argue 2007). Responsibility for implementing stormwater management mainly lies with local governments, who play a critical role in stormwater management and land use planning and therefore are integral in managing the urban water cycle (Coombes, Smit et al 2015).…”

The Value of Aggregated City Scale Models to Rapidly Assess SuDS in Combined Sewer Systems

“…Spatially aggregated hydraulic modelling has been used to represent the whole water cycle to inform decisions related to river water quality (Dobson and Mijic, 2020), real-time flood forecasting (Li and Willems, 2020) and supply-sewerage runoff treatment (Coombes et al, 2016). These integrated models were developed with the aim to reveal a wide range of alternative catchment management options without the need to run computationally expensive simulations.…”

A brave new world – expanding the remit of the Australian Journal of Water Resources

“…exist in economic analysis of water systems, as well as a comparative case-study analysis of two economic analyses looking at the costs and benefits of rainwater harvesting in South-East Queensland, Australia, linked to the repeal of Queensland State legislation on sustainable buildings. The authors particularly reflect on the different paradigms of water systems analysis and boundary judgments that permeate policy and decision-support and propose a need to move beyond mechanistic and deterministic understandings and representations of water systems, to whole of water cycle systems analyses (Coombes et al 2016).…”