The Supreme Court’s acceptance of a new 100-metre definition for the Aravalli hills has triggered serious concerns among environmental experts and raised questions about the process followed by the Union Ministry of Environment, Forest and Climate Change (MoEF & CC). The decision, taken on November 20, came despite reservations expressed by the court’s own Central Empowered Committee (CEC), a statutory body constituted in 2002 to monitor compliance with Supreme Court orders on forests and environmental protection.
What Is the 100-Metre Aravalli Definition?
On October 13, the MoEF & CC proposed before the Supreme Court that only landforms rising at least 100 metres above the surrounding plains should be classified as Aravallis. This definition significantly narrows the ecological footprint of one of India’s oldest mountain ranges, which spans parts of Rajasthan, Haryana, Gujarat and Delhi and plays a critical role in preventing desertification, regulating climate and acting as a wind barrier against the Thar Desert.
CEC’s Objection and the FSI Definition
Just a day after the ministry’s proposal, on October 14, the Central Empowered Committee wrote to the amicus curiae assisting the Supreme Court bench, clarifying that it had neither examined nor approved the 100-metre recommendation. The CEC strongly reiterated that the definition prepared by the Forest Survey of India (FSI) should instead be adopted to ensure long-term ecological protection of the Aravalli range.
Under the FSI’s definition, Aravallis are identified based on terrain characteristics rather than height alone. The FSI mapped 40,481 square kilometres across 15 districts of Rajasthan as Aravalli areas, classifying landforms above a minimum elevation with a slope of at least 3 degrees as part of the range. This approach includes lower hills, which are ecologically significant despite their modest height.
Notably, the FSI exercise was undertaken after the Supreme Court, in a 2010 order, engaged the agency through the CEC to scientifically delineate the Aravalli landscape.
Environmental Implications of the 100-Metre Cut-Off
According to internal assessments by the Forest Survey of India, if all 1,18,575 hills in the Aravalli region are evaluated using the 100-metre height criterion, more than 99 per cent would fall outside the definition. This is particularly worrying because even hills as low as 20 metres are crucial for functioning as wind barriers and supporting local ecology.
Excluding lower hill systems could open vast stretches of land to mining, construction and real estate development, potentially accelerating environmental degradation in an already fragile region.
Questions Around Mining Claims
On Monday, Union Environment Minister Bhupender Yadav stated that mining is permitted in only 0.19 per cent of the total Aravalli area, which he described as spanning 1.44 lakh square kilometres. He added that this amounts to just 278 square kilometres.
However, ministry data itself indicates that 278 square kilometres is not the permissible mining area but the total area already under mining across Rajasthan, Gujarat and Haryana. The ministry has yet to clarify what scope will exist for future mining and development in areas excluded from the Aravalli definition under the new 100-metre rule.
Lack of Transparency and Ground Demarcation Issues
The minister also told the media that the actual extent of Aravalli land covered by the 100-metre definition would only be known after ground demarcation is completed. This raises a key question: how did the ministry assure the Supreme Court that more areas would qualify as Aravallis under the 100-metre definition than under the FSI’s slope-based 3-degree criterion, when precise mapping has not yet been done?
Adding to the uncertainty, amicus curiae K Parmeshwar declined to comment on whether the CEC’s objections were conveyed to the Supreme Court bench led by then Chief Justice of India BR Gavai before the November 20 decision.
A Decision With Far-Reaching Consequences
The Supreme Court’s acceptance of the 100-metre definition marks a potentially significant shift in how the Aravalli hills are protected under law. Environmentalists warn that narrowing the definition could undermine decades of judicial and scientific efforts to conserve the range. As ground demarcation and policy clarity remain pending, the long-term impact of this decision on mining, development and ecological balance in northwestern India remains uncertain.