Water-sensitive urban design

Water-sensitive urban design (WSUD) is a land planning and engineering design approach which integrates the urban water cycle, including stormwater, groundwater and wastewater management and water supply, into urban design to minimise environmental degradation and improve aesthetic and recreational appeal. WSUD is a term used in the Middle East and Australia and is similar to low-impact development (LID), a term used in the United States; and Sustainable Drainage System (SuDS), a term used in the United Kingdom.

Traditional urban and industrial development alters landscapes from permeable vegetated surfaces to a series of impervious interconnected surfaces resulting in large quantities of stormwater runoff, requiring management. Historically Australia, like other industrialised countries including the United States and United Kingdom, has treated stormwater runoff as a liability and nuisance endangering human health and property. This resulted in a strong focus on the design of stormwater management systems that rapidly convey stormwater runoff directly to streams with little or no focus on ecosystem preservation. This management approach results in what is referred to as urban stream syndrome. Heavy rainfall flows rapidly into streams carrying pollutants and sediments washed off from impervious surfaces, resulting in streams carrying elevated concentrations of pollutants, nutrients and suspended solids. Increased peak flow also alters channel morphology and stability, further proliferating sedimentation and drastically reducing biotic richness.

Increased recognition of urban stream syndrome in the 1960s resulted in some movement towards holistic stormwater management in Australia. Awareness increased greatly during the 1990s with the Federal government and scientists cooperating through the Cooperative Research Centre program. Increasingly city planners have recognised the need for an integrated management approach to potable, waste and stormwater management, to enable cities to adapt and become resilient to the pressure which population growth, urban densification and climate change places on ageing and increasingly expensive water infrastructure. Additionally, Australia's arid conditions means it is particularly vulnerable to climate change, which together with its reliance on surface water sources, combined with one of the most severe droughts (from 2000–2010) since European settlement, highlight the fact that major urban centres face increasing water shortages. This has begun shifting the perception of stormwater runoff from strictly a liability and nuisance to that of having value as a water resource resulting in changing stormwater management practices.

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