‘Sponge City’ - Helps to Solve Urban Water Crisis in Smart Way

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Trillion liters of free water drop from the sky onto the world’s cities each year, yet most of it is channeled straight into gutters, drains and rivers. At best, this represents a waste of a valuable natural resource. In traditionally managing surface water runoff in an urban location is to funnel that wateraway from cities as fast as possible.It can lead to devastating urban floods like in the Mumbai and Chennai that destroyed hundreds of homes. With cities getting bigger, climate changes threatening to bring more extreme weather, there is a need to rethink about the urban environment where almost every raindrop can be captured, controlled and reused.To design a city in such a way that it retains all the surface water runoff that can be reused at a later date, thereby creating an urban environment that absorbs water then releases that water when required in a similar manner to a sponge.

A sponge city follows the philosophy of innovation: that a city can solve water problems instead of creating them. In the long run, sponge cities will reduce carbon emissions and help fight climate change says Qiu Baoxing, a former vice-minister of housing and urban-rural development in China.

Instead of funneling rainwater away, a sponge city retains it for use within its own boundaries. Some might be used to recharge depleted aquifers or irrigate gardens and urban farms. Some could replace the drinking water we use to flush our toilets and clean our homes. It could even be processed to make it clean enough to drink.

A sponge city refers to sustainable urban development including flood control, water conservation, water quality improvement and natural ecosystem protection. The sponge city program takes inspiration from the low impact development (LID) and green infrastructure in the US and Canada, sustainable drainage systems (SusDrain) in the UK and other European countries and water sensitive urbandesign (WSUD) in Australia and New Zealand. It promotes natural and semi-naturalmeasures in managing urban stormwater and wastewater as well as other water cycles. China has taken up the 'Sponge City' concept because with the facts of rapidly growing urban populations, poor water management and climate change.

There are various mitigation techniques that a sponge city might use.Water can be collected at the tops of buildings, and stored in soil(mostly in tanks for later use in the garden). Collected water could be used for gardening and other nondrinking purposes. A classical example of water collection is “Swales” which is a permeable space between sidewalks, roads or other paved surfaces that can absorb runoff. “It’s a new way of thinking about stormwater, not as a problem but as an opportunity and a resource to augment our water supply,” says Richard Luthy, professor of civil and environmental engineering at Stanford University.Sponge city infrastructure is beneficial because it is also changing the living standard by creating abetter quality of life and creates investment opportunities ininfrastructure upgrading, engineering products,and new green technologies.

Traditionally, in India water harvesting techniques were used from age old time which is a key functional component in the Sponge City concept. Integrating them judiciously to urban planning and design will lead to development of sponge like cities or otherwise smart cities. ‘Rain water harvesting’ practiced in many of our cities is a way towards sustainable water management.

Author: Dileep Kumar Yeruva, Project Assistant-II and PhD Scholar, Bioengineering and Environmental Sciences Lab, EEFF Department, CSIR-IICT.

Posted By : ScienceIndia Administrator