Why the Supreme Court’s New Aravalli Definition Has Triggered Fears of Large-Scale Ecological Loss?

The Supreme Court’s acceptance of the Centre’s 100-metre elevation rule for defining the Aravalli hills has intensified anxiety among conservationists, planners and scientists. While the ruling currently applies to mining regulation, experts say the new benchmark could influence broader land-use planning across NCR, potentially excluding vast stretches of ecologically vital ridges and scrublands from protection.

Background / What Happened

On 21 November 2025, the Supreme Court approved the Environment Ministry’s proposal to classify the Aravallis as landforms that rise 100 metres or more above local relief. The Court directed the Centre to prepare a sustainable mining management plan and barred the issuance of new mining leases until the mapping is completed.

While pitched as a uniform and scientific standard, the threshold dramatically alters the landscape legally recognised as part of the Aravallis. An internal assessment by the Forest Survey of India found that only 1,048 of 12,081 mapped hills above 20 metres qualify under this definition—less than 9%. This means more than 90% of Aravalli hills, ridges, spurs and scrub slopes may fall outside formal classification.

Why This Issue Matters

The Aravallis are among the world’s oldest fold mountains and form a climatic buffer that slows the movement of dust and sand from the Thar desert into the Indo-Gangetic plains. Even the lower ridges—some just 20–80 metres above nearby terrain—play a crucial role in moderating air pollution, enabling groundwater recharge, and sustaining wildlife movement, especially around Gurugram, Faridabad, Alwar and parts of Rajasthan.

Experts fear that applying the 100-metre rule beyond mining could weaken protections for these landscapes. With the NCR Regional Plan 2041 still being finalised, planners warn that Natural Conservation Zones (NCZs) could shrink considerably if height becomes a primary criterion. In Haryana alone, former conservator R.P. Balwan has estimated that 95% of Gurugram’s and 90% of Faridabad’s Aravallis would not qualify under the new definition—potentially opening them to real-estate and infrastructure pressure.

The Larger Context

The Aravallis have long been the subject of judicial scrutiny. Courts and tribunals, including the National Green Tribunal, have repeatedly intervened to halt illegal mining, protect deemed forests, and preserve fragile slopes. However, the absence of a uniform definition across states often resulted in fragmented protection and localised disputes.

The Centre argued that the 100-metre benchmark would bring consistency across Rajasthan, Haryana, Delhi and Gujarat. Yet several districts with documented Aravalli features—such as Chittorgarh and Sawai Madhopur—were not included in the official list, raising concerns about narrow geomorphological interpretation. Scientists note that the Aravallis’ weathered, ancient nature means ecological significance does not correlate neatly with height. As Prof. C.R. Babu has cautioned, isolated hillocks cannot be separated from adjoining slopes and plateaus that form part of the same geological system.

The Key Concerns / Challenges

Environmentalists argue that the new definition leans toward exclusion rather than ecological precaution. By focusing on elevation rather than ecological function, the rule overlooks several critical roles played by lower hills and degraded slopes.

Scientists warn that excluding low ridges could accelerate desertification, weaken wildlife corridors, and worsen dust storms in Delhi-NCR. The Forest Survey of India has highlighted that these low ridges act as natural wind-breaks; degrading them could exacerbate particulate pollution across one of the world’s most polluted regions.

Concerns also extend to groundwater. The southern Aravallis form one of NCR’s key recharge zones. Removing large portions of this terrain from protected status could intensify aquifer depletion in urban and peri-urban districts.

The Implications

Although the ruling is currently limited to mining regulation, experts worry that the height benchmark could influence how governments interpret the extent of the Aravallis in city planning, environmental clearances, and land-use policies. In regions such as Haryana—where mining and real-estate interests have historically exerted pressure on ridge systems—the redefinition could weaken long-standing safeguards.

There are also political implications. The upcoming NCR Regional Plan 2041 will determine zoning across one of the fastest urbanising regions of India. If the 100-metre rule shapes the delineation of Natural Conservation Zones, large ecologically sensitive tracts could be reclassified, shrinking protected areas even before restoration programmes gain traction.

What Needs to Be Done

Environmental scientists and planners emphasise the need for a broader, ecosystem-based definition of the Aravallis—one that incorporates geomorphology, ecological connectivity, vegetation patterns, and hydrological functions rather than relying solely on elevation.

A robust sustainable mining plan must integrate independent scientific review, transparent mapping, and strict monitoring. Strengthening ridge protections under forest laws, expanding the Aravalli Green Wall initiative, and safeguarding low-elevation recharge zones will be critical to preventing irreversible ecological decline.

As the Court-mandated mapping begins, experts continue to urge a more holistic framework—one that recognises the Aravallis not just as a set of hills defined by height, but as a continuous ecological shield vital to the long-term environmental stability of Delhi-NCR.