Decision support for sustainable option selection in integrated urban water management

Conventional urban water management practices aim to meet water supply-demands while conveying wastewater and stormwater away from urban settings. Alternative approaches which consider water demands to be manageable and wastewater and stormwater as valuable resources, although being increasingly sought, lack reliable site specific implementation methodologies. This paper describes the development of a decision support tool (termed the Urban Water Optioneering Tool (UWOT)) to facilitate the selection of combinations of water saving strategies and technologies and to support the delivery of integrated, sustainable water management for new developments. The tool is based on a water balance model which allows the investigation of interactions between the major urban water cycle streams. The model is informed by a knowledge library which is populated with technological options and information on their major characteristics and performance. The technology selection is driven by a GA algorithm allowing efficient exploration of the decision space. Quantitative and qualitative sustainability criteria and indicators are used to compare between alternative composite water management strategies while preserving the multiobjective nature of the problem. The tool has been successfully tested on a case study site in the UK, and the results are presented and discussed. It is suggested that ‘‘optioneering’’ tools will increasingly become part of urban water management planning toolkits as practice moves towards more decentralised, integrated, context-specific solutions to address issues of sustainability.