Water is an important component of the urban environment, and principally appears in cities and towns in the form of drinking water, wastewater, storm-water, natural water bodies and artificial water bodies and features in open spaces. Features of the built environment interrupt the natural cycle of precipitation, infiltration, surface runoff and evaporation, with serious implications on the urban climate. Water in the urban area cannot infiltrate into the ground due to paved surfaces, but is rapidly discharged to the public drainage systems, with little time to evaporate. As a result, groundwater recharge is grossly minimised. Furthermore, the water is highly polluted, and so negatively impacts on the qualitative and quantitative state of the receiving water. Historically, storm-water management, which is dominated by engineers, has been the main discipline at the centre of solving these problems.
There are a few techniques that have been developed worldwide to achieve sustainable storm-water management, by mimicking natural surface water flow patterns. Examples are the sustainable urban drainage systems (Suds) in the UK; best management practices in Europe; low impact development and green infrastructure in the USA; decentralised rainwater/storm-water management in Germany; integrated urban water resources management worldwide; and water-sensitive urban design (WSUD) in Australia (Hoyer et al., 2011). Although initially a WSUD approach was predominantly used for sustainable storm-water management, it has evolved into a framework for interdisciplinary cooperation of water management, urban design and landscape planning; and is rapidly being adopted worldwide.
WSUD is defined as ‘the integration of urban planning with the management, protection and conservation of the urban water cycle that ensures that urban water management is sensitive to natural hydrological and ecological processes’ (Wong, 2006). WSUD is a platform that may be used to incorporate water cycle management with the built environment throughout planning and urban design, and requires early collaboration between engineers, planners, architects, urban designers and landscape architects (Morgan, 2013).
Recent research conducted as part of the EU-funded Switch (Sustainable Urban Water Managements Improves Tomorrow’s City’s Health) project on ‘managing water for the city of the future’ developed 12 principles that should be considered for effective WSUD (Hoyer et al., 2011). These principles fall into six categories, as shown below. This issue of Municipal Engineer explores some of these principles in further detail.
Water sensitivity
Using decentralised urban water management systems, so as to mimic the natural water cycle
Aesthetics
Providing aesthetic benefits wherever possible
Adapting the design to the surrounding urban landscape
Functionality
Adapting to the local conditions and the intended use
Considering maintenance requirements of the infrastructure
Adaptation to uncertain and changing conditions (e.g. extreme climate events)
Usability
Creating places that are usable for recreation and/or nature conservation purposes
Public perceptions and acceptability
Considering the demands of all stakeholders and involving them in the planning process
Costs to be comparable to those for conventional solutions
Integrative planning
Combination of function, aesthetics and usability
Interdisciplinary co-operation of urban planning, urban design, landscape architecture and water management
WSUD-solutions should be designed in an aesthetic, well-functioning and usable way in order to improve the public perception and acceptability of WSUD
The paper by Ashley et al. (2013) defines WSUD in the context of urban water management, traces the evolution of the WSUD paradigm on the international scene, and proposes a pragmatic approach that can be adapted for implementing WSUD in the UK and Europe.
Ellis et al. (2013) describe research conducted as part of the Switch project, on the urban water cycle (UWC) approach, integrating water management at centralised and decentralised levels, and seeking to harmonise the objectives/aspirations of the various relevant stakeholder organisations. The paper then demonstrates how the UWC approach can successfully be applied to the assessment of small urban (re)development sites, using an urban regeneration initiative in Birmingham city centre as a case study.
Dolman et al. (2013) briefly describe the application of some WSUD principles in the planning of Dutch cities, and discuss opportunities for adaptation of these principles in the UK. The paper also discusses a set of WSUD indicators and control parameters developed by Royal HaskoningDHV, in the Netherlands.
The paper by Morgan and Woods (2013) demonstrates how the principles of WSUD can practically be taken on board in the development of master plans for cities. Using the case of north-west Cambridge (UK), the paper shows how a multidisciplinary team of urban designers, landscape architects, engineers, ecologists and planners have developed a WSUD strategy for a major urban extension site.
The paper by Reed (2013) synthesizes findings from ten Loughborough University MSc dissertations on the state of storm-water management in six developing countries. In common, the papers show that institutional capacity is a barrier to effective storm-water management.
On the other hand, Suárez et al. (2013) present a design procedure for a sand filter in a highway catchment. The paper also describes a novel pilot technique that reduces the pollution load received by estuarine receiving waters, hence improving the performance of sustainable urban drainage facilities.
The last two papers are concerned with municipal water supply, which is a component of urban water management. The paper by Ezeji et al. (2013) looks at a case study from Nigeria, and advocates inclusion of the wider ecosystem indicators in the performance management framework of water utilities, in order to mitigate hazards and risks such as flooding, land erosion, land inundation and salt water intrusion. Lastly, the paper by Ahmed (2013) highlights the lack of capacity by Karachi Water and Sewerage Board, an urban water utility, to cope with the escalating urbanisation rates in Karachi, Pakistan. This paper advocates greater consultation between the water utility and low-income urban communities, for improvement of service delivery.
Collectively, these papers justify the need for adapting principles of WSUD for managing urban water systems in a more effective manner, so as to enhance environmental sustainability.
