WSUD can be Cost-effective and Low- maintenance, not to mention all the other benefits

At the 2018 Water NZ Stormwater Conference we introduced the ‘Activating Water Sensitive Urban Design (WSUD)’ research project, part of the Building Better Homes Towns and Cities National Science Challenge. We described the results of surveys and workshops with WSUD practitioners and set out a plan for a programme of research activities to support WSUD uptake. Twelve months on, this paper summarizes our progress across a wide ranging, but linked, suite of research to progress three main ‘quick win’ areas. Through focused case-studies we have investigated costs, assessed benefits and explored operations and maintenance requirements; these being leading themes expressed by practitioners in conversations on barriers to the adoption of WSUD.

We have found that WSUD can be a cost-effective alternative to conventional approaches to stormwater management. It can avoid some costs of building hard infrastructure and the hidden costs of deferred environmental remediation, while delivering better ‘bang-for- buck’ in removing stormwater contaminants. On the benefits side, we have demonstrated that the reasons for adopting WSUD can extend well beyond those of hydrological and water quality management, for instance by enhancing the terrestrial environment and contributing to the well-being of urban communities. In complementary research, the project has started to investigate how WSUD in Aotearoa values, recognizes, and provides for Te Ao Māori and how it could do better (described in a complementary paper at the present conference). We have developed the ‘More Than Water’ tool to help assessments of projects reflect the costs and benefits advantages of adopting WSUD approaches, for instance to support project planning and consultation.

We have found that problems around WSUD maintenance are linked to inadequate consideration at the design stage and inadequate recording of the location and condition of WSUD assets at ‘handover’, especially those in public spaces. Together, these have led to acceptance of defective devices and a lack of maintenance. Based on observations at our case-study locations, we have developed guidance on the design of low-maintenance WSUD and checklists for acceptance. In addition we have reviewed financial incentives employed overseas, finding that, while there is no ‘silver bullet,’ a tool box of approaches is available to incentivize the uptake of WSUD in New Zealand.

The research effort has been supported by continued conversations with WSUD stakeholders. These have included targeted discussions with the roading and asset maintenance sectors and engaging with Melbourne’s WSUD community to learn from the experience of researchers and water managers there. A wide range of learnings from that City’s transition appear to be relevant to New Zealand, with the importance of effective governance, leadership and collaboration at the top of the list.

The findings of our research are being delivered through workshops for NZ’s WSUD community, including a workshop and linked site visit as part of this conference. Outputs are also posted on the project web site. Looking beyond the current project, these outputs include an assessment of longer-term research needs to help WSUD in New Zealand to deliver outcomes that urban New Zealanders value.