Water sensitive urban design: A paradigm shift in urban design

It is widely recognised that catchment urbanisation will lead to increases in the volume and rate of stormwater runoff due to the increase in impervious surfaces. Urban stormwater management has traditionally focussed on stormwater drainage and flood protection with the provision of a hydraulically efficient drainage system to accommodate the expected increase in stormwater discharge resulting from catchment urbanisation. Increased emphasis on improving stormwater quality for the protection of urban aquatic ecosystems has led to the re-examination of current stormwater management practices. Many urban stormwater management authorities, at both state and local government levels, are adopting water sensitive principles in their planning, design, management and regulatory practices. Stormwater management objectives go beyond that of drainage and now include managing stormwater as a resource, for protection of receiving water quality and for protection of downstream aquatic habitats. Water Sensitive Urban Design (WSUD) practices encompass the full spectrum of planning and engineering practices. Ecologically-based stormwater management systems can be readily implemented in new developments at “greenfield” sites through effective planning of non-structural and structural stormwater management measures. The challenges are different in built-up catchments, with the emphasis shifting from strategic planning to the implementation of stormwater management measures to achieve a combination of short-term and long-term objectives. This paper describes the paradigm shift required in the management of urban stormwater for multiple objectives spanning from flood protection to protection of the aquatic ecosystem of the receiving waters.