Multiobjective Planning and Design of Distributed Stormwater Harvesting and Treatment Systems through Optimization and Visual Analytics

Abstract

Stormwater harvesting (SWH) is an important water sensitive urban design (WSUD) approach that provides an alternate water source and/or improves runoff quality through stormwater best management practice technologies (BMPs). Through integrated SWH system design at the development scale practitioners must account for trade-offs between cost, harvested volume, and water quality improvement performance which are usually dependent on design decisions for the type, size, and spatial distribution of BMPs. In catchment management planning, additional objectives such as catchment vegetation improvement and public recreation benefit need to be maximized for a catchment region within a limited budget. As such, planning and design of SWH systems with distributed BMPs is a complex problem that requires optimal allocation of limited resources to maximize multiple benefits. In this thesis, two innovative formal optimization approaches are presented for formulating and identifying optimal solutions to problems requiring distributed BMPs. Firstly, a multiobjective optimization framework is presented and applied to a case study for the conceptual design of integrated systems of BMPs for stormwater harvesting. The aim of this work is to develop a conceptual design modelling framework that handles the optimal placement of stormwater harvesting (SWH) infrastructure within an urban development. The framework produces preliminary SWH system designs representing optimal trade-offs between cost, water harvesting, and water quality improvement measures. Secondly, a many (>3) -objective optimization framework is presented and applied to a case study for catchment planning requiring the selection of a portfolio of distributed BMP projects. The framework produces portfolios that are optimal with respect to four objectives, and enables exploration of the many-objective trade-off surface using interactive visual analytics. In addition, a multi-stakeholder method is presented, which enables catchment managers and local government authorities to identify solutions that represent a compromise between 16 objectives and eight optimization problem representations using interactive visual analytics to encourage a negotiated solution. This thesis contains one paper accepted in the Journal of Water Resources Planning and Management (Paper 1), and one paper submitted (Paper 2), and one paper to be submitted (Paper 3) to peer-reviewed journals in the field of water resources management.