Water Sensitive Planning  

                      

Urban
water systems are confronted with significantly changing conditions. The
impacts of climate change, rapid urbanization, and deteriorating and outdated
infrastructure aggravate current water challenges of causing flooding, water
scarcity and rehabilitation costs on a scale that will overwhelm the capacities
of cities. The World Resource Institute global water-stress rankings (2013)
indicate that the ratio of withdrawal to supply in India is 40 to 80 per cent
and the country experiences high water stress. India has witnessed a rapid
increase in the urban population during the last few decades. All towns and
cities currently face the problem of increasing gap between water supply and
demand, which puts pressure on water resources and its supply requirements. By
2030, India will have 68 cities with populations of over 1 million. Growing
urban centres, with the concurrent process of urbanization, have brought
several issues to the fore, from governance and management of these areas to
the provision of basic civic services. Consequently, there is heavy pressure on
water management.

In
the last two decades, built-up area has grown faster than population in nearly
all of India’s largest cities. A comparison shows that the spatial expansion
has accelerated between 2000 and 2010. Water supply in most Indian cities
refers to the layout of infrastructure, i.e. piped water-supply lines, sewage
lines, sewage treatment plants (STPs) and layout of drainage lines. If the
piped water supply is inadequate, it is supplemented by private uncontrolled
groundwater extraction, which contributes to pollution of urban aquifers and
fall in groundwater levels. People either dig wells and tube wells on their
properties for their water needs or buy water from private tankers that, in turn,
extract groundwater for sale.

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Water
sources are also highly polluted, limited and subsidized for domestic
consumption. No fixed or standard pricing exists for groundwater extraction.
According to a Centre for Science and Environment (CSE) study, the water price
charged to consumers in metro cities such as Delhi and Bengaluru is Rs 0.35 per
1,000 litres and Rs 5 per 1,000 litres respectively, which is fairly low as
compared to actual cost of water supply, i.e. Rs 72 per 1,000 litres and Rs 93
per 1,000 litres, respectively. This leads to increased consumption and
wasteful utilization of water in the country. Around 40–90 per cent of the
total water consumption goes out as wastewater. A CSE survey indicates that
there is a complete disconnect between water supply and sewage management in
India. Only 30 per cent of sewage from Indian cities is treated at STPs. The
remainder pollutes natural waterbodies.

The
increasing demand–supply gap and deteriorating environmental conditions are
increasing the need for environmentally friendly alternatives. It is important
to take up the challenge in controlling and judiciously using natural resources
to reduce our ecological footprint. Sustainable water management requires a
holistic approach toward sustainability along with prudent use of water
resources.

It
is clear from the existing situation that a re-focussing of priorities is
required by way of careful planning to have sustainable water management.
Adopting water sensitivity at the stage of planning and designing new and
existing developments can maintain the water cycle by managing the supply and
demand for water, storm water, wastewater and groundwater as well as bring
benefits such as reduction in temperature with respect to climate change and
adaptation.

Protecting
local waterbodies (lakes, ponds and wetlands) for supplementary water sources.

 Storm-water management at public places,
including open areas in cities through elements of landscape design (e.g.
vegetated swales and buffer strips, bio-retention systems).

Recycling
and reusing wastewater naturally (low cost/low energy) and not treating it as a
liability.

Increasing
water-conservation approaches at various scales (buildings/ campus)—i.e. by
adopting water-efficient fixtures, xeriscaping landscape (i.e. planting native
species) and using water-efficient irrigation methods— thereby minimizing load
on the municipal supply system and groundwater sources. On-site water
conservation with rainwater harvesting (RWH) is also important to reduce water
scarcity.

Adding
value to the social and ecological aspects of areas by planning and designing
the built environment in accordance with community needs and water issues.

 Connecting the urban water cycle by
collaborating with practitioners of different disciplines to bring different
perspectives and expertise.

The
sustainability approach needs to include elements of water quantity, water
quality and ecology, along with community involvement. Therefore, prime
potential sustainability factors to facilitate accreditation of
water-management options with regard to capital cost, resource use, performance
and maintenance are technical, environmental, social and economic elements.
There
is growing realization at the Central/state level that the risk of not
addressing water management in the early stages of planning and design causes
constraints to new development or (re)development, missed opportunities for
cost saving, poor quality of urban environment and overall unsustainable urban
development. The need is for more integrated land and water management from
early stages to reduce the increasing water footprint of urban centres.

CASE STUDY: Scope of RWH
intervention, Chandigarh, India

Chandigarh
has grown rapidly in the last decade (1991–2001). Its population growth rate
was 40 per cent. Its population density of 7,900/ sq. km is one of the highest
in the country and it is estimated that its demand for water will grow steeply.
By 2025, the city’s demand for water is estimated to be 800 MLD, an increase of
58 per cent over the 2011 demand of 494.25 MLD. To ensure long-term
sustainability of water sources for the city, RWH is a simple and effective
solution. It can be done using roads, roundabouts, parks, rooftops, paved areas
in almost the entire city. The storm-water network collects water from roads
(15.89 sq. km), rooftops of residential areas, (30.19 sq. km), shopping areas
(3.97 sq. km), and public and institutional buildings (7.94 sq. km). This
amounts to over 70 per cent of the total land area. The total quantum of water
that would be available for recharge annually would be 58 sq. km (area) x
1059.3 mm (rainfall) x 0.5 (rainfall coefficient) = 30,720 million litres
(18.46 million gallons per day [MGD]). This is equivalent to almost 90 per cent
of the total groundwater supply and is available only from tapping the
storm-water-drain network. By careful planning of recharge in parks and green
areas of the city, it would be possible to recharge the entire groundwater the
city takes out.

 

CASE STUDY: Scope of RWH
intervention, Noida, India

Noida
requires an unparalleled infrastructure of sustainable water management.
However, unregulated and increasingly unsustainable exploitation of aquifers
has led to a decline in the water table and deterioration in the quality of
groundwater in the area. The projected increase in the proportion of hard
surface has further increased runoff while decreasing percolation in the area.
The overarching framework of RWH systems that can be implemented in the area
depends on its physical and land-use features. Implementing RWH systems in
Noida can contribute significantly to addressing the water demand–supply gap,
dealing with waterlogging, flooding and recharging aquifers.

CASE STUDY: Scope of WSUDP
intervention, Dwarka, New Delhi, India

The
objective of this case study is to provide sustainable solutions by showcasing
interventions with regard to planning current Indian urban areas. To identify
and analyse the issues and challenges of water management in the India’s
capital New Delhi, it is pertinent to note that the population of Delhi has
been projected to cross 20 million by 2021. Housing projects such as Dwarka
were envisaged in early 1990 to accommodate approximately one million people.
However, the master plan makes no distinction between semi-urban/ peri-urban
areas and areas in transition, such as Dwarka sub-city. Hence, there are no
specific norms or recommendations for these areas, resulting in a wide
demand–supply gap. An analysis of the area is conducted in terms of three main
areas: storm-water management, water-supply management and wastewater
management. Dwarka site was analysed with WSUDP approach leading to proposals
and conclusions for each of the water resource integrating with spatial
planning.

1.
Storm-water management

i.
Delineation of catchment areas and sub-catchment areas according to trunk drain

 ii. Calculation of additional runoff discharge
in peak hours for storms over 25 years for the respective watersheds by the
rational formula (Q = CIA). (In the case of Delhi, the intensity of one-hour
peak rainfall is of 90 mm/hr for storms over 25 years.)

 iii. Identifying potential sustainable
strategies based on site characteristics and pollution levels according to
land-use characteristics in different watersheds iv. Preparation of matrices
for suitable strategies for sustainable urban drainage systems at the watershed
and neighbourhood levels (for different land uses) and listing out other environmental
benefits

2.
Water-supply management

i.
Evaluating the current water supply scenario in Dwarka

 ii. Accessing potential water quantity
on-site, comprising runoff, groundwater, wastewater and floodwater

 iii. Calculating the sustainable quantity if
all the sustainable drainage strategies are applied and regional water
collection in potential site area and present MCD supply is taken into
consideration iv. Accessing water supply and demand projection by present and
projected water supply cost–benefit scenario

3.
Wastewater management

i.
Calculating the potential grey water that can be reused, listing the currently
used conventional infrastructure and calculating the cost incurred by using the
same techniques

 ii. Listing out the different natural
decentralized techniques that can be used for treatment along with the cost and
the area required for them. This leads us to propose the purposes for use of
treated wastewater in Dwarka.

Water-sensitive planning (city/zonal
scale)

Water-sensitive
planning can conserve water resources while offering numerous benefits by way
of improving the urban environment, reducing the danger of flooding, increasing
opportunities for recreation and leisure activities, and reducing flooding
damage and cost of drainage systems. Any open space designed according to
water-sensitive planning principles provides recreational and visual amenities
while filtering runoff that infiltrates to replenish groundwater. It also acts
as a detention reservoir designed to reduce flood discharges and pollutant
loadings.

The
water cycle in urban areas is lost due to excess construction and paved areas,
including in major recharge zones such as lake catchments, riverbanks and
wetlands. In addition, contamination of existing water resources with sewage
adds to the loss of usable water. The need is to maximize use of open spaces to
rejuvenate the lost water cycle. Planning for new areas requires allocating
land uses according to hydro-geographic layout. The placement of open
spaces—recreational areas, roads etc.—plays a major role in complying with the
water-sensitive principle.

Significance
of open/buffer areas in water-sensitive planning . -Open spaces provide the
opportunity to combine the function of public open space with habitat retention
(trees and watercourses), pollution abatement and storm-water management.

Wetlands/lakes:
In densely populated urban areas, lakes and waterbodies are highly contaminated
by the inflow of untreated sewage from areas lacking or having inefficient
sanitation services. These waterbodies and lakes can be planned with a green
buffer area that can act as a treatment zone. Waterbodies play a major role in
the natural hydrological cycle and offer healthy recreational spaces. Since the
source of the pollution-degrading waterbody may be unknown, these buffer areas
act as protective layers.

Recreational
areas: Where open spaces are located in consideration with the natural stream
system, they can be also used to prevent and mitigate floods by retaining and
detaining storm water and to purify and infiltrate runoff, thus recharging
groundwater with clean water. Storm water that reaches open spaces may be used
for irrigation and as landscaping elements.

 Roads and streets: Roads and streets
constitute up to 70 per cent of the impervious urban area and serve primarily
to transport people and goods. But they also act as important conveyors of
storm water; in fact, they constitute the major drainage system that serves as
an important flow path when the drainage pipes underneath go beyond their
capacity.

 Inclusion of storm-water streams in urban
fabric: Storm-water streams/ watercourses represent natural drainage lines and
therefore need to be considered part of the storm-water management strategy for
a development site. The concept of storm-water streams in urban fabric
recognizes that there are benefits in considering maintenance of water quality,
habitat retention and restoration, water conservation and a wider choice of
recreational opportunities in an integrated fashion. Watercourses/streams are
generally linear-shaped spaces and therefore present a longer frontage to
adjacent residential development than square or circular plan forms. They
provide accessible open spaces to people. Their linear nature also offers
opportunities to integrate offroad pedestrian and cycle paths .

Water-sensitive designing
(neighbourhood/institutional scale)

Built-up
areas need to be drained to remove surface water. The conventional approach to
draining surface water is through underground drainage systems that convey
water from built-up areas. These traditional urban drainage systems focus on
quantity as they aim to remove excess water from urban areas as quickly as
possible to avoid flooding. These drainage systems have not been designed with
sustainability in mind. The majority do not pay sufficient regard for flood
control, water quality, water resources or biodiversity requirements. Urban
drainage systems have caused an alteration in natural flow patterns, not
necessarily having an effect locally, but causing flooding problems elsewhere
in the catchment area. Water quality has also become an increasingly
significant issue as surface run-off from these urban areas results in
contamination of the watercourse. Resulting urban flooding is extremely
difficult to resolve and is an important issue that drainage systems must take
into consideration. In urban areas, continued water management is a necessity
and for this to be sustainable, a broad approach to the issue of drainage must
be adopted. A similar situation is encountered with the conventional wastewater
management approach which involves centralized systems of sewerage networks to
provide treatment and disposal. The conventional technologies of a centralized
system of wastewater (sewage) collection and treatment are not just
resource-intensive (use of water first to flush, then to carry the waste), but
also capital- and energy- intensive. This further makes scope of recycle/reuse
bleak as the treated water would again be needed to be conveyed back for reuse
and would add to the capital and energy cost. The alternative approach of
decentralized wastewater management is based on the principle of devolving
application so that sewage can be treated affordably and treated wastewater can
be promoted for local reuse.

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