Analysis of Options to Increase Supply for the Virginia Pipeline Irrigation Scheme Utilising Multi-Criteria Decision Analysis

Many decisions in the water industry, particularly related to large infrastructure projects, involve numerous discrete alternatives and criteria and are often characterised by uncertain consequences, complex interactions, and the participation of multiple stakeholders with conflicting interests. Multi-criteria decision analysis (MCDA) is a methodology that can be used to aid decision making when discrete alternatives are involved, as it facilitates stakeholder participation and collaborative decision making and does not require the assignment of monetary values to environmental or social criteria. This paper demonstrates the application of MCDA to a real case study in the water industry in South Australia. The case study involved undertaking an analysis of options for ensuring sufficient supply of treated wastewater to an expanded horticultural irrigation scheme. Participants from the water utility, United Water, and the water authority, SA Water, were involved in the decision analysis process through two workshops. Eleven options were assessed using fourteen criteria. The ranking of options utilised a reliability approach which took into account the participants preferences (i.e. criteria weights) and the uncertainty in the values assigned to the criteria.