Why is it in News?
- Supreme Court (20 Nov 2024) accepted a Union Environment Ministry panel’s recommendation to define Aravalli Hills as only those landforms with 100 m or more elevation + local relief.
- This new definition excludes over 90% of Aravalli landforms, allowing potential mining and construction.
- A Forest Survey of India (FSI) internal analysis had warned the government that such a definition would be ecologically disastrous — this “red flag” was ignored.
- New data show only 1,048 of 12,081 Aravalli hills in Rajasthan (8.7%) are ≥100 m, meaning 91.3% lose protection.
Relevance
GS1 – Geography
- Geomorphology of ancient fold mountains.
- Desertification & land degradation.
GS2 – Governance
- Environmental decision-making.
- Regulatory bodies (MoEFCC, SC committees).
GS3 – Environment & Conservation
- Air pollution (PM2.5, PM10).
- Wildlife corridors.
- Forest governance & definitions (critical).
- Mining regulation and ecological risk.
Aravali Range
- One of the oldest fold mountains (Precambrian).
- Length: ~700 km (Gujarat–Rajasthan–Haryana–Delhi).
- Natural barrier to dust storms from Thar Desert into NCR.
- Key wildlife corridors (Sariska–Ranthambore, Kumbhalgarh, etc.)
- Major groundwater recharge zone for semi-arid regions of Haryana & Rajasthan.
The “100m cut-off”
- Hills counted as Aravalli only if:
- Height ≥100 metres, AND
- Local relief ≥100 metres, AND
- Considered with slopes + adjacent land
Implication: Anything <100 m elevation = not Aravalli, even if geomorphologically part of the range.
FSI’s red flag
- FSI analysis (reviewed by Indian Express):
- Only 1,048 of 12,081 hills in 15 Rajasthan districts exceed 100 m.
- Thus >90% Aravalli hills lose protection under the new definition.
- FSI emphasized importance of lower hills:
- Block coarse dust and slow down easterly dust flow into NCR.
- Act as buffers against desertification.
- Maintain ecological connectivity.
- The ministry ignored these warnings in submissions to SC.
Why this matters for NCR Pollution ?
- Upper Aravallis obstruct fine pollutants (PM2.5).
- Lower Aravallis obstruct heavier dust particles.
- Together they create a barrier protecting Delhi from dust inflow.
- Removing protection accelerates:
- Dust-laden winds into NCR
- Temperature rise and heat-island effects
- Loss of wildlife corridors
- Groundwater depletion
What was the earlier yardstick(FSI – 2010 onwards)
FSI used a 3-degree slope method to identify Aravallis.
- A 2024 technical committee revised this:
- Slope ≥4.57°
- Height ≥30 m
- This older method covered ~40% of Aravallis, far more than the new definition.
Govt’s Submission
- The ministry submitted:
- Only hills ≥100 m count as Aravalli.
- Confused height with slope, creating a subjective & improper definition.
- Ignored FSI’s scientific warnings.
SC nevertheless accepted the panel’s recommendations.
Environmental Impacts
- Mining intensification (legal + illegal).
- Real estate expansion, especially in Gurgaon–Faridabad–Aravali belt.
- Accelerated desertification of NCR and Haryana.
- Decline in groundwater aquifers (Aravallis as recharge zones).
- Collapse of wildlife corridors (leopards, hyenas, ungulates).
- Increased PM10/PM2.5 loads in NCR.
