Explained: What Defines The Aravalli Range Now?

Peaceful protests have broken out across northern India following the apex court decision to redefine the Aravalli hills, one of the world’s oldest geological formations that stretch across Rajasthan, Haryana, Gujarat and the national capital, Delhi.

The new definitions could remove shields from almost 90 per cent of the hills, and expose them to mining and construction. 

The move has raised serious ecological concerns, as the Aravallis play a critical environmental role. The mountain system acts as a natural barrier against desertification from the Thar, supports biodiversity and aids groundwater recharge. 

The range also helps regulate the regional climate, influencing local weather patterns and rainfall. It has been vital in shaping the climate of the upper Indo-Gangetic plain, safeguarding the Delhi-NCR from air pollution. 

Samajwadi Party chief Akhilesh Yadav said protecting the Aravallis is “inseparable from Delhi’s survival.”

The Aravallis have served as a green buffer and natural windbreak for Delhi-NCR and adjoining regions for centuries. The hills block dust-laden westerly winds, stabilise the soil, curb dust storms and help reduce air pollution. Change to the Aravallis could lead to higher pollution levels and a further deterioration in urban air quality, opening the region to more heat waves. 

According to a statement, issued by the government, all the landforms enclosed within the lowest binding contour encircling Hills of height 100 metre or more irrespective of their height and slopes are excluded for the purposes of grant of mining lease. 

Similarly, the claims state that Aravalli range has been explained as all the landforms which exist within 500 metres of two adjoining Hills of height 100 metre or more. All landforms existing within this 500 metre zone irrespective of their height and slopes are therefore excluded for the purposes of grant of mining lease.

It is, therefore, “wrong to conclude that mining is permitted in all landforms below 100 metre height” the statement read. 

Environmentalists and opposition leaders warn the change could strip protection from nearly 90 per cent of the hills, exposing them to mining and construction and worsening air pollution.

What happened now?

In May 2024, the Supreme Court directed the government to frame a uniform definition of the Aravalli hills. Since 2010, the Forest Survey of India has defined the Aravallis using a 3-degree slope criterion. However, a technical committee constituted last year revised this benchmark, proposing that any landform with a slope of at least 4.57 degrees and a minimum height of 30 metres be classified as part of the Aravalli hills. These criteria would have brought up to 40 per cent of the range under the Aravalli definition, The Indian Express reported.

Despite this, the environment ministry submitted an unsigned report to the Supreme Court as part of its affidavit, prescribing a much narrower 100-metre height threshold. In doing so, it also merged slope and height parameters to defend the revised definition and introduced subjective height references which could result in the exclusion of even several hills that are 100 metres high or more, as per The Indian Express.

According to the government statement, the measures ensure a clear, map-verifiable operational definition of “Aravalli Hills” and “Aravalli Range,” and a regulatory framework that protects core/inviolate areas, restricts new mining, and hardens safeguards and enforcement against illegal mining.

Aravalli Hills are now defined as having an elevation of 100 metres or more from the local relief; whereas Aravalli Range are two or more Aravalli Hills located within the proximity of 500m from each other, measured from the outermost point on the boundary of the lowest contour line on either side.

What is the government saying?

Union Environment Minister Bhupender Yadav on Monday said the new and controversial definition of the Aravalli hills applies only to mining activities, asserting that just 277.89 sq km — around 0.19 per cent — of the total Aravalli landscape is currently open to mining, and that no new mining leases will be granted until a detailed scientific study is completed.

In a press conference to address concerns over the revised definition, Bhupender Yadav said the Modi government remains fully committed to the Green Aravalli mission, insisting that fears of large-scale ecological dilution were unfounded. 

The opposition has claimed that the changes would benefit mining interests, an allegation rejected by the minister.  

“This definition related to the Aravalli hills is applicable only for mining purposes. It will be used solely in the context of mining. Mining is permitted only in 277.89 sq km out of the total 1,43,577 sq km of the Aravalli area,” the minister said.

The minister, however, declined to specify a timeline for the report being prepared by the Indian Council of Forestry Research and Education (ICFRE), which is mandatory before any fresh mining lease can be considered. "The matter is in court. I cannot comment on the timeline as of now," he added.

The Supreme Court has directed the Environment Ministry to prepare a Mining Plan for Sustainable Mining covering the entire Aravalli range before granting any new leases. With the revised definition now in force, the court has ordered that no fresh mining leases be issued until the MPSM is finalised, a step officials say serves as a preventive shield against immediate ecological damage.