Haryana redefines Aravalis – Why most hills in Gurugram and Faridabad could disappear from Maps

The Aravali hills, one of the world’s oldest mountain ranges, are facing a new challenge. The Haryana Mines and Geology Department sent a letter to the state Environment and Forests Department outlining a revised definition on October 4.

According to the proposal, only hills and ranges belonging to the Aravali Supergroup and Delhi Supergroup, formed between 2.5 and 1 billion years ago, and rising at least 100 metres above surrounding land, will be considered “Aravali Hills and Ranges.”

Conservationists warn that a proposed change in their definition by the Haryana government could open large areas to real estate and mining, with serious ecological consequences.

What is Haryana’s new definition of the Aravali Hills?

As per the mines and geology department, only hills and ranges of the Aravali Supergroup and Delhi Supergroup, which originated during the Palaeoproterozoic to Mesoproterozoic, and which rise higher than 100 metres (+5 metres) above the surrounding terrain, may be defined as ‘Aravali Hills and Ranges’. Notably, the Palaeoproterozoic Era spans from 2.5 to 1.6 billion years ago (gigaannum or Ga) and the Mesoproterozoic from 1.7-1 Ga.

This change excludes younger hills, formed during the Neoproterozoic era (about 1 billion to 540 million years ago), and any smaller landforms, regardless of their environmental value. Conservationists argue that such a move could remove legal protections for many hills that currently play an important ecological role, The Indian Express reported.

How much of the Aravalis could lose protection?

M D Sinha, a former Conservator of Forests in South Haryana, warns that the 100-metre criterion could erase most of the Gurgaon and Faridabad Aravalis from official maps. “These areas are mostly scrub hills and grasslands with small forest patches. If protections are lifted, almost all hills outside notified forest zones could be opened up for commercial projects and mining,” Sinha was quoted by The Indian Express as saying.

According to the former conservator, the change could have far-reaching consequences for the ecology of Haryana and the wider Delhi-NCR region, where these hills play a vital role in maintaining environmental balance.

Why is the government making this change?

The Mines and Geology Department says the new definition aligns with the Geological Survey of India’s classification. The aim is to include only ancient, continuous ranges made of Aravali or Delhi Supergroup rocks. The department also cites Rajasthan’s 100-metre height rule as a precedent.

Sinha, however, argued that this rationale is flawed, since the age and height of hills have no bearing on their ecological function – and many of India’s oldest mountain systems, including large portions of the Eastern Ghats, would fail the test of being continuous as they are ravaged by weather over time.

He added that restricting protections to only these select patches could reduce Haryana’s natural forest cover to the lowest in the country.

He mentioned that Rajasthan’s policy serves a different purpose, which is identifying mining zones, while Haryana should prioritise forest conservation.

Environmental problems from lifting protections

The Aravali hills, even low and scrubby, provide essential ecological functions. They conserve biodiversity, store water, trap heat, and regulate the climate in the Delhi-NCR region. Losing these hills could worsen dust pollution, water shortages, and extreme weather events, affecting millions of residents.

“Only a few powerful landowners and companies would benefit from unlocking the real estate potential of unprotected hills. The change, if implemented, could set a precedent for other states and Delhi itself, where nearly all ridge lands could vanish from conservation maps,” Sinha added.

According to Sinha, the “jargonistic sophistry” of the new definition will accelerate ecological damage in NCR and much of Haryana.

How do recent forest definitions add to the risk?

Earlier in August, the Haryana government issued a new definition of “forest” for conservation purposes. Under this notification, only land patches of at least five hectares (isolated) or two hectares (adjacent to government forests) with 40% canopy density will be considered forests. Linear plantations and orchards outside these zones will not count.

According to the experts, combined with the proposed Aravali definition, this could significantly reduce protected green areas. Such linear plantations along roads, canals, and railways, which often serve environmental purposes, would no longer be protected.

Sinha emphasises the consequences for air quality and climate. “The NCR region already suffers from high dust loads due to dryness. Reducing vegetation will worsen pollution and disrupt local climate regulation. The Aravalis are vital for mitigating these issues.”