Multiobjective Optimization of Distributed Stormwater Harvesting Systems

Abstract

Stormwater harvesting (SWH) is an important water-sensitive urban design (WSUD) approach that provides an alternate water supply source and improves runoff quality through integrated systems of stormwater best management practice (BMP) technologies. In SWH system design, practitioners must account for trade-offs between cost, supply volume, and water quality improvement performance, which depend on design decisions for the type, size, and spatial distribution of BMPs. As such, the design of SWH systems with distributed BMPs is a complex, multiobjective optimization problem with a large decision space. This paper presents a multiobjective optimization framework to assess trade-offs in spatially distributed SWH system designs. The framework was applied to a case study for a housing development in Adelaide, South Australia. The results illustrated the potential benefits of distributing BMPs in an integrated SWH system where space at the catchment outlet is limited. Trade-offs between volumetric reliability and total suspended solids (TSS) reduction indicate that large gains in TSS reduction can be achieved with limited reduction in volumetric reliability. Concept designs in low-cost/moderately reliable and low-cost/high TSS reduction trade-off regions contained biofilters in locations receiving large inflows.