This project was Phase 2 of the Goyder Institute for Water Research Water Sensitive Urban Design (WSUD) (U.1) Urban Water Theme. The purpose of this project was to address outcomes of Phase 1, which identified key areas that influenced the impediments for WSUD uptake and where opportunities exist to overcome impediments. Several potential activities were outlined and the most desirable activities were selected for this project based on a priority ranking activity involving the Goyder WSUD project Phase 1 Steering Committee (including state government, local government and industry representation).
The project was strongly aligned with Goyder Institute for Water Research WSUD roadmap priorities as well as Action 10 of the South Australian Government WSUD Policy document: “Promote support for WSUD in catchment-based Stormwater Management Plans”. The refinement of existing WSUD approaches in stormwater management plans (SMPs) is expected to be completed in December 2016.
The review of existing SMPs in SA demonstrated that they were based on rigorous and comprehensive analyses, and considered WSUD to manage stormwater quantity and quality. However, there were limitations and inconsistencies in the way in which WSUD was proposed, analysed and reported and recommendations to improve the inclusion of WSUD were reported.
The hydrological assessment of storage based WSUD systems for quantity management demonstrated that the design of WSUD systems for flow and runoff volume management is influenced by antecedent conditions. This can limit the effectiveness of the current standard practice of using design storm events for sizing WSUD retention and detention systems. While no guideline currently exists with appropriate alternative methodologies, it is understood that the revised Australian Rainfall and Runoff guideline will include consideration of an approach, which should be referenced in any revision of the current SMP guidelines.
The Model for Urban Stormwater Improvement Conceptualisation (MUSIC) is commonly applied in Australia and SA to estimate stormwater runoff volume, pollutant loads and the effectiveness of WSUD approaches in reducing them. Unlike other states, there were no guidelines for the use of MUSIC specific to SA. This project developed recommendations for the use of MUSIC in SA at the SMP or developer level. This included identifying opportunities for further research and refinement of guidelines.
In the context of the role and application WSUD measures in the development of stormwater management plans a review of frequent flow management approaches for maintaining natural (pre urbanisation) stream habitat and geomorphology as conducted. Case studies and approaches were investigated and a set of recommendations were developed. This included the need to adopt a minimum flow frequency threshold for maintaining aquatic habitats and the stream two year (recurrence interval) flow for geomorphology management. Guidance on the type of WSUD functions that mimic the natural flow regimes are provided.
The research findings underpinned a review of the SMP guidelines. This project also supported the following actions listed in the SA Government Water Sensitive Urban Design Policy document, released in December 2013.
Action 7: Commence a WSUD capacity building program that provides for relevant State agencies, Local Government, industry, and others to effectively engage so that WSUD is implemented in the most appropriate way.
Action 8: Engage relevant research bodies in relation to the development of improved information and guidance on WSUD.
Action 10: Promote support for WSUD in catchment-based Stormwater Management Plans.
Action 12: Develop a process for recording and reporting the extent to which WSUD is adopted in new developments that the State manages and oversees, for example, arterial roads and other major Government infrastructure projects, and in projects that entail re-development or renewal of existing State-owned infrastructure.