Water Sensitive Urban Design: Modern Stormwater Management Approaches

This research paper evaluates the water sensitive urban design by focusing on the modern urban stormwater management approaches. It discusses the structural stormwater management practices, including hardscape design, legislation, vegetative management practices, wet ponds, and permeable materials.

Water Sensitive Urban Design 1
WATER SENSITIVE URBAN DESIGN
A Research Paper on Urban Design By
Student’s Name
Name of the Professor
Institutional Affiliation
City/State
Year/Month/Day

Water Sensitive Urban Design 2
ABSTRACT
An urban environment is a place that has huge opportunities for social interaction with
planning and design of public spaces. The implementation of the public spaces can issue for the
future and current needs of the population for social interaction. Designers should consider
factors like stormwater runoff when constructing public spaces, streets, and buildings. Practices
of stormwater management have been established so as to treat the water and also reduce the
stormwater runoff. This research paper evaluates the water sensitive urban design by focusing on
the modern urban stormwater management approaches.
Water sensitive urban design is an engineering design and land planning approach which
integrates the water cycle in the urban areas, including water supply, wastewater, groundwater,
and stormwater management, into the urban design to improve recreational an aesthetic appeal
and reduce environmental degradation. Some of the stormwater management practices that have
been implemented in numerous states and can be considered as standard approaches for
management of stormwater include hardscape design, legislation, vegetative management
practices, wet ponds, and permeable materials

Water Sensitive Urban Design 3
INTRODUCTION
This research paper is about the water sensitive urban design while focusing on the
modern urban stormwater management approaches. Water sensitive urban design is an
engineering design and land planning approach which integrates the water cycle in the urban
areas, including water supply, wastewater, groundwater, and stormwater management, into the
urban design to improve recreational an aesthetic appeal and reduce environmental degradation.
Urban planning is greatly advocated as a significant way of encouraging the more sustainable of
stormwater in urban areas through application of alternatives to piped systems. Water bodies in
the entire country are facing issues as a result of runoff stormwater and also urbanization.
Huge quantities of impervious constructions and surfaces have resulted to rise of the
quantity of runoff and consequently promote pollution. Pollution during storms can be as a result
of the combined overflow of sewers that carry bother stormwater and raw sewage, permitting
sewage that is untreated together with stormwater to flow into the water bodies. With the
pollution triggered by combined overflows of sewage and the state of the water bodies in major
urban centers, there is need to assess to stormwater runoff in every element of the urban fabric
through environmental and creative design (Arnold, 2010).
Terminologies
Some of the terms used to refer to the water sensitive urban design which is a term used
in Australia and the Middle East include Sustainable Drainage System and Low impact
development. Sustainable Drainage System is a term used in the UK and it is designed to
minimize the potential effects of existing and new developments relative to the discharges of
surface water drainage. The term urban was removed so as to accommodate sustainable

Water Sensitive Urban Design 4
management of water in rural areas. Low impact development is a term used in Canada and also
in the United States to describe an engineering and land planning design approach of managing
runoff of stormwater as part of the green infrastructure. It stresses the use of natural features on-
site and conservation to protect the quality of water (Authority, 2008).
Evolution of Modern Drainage System
The modern drainage system evolved from the combined sewer system which was
introduced in the 1850s so as to enable urban areas to do away with traditional ditches that were
being used. These sewer systems were used to assist in drying the streets and keeping both
sewage and runoff stormwater underground in a pipe network. However, there have been drastic
improvements in this system since, during large storms, the sewer systems would be filled with
both runoffs of stormwater and sewage and then would spill over into numerous sections of the
local water bodies and streets. The modern drainage system has been improvements to replace
the traditional sewage system (Booth, 2012).
These improvements have been put in place to minimize the runoff of stormwater that
reaches the combines systems through eliminating the section of the load that the system has to
convey. Through suitable practices of stormwater management and design, the public reams are
normally used to relieve the drainage systems and assist to minimize the frequency and
likelihood of the mixture of stormwater runoff, commercial and industrial waste, and domestic
sewage in the urban environment (Borah, 2009).
Hardscape Design
The old and new public places tackle the questions concerning the environmental
accountability and sustainability. Public space or public realms is composed of two sections,

Water Sensitive Urban Design 5
these include the components of the public of the physical space and the way in which the
society decisions are made for the public space. Urban design is involved in both sections of the
public realm. The physical components used for public spaces are the urban design products,
however, the objective of the development of the space affects the urban design process directly.
The public realm includes those regions in which the public has access to, even though that
permission may be sometimes restricted. It consists of both outdoor and indoor spaces such as
parks, plazas, squares, streets, arcade, and public buildings (Bozeman, 2010).
Hardscape is a space that uses a type of solid material or pavement for its foundation and
does not possess numerous green spaces. These public spaces also include natural attributes
natural features like small green space components and vegetation, they are also characterized by
variations of the natural state and the application of pavements. Public spaces design may be
lacking relative to the integration of permeable pavements and stormwater management. There is
need of developing a public space that has the ability to deal with stormwater in an
environmentally sensitive and efficient manner without forgetting the appeal of the space itself.
It is initially significant to plan and design public hardscapes for the public who will be using the
spaces (Clarke, 2015).
During planning new designs of public hardscape, it is critical that the needs of the public
take first significance since cities are filled with public spaces and majority of them have been
designed for social interaction while other have become public space as a result of interactions
that takes places in those areas. Some of the features that the local populations desire from the
public space include comfort, relaxation, and engagement. The idea of comfort incorporates
safety from traffic and crime, natural features, and sunlight. There is also need for relaxation for

Water Sensitive Urban Design 6
the population after busy life within the urban environment, this may include water and natural
features, retreats, and seating (Committee, 2009).
The culture and location of these public spaces will normally define the character of the
place. Urban design should be keen so as not to ignore the locality when designing the public
hardscapes. There is the need for incorporating porous pavements on the public hardscapes as a
step towards stormwater management practices. The structural stormwater management practices
include the engineered and constructed systems that are designed to provide water quality control
and water quality of stormwater runoff. The public space's design focuses the requirement of
physical features which will efficiently deal with stormwater such as structural stormwater
management practices as discussed below (Council, 2011).
Stormwater Management
When raining, water falls onto a surface that is impermeable before flowing to the nearest
local water body or storm drain. This can also come in form of street wash water or snowmelt, all
of which describe stormwater. The major concern regarding runoff stormwater is the safety
which focuses on draining and directing water from the hardscape surfaces as efficiently and
quickly as possible. Stormwater runoff is normally not considered after it is out of the vicinity,
however, the results associated remain after moving off from the impermeable hardscape surface.
This section illustrates the stormwater management practices that have been implemented in
numerous states and can be considered as standard approaches for management of stormwater
(Fletcher, 2009).
As discussed above, porous pavements are one of the recognized stormwater
management practices recognized by numerous states. This section discusses the structural

Water Sensitive Urban Design 7
stormwater management practices by considering the constructed and engineered systems that
are designed to give control of water quality of the stormwater runoff. The structural stormwater
management practices can be narrowed into wet ponds and vegetative system and structural
management practices based on the public space design as discussed above. The stormwater
management practices can be defined as the structural control, measure, or technique that is used
for a certain condition to improve the quality and manage the quality of stormwater runoff in a
manner that is cost-effective (Gaffield, 2013).
These measures are the method of monitoring the water that moves through the
stormwater management practices and also the capability of reducing the pollutants conveyed by
the stormwater. Urban areas are defined by a huge percentage of impermeable surfaces which
generates difficulties when dealing with stormwater because the natural hydrology of the area is
disseminated as a result of urban growths. The changes in the pathways of water from the urban
developments have resulted in issues concerning stormwater along with implementation and
creation of the stormwater management practices (Hoyer, 2011).
Impacts of Stormwater
The stormwater is conveyed within urban regions where pollutants like synthetic
organics, metals, hydrocarbons, pathogens, phosphorous and nitrogen, oxygen-demanding
substances, and solids are moved into storm drains and then disposed of in water bodies. These
pollutants result in environmental degradation to the urban water bodies which receive them and
also to the ecosystem surrounding which depend on the water adjacent. Research shows that 32%
of estuaries impaired, 18% of lakes impaired, and 13% of rivers impaired in the majority of
urban areas are affected by the suburban/urban stormwater runoff. There are a lot of damages

Water Sensitive Urban Design 8
caused by runoff that takes place as a result of that takes place as a result of the increased
quantity of water that is conveyed during periods of peak flows (Lloyd, 2010).
Peak flows is promoted in numerous urban centers due to compact developments and in
the majority of instances results in new events of runoff. The high level of frequency of events of
peak flow and quantity of runoff results in a greater contaminated volume of stormwater to be
discharged into the water bodies receiving. The discharge of stormwater can result in the
displacement of natural habitats and also contamination of drinking water for the users living
downstream. The rowing urban centers also call for the growth of the need to tackle the issues of
stormwater to make sure that the unnatural pollutants do not pollute the receiving water bodies
(Pitt, 2009).
Stormwater Regulation Practices
There is need of the urban authorities to set limits on industrial waste and also establish
the standards for control of quality water. This will prevent pollutant discharge from a point
source unless a permit is acquired to allow such discharge. In the US, a body known as the
National Urban Runoff Program was established to assess the stormwater runoff quality in urban
residential and commercial areas. Their findings show that the suspended solid discharge in
drainage systems was near the magnitude of solids suspended that were discharged the plant of
sewage treatment of the municipal. There is need of reducing the pollutants of discharge at
higher density positions not only to the point source runoff but also to non-point source runoff.
The stormwater management approaches should be applied in phase one of the stormwater
programs such as vegetative practices, public education, and the use of alternative materials for
paving (Ruth, 2009).

Water Sensitive Urban Design 9
Approaches to Stormwater Management
Vegetative systems
The basic purpose of vegetative systems in the urban centers are to relax the population
and also provide a sense of natural amenity. The function of vegetative systems in the
stormwater management practices of more than for natural appeal or aesthetic, but to minimize
the runoff of stormwater and also treat water before the process of soil infiltration. As rainfalls
begin accumulating on the surface, it is directed to the area of bio-retention where there is
infiltration of stormwater into the soil. This biofiltration and bio-retention processes removes
pollutants from numerous processes such as decomposition, ion change, volatilization, filtration,
and adsorption. The application of the vegetative system in the stormwater management practice
provides stormwater with the chance to be cleaned and filtered and can be an excellent source of
recharge of groundwater (Ruth, 2009).
The public space should not be identically designed while incorporating the climate,
culture, and location of the local community. The same applied to the vegetative management
practices. There should be numerous vegetative components that should be used based on the
requirements of a given location. These components include plants, sand beds, planting soil bed,
organic mulch layer, ponding area, vegetative swales, grass filter strip, and grass buffer strip.
Numerous components create many implementation options and also a combination of numerous
components. The climate and location of the urban area normally determine the plant species that
can be utilized by the by the vegetative system, hence developing a landscape design that is
unique for every location and their application in this structural management practice (Shaver,
2014).

Water Sensitive Urban Design 10
Wet Ponds
This is the second type of structural management stormwater practice. Wet ponds are one
of the categories of the system retention that can be defined by the capability of capturing
stormwater runoff and retaining it until the future runoff substitutes it. The water remains in the
wet pond unlike dry ponds and services as a place for huge runoff quantity and also treats the
water quality during retention. Water storage and treatment are designed objective for wet ponds,
however, it may also give terrestrial and aquatic habitat for numerous animals and plant, and also
provides aesthetic value (Water, 2013).
Pollution conveyed by runoff gets in the wet pond through design such as settling
process, then the runoff is cleaned to replenish and infiltrate supplies of the groundwater in case
the wet pond does not possess a bottom liner. Wet ponds are one of the most effective retention
systems of pollutant removal because of shallow depths and consistent water pool. The wet
ponds applications for the environment of the urban areas may satisfy both the aesthetic value of
the public space and also the stormwater management function (William, 2011).
Permeable Materials
The approach to public hardscape sustainability in regards to the management of
stormwater should address the real materials used in hardscape. There has been broad use of
impermeable materials on the surface in the past for the public hardscape, sidewalks, and
systems of national highways. Currently, a lot of progress has been made in the development of
paving materials that minimize the adverse impacts on the environment. These porous pavement
treats and infiltrates rainwater as it falls, this instance rainwater infiltration minimizes the volume
of runoff that is generated and the capability of capturing and heating stormwater on a wide

Water Sensitive Urban Design 11
surface and enable the land to function at its full potential in the management of stormwater
(Wong, 2012).
These porous pavements can save the urban developers the cost of having to purchase an
extra piece of land for the purposes of stormwater management. The effects caused by runoff of
stormwater on the urban areas are substantial, however, the application of porous pavements may
minimize some impacts related with paved sections. With intentions of creating public hardscape
which imitates the features of natural land such as hydrology, the porous pavements are the
alternative design on such spaces. Some of the types of porous pavements that can be used to
minimize the impacts of stormwater runoff in the urban areas include porous asphalt, porous
concrete, and permeable interlocking concrete pavement (Booth, 2012). These porous materials
are discussed below:
Porous Asphalt: This material has fine particles of stone to enable screening and reduce to permit
the flow of water through. The actual asphalt layer is produced to enable water to pass through it
so as to reach the following level of loosely compacted particles or stone aggregate. This
material is the most affordable option for porous pavements as determined in its life cycle cost
analysis. Some of the factors that should be considered during the implementation of these
porous pavements include depth of water table, depth of bedrock, infiltration rate, and the type of
soil (Bozeman, 2010).
Pervious Concrete: Materials such as pervious concrete enables percolation of water into the soil
and not halting the process of infiltration. This process can take place through pervious concrete
since there is no sand that can fill the aggregates spaces. The strength of this type of pavement is
one of its advantages since it can withstand a strength of approximately 3000 psi. This material
can also develop a detention section for stormwater and hence can assist as an alternative to other

Water Sensitive Urban Design 12
stormwater management practices. This can minimize the cost of materials, construction, and
labour for a given site. This pavement option is an effective tool of stormwater runoff
management in the urban areas since it reduces the effect on natural surrounding by minimizing
the total quantity of runoff that is produced by capturing initial precipitation (Clarke, 2015).
Interlocking Concrete: This pavement option is composed of two different options. Open-celled
paving grids and open-jointed paving blacks. These features enable increased water infiltration
of the surface since it enables the water to pass through the blocks and also infiltrating the joints.
This pavement option decreases the quantity of runoff leading to reduced pollution inflowing the
water bodies (Ruth, 2009).
Water Re-use
There are two options of re-using the stormwater collected during rain before it could
reach the surface, these include rainwater tanks and aquifer storage and recovery. The rainwater
tanks are designed to collect water harvested from the stormwater o as to partially meet the
domestic demand. These rainwater tanks minimize the volumes of stormwater runoff and also
pollutants of stormwater from reaching the water bodies. Stormwater and rain from the rooftops
of the structures can be accessed and collected precisely for the purposes of car washing, garden
watering, laundry, and toilet flushing. Buffer tanks can also be implemented to enable
stormwater collected from the pavement surfaces or drainage system to seep into the site and
assist in maintaining the groundwater level and aquifer (Booth, 2012).
These tanks should be installed according to the drainage and plumbing standards of the
particular state. Some of the issues that should be considered when using the stormwater tanks
include material, shape, size, maintenance, available space, cost, stormwater benefits, water

Water Sensitive Urban Design 13
quality, and supply and demand. Aquifer recovery and storage involves enhanced recharge of
water to aquifers underground through pumping or gravity feed. This system can also use treated
wastewater or stormwater (Authority, 2008).
Benefits of Water Sensitive Urban Design
Water sensitive urban design stresses the benefits of waterways and water as assets and
resources, and not as a nuisance as conventionally viewed. The WSUD ensures increased water
conservation since a lot of water which could have gone into the water can be conserved through
methods such as water tanks or wet ponds. This conserved water can be used in numerous ways
that this conserved water can be put into use, these ways include car washing, garden watering,
laundry, and toilet flushing. The WSUD also improves the quality of stormwater in the through
filtration and water treatment before it can be channelled to the water sources. The quality of
water is also improved through removal of pollutants by the porous pavements, these pollutants
may be from processes such as decomposition, ion change, and volatilization, filtration, and
adsorption processes (Water, 2013).
The WSUD also reduces the greenhouse gas emission through minimizing the
consumption of water and improving the harvesting of rainwater as well as alternative natural
treatments of water. Some of the natural ways of water treatment include passing of stormwater
runoff through wet pons where the water can be treated by passing it through porous pavements
used to secure the surrounding of the pond. The design also discourages excessive and
irresponsible discharge of water from industrial sector into the drainage system without acquiring
the permit from the urban authority. These regulations reduce the consumption of water by both
the commercial and domestic sectors. The WSUD also provides an adoption measure to tackle
the change in climate impacts such as heat island and flooding. This is made possible by

Water Sensitive Urban Design 14
legislation put in place by the urban authority such as encouraging the vegetative management
practices (William, 2011).
Conclusion
Stormwater management can be defined as a structural control, measure, or technique
that can be applied for a given set of conditions to improve quality and manage the quality of
stormwater runoff in a way that is cost-effective. Some of the stormwater management practices
that have been implemented in numerous states and can be considered as standard approaches for
management of stormwater include hardscape design, legislation, vegetative management
practices, wet ponds, and permeable materials. Some of the benefits of the water sensitive urban
design include aesthetic purposes, filtering pollution out of stormwater, supporting aquatic life,
protecting environmental values, reducing greenhouse gas emissions, improving biodiversity,
improving the stormwater quality, and increasing water conservation.
Future Direction
There is the need for improving the integration of stormwater management practices in
the design of the public landscape. From the literature above, there is the need for improving
stormwater legislation and regulations in every state so all the stakeholders in the urban areas
could be aware of the issues involving stormwater management. Through enforcement and
passing of these regulations concerning the stormwater management, both nationally and locally,
steps should be taken to promote the control of runoff. Education is also a direction that should
be taken to ensure that integration is fully used and accepted in public hardscapes. The parties
that should be involved in this integration education include public as a whole, neighborhood
organizations, developer organization, and public officials (Booth, 2012).

Water Sensitive Urban Design 15
Bibliography
Arnold, C., 2010. Impervious surface coverage. Melbourne: Journal of the American Planning
Association.
Authority, P., 2008. Maintaining Water Sensitive Urban Design Elements. Sydney: Environment
Protection Authority.
Booth, D., 2012. “Urbanization and the Natural Drainage System – Impacts, Solutions, and Prognoses.
Toledo: The Northwest Environmental Journal.
Borah, D., 2009. Watershed-scale hydrologic and nonpoint source pollution models: Review of
applications. Perth: Transactions of the ASAE 47(3).
Bozeman, M., 2010. Sources of Urban Runoff Pollution and Its Effects on an Urban Creek. Colorado:
Cincinnati, OH.
Clarke, M., 2015. Water Sensitive Urban Design. Michigan: Healthy Waterways.
Committee, J., 2009. Evaluating Options for Water Sensitive Urban Design. Melbourne: Joint Steering
Committee for Water Sensitive Cities.
Council, T., 2011. Water sensitive urban design for the Coastal Dry Tropics. Moscow: Townsville City
Council.
Fletcher, T., 2009. Urban Drainage Modelling and Water Sensitive Urban Design. London: IWA
Publishing.
Gaffield, S., 2013. Public Health Effects of Inadequately Managed Stormwater Runoff. California:
American Journal of Public Health.
Hoyer, J., 2011. Water Sensitive Urban Design: Principles and Inspiration for Sustainable Stormwater
Management in the City of the Future. Perth: Jovis.
Lloyd, D., 2010. Water Sensitive Urban Design: A Stormwater Management Perspective. Sydney: CRC for
Catchment Hydrology.
Pitt, R., 2009. Small storm hydrology and why it is important for the design of stormwater control
practices. New York: CHI and Lewis Publishers.
Ruth, R., 2009. Transition to Water Sensitive Urban Design. Colorado: Facility for Advancing Water
Biofiltration.
Shaver, H., 2014. Infiltration as a Stormwater Management Component. Michigan: American Society of
Civil Engineers.
Water, M., 2013. WSUD Engineering Procedures: Stormwater. Melbourne: Csiro Publishing.
William, H., 2011. The Social Life of Small Urban Spaces. New York: Project for Public Spaces.

Water Sensitive Urban Design 16
Wong, H., 2012. Australian Runoff Quality: A Guide to Water Sensitive Urban Design. Perth: National
Committee on Water Engineering.