SC Accepts Centre's Definition of Aravalis—Experts Warn 90% of Hills Excluded, Vulnerable to Exploitation

Key Points

Environmentalists and conservation planners have raised serious concerns after the Supreme Court, on 21 November 2025, accepted the Environment Ministry’s recommendation for a uniform definition of the Aravalli hills. The SC defined them as landforms with an elevation of 100 metres or more above local relief. Though the ruling applies to mining regulation, experts fear the benchmark could influence planning decisions in NCR and beyond.

The NCR master plan for 2041, recently proposed by the BJP government, is still under finalisation, and how Aravallis are categorised will determine the extent of protected Natural Conservation Zones (NCZs). Planners and conservationists warn that applying the height threshold outside the mining context could severely dilute safeguards for ecologically fragile landscapes in Delhi, Haryana and Rajasthan.

In Haryana, the mining department had already proposed a definition recognising only hills with rocks at least a billion years old and rising 100 metres above surrounding land. If that filter is used, most of the region’s hills would fall outside the definition. Former forest conservator RP Balwan said 95% of the Aravallis in Gurgaon and 90% in Faridabad would not qualify. He warned that the move would allow greater real estate pressure and largely erase scrub hills, grasslands and ridge areas from conservation maps.

The concern has been amplified by a detailed internal assessment of the Forest Survey of India, which found that only 1,048 of 12,081 mapped Aravalli hills above 20 metres reach the 100-metre mark. The FSI stressed that lower hills act as critical wind barriers that slow sand and dust movement from the Thar desert into the Indo Gangetic plains. Losing these natural buffers could worsen already severe air pollution across Delhi NCR.

See Also: Study: Global deforestation leads to more mercury pollution

Experts say the definition’s logic is flawed. The ministry justified the height threshold using average ground elevation, a measure based on height above sea level. But hills are defined relative to immediate surroundings, making the comparison inappropriate. Environmental lawyer Ritwick Dutta said the government leaned toward exclusion rather than caution.

Several districts with known Aravalli presence were also omitted from the ministry’s list, including Chittorgarh and Sawai Madhopur. Technical experts note that the Aravalli system is a weathered, ancient fold mountain chain where many ecologically vital ridges fall under the 100-metre benchmark. Prof CR Babu said isolated hillocks cannot function as a range and that even degraded slopes and plateaus form part of a single ecosystem. Mining, he warned, had already caused entire hills to disappear.

The Supreme Court’s order brings all Aravalli states under a uniform mining definition and asks the ministry to prepare a sustainable mining management plan. The ruling does not alter protections under forest laws or ridge notifications, but experts fear that the new height benchmark could shape future interpretations of what the Aravallis encompass.

Environmental scientist Laxmi Kant Sharma said any protection framework must be guided by geomorphology and ecological function. Excluding low elevation ridges, he warned, will accelerate desertification and undermine the natural shield that protects Delhi NCR from dust and groundwater decline.

For now, conservationists continue to press for a more holistic definition that reflects the ecological reality of the Aravallis rather than an arbitrary height threshold. [Rh]

Suggested Reading: