Which is India’s greenest metro?

If green spaces were a city’s lungs, most people would agree that smoke-filled Delhi needs them the most. Yet, among India’s six metros Delhi is already the greenest. According to a Mint analysis, the average urban resident in Delhi has the most access to green spaces, while their Mumbai counterpart has the least.

In the concrete jungle of cities, open green spaces can provide welcome relief. Vast parks and lush gardens bring beauty and calm to a city, alleviate the strains of daily life, but more importantly, they make life healthier. Trees and plants produce oxygen, a critical, natural air filter for India’s increasingly polluted cities.

To measure which Indian city provides the best green cover, Mint analysed LANDSAT satellite image data using Google’s Earth Engine, the largest publicly-available database of satellite images of our planet. Compiling images of each metro, we analysed how much of a city’s area was “green”. Greenness was measured using the normalized difference vegetation index (NDVI), a measure that analyses satellite images to identify areas of natural vegetation.

Naturally, greenness in Indian metros depends on geography. The arid landscape around Hyderabad is never going to produce the same lushness as the foliage in Bengaluru.

To adjust for this, we consider the lowest threshold of greenness (NDVI of 0.3) which ensures even open grasslands and shrubbery—commonly found in Delhi and Hyderabad—are captured.

Our calculations show that Mumbai is India’s least green metro with just 12.3% of the city classified as green, while Delhi is the most green (56.2%) followed by Kolkata and Bengaluru. Even after adjusting for population, Delhi provides the greatest green space per resident (41 square metres per person), while Mumbai provides for only 4.4 sq metres (Chart 1a and 1b).

Measuring the aggregate green cover in cities, though, can mask disparities within cities. In metros, the greenest areas are often the furthest from where people live.

Some of the biggest benefits of green spaces, such as the space for physical activity, only comes with easy access.

In Mumbai, the sprawling Sanjay Gandhi national park lies on the outskirts of the city, far from the densely populated city core; similarly in Delhi, Lodhi Gardens and the Nehru Park, only remain easily accessible to the residents of some of Delhi’s most exclusive neighbourhoods.

To adjust for this, we calculated the green cover measure at the ward-level, the most granular level of administration within a city. Across the 976 wards in the six metros, 218 have more than 50% of green cover.

The majority of these wards are in Delhi, which manages to provide 24% of its population with at least 50% of green cover. The least green wards are all largely in Mumbai, where two-thirds of the city’s population live in wards with less than 10% green cover.

Our analysis, though, suggests that most of India’s wards fail to meet the World Health Organization (WHO) standards, which recommend that every urban resident lives within 300 metres (or five minutes) from a green space

Note: The calculations of greenery are on the basis of Landsat satellite imagery between 2010 and 2018. The Normalized Differenced Vegetation Index which captures vegetation cover was determined for each area in these cities with a resolution of 30 x 30 metres. Areas whose NDVI values lie between 0.3 to 0.8 have been considered as 'green' in our analysis. From these NDVI values, proportion of area with green cover is calculated. The satellite data identifies green cover uniformly and thus identifies open green spaces such as golf courses. This analysis replicates the methodology of the Berliner Morgenpost's 2016 story on greenery.

The provision and preservation of greenery is the responsibility of city governments—but these can be at odds with other priorities.

In Mumbai, for instance, the planned metro construction through Aarey Colony will come at the cost of one of the city’s greenest spaces.

But for sustainable development, building infrastructure, and maintaining and enhancing green spaces need to be treated as concurrent, not conflicting, priorities.

For example, the WHO suggests that green space considerations need to be incorporated into all aspects of urban planning, including transport infrastructure.

*This is the eighth story of a 10-part series on life in Indian cities.