How damage to Aravalli Hills could worsen heatwaves, floods and air pollution in Delhi-NCR

New Delhi: Recently, the Supreme Court gave its nod to a revised definition of the Aravalli Hills which was spelt out by a government-appointed expert committee. This effectively is aimed to redefine the hill range.

Under the new definition, only landforms rising at least 100 metres above the surrounding area would be counted as part of the Aravalli range. This could remove shield from almost 90% of the hills, and expose them to mining and construction, it is feared. Environmentalists have sounded a caution and said that such a step would be a "death warrant” for the climate resilience of the region.

According to some reports, internal mapping by the Forest Survey of India (FSI) suggests that only 1,048 of the 12,081 hills —- roughly 8.7% -— meet the new criterion of height.

The implications of reducing a living, functioning ecosystem to a simple "height-based definition” could be massive, say the green activists. To reduce the Aravalli landscape to "just hills” goes a long way in hampering the very foundation of landscape ecology, they believe.

The Aravalli Hills are believed to be one of the oldest mountain ranges in the world. It stretches about 700 km across north-western India, running Gujarat through Rajasthan to Haryana and Delhi.

As ecologists underline, the Aravallis are not merely tall hills but a varied landscape of low ridges, groundwater recharge areas, scrub-covered slopes, gentle slopes, rocky zones, seasonal streams, and fragile forest patches —- many of which are less than 100 metres high.

It supports rivers like the Luni, Banas, and Sahibi. The range is home to dry deciduous forests, grasslands, wildlife corridors, and many rare flora and fauna. Aravallis shouldn't be seen just as "hills” as the range has crucial hydrological, climatic, and ecological functions.

The Aravallis are instrumental in regulating the climate, affecting local weather patterns and rainfall, and have been crucial in shaping the climate of the upper Indo-Gangetic plain. No wonder they are often called as the ‘lungs’ of one of the world’s most polluted regions, Delhi-NCR.

The Aravallis act as a natural protection against the rapid spread of the Thar Desert, and help slow the march of desertification. The low-lying landforms serve as natural barriers against wind and dust, preventing sand and desert dust from the Thar from spreading eastward into the plains.

For centuries, the Aravallis have stood as green buffer and windbreak for Delhi-NCR and the surrounding areas. The hills block dust-laden westerly winds and stabilise the soil, while curbing dust storms, and reduce air pollution.

According to environmentalists, if these hills are redefined, it will give rise to new "dust corridors” in areas which are shielded by the Aravallis. This will increase pollution and the urban air quality will plunge further.

Not just air pollution, the loss of hills will also give lead to more frequent heatwaves, and the increasing number of dust storms that have been paralysing Delhi-NCR in recent years.

The apex court has instructed the government to chalk out a "Management Plan for Sustainable Mining (MPSM)” for the entire Aravalli region.

Mining, deforestation, toxic landfills, real estate development, illegal encroachments, and other development projects have already made this range vulnerable. Surface mining, quarrying and orgaised construction activity will cause enormous damage to the natural cracks, soil layers, and rock formations that allow water to infiltrate. Any mining activity will cause the rainfall to flow off rapidly, resulting in soil erosion, and loss of topsoil. This will increase flood risk.

Neelam Ahluwalia, an Aravalli Bachao Citizens Movement activist, has reportedly said that NCR Draft Regional Plan 2041 - in which conservation of Aravallis has been completely ignored -- would, "threaten the right to breathe and water security of millions of people living in one of the most polluted regions of the world, Delhi-NCR”.

A 2020 report by the South Haryana Forest Department submitted to the National Green Tribunal revealed that the Aravalli range lost over 10,000 acres of green cover between 2012 and 2020.

Redefining the Aravalli Hills could expose previously protected areas to mining, construction, and other development, threatening their ecological functions. And the region could witness environmental catastrophe that will start from spiralling AQI and end in more severe heatwaves. Floods will be the last nail in the coffin.