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.
Australian states, building on the Federal government's foundational research in the 1990s, began releasing WSUD guidelines with Western Australia first releasing guidelines in 1994. Victoria released guidelines on the best practice environmental management of urban stormwater in 1999 (developed in consultation with New South Wales) and similar documents were released by Queensland through Brisbane City Council in 1999. Cooperation between Federal, State and Territory governments to increase the efficiency of Australia's water use resulted in the National Water Initiative (NWI) signed in June 2004. The NWI is a comprehensive national strategy to improve water management across the country, it encompasses a wide range of water management issues and encourages the adoption of best practice approaches to the management of water in Australia, which include WSUD.
WSUD regards urban stormwater runoff as a resource rather than a nuisance or liability. This represents a paradigm shift in the way environmental resources and water infrastructure are dealt with in the planning and design of towns and cities. WSUD principles regard all streams of water as a resource with diverse impacts on biodiversity, water, land, and the community's recreational and aesthetic enjoyment of waterways.
Common WSUD practices used in Australia are discussed below. Usually, a combination of these elements are used to meet urban water cycle management objectives.
Bioretention systems involve the treatment of water by vegetation prior to filtration of sediment and other solids through prescribed media. Vegetation provides biological uptake of nitrogen, phosphorus and other soluble or fine particulate contaminants. Bioretention systems offer a smaller footprint than other similar measures (e.g. constructed wetlands) and are commonly used to filter and treat runoff prior to it reaching street drains. Use on larger scales can be complicated and hence other devices may be more appropriate. Biorentention systems comprise bioretention swales (also referred to as grassed swales and drainage channels) and bioretention basins.
Bioretention swales, similar to buffer strips and swales, are placed within the base of a swale that is generally located in the median strip of divided roads. They provide both stormwater treatment and are. A bioretention system can be installed in part of a swale, or along the full length of a swale, depending on treatment requirements. The runoff water usually goes through a fine media filter and proceeds downwards where it is collected via a perforated pipe leading to downstream waterways or storages. Vegetation growing in the filter media can prevent erosion and, unlike infiltration systems, bioretention swales are suited for a wide range of soil conditions.
Bioretention basins provide similar flow control and water quality treatment functions to bioretention swales but do not have a conveyance function. In addition to the filtration and biological uptake functions of bioretention systems, basins also provide extended detention of stormwater to maximise runoff treatment during small to medium flow events. The term raingarden is also used to describe such systems but usually refers to smaller, individual lot-scale bioretention basins. Bioretention basins have the advantage of being applicable at a range of scales and shapes and therefore have flexibility in their location within developments. Like other bioretention systems, they are often located along streets at regular intervals to treat runoff prior to entry into the drainage system. Alternatively, larger basins can provide treatment for larger areas, such as at the outfalls of a drainage system. A wide range of vegetation can be used within a bioretention basin, allowing them to be well integrated into the surrounding landscape design. Vegetation species that tolerate periodic inundation should be selected. Bioretention basins are however, sensitive to any materials that may clog the filter media. Basins are often used in conjunction with gross pollutant traps (GPTs or litter traps, include widely used trash racks), and coarser sediment basins, which capture litter and other gross solids to reduce the potential for damage to the vegetation or filter media surface.
Infiltration trenches are shallow excavated structures filled with permeable materials such as gravel or rock to create an underground reservoir. They are designed to hold stormwater runoff within a subsurface trench and gradually release it into the surrounding soil and groundwater systems. Although they are generally not designed as a treatment measure but can provide some level of treatment by retaining pollutants and sediments. Runoff volumes and peak discharges from impervious areas are reduced by capturing and infiltrating flows.
Due to their primary function of being the discharge of treated stormwater, infiltration systems are generally positioned as the final element in a WSUD system. Infiltration trenches should not be located on steep slopes or unstable areas. A layer of geotextile fabric is often used to line the trench in order to prevent the soil from migrating into the rock or gravel fill. Infiltration systems are dependent on the local soil characteristics and are generally best suited to soils with good infiltrative capacity, such as sandy-loam soils, with deep groundwater. In areas of low permeability soils, such as clay, a perforated pipe may be placed within the gravel.
Regular maintenance is crucial to ensure that the system does not clog with sediments and that the desired infiltration rate is maintained. This includes checking and maintaining the pre-treatment by periodic inspections and cleaning of clogged material.
Sand filters are a variation of the infiltration trench principle and operate in a way similar to bioretention systems. Stormwater is passed through them for treatment prior to discharge to the downstream stormwater system. Sand filters are very useful in treating runoff from confined hard surfaces such as car parks and from heavily urbanised and built-up areas. They usually do not support vegetation owing to the filtration media (sand) not retaining sufficient moisture and because they are usually installed underground. The filter usually consists of a sedimentation chamber as pre-treatment device to remove litter, debris, gross pollutants and medium-sized sediments; a weir; followed by a sand layer that filters sediments, finer particulates and dissolved pollutants. The filtered water is collected by perforated underdrain pipes in a similar manner as in bioretention systems. Systems may also have an overflow chamber. The sedimentation chamber can have permanent water or can be designed to be drained with weep holes between storm events. Permanent water storage however, can risk anaerobic conditions that can lead to the release of pollutants (e.g. phosphorus). The design process should consider the provision of detention storage to yield a high hydrologic effectiveness, and discharge control by proper sizing of the perforated underdrain and overflow path. Regular maintenance is required to prevent crust forming.
Porous paving (or pervious paving) is an alternative to conventional impermeable pavement and allows infiltration of runoff water to the soil or to a dedicated water storage reservoir below it In reasonably flat areas such as car parks, driveways and lightly used roads, it decreases the volume and velocity of stormwater runoff and can improve water quality by removing contaminants through filtering, interception and biological treatment. Porous pavements can have several forms and are either monolithic or modular. Monolithic structures consist of a single continuous porous medium such as porous concrete or porous pavement (asphalt) while modular structures include porous pavers individual paving blocks that are constructed so that there is a gap in between each paver. Commercial products that are available are for example, pavements made from special asphalt or concrete containing minimal materials, concrete grid pavements, and concrete ceramic or plastic modular pavements. Porous pavements are usually laid on a very porous material (sand or gravel), underlain by a layer of geotextile material. Maintenance activities vary depending on the type of porous pavement. Generally, inspections and removal of sediment and debris should be undertaken. Modulate pavers can also be lifted, backwashed and replaced when blockages occurs. Generally porous pavement is not suited for areas with heavy traffic loads. Particulates in stormwater can clog pores in the material.
Sedimentation basins (otherwise known as sediment basins) are used to remove (by settling) coarse to medium-sized sediments and to regulate water flows and are often the first element in a WSUD treatment system. They operate through temporary stormwater retention and reduction of flow velocities to promote settling of sediments out of the water column. They are important as a pretreatment to ensure downstream elements are not overloaded or smothered with coarse sediments. Sedimentation basins can take various forms and can be used as permanent systems integrated into an urban design or temporary measures to control sediment discharge during construction activities. They are often designed as an inlet pond to a bioretention basin or constructed wetland. Sedimentation basins are generally most effective at removing coarser sediments (125 μm and larger) and are typically designed to remove 70 to 90% of such sediments. They can be designed to drain during periods without rainfall and then fill during runoff events or to have a permanent pool. In flow events greater than their designed discharge, a secondary spillway directs water to a bypass channel or conveyance system, preventing the resuspension of sediments previously trapped in the basin.
Constructed wetlands are designed to remove stormwater pollutants associated with fine to colloidal particles and dissolved contaminants. These shallow, extensively vegetated water bodies use enhanced sedimentation, fine filtration and biological uptake to remove these pollutants. They usually comprise three zones: an inlet zone (sedimentation basin) to remove coarse sediments; a macrophyte zone, a heavily vegetated area to remove fine particulates and uptake of soluble pollutants; and a high flow bypass channel to protect the macrophyte zone. The macrophyte zone generally includes a marsh zone as well as an open water zone and has an extended depth of 0.25 to 0.5m with specialist plant species and a retention time of 48 to 72 hours. Constructed Wetlands can also provide a flow control function by rising during rainfall and then slowly releasing the stored flows. Constructed wetlands will improve the runoff water quality depending on the wetland processes. The key treatment mechanism of wetlands are physical (trapping suspended solids and adsorbed pollutants), biological and chemical uptake (trapping dissolved pollutants, chemical adsorption of pollutants), and pollutant transformation (more stable sediment fixation, microbial processes, UV disinfection).
The design of constructed wetlands requires careful consideration to avoid common problems such as accumulation of litter, oil and scum in sections of the wetland, infestation of weeds, mosquito problems or algal blooms. Constructed wetlands can require a large amount of land area and are unsuitable for steep terrain. High costs of the area and of vegetation establishment can be deterrents to the use of constructed wetlands as a WSUD measure. Guidelines for developers (such as the Urban Stormwater: Best Practice Environmental Management Guidelines in Victoria) require the design to retain particles of 125μm and smaller with very high efficiency and to reduce typical pollutants (such as phosphorus and nitrogen) by at least 45%. In addition to stormwater treatment, the design criteria for constructed wetlands also include enhanced aesthetic and recreational values, and habitat provision. The maintenance of constructed wetlands usually includes the removal of sediments and litter from the inlet zone, as well as weed control and occasional macrophyte harvesting to maintain a vigorous vegetation cover.
Swales and buffer strips are used to convey stormwater in lieu of pipes and provide a buffer strip between receiving waters (e.g. creek or wetland) and impervious areas of a catchment. Overland flows and mild slopes slowly convey water downstream and promote an even distribution of flow. Buffer areas provide treatment through sedimentation and interaction with vegetation.
Swales can be incorporated in urban designs along streets or parklands and add to the aesthetic character of an area. Typical swales are created with longitudinal slopes between 1% and 4% in order to maintain flow capacity without creating high velocities, potential erosion of the bioretention or swale surface and safety hazard. In steeper areas check banks along swales or dense vegetation can help to distribute flows evenly across swales and slow velocities. Milder-sloped swales may have issues with water-logging and stagnant ponding, in which case underdrains can be employed to alleviate problems. If the swale is to be vegetated, vegetation must be capable of withstanding design flows and be of sufficient density to provide good filtration). Ideally, vegetation height should be above treatment flow water levels. If runoff enters directly into a swale, perpendicular to the main flow direction, the edge of the swale acts as a buffer and provides pre-treatment for the water entering the swale.
Ponds and Lakes are artificial bodies of open water that are usually created by constructing a dam wall with a weir outlet structure. Similar to constructed wetlands, they can be used to treat runoff by providing extended detention and allowing sedimentation, absorption of nutrients and UV disinfection to occur. In addition, they provide an aesthetic quality for recreation, wildlife habitat, and valuable storage of water that can potentially be reused for e.g. irrigation. Often, artificial ponds and lakes also form part of a flood detention system. Aquatic vegetation plays an important role for the water quality in artificial lakes and ponds in respect of maintaining and regulating the oxygen and nutrient levels. Due to a water depth greater than 1.5m, emergent macrophytes are usually restricted to the margins but submergent plants may occur in the open water zone. Fringing vegetation can be useful in reducing bank erosion. Ponds are normally not used as stand-alone WSUD measure but are often combined with sediment basins or constructed wetlands as pretreatments.
In many cases however, lakes and ponds have been designed as aesthetic features but suffer from poor health which can be caused by lack of appropriate inflows sustaining lake water levels, poor water quality of inflows and high organic carbon loads, infrequent flushing of the lake (too long residence time), and/or inappropriate mixing (stratification) leading to low levels of dissolved oxygen. Bluegreen algae caused by poor water quality and high nutrient levels can be a major threat to the health of lakes. To ensure the long-term sustainability of lakes and ponds, key issues that should be considered in their design include catchment hydrology and water level, and layout of the pond/lake (oriented to dominant winds to facilitate mixing. Hydraulic structures (inlet and outlet zones) should be designed to ensure adequate pre-treatment and prevent large nutrient ‘spikes' Landscape design, using appropriate plant species and planting density are also necessary. High costs of the planned pond/lake area and of vegetation establishment as well as frequent maintenance requirements can be deterrents to use of ponds and lakes as WSUD measures.
The maintenance of pond and lake systems is important to minimise the risk of poor health. The inlet zone usually requires weed, plant, debris and litter removal with occasional replanting. In some cases, an artificial turn over of the lake might be necessary.
Rainwater tanks are designed to conserve potable water by harvesting rain and stormwater to partially meet domestic water demands (e.g. during drought periods). In addition, rainwater tanks can reduce stormwater runoff volumes and stormwater pollutants from reaching downstream waterways. They can be used effectively in domestic households as a potential WSUD element. Rain and stormwater from rooftops of buildings can be collected and accessed specifically for purposes such as toilet flushing, laundry, garden watering and car washing. Buffer Tanks allow rain water collected from hard surfaces to seep into the site helps maintain the aquifer and ground water levels.
In Australia, there are no quantitative performance targets for rainwater tanks, such as size of tank or targeted reductions in potable water demand, in policies or guidelines. The various guidelines provided by state governments however, do advise that rain water tanks be designed to provide a reliable source of water to supplement mains water supply, and maintain appropriate water quality. The use of rainwater tanks should consider issues such as supply and demand, water quality, stormwater benefits (volume is reduced), cost, available space, maintenance, size, shape and material of the tank. Rainwater tanks must also be installed in accordance with plumbing and drainage standards. An advised suitable configuration may include a water filter or first flush diversion, a mains water top-up supply (dual supply system), maintenance drain, a pump (pressure system), and an on-site retention provision.
Potential water quality issues include atmospheric pollution, bird and possum droppings, insects e.g. mosquitoe larvae, roofing material, paints and detergents. As part of maintenance, an annual flush out (to remove built up sludge and debris) and regular visual inspections should be carried out.
Aquifer storage and recovery (ASR) (also referred to as Managed Aquifer Recharge) aims to enhance water recharge to underground aquifers through gravity feed or pumping. It can be an alternative to large surface storages with water being pumped up again from below the surface in dry periods. Potential water sources for an ASR system can be stormwater or treated wastewater. The following components can usually be found in an ASR system that harvests stormwater:
The possible aquifer types suitable for an ASR system include fractured unconfined rock and confined sand and gravel. Detailed geological investigations are necessary to establish the feasibility of an ASR scheme. The potential low cost of ASR compared to subsurface storage can be attractive. The design process should consider the protection of groundwater quality, and recovered water quality for its intended use. Aquifers and aquitards need also be protected from damaged by depletion or high pressures. Impacts of the harvesting point on downstream areas also require consideration. Careful planning is required regarding aquifer selection, treatment, injection, the recovery process, and maintenance and monitoring.
In Australia, due to the constitutional division of power between the Australian Commonwealth and the States, there is no national legislative requirement for urban water cycle management. The National Water Initiative (NWI), agreed upon by Federal, State and Territory governments in 2004 and 2006, provides a national plan to improve water management across the country. It provides clear intent to “Create Water Sensitive Australian Cities” and encourages adoption of WSUD approaches. National guidelines have also been released in accordance with NWI clause 92(ii) to provide guidance on evaluation of WSUD initiatives.
At the state level, planning and environmental legislation broadly promotes ecologically sustainable development, but to varying degrees have only limited requirements for WSUD. State planning policies variously provide more specific standards for adoption of WSUD practices in particular circumstances.
At the local government level, regional water resource management strategies supported by regional and/or local catchment-scale integrated water cycle management plans and/or stormwater management plans provide the strategic context for WSUD. Local government environment plans may place regulatory requirements on developments to implement WSUD.
As regulatory authority over stormwater runoff is shared between Australian states and local government areas, issues of multiple governing jurisdictions have resulted in inconsistent implementation of WSUD policies and practices and fragmented management of larger watersheds. For example, in Melbourne, jurisdictional authority for watersheds of greater than 60 ha rests with the state-level authority, Melbourne Water; while local governments govern smaller watersheds. Consequently, Melbourne Water has been deterred from investing significantly in WSUD works to improve small watersheds, despite them affecting the condition of the larger watersheds into which they drain and waterway health including headwater streams.
In Victoria, elements of WSUD are integrated into many of the overall objectives and strategies of the Victorian planning policy. The State Planning Policy Framework of the [Victoria Planning Provisions] which is contained in all planning schemes in Victoria contains some specific clauses requiring adoption of WSUD practices.
New residential developments are subject to a permeability standard that at least 20 per cent of sites should not be covered by impervious surfaces. The objective of this is to reduce the impact of increased stormwater run-off on the drainage system and facilitate on-site storm-water infiltration.
New residential subdivisions of two or more lots are required to meet integrated water management objectives related to:
Specifically regarding urban run-off management, the Victoria Planning Provisions c. 56.07-4 Clause 25 states that stormwater systems must meet best practice stormwater management objectives. Currently, whilst no longer considered best practice, the state standard is Urban Stormwater: Best Practice Environmental Management Guidelines. The current water quality objectives, which do not protect waterways from the impacts of stormwater are:
Urban stormwater management systems must also meet the requirements of the relevant drainage authority. This is usually the local council. However, in the Melbourne region, where a catchment greater than 60ha is concerned it is Melbourne Water. Inflows downstream of the subdivision site are also restricted to pre-development levels unless approved by the relevant drainage authority and there are no detrimental downstream impacts.
Melbourne Water provides a simplified online software tool, STORM (Stormwater Treatment Objective – Relative Measure), to allow users to assess if development proposals meet legislated best practice stormwater quality performance objectives. The STORM tool is limited to assessment of discrete WSUD treatment practices and so does not model where several treatment practices are used in series. Of It is also limited to sites where coverage of impervious surfaces is greater than 40%. For larger more complicated developments more sophisticated modelling, such as MUSIC software, is recommended.
At the state level in New South Wales, the State Environmental Planning Policy (Building Sustainability Index: BASIX) 2004 (NSW) is the primary piece of policy mandating adoption of WSUD. BASIX is an online program that allows users to enter data relating to a residential development, such as location, size, building materials etc.; to receive scores against water and energy use reduction targets. Water targets range from a 0 to 40% reduction in consumption of mains-supplied potable water, depending on location of the residential development. Ninety per cent of new homes are covered by the 40% water target. The BASIX program allows for the modelling of some WSUD elements such as use of rainwater tanks, stormwater tanks and greywater recycling.
Local Councils are responsible for the development of Local Environment Plans (LEPs) which can control development and mandate adoption of WSUD practices and targets Local Government Act 1993 (NSW). Due to a lack of consistent policy and direction at the state-level however, adoption by local councils is mixed with some developing their own WSUD objectives in their local environmental plans (LEP) and others having no such provisions.
In 2006 the then NSW Department of Environment and Conservation released a guidance document, Managing Urban Stormwater: Harvesting and Reuse. The document presented an overview of stormwater harvesting and provided guidance on planning and design aspects of integrated landscape-scale strategy as well as technical WSUD practice implementation. The document now however, although still available on the governmental website, does not appear to be widely promoted.
The Sydney Metropolitan Catchment Management Authority also provides tools and resources to support local council adoption of WSUD. These include
Simplified modelling programs are provided by some jurisdictions to assess implementation of WSUD practices in compliance with local regulations. STORM is provided by Melbourne Water and BASIX is used in NSW, Australia for residential developments. For large, more complicated developments, more sophisticated modelling software may be necessary.
Major issues affecting the adoption of WSUD include:
The transition of Melbourne city to WSUD over the last four decades has culminated in a list of best practice qualities and enabling factors, which have been identified as important in aiding decision making to facilitate transition to WSUD technologies. The implementation of WSUD can be enabled through the effective interplay between the two variables discussed below.
WSUD technologies can be implemented in a range of projects, from previously pristine and undeveloped, or Greenfield sites, to developed or polluted Brownfield sites that require alteration or remediation. In Australia, WSUD technologies have been implemented in a broad range of projects, including from small-scale road-side projects, up to large-scale +100 hectare residential development sites. The three key case studies below represent a range of WSUD projects from around Australia.
The WSUD Roadway Retrofit Bioretention System is a small-scale project implemented by the Ku-ring-gai Council in NSW as part of an overall catchment incentive to reduce stormwater pollution. The Raingarden uses a bioretention system to capture and treat an estimated 75 kg of total suspended solids (TSS) per year of local stormwater runoff from the road, and filters it through a sand filter media before releasing it back into the stormwater system. Permeable pavers are also used in the system within the surrounding pedestrian footpaths, to support the infiltration of runoff into the ground water system. Roadside bioretention systems similar to this project have been implemented throughout Australia. Similar projects are presented on the Sydney Catchment Management Authority's WSUD website:
The Lynbrook Estate development project in Victoria, demonstrates effective implementation of WSUD by the private sector. It is a Greenfield residential development site that has focused its marketing for potential residents on innovative use of stormwater management technologies, following a pilot study by Melbourne Water.
The project combines conventional drainage systems with WSUD measures at the streetscape and sub-catchment level, with the aim of attenuating and treating stormwater flows to protect receiving waters within the development. Primary treatment of the stormwater is carried out by grass swales and an underground gravel trench system, which collects, infiltrates and conveys road/roof runoff . The main boulevard acts as a bioretention system with an underground gravel filled trench to allow for infiltration and conveyance of stormwater. The catchment runoff then undergoes secondary treatment through a wetland system before discharge into an ornamental lake. This project is significant as the first residential WSUD development of this scale in Australia. Its performance in exceeding the Urban Stormwater Best Practice Management Guidelines for Total Nitrogen, Total Phosphorus and Total Suspended Solids levels, has won it both the 2000 President's Award in the Urban Development Institute of Australia Awards for Excellence (recognising innovation in urban development), and the 2001 Cooperative Research Centres' Association Technology Transfer Award. Its success as a private-sector implemented WSUD system led to its proponent Urban and Regional Land Corporation (URLC) to look to incorporate WSUD as a standard practice across the State of Victoria. The project has also attracted attention from developers, councils, waterway management agencies and environmental policy-makers throughout the country.
For the establishment of the Sydney 2000 Olympic Games site, the Brownfield area of Homebush Bay was remediated from an area of landfill, abattoirs and a navy armament depots into a multiuse Olympic site. A Water Reclamation and Management Scheme (WRAMS) was set up in 2000 for large-scale recycling of non-potable water, which included a range of WSUD technologies. These technologies were implemented with a particular focus on addressing the objectives of protecting receiving waters from stormwater and wastewater discharges; minimising potable water demand; and protecting and enhancing habitat for threatened species 2006. The focus of WSUD technologies was directed towards the on-site treatment, storage and recycling of stormwater and wastewater. Stormwater runoff is treated using gross pollutant traps, swales and/or wetland systems. This has contributed to a reduction of 90% in nutrient loads in the Haslams Creek wetland remediation area. Wastewater is treated in a water reclamation plant. Almost 100% of sewage is treated and recycled. The treated water from both stormwater and wastewater sources is stored and recycled for use throughout the Olympic site in water features, irrigation, toilet flushing and fire fighting capacities. Through the use of WSUD technology, the WRAMS scheme has resulted in the conservation of 850 million litres (ML) of water annually, a potential 50% reduction in annual potable water consumption within the Olympic site, as well as the annual diversion of approximately 550 ML of sewage normally discharged through ocean outfalls. As part of the long-term sustainability focus of the 'Sydney Olympic Park Master Plan 2030', the Sydney Olympic Park Authority (SOPA) has identified key best practice environmental sustainability approaches to include, the connection to recycled water and effective water demand management practices, maintenance and extension of recycled water systems to new streets as required, and maintenance and extension of the existing stormwater system that recycles water, promotes infiltration to sub soil, filters pollutants and sediments, and minimises loads on adjoining waterways. The SOPA has used WSUD technology to ensure that the town remains 'nationally and internationally recognised for excellence and innovation in urban design, building design and sustainability, both in the present and for future generations.
Bishan-Ang Mo Kio Park (formerly known as Bishan Park) is a major park in Singapore, located in the popular heartland of Bishan. Serving the residents of Bishan and Ang Mo Kio, the park sits entirely within Bishan, running along the Ang Mo Kio–Bishan boundary line, which is situated at Ang Mo Kio Avenue 1. In the middle of the park lies the Kallang River, which runs through it in the form of a flat riverbed.Check dam
A check dam is a small, sometimes temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity. Check dams themselves are not a type of new technology; rather, they are an ancient technique dating from the second century A.D. Check dams are typically, though not always, implemented in a system of several dams situated at regular intervals across the area of interest.EWater
eWater is a non-profit organisation established by Australian Federal and State Governments. The role of eWater is to support integrated water resources management in Australia through development and implementation of the national hydrological modelling strategy (NHMS).eWater develops and supports a number of software tools for hydrological modelling. Some tools include Source, MUSIC, Rainfall Runoff Library, Stochastic Climate Library and SedNet.Flow control structure
A flow control structure is a device that alters the flow of water in a stream, drainage channel or pipe. As a group these are passive structures since they operate without intervention under different amounts of water flow and their impact changes based on the quantity of water available. This includes weirs, flow splitters and proprietary-design devices that are used for stormwater management and in combined sewers.Flow-control structures are known to have existed for thousands of years. Some built by the Chinese have been in continuous use for over 2,000 years. The Chinese used these structures to divert water to irrigate fields and to actually deposit silt in specific areas so that the channels were not blocked by silt build-up. Structures like this required yearly maintenance to remove the accumulated silt.
More modern structures add to these basic principles. In Hawaii, there are numerous flow-control structures that have been built to irrigate the pineapple and sugar cane fields. The purpose of these structures is to divert water into the various canals and to keep them full. When over full, they dump excess water back into either streams or other canals. Among the simplest is a low dam across a shallow stream, forcing all of the water to one side to allow it to be easily collected in a canal. This can keep a canal full even with very low flows in a stream.
Another simple device is a series of concrete piers installed in a spillway to slow down the descending water so that it does not cause damage at the bottom of the spillway.Integrated urban water management
Integrated urban water management (IUWM) is a philosophy of varying definitions and interpretations. According to the authors of the book entitled, "Integrated Urban Water Management: Humid Tropics", IUWM is described as the practice of managing freshwater, wastewater, and storm water as components of a basin-wide management plan. It builds on existing water supply and sanitation considerations within an urban settlement by incorporating urban water management within the scope of the entire river basin. One of the early champions of IUWM, SWITCH is a research program funded by the European Union and seeks to shift urban water management away from ad hoc solutions to a more integrated approach. IUWM within an urban water system can also be conducted by performance assessment of any new intervention strategies by developing a holistic approach which encompasses various system elements and criteria including sustainability type ones in which integration of water system components including water supply, waste water and storm water subsystems would be advantageous. Simulation of metabolism type flows in urban water system can also be useful for analysing processes in urban water cycle of IUWM.IUWM is commonly seen as a strategy for achieving the goals of Water Sensitive Urban Design. IUWM seeks to change the impact of urban development on the natural water cycle, based on the premise that by managing the urban water cycle as a whole; a more efficient use of resources can be achieved providing not only economic benefits but also improved social and environmental outcomes. One approach is to establish an inner, urban, water cycle loop through the implementation of reuse strategies. Developing this urban water cycle loop requires an understanding both of the natural, pre-development, water balance and the post-development water balance. Accounting for flows in the pre- and post-development systems is an important step toward limiting urban impacts on the natural water cycle.Jocelyn Dela-Cruz
Jocelyn Dela-Cruz (born Philippines) is a Principal Environmental Scientist at the New South Wales Office of Environment and Heritage, Australia. She was educated at the University of Sydney (BSc. Hons1 and MSc) and University of New South Wales (Ph.D.).Lisa Gervasoni
Lisa Gervasoni (born 1969) is a strategic planner in Warrnambool, photographer and artist. She was born in Melbourne, Australia. Gervasoni is part of a long family tradition of working with heritage sites in Australia. She is a member of ICOMOS (International Council on Monuments and Sites) and is a member of their Executive Committee. She has been a keynote speaker in Victoria, Australia. Gervasoni was instrumental in getting Hepburn Pool listed on the Victorian Heritage Register.Low-impact development (U.S. and Canada)
Low-impact development (LID) is a term used in Canada and the United States to describe a land planning and engineering design approach to manage stormwater runoff as part of green infrastructure. LID emphasizes conservation and use of on-site natural features to protect water quality. This approach implements engineered small-scale hydrologic controls to replicate the pre-development hydrologic regime of watersheds through infiltrating, filtering, storing, evaporating, and detaining runoff close to its source. Green infrastructure investments are one approach that often yields multiple benefits and builds city resilience.Broadly equivalent terms used elsewhere include Sustainable drainage systems (SuDS) in the United Kingdom (where LID has a different meaning), water-sensitive urban design (WSUD) in Australia, natural drainage systems in Seattle, Washington and "Onsite Stormwater Management", as used by the Washington State Department of Ecology.Oasis effect
The oasis effect refers to the creation of a local microclimate that is cooler than the surrounding dry area due to evaporation or evapotranspiration of a water source or plant life and higher albedo of plant life than bare ground. The oasis effect is so-named because it occurs in desert oases. Urban planners can design a city's layout to optimize the oasis effect to combat the urban heat island effect. Since it depends on evaporation, the oasis effect differs by season.Rain garden
One of the wide variety of soil-absorption/filter systems, a rain garden, also called a stormwater garden, is a designed depression storage or a planted hole that allows rainwater runoff from impervious urban areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas, the opportunity to be absorbed. The primary purpose of a rain garden is to improve water quality in nearby bodies of water and to ensure that rainwater becomes available for plants as groundwater rather than being sent through stormwater drains straight out to sea. In fact, it can actually reduce rain runoff by allowing stormwater to soak into the ground (as opposed to flowing into storm drains and surface waters which causes erosion, water pollution, flooding, and diminished groundwater) and cut down on the amount of pollution reaching creeks and streams by up to 30%.The plants—a selection of wetland edge vegetation, such as wildflowers, sedges, rushes, ferns, shrubs and small trees—take up excess water flowing into the rain garden. Water filters through soil layers before entering the groundwater system. Deep plant roots also create additional channels for stormwater to filter into the ground. Root systems enhance infiltration, maintain or even augment soil permeability, provide moisture redistribution, and sustain diverse microbial populations involved in biofiltration. Microbial populations feed off plant root secretions and break down carbon (such as in mulch or desiccated plant roots) to aggregate soil particles which increases infiltration rates. Also, through the process of transpiration, rain garden plants return water vapor to the atmosphere.A more wide-ranging definition covers all the possible elements that can be used to capture, channel, divert, and make the most of the natural rain and snow that falls on a property. Thus, the whole garden can become a rain garden, and each component of the whole can become a small-scale rain garden in itself.Ramboll Studio Dreiseitl
Ramboll Studio Dreiseitl is one of the leading landscape architecture practices of Germany specialising in the integration of art, urban hydrology, environmental engineering, and landscape architecture within an urban context.
The practise was founded in 1980 by the German landscape architect Herbert Dreiseitl with a goal to promote sustainable projects with a high aesthetic and social value. Today it has offices in Germany, Singapore and Beijing.
In May 2013, Atelier Dreiseitl (now Ramboll Studio Dreiseitl) GmbH formed a new partnership with the international engineering consultancy, the Ramboll Group A/S, based in Copenhagen.Sedimentation (water treatment)
Sedimentation is a physical water treatment process using gravity to remove suspended solids from water. Solid particles entrained by the turbulence of moving water may be removed naturally by sedimentation in the still water of lakes and oceans. Settling basins are ponds constructed for the purpose of removing entrained solids by sedimentation. Clarifiers are tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. This can also be seen, for example in Aromatherapy oils. Clarification does not remove dissolved species. Sedimentation is the act of depositing sediment.Stormwater
Stormwater, also spelled storm water, is water that originates during precipitation events and snow/ice melt. Stormwater can soak into the soil (infiltrate), be held on the surface and evaporate, or runoff and end up in nearby streams, rivers, or other water bodies (surface water).
In natural landscapes such as forests, the soil absorbs much of the stormwater and plants help hold stormwater close to where it falls. In developed environments, unmanaged stormwater can create two major issues: one related to the volume and timing of runoff water (flooding) and the other related to potential contaminants that the water is carrying (water pollution).
Stormwater is also an important resource as the world's human population demand exceeds the availability of readily available water. Techniques of stormwater harvesting with point source water management and purification can potentially make urban environments self-sustaining in terms of water.Sustainable drainage system
Sustainable Drainage Systems (also known as SuDS, SUDS, or Sustainable Urban Drainage Systems) are a collection of water management practices that aim to align modern drainage systems with natural water processes. SuDS efforts make urban drainage systems more compatible with components of the natural water cycle such as storm surge overflows, soil percolation, and bio-filtration. These efforts hope to mitigate the effect human development has had or may have on the natural water cycle, particularly surface runoff and water pollution trends. SuDS have become popular in recent decades as our understanding of how urban development affects natural environments, as well as concern for climate change and sustainability, have increased. SuDS often use built components that mimic natural features in order to integrate urban drainage systems into the natural drainage systems or a site as efficiently and quickly as possible.Swale (landform)
A swale is a shady spot, or a sunken or marshy place. In particular, in US usage, it is a shallow channel with gently sloping sides. Such a swale may be either natural or man-made. Artificial swales are often infiltration basins, designed to manage water runoff, filter pollutants, and increase rainwater infiltration.Urban design
Urban design is the process of designing and shaping the physical features of cities, towns and villages and planning for the provision of municipal services to residents and visitors. In contrast to architecture, which focuses on the design of individual buildings, urban design deals with the larger scale of groups of buildings, streets and public spaces, whole neighbourhoods and districts, and entire cities, with the goal of making urban areas functional, attractive, and sustainable.Urban design is an inter-disciplinary field that utilizes elements of many built environment professions, including landscape architecture, urban planning, architecture, civil engineering and municipal engineering. It is common for professionals in all these disciplines to practice urban design. In more recent times different sub-subfields of urban design have emerged such as strategic urban design, landscape urbanism, water-sensitive urban design, and sustainable urbanism.
Urban design demands an understanding of a wide range of subjects from physical geography to social science, and an appreciation for disciplines, such as real estate development, urban economics, political economy and social theory.
Urban design is about making connections between people and places, movement and urban form, nature and the built fabric. Urban design draws together the many strands of place-making, environmental stewardship, social equity and economic viability into the creation of places with distinct beauty and identity. Urban design draws these and other strands together creating a vision for an area and then deploying the resources and skills needed to bring the vision to life.
Urban design theory deals primarily with the design and management of public space (i.e. the 'public environment', 'public realm' or 'public domain'), and the way public places are experienced and used. Public space includes the totality of spaces used freely on a day-to-day basis by the general public, such as streets, plazas, parks and public infrastructure. Some aspects of privately owned spaces, such as building facades or domestic gardens, also contribute to public space and are therefore also considered by urban design theory. Important writers on urban design theory include Christopher Alexander, Peter Calthorpe, Gordon Cullen, Andres Duany, Jane Jacobs, Mitchell Joachim, Jan Gehl, Allan B. Jacobs, Kevin Lynch, Aldo Rossi, Colin Rowe, Robert Venturi, William H. Whyte, Camillo Sitte, Bill Hillier (Space syntax) and Elizabeth Plater-Zyberk.Urban planning in Australia
Urban planning in Australia has a significant role to play in ensuring the future sustainability of Australian cities. Australia is one of the most highly urbanised societies in the world. Continued population growth in Australian cities is placing increasing pressure on infrastructure, such as public transport and roadways, energy, air and water systems within the urban environment.
Urban planning is undertaken at all levels of Government in Australia. However, the Federal Government is playing an increasing part in setting policy as part of an overall response to developing climate adaptation and mitigation strategies. The local government has also been engaging with the community to make decisions on urban planning designs that help to promote social cohesion. Over the past few decades Australians have developed a respect for urban heritage places and community groups have fought hard to stop developers from destroying them.Urban runoff
Urban runoff is surface runoff of rainwater created by urbanization. This runoff is a major source of flooding and water pollution in urban communities worldwide.
Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain storms and other precipitation events, these surfaces (built from materials such as asphalt and concrete), along with rooftops, carry polluted stormwater to storm drains, instead of allowing the water to percolate through soil. This causes lowering of the water table (because groundwater recharge is lessened) and flooding since the amount of water that remains on the surface is greater. Most municipal storm sewer systems discharge stormwater, untreated, to streams, rivers and bays. This excess water can also make its way into people's properties through basement backups and seepage through building wall and floors.Wetland
A wetland is a distinct ecosystem that is inundated by water, either permanently or seasonally, where oxygen-free processes prevail. The primary factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil. Wetlands play a number of functions, including water purification, water storage, processing of carbon and other nutrients, stabilization of shorelines, and support of plants and animals. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life. Whether any individual wetland performs these functions, and the degree to which it performs them, depends on characteristics of that wetland and the lands and waters near it. Methods for rapidly assessing these functions, wetland ecological health, and general wetland condition have been developed in many regions and have contributed to wetland conservation partly by raising public awareness of the functions and the ecosystem services some wetlands provide.Wetlands occur naturally on every continent. The main wetland types are swamp, marsh, bog, and fen; sub-types include mangrove forest, carr, pocosin, floodplains, mire, vernal pool, sink, and many others. Many peatlands are wetlands. The water in wetlands is either freshwater, brackish, or saltwater.
Wetlands can be tidal (inundated by tides) or non-tidal. The largest wetlands include the Amazon River basin, the West Siberian Plain, the Pantanal in South America, and the Sundarbans in the Ganges-Brahmaputra delta.The UN Millennium Ecosystem Assessment determined that environmental degradation is more prominent within wetland systems than any other ecosystem on Earth.Constructed wetlands are used to treat municipal and industrial wastewater as well as stormwater runoff. They may also play a role in water-sensitive urban design.