Metro Matters | Green infra is the health insurance Delhi needs

It took extreme rain to offer relief from Delhi’s high pollution in Delhi. But two wrongs do not make a right and the capital must act now to safeguard against these human-induced threats
Controlling farm fires and baseline local pollution will still require combined administrative action and citizen participation from Delhi and its neighbouring states (Sanchit Khanna/ Hindustan Times) PREMIUM
Controlling farm fires and baseline local pollution will still require combined administrative action and citizen participation from Delhi and its neighbouring states (Sanchit Khanna/ Hindustan Times)
Updated on Oct 25, 2021 08:03 PM IST
Copy Link
ByShivani Singh, Hindustan Times, New Delhi

For long, Delhi learnt to associate even moderate spells of downpour with waterlogged roads. But last Monday, few seemed to resent traffic snarls triggered by the heaviest 24-hour rainfall recorded for October since 1956. The intense shower washed away pollutants that were setting the stage for the city’s annual choking season, giving Delhi its first “good’ air day of 2021.

Ironical as it may sound, it took extreme rain to offer relief from high pollution. But two wrongs don’t make a right and the respite was temporary. Soon enough, the wind pattern changed and smoke from the stubble burning on the paddy fields of Punjab and Haryana combined with local pollutants started fouling up the air in the national capital. In 48 hours, “good” category air entered into the “poor” zone on the national air quality index, only to fall into the “moderate” zone with a change in wind direction, followed by another spell of unseasonal rain this Sunday.

But controlling farm fires and baseline local pollution will still require combined administrative action and citizen participation from Delhi and its neighbouring states. Just as we need to rethink our development strategies to cope with severe weather conditions than can no longer be dismissed as seasonal vagaries.

Erratic weather trends

In 15 months, Delhi’s weather has thrown up many surprises. An exhaustive list of meteorological trends compiled by my colleague Soumya Pillai showed a succession of extreme rainfall, heat and cold events.

If August 2020 recorded the highest rainfall since 2013, October witnessed the lowest average minimum temperature in 58 years. In January 2021, Delhi received the highest rainfall for the month in 21 years. February, a winter month, was the second warmest in 120 years. While March 29 was the hottest March day in 76 years, at 11.7 degrees C, April 4 recorded the lowest minimum temperature for April in at least a decade. The first few days of July were unusually hot, registering four heatwave days. In the much-delayed monsoon season that followed, Delhi not only saw prolonged dry spells, but also recorded the second-highest rainfall since 1964 and the wettest September since 1944. The post-monsoon downpour in October is already the highest monthly rainfall since 1960.

Weather scientists have attributed the current set of extreme events to “temporary atmospheric conditions”, but the future looks worrisome. The Delhi action plan on climate change, which was submitted in 2019 and expired soon after, in its chapter on vulnerability assessment states that by 2050, the annual temperature of Delhi is slated to increase by 1-4 degrees Celsius and rainfall too would intensify, and these changes in climate can lead to large-scale damage to life and property.

Delhi is not alone

Like Delhi, numerous cities across the world and many within India have witnessed extreme weather events. Inundated by record-breaking rain, the central Chinese city of Zhengzhou had cars swept away and passengers trapped inside the mass transit this July. Videos of a stream of water gushing down an underground subway station in New York City last month triggered debates on whether Big Apple’s infrastructure was designed to withstand such events.

A heatwave gripped North America this summer as the temperature peaked at 49.6 degrees Celsius in British Columbia’s Lytton village. In the United States, Portland suspended streetcar services and Seattle ran light rail at reduced speeds because of overheating of infrastructure. Closer home, Nanital, Chennai, Mumbai, Kolkata, Bhubaneswar and Bengaluru have recorded unusually heavy rain in short spells.

Cause and effect

As Delhi jumps from one seasonal meltdown to another, it has only bad planning to blame for the mess — a manifestation of haphazard urbanisation, mindless tendency to overbuild, inadequacies in the city’s basic infrastructure and poor civic upkeep. Fixing accountability for any of these has remained a challenge due to the national capital’s complicated governance structure and multiplicity of authority.

Unsurprisingly, for a city that gets waterlogged after every shower, Delhi’s water table has sunk dangerously low. The obsession with brick and mortar and excessive use of asphalt and concrete — 21% of Delhi’s land area is roads — leave little space for rainwater to percolate underground and replenish the aquifers. Sealed with concrete, even trees and plants are choking.

Concretisation, emissions from vehicles — Delhi has 11.9 million registered vehicles — overuse of air-conditioners, and closely-packed, poorly-ventilated buildings in dense neighbourhoods have turned many pockets in the city into heat islands, characterised by a localised increase in air and surface temperatures chiefly due to heat absorption.

Cost of urbanisation

The National Capital Region (NCR), which has 20 cities and towns including Delhi, has seen a 17-fold increase in urban and built-up areas between 1972 and 2014, stated a 2018 study by IIT-Delhi’s Centre for Atmospheric Sciences’ Ankur Prabhat Sati and Manju Mohan.

Another study by Manju Mohan, Shweta Bhati and Ankur Prabhat Sati published in Urban Climate last year drew linkages between urbanisation, heat island intensities and thermal comfort over Delhi-NCR between 1972 and 2014. It found that n NCR areas, where cropland was converted to the urban landscape, the surface heat island saw an increase of 4 to 6 degrees Celsius, and canopy layer heat island intensified by 2 to 4 degrees C at night. The daytime temperature saw an increase of 2 degrees Celsius at the surface and 1 degree C at the canopy level.

Specifically, in Delhi, increased urbanisation and modification of land surfaces pushed up the average ambient temperatures by 1.02 degrees Celsius in these five decades. Around 500 sq km area, experienced an increase in night-time canopy level heat island of more than 4 degrees Celsius, which the study stated was non-existent 50 years ago. Within this pocket, 23 sq km has in the last decade seen a canopy heat island effect of 5 °C and more.

Consequently, “thermally uncomfortable” hours increased from an average of 10 to 13 hours a day and comfortable hours decreased from around three hours to around one hour per day, the study said, adding that the heat island intensity would exacerbate after anthropogenic (caused by human activity) heat, greenhouse gases, and other pollutant emissions are factored in.

This month, another study ranked Dhaka, Delhi, Kolkata, Bangkok and Mumbai as the top five settlements with the highest annual increase in extreme heat exposure. The study, published in Proceedings of the National Academy of Sciences by researchers from UC Santa Barbara and Columbia University, tracked urban population exposure to extreme heat from 1983 to 2016 in more than 13,000 settlements and calculated the share of exposure from population growth versus total urban warming (from urban heat island effect and anthropogenic climate change). While the exposure trajectories for Delhi and Kolkata matched, Delhi’s population growth contributed to nearly 75% of the increase in the city’s heat exposure, while population growth accounted for only 48% of the annual rate of increase in exposure in Kolkata.

Of the 1,483 sq km of Delhi’s total area, 977 sq km is built up or proposed for urbanisation; 200 sq km is kept for public utilities; 195 sq km is forest, ridge, floodplain, water bodies and drains; and 110 is agriculture land and greenbelt. As much as 97.5% of Delhi’s population lives in urban areas, which is the highest among all Indian states and UTs.

A health warning

Plummeting water tables, rising temperatures and frequent flooding have obvious consequences for health and Delhi is already showing serious symptoms.

The Yamuna water is over-extracted, leaving little to maintain the minimum flow required to keep the river alive even as the city continues to bank on borrowed water. The demand-supply gap stands at 300 million gallons per day against the daily supply of 935 MGD from the Delhi Jal Board. With unpaved surfaces shrinking, precious rainwater, which can recharge groundwater, is lost in run-off, flowing directly into stormwater drains, which are already filled with sewage, and reaching the Yamuna as a toxic mix.

Delhi’s clogged, encroached and, in many places, absent drainage is not just an eyesore but a disease factory throughout the year. In 2010, for instance, when Delhi saw a prolonged monsoon, as many as 6,259 cases of dengue were recorded. This year again, record rainfall combined with general civic apathy is being blamed for a spurt in dengue cases as Delhi reported the season’s first fatality last Monday.

The health woes don’t stop here. Heatwave-triggered cramps and heat strokes are commonly reported in Delhi throughout the summer even as the rising levels of air pollution are suppressing the immunity of Delhi residents, leaving them vulnerable to lung and heart diseases, and even cancer.

Inequality makes it worse

Those who can afford have made all efforts to weather-proof their living environment. A study by researchers Santosh Harish, Nishmeet Singh and Rahul Tongia published in Energy Policy last year shows that with the temperature rising from 30 degrees Celsius to 39 degrees Celsius, the aggregate demand for electricity in Delhi shoots up from 30 to 43%. It also increased from 2 to 12% as the temperature dropped from 12 degrees to 6 degrees Celsius. This is mainly on account of the use of air-conditioners in summers and heating equipment in winters.

“As temperature extremes worsen due to urban heat island effects and over the long-term climate change, households respond through increased use of electricity. Unsurprisingly, wealthier households have a much greater ability to respond to extreme temperatures, hot or cold. Our analysis shows how lower-income households are unable to respond beyond a point, due to the limitations of fans and coolers compared to ACs,” explained Harish, fellow at Centre for Policy Research.

He pointed to a “feedback loop” between increased AC use and increased local temperatures in cities such as Delhi, which further worsens this inequity.

In unauthorised colonies and informal settlements that house one-third of Delhi’s population, buildings are so tightly packed that they block sunlight and air coming into the homes.

Greenery mitigates air pollution, absorbs stormwater run-offs locally, and is known to have a cooling effect. But a park, or even a tree, is a luxury in most of Delhi’s working-class neighbourhoods. Clearly, reimagining Delhi will require reasonable democratisation of public infrastructure as well as green and open spaces.

The way out

The past year’s weather events are a wake-up call and Delhi must do all it can to safeguard against their unpredictability.

After a series of urban flooding episodes this monsoon, the Delhi government has decided to implement the drainage master plan. Prepared by IIT-Delhi, the plan calls for overhauling the faulty drainage system and expanding the network. It also sets some ground rules for housekeeping — garbage and sewage should not enter stormwater drains, construction should not block or encroach upon critical infrastructure, and desilting must be efficient.

But an overhaul of the city’s drainage will require big funds and coordination between as many as 11 agencies. Putting in place an institutional mechanism will require administrative unity and a political will.

Harvesting rain is the cheapest and fastest remedy for urban flooding. The drainage plan itself recommends “low impact development” options such as creating infiltration trenches, rain gardens, bio-retention ponds, bio-swales, which can absorb rainwater right where it falls, and incorporating water bodies and other water retention zones into the drainage system.

Delhi government’s “city of lakes” project, which aims to restore 255 water bodies and 23 lakes in the next two years, and Delhi Development Authority’s move to acquire and restore 650 water bodies located in 168 rural-turned-urban villages is a good complementary initiative, provided they keep up the momentum and maintain the right ecological balance in the restoration process.

As for fighting the summer heat, Delhi could start by losing some concrete, asphalt and dark surfaces. Building permeable pavements that allow grass and trees to grow freely offer the twin benefits of cooling and stormwater absorption.

Many cities across the world are experimenting with cool roofs. Use of highly reflective paint or reflective tiles reduces heat absorption and cut energy use by up to 20%. New York City even offers free installation of cool roofs in lower-income housing and community building. Building codes in certain specified building types in Philadelphia, Washington DC and Los Angeles require the use of cool roofing materials, states a resource guide of C40, a cities climate leadership group.

Nature-based infrastructure is not just good aesthetics, it is also a city’s best health insurance against the human-induced crises of air pollution, overheating and flooding.

HT’s metro editor and one of the most perceptive and experienced journalists covering India’s capital region, Shivani Singh, resumes her column, Metro Matters exclusively for HT Premium readers

The views expressed are personal

Enjoy unlimited digital access with HT Premium

Subscribe Now to continue reading

    Shivani Singh leads the Delhi Metro team for Hindustan Times. A journalist for two decades, she writes about cities and urban concerns. She has reported extensively on issues of governance, administrative and social reforms, and education.

Close Story
Story Saved
Saved Articles
My Reads
Sign out
New Delhi 0C
Tuesday, December 07, 2021