Using catchment history to define a naturalised urban stream when restoration is impossible
Abstract
Expanding cities worldwide are gradually absorbing peripheral greenfield streams that often require some level of improvement to fulfil their role as central public spaces in the urban landscape. Restoration is often impossible due to physical constraints imposed by urban development coupled with fundamental biophysical modification from previous land use. However, it is possible to provide social amenity and improve stream ecosystem condition through the process of naturalisation – an implicitly social undertaking reliant on the well-informed participation of stakeholders. Urbanising greenfield sites present a special case of naturalisation that does not include a local community as it is absent in advance of development. The authors present a case study where they were involved as advising scientists in a stream naturalisation project in Melbourne, Australia. In the case study, the lack of this founder community in the consultation process coupled with limited integration between other stakeholders resulted in naturalisation goals unlikely to result in improved in-stream ecosystem condition. The final design adopted some features that extended beyond baseline regulatory standards for drainage schemes in new developments, but with insufficient provision for catchment-scale treatment of stormwater runoff, which has been recognised as a primary source of urban stream degradation. This study expands the concept of naturalisation – originally developed in the context of rural stream management – to include urbanising greenfield catchments where advocacy groups and urban planning officials from local government hold chief responsibility to represent the values and attitudes of the founder community in the consultation process.