THE EVOLUTION OF LOW IMPACT DEVELOPMENT
Water Sensitive Urban Design and its extension to China as “sponge cities”
J C Radcliffe
Publication Date (Web): 20 January 2017
Since the 1980s, there has been recognition that urban development should take account of the natural water cycle, seeking to manage water flows as would have occurred on the original greenfield site, emulating the original ecosystem services it provided and the quality and quantity of water flowing therefrom. These approaches advanced in North America under the name of Low Impact Development (LID) and later Green Infrastructure (GI) in response to the 1972 passage of the Clean Water Act (US). Such developments can incorporate green roofs, rain gardens, swales, permeable pavements, wetlands, green spaces, and urban natural vegetation corridors to improve urban amenity as well as reducing flood and pollution risks, though there is considerable variability in the regulatory environment between the states governing such facilities. Britain adopted Sustainable Urban Drainage Systems (SUDS) techniques, incorporating the integration of surface run-off within the urban form. In Europe, planners and local government respond to the EU Water Management and Flooding Directives on a river basin basis. In Australia, similar policy developments took place under the philosophy of Water Sensitive Urban Design (WSUD). The components and drivers varied somewhat between the states, each choosing emphases appropriate to their catchments, infrastructure, seasonal climate, local water cycle and community expectations. Water use efficiency was highlighted in planning of new Sydney developments. Protection of watercourse and littoral environments were especially important considerations in Brisbane, Melbourne and Adelaide. Perth was protective of the groundwater on which the city’s water supply depends. In some but not all states, a statutory basis was provided for the approach adopted. New Zealand policies were developed for adoption by local government using the approach of Low Impact Urban Design and Development (LIUDD) which included awareness of Māori cultural interests in its framework.
Cities in East Asia, have been undergoing urbanisation at a much faster rate over the past 40 years than those of the developed world, but often accompanied by increased flooding. This is especially so in China where the building of high-rise urban conurbations has threatened water supply sustainability and has increased flooding, pollution and ecosystem problems. In 2013, the President of China, Xi Jinping Introduced new urban development policies which included the concept of building and even retrofitting urban areas as Sponge Cities where “stormwater can be naturally conserved, infiltrated, and purified" for potential reuse, thereby reducing flood risks and increasing water availability. By 2015, construction guidelines for sponge cities had been issued. Thirty major cities have been identified to participate as pilot cities. Each is eligible for central government subsidies of between 400 and 600 million RMB (approximately A$85 million to A$128 million). Addressing technical integration problems, legislative constraints and community acceptance will be necessary. There will be inevitable conflicts between the traditional large “end-of-pipe” solutions, some of which may still be needed for extreme storm events, the adoption of green, environmentally sensitive “sponge city” approaches and ensuring a resilient urban water supply system. Effective integration of responsibilities between departments within local government must occur. In some cases, legislative changes to allow the adoption of sponge city standards may be required.
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