Behaviour change: Trialling a novel approach to reduce industrial stormwater pollution

Protecting and restoring freshwater biodiversity across urban areas in Aotearoa New Zealand: Citizens' reporting of pollution in stormwater drains and waterways

Urbanization poses numerous challenges to freshwater biodiversity. This paper describes two studies with the joint aim of demonstrating the benefits of applying a systematic behaviour change framework and providing the foundational knowledge to inform future behavior change work to protect and restore urban freshwater biodiversity. In Study 1 we used a mixed-methods research design, involving 14 key informant interviews followed by an online survey targeting 17 freshwater biodiversity experts and another targeting a representative sample of 550 urban residents, to identify and prioritize the most promising resident behaviors to target to reduce stormwater pollution and improve natural waterway habitats in urban areas. Study 2 focused on the top-ranked short-term behavior identified in Study 1, citizen reporting of pollution in stormwater drains and waterways. We surveyed a representative sample of 1901 urban residents across Aoteraoa New Zealand to identify four main determinants influencing this behavior: awareness and uncertainty about reporting, lack of opportunity to report, social motivation and personal motivation to report, and five potential target audiences: 'Supportive', 'Unaware but receptive', 'Motivated but lack support', 'Reluctant', and 'Not my problem'. We make recommendations for the most appropriate intervention designs to target each of these audience segments to promote the reporting of stormwater pollution in urban areas. This knowledge will allow for a more coordinated and effective approach for addressing the 'human element' that lies at the heart of many urban freshwater management problems.

Review of hydraulics of Floating Treatment Islands retrofitted in waterbodies receiving stormwater

Stormwater pollution causes an excessive influx of nutrients and metals to the receiving waterbodies (stormwater ponds, lakes, and rivers), which can cause eutrophication and metal toxicity. One of the most cost-effective and eco-friendly solutions to stormwater pollution is constructing Floating Treatment Islands (FTIs) within the waterbodies receiving stormwater runoff. Treatment efficiency of FTIs depends on many factors including plant species, temperature, detention time, and pollutant loading rate. Another important factor is FTI hydraulics, which determines the amount of inflow to the root zone and residence time, greatly impacting the treatment. However, only a few studies refer to the hydraulics of waterbodies retrofitted with FTIs. This paper reviews available literature on field-scale, laboratory-scale and numerical studies on the hydraulics of FTI retrofitted waterbodies. Because of limited knowledge on the factors affecting hydraulics of waterbodies retrofitted with FTIs, current practices cannot ensure maximum hydraulic performance of this system. This review paper identifies different factors affecting the FTI hydraulics, investigates knowledge gaps, and provides future research direction for hydraulically efficient design of FTIs to treat stormwater. It was found that there is a need to investigate the impact of new design parameters such as FTI shape, FTI coverage, inlet-outlet configurations, and shape of waterbody on the hydraulic performance of FTI retrofitted waterbodies. A lack of dimensional analysis on FTI retrofitted waterbodies in existing literature revealed that field-scale values were not properly scaled down in laboratory experiments. Although a few short-circuiting prevention mechanisms (SPMs) were used in different field-scale studies, those mechanisms may be vulnerable to short-circuiting in the vertical dimension. It was revealed that studying the role of eddy diffusion and gap layer for vertical short-circuiting can help designing better SPMs. This review also identified that further investigation is required to incorporate root flexibility in the current modeling approach of FTI retrofitted waterbodies.

Stakeholders' perceptions and preferences towards industrial water sensitive development in New Zealand

Understanding stakeholders' perceptions and preferences is key to promoting Industrial Water Sensitive Design (IWSD). A questionnaire was distributed to stakeholders in a conventional New Zealand industrial area. The results showed that technological feasibility limitation, institutional inertia, and cognitive shortage were the main barriers to IWSD application, though stakeholders supported IWSD and preferred the vegetation-based measures. IWSD should focus on achieving the enhancement of environmental quality, greening functions, community well-being, traffic and driving convenience, and balancing the aesthetic demand and attractiveness of IWSD projects. Improving the threshold of IWSD measures' pollutant removal capacity and optimizing infiltration places and flow paths are also vital. Results suggest IWSD implementation requires the transformation of public awareness, the establishment of sound regulations, plus IWSD guidance, practitioner training guidance, and incentive mechanisms. The findings facilitate public acceptance, strategic planning, the formulation of regulations for future IWSD application, and achievement of sustainable industrial development. The study concludes by providing recommendations for future work. PRACTITIONER POINTS: Industrial Sustainable Stormwater Management is a research and practice gap. The main barriers of IWSD are technological feasibility limitation, institutional inertia, and cognitive shortage. Traffic and driving convenience, greening functions, aesthetic value balance, and health improvement are vital for improving social acceptance of IWSD. IWSD requires sound policy, awareness transformation, and reasonable design for capacity of IWSD measures and stormwater infiltration and flow.