Could emulating China's 'sponge cities' help prevent the worst of flooding in urban India?

Editor's note: Beginning 15 October 2017, we're running a new series called 'By Design' that looks at Indian cities from the perspective of urban design. How can design make the quality of life in India cities better? How can the architecture of our infrastructure prevent life-threatening situations like flooding, or rush-hour stampedes? What solutions can simple design changes offer to monumental urban problems? We'll be discussing all this and more, in 'By Design'.

The metropolis is a graceless goliath with rancid morning breath. It is also a terrible beauty, notorious for its mood swings — calm at dawn, simmering by mid-morning, stormy at dusk. Perhaps poetry captures with a lucidity and diction that escapes statistics, the havoc wrecked by urbanisation upon lives trapped in glass-and-chrome or navigating through treacherous streets or suspended across filthy skies. So, before one computes and tallies to arrive at a delineation of loss in numbers, one ought to dwell on these lines by Nissim Ezekiel, from the poem ‘A Morning Walk’, from the collection titled The Unfinished Man, published in 1960:

Barbaric city sick with slums,
Deprived of seasons, blessed with rains.
Its hawkers, beggars, iron-lunged,
Processions led by frantic drums…

This is Ezekiel’s Bombay; this is our Mumbai, where only the rains are incompatible with the poet’s epithet. The rains are no longer a blessing upon the city; they, as the statistics verify, unleash the misfortunes of disease and death upon those who dwell under tempestuous skies. On 29 August this year, the day of the deluge, Mumbai reportedly received around 298 mm of rainfall between 8.30 am and 5.30 pm, the heaviest since a cloudburst in 2005, when around 944 mm of rain lacerated the city in 24 hours.

Could emulating Chinas sponge cities help prevent the worst of flooding in urban India?

A man walks past a stranded public transport bus on a road flooded by heavy rains in Mumbai. REUTERS

Other cities too, were inundated in a manner similar to Mumbai. On 21 August, Chandigarh was besieged by 112 mm of rainfall; on 11-12 August Agartala received over 11 times and Bengaluru (on 15 August) received over 37 times its average daily monsoon rainfall of the last five years. In fact, 2017 has been the wettest year for Bengaluru. It has grappled with 1,666 mm of rain so far, a figure surpassing the record rainfall of 1,606 mm in 2005. In the month of October alone, the capital of Karnataka was flooded with 386 mm of rainfall.

Perhaps global warming, responsible for climate changes, has led to frequent episodes of extreme rainfall. As per the Intergovernmental Panel on Climate Change (IPCC) Report on Extreme Events, global warming leads to “changes in the frequency, intensity, spatial extent, duration, and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events.”

But there are several activities, undertaken by city planners, builder, and engineers, that lead to a proliferation of construction on existing topographies and surface water bodies. Rapid urban development has scant regard for the hydrology of the land, and blocks natural drainage channels. So, when “Clouds heap upon clouds and it darkens,” as Rabindranath Tagore evokes in Gitanjali, the darkness heralds not the ecstasy of peacocks and a season in a swoon, but the fear and trembling of a drowning city.

The metropolis: Water-tight and sinking

Cities in India, with their impermeable surfaces, blocked drains, and rampant construction on lake beds and other water bodies, have metamorphosed into water-resistant barriers, prone to flooding. Professor Dr N Sridharan, director of the School of Planning and Architecture (SPA) Bhopal and director, SPA Delhi — additional in charge, refers to two prominent waterways in Delhi: the Barapullah nallah and the Najafgarh nallah, that are clogged with the effluence of rapidly-expanding townships. “Development, both unauthorised and state planned — like the expansion of roads — has been allowed, choking these drains. Every year, even if the area receives one millimetre of rain, it gets flooded,” he emphasises.

The blocking of a city’s natural water bodies obstructs the flow of rainwater. Chennai, for instance, had around 650 water bodies two decades ago, according to the estimation of the Centre for Environmental and Water Resource Engineering, IIT Madras. Those have dwindled rapidly over the years. Several lakes — such as the Maduravoyal Lake, which has been reduced to 25 acres from 120 acres — have diminished into dry patches.  Sujatha Byravan a scientist based in Chennai, mentions the destruction of the Pallikaranai marsh and similar wetlands, caused by the encroachment of housing complexes, slums, and commercial buildings. “The floods across the Coromandel Coast were not caused by global warming,” she affirms, referring to the whiplash of rain and waterlogging brought about by the northeast monsoon in 2015.

Professor Dr Sanjukkta Bhaduri, who teaches in the department of urban planning at SPA, New Delhi, enumerates the reasons why cities sink under torrential rains: too much rainfall in a short span of a few days, blocked drainage channels (including natural water bodies and storm-water drains), and the encroachment of ecotones or transitional areas between two bio zones. Alluding to the recent deluge in Mumbai, she says, “Planned development is forever at loggerheads with environmental concern; in Mumbai, the Mithi River has shrunk considerably over the years.” The mushrooming of slums and illegal commercial units have turned the river into a sewer, reducing its efficacy as a drainage system.

The Mithi River’s contamination brings to mind these lines from Keki N Daruwalla’s poem, ‘The Ghaghra in Spate’:

In the afternoon she is a grey smudge
Exploring a grey canvas
When dusk reaches her
Through an overhang of cloud
She is overstewed coffee

Architects too, are against the profligacy of city builders and developers, which turns water bodies into a ‘grey smudge’ or óverstewed coffee’.

“As long as we think that the purpose of a city is to make money through the development of land, our cities are doomed to environmental risk as well as socio-economic disparities,” says Ashok B Lall, the principal at Ashok B Lall Architects, and an active advocate for, and researcher in sustainable urban development for developing societies.

Urban development at the cost of a city’s ecosystem is perhaps the surest way to ensure floods, and the miasma of rotting flesh.

Professor Dr N Sridharan. Photo courtesy Radhika Oberoi

Professor Dr N Sridharan. Photo courtesy Radhika Oberoi

Professor Dr Sanjukkta Bhaduri. Photo courtesy Radhika Oberoi

Professor Dr Sanjukkta Bhaduri. Photo courtesy Radhika Oberoi

Sponge Cities: Resilient to the Rains

While concretised cityscapes are vulnerable to nature’s fury, a porous landscape allows rainwater to be absorbed and reused. A ‘sponge’ city, as the nomenclature suggests, is a reimagined metropolis that captures stormwater and uses it as a resource to augment the city’s water supply. China, for instance, grapples with rapid urbanisation and inefficient management of its water resources — urban predicaments similar to those that grip Indian cities. In 2012, a flood in Beijing destroyed the city’s transportation system, and in 2016, floods damaged the drains of Wuhan, Nanjing and Tianjin.

In 2015, China picked 16 urban districts as pilot sponge cities, to demonstrate the efficacy of measures like rooftops covered by plants, wetlands for rainwater storage and permeable pavements that store excess water. The city of Lingang in Shanghai’s Pudong district exemplifies this sponge city; its government has invested $ 119 million in innovations that other Chinese cities could emulate. Shanghai too, has announced the development of 400,000 square metres of rooftop gardens, in a bid to increase urban greenery.

In Singapore, rooftop reservoirs are used as a method of capturing rainwater. The country’s Marina Barrage, a dam built in 2008, provides water as well as resilience to floods, acting as a tidal barrier and protecting low-lying areas such as Chinatown, Jalan Besar and Geylang.

There are a variety of ways in which a city can become a ‘sponge’. De-clogging and protecting its natural water ways should be foremost. “Let’s respect our natural water systems,” says Professor Sridharan. A drainage master plan for Delhi, prepared by the city’s Indian Institute of Technology, and submitted to the government in December 2016, recommends the removal of sewage and solid waste from the capital’s storm-water drains.

“Construct wetlands; identify areas that can act as a water sink,” suggests Professor Bhaduri. Suggestions abound. But for development to be ecologically sensitive and follow the contours of a city, the collaborative effort of policy makes, city builders, environmentalists and local communities is imperative, so that lashing of rain bring about not destruction, but what Daruwalla calls a ‘cleansed feeling’:

the kind you experience
walking in a  temple (Ruminations: 1)

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Updated Date: Oct 22, 2017 09:46:51 IST

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