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Defining The Aravalli Hill Range And Associated Concerns

Context

  • Expert committee: A new expert committee is being constituted to develop a uniform definition of the Aravalli hill range amid disputes over criteria used for its identification.
  • Underlying issue: The issue follows Supreme Court directions and concerns over environmental implications of existing definitions.
  • Source: How to define an ancient hill range? By protecting a delicate balance, The Indian Express

Evolution of Mapping and Legal Intervention

  • Supreme Court mandate: SC order (February 19, 2010) directed mapping of mining areas in the Aravalli hills of Rajasthan
  • FSI mapping initiative: Forest Survey of India independently mapped the Aravalli across 15 districts and submitted delineation in April 2011
  • Recent developments: SC (May 9, 2024) directed formation of a committee to evolve a uniform definition of Aravalli hills and ranges
  • Judicial review: SC judgment (November 20, 2025) led to concerns and protests, followed by a stay order (December 29, 2025) and direction to form a new committee

Dispute Over Definition Criteria

  • 100 m elevation criterion: Proposed definition based on elevation above reference level was opposed due to environmental risks
  • Impact concern: Excluding hills below 100 m could significantly alter the extent of the Aravalli and affect ecological balance
  • Need for consistency: Suggestion to avoid redefining when detailed mapping already exists

FSI Methodology and Technical Approach

  • Data base: Digitised contour data derived from 1:50,000 Survey of India topographic sheets (2011)
  • Coverage limitation: Analysis restricted to 15 districts based on Rajasthan government’s earlier position
  • Slope-based delineation: FSI used a 3-degree slope criterion to define hill boundaries
  • Technological basis: Use of remote sensing and GIS techniques in mapping and analysis

Divergence in District Identification

  • FSI findings: 62 districts identified as part of the Aravalli region (September 22, 2025 report)
  • Committee findings: Only 37 districts included in affidavit (October 3, 2025)
  • Exclusion issue: Districts like Sawai Madhopur and Chittaurgarh omitted despite recognition under other initiatives
  • Institutional inconsistency: Various agencies (environment ministry, Ministry of Culture, CGWB, GSI) include these districts under Aravalli

Need for Reassessment

  • Replication of study: Suggested re-evaluation using the original Survey of India dataset without alteration
  • Validation requirement: Reassessment necessary to address SC concerns on accuracy
  • Method robustness: Reconsideration of the 3-degree slope criterion as a reliable and tested approach

Environmental Significance

  • Forest cover concentration: Rajasthan has only 8% forest and tree cover (ISFR 2023), largely concentrated in the Aravalli region
  • Ecological sensitivity: Incorrect delineation may lead to degradation and loss of hill ecosystems

Aravalli Hill Range Delineation Framework

The delineation of the Aravalli Hill Range has undergone legal and technical changes following the Supreme Court judgment of November 2025. A uniform definition was introduced to regulate activities such as mining across Delhi, Haryana, Rajasthan, and Gujarat, though its implementation remains under review.

Core Delineation Criteria (2025 Definition)

  • Aravalli hills: Defined as landforms with elevation of 100 metres or more above local relief
  • Measurement basis: Local relief is calculated from the lowest contour line encircling the landform
  • Scope of hills: Includes peaks, slopes, foothills, and associated landforms irrespective of gradient
  • Aravalli ranges: Defined as clusters of two or more such hills within 500 metres
  • Range coverage: Includes intervening valleys, slopes, and smaller hill features as part of the system

Shift from Earlier Methodology

  • New metric: Emphasis on elevation-based classification using the 100-metre threshold
  • Earlier approach: Based on terrain using a 3-degree slope and foothill buffer mapping
  • Connectivity rule: Both approaches use inter-hill distance, but interpretation differs
  • Status: 2025 definition adopted by Supreme Court in November 2025 and later stayed for review

Current Legal Status

  • Interim stay: Supreme Court stayed implementation in December 2025–January 2026 following criticism
  • Expert review: A new court-supervised committee is being formed to reassess the definition
  • Mining regulation: New mining leases are currently frozen until a Management Plan for Sustainable Mining (MPSM) is finalised by ICFRE

Geological and Ecological Classification

  • Residual mountains: Aravallis are remnants of ancient fold mountains shaped by long-term weathering
  • Geological age: Precambrian formations, approximately 2 billion years old
  • Geological composition: Includes Aravalli Supergroup and Delhi Supergroup
  • Climatic role: Acts as a barrier limiting the eastward expansion of the Thar Desert

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