- Why in news
- On 12 June 2026, the Road Transport Ministry (MoRTH) described its landslide mitigation steps for hill highways. These include an InSAR-based monitoring and early warning pilot on a 100-km stretch of the Char Dham route in Uttarakhand.
- What it is
- InSAR (Interferometric Synthetic Aperture Radar) compares radar images of the same area taken at different times from satellites. It detects very small ground movements, often millimetres, so unstable slopes can be flagged early. It works through cloud and at night because radar does not depend on sunlight.
- Pilot location
- InSAR-based monitoring and early warning is deployed along a 100-km stretch of the Char Dham route in Uttarakhand.
- Second warning system
- A real-time warning and alert system is planned on the Parwanoo-Solan section of NH-5 in Himachal Pradesh.
- GSI role
- MoRTH signed an MoU with the Geological Survey of India for tunnel geological investigations and geohazard data sharing. GSI's National Landslide Susceptibility Mapping is being used in highway planning and alignment.
- Slope framework
- A framework report by an Expert Committee led by IIT Delhi guides site-specific slope treatment based on rainfall, groundwater and geology.
- Phased construction
- The first year of a hill project is used only for slope cutting and protection works. Road construction starts only after slopes stay stable through at least one monsoon.
- Uttarakhand progress
- In Uttarakhand, 58 landslide-prone locations are treated, 96 are under works and 104 more are at DPR or investigation stage.
Don’t confuse with InSAR vs LiDAR: InSAR uses satellite radar images over time to measure ground movement. LiDAR uses laser pulses, usually from aircraft or drones, to map terrain in detail.
Don’t confuse with GSI vs DGRE: GSI is the national geological survey and produces landslide susceptibility maps. DGRE is a DRDO lab that works on snow, avalanche and geo-informatics.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Moves hill-road management from post-disaster repair to prediction and prevention.
- Can cut repair costs and traffic disruption on costly mountain highways.
Problems
- Satellite data shows ground movement but needs ground validation and local rainfall and groundwater data to give reliable warnings.
- The pilot covers only 100 km, and warnings help only if agencies act on them quickly.
Way forward
- Scale up the pilot after evaluating its accuracy, and link alerts to local disaster authorities.
- Combine monitoring with drainage management, slope-specific treatment and limits on slope cutting.
Put in your answer
Hill NH scale: About 16,788 km of National Highways lie in hill states, out of a network above 1,46,570 km.
Cost of landslides: A single moderate landslide can cost ₹10-25 crore in repairs and block traffic for 2-5 days.
Karnaprayag example: Stabilisation at Karnaprayag in Uttarakhand combined terracing, drainage, hydroseeding, rock anchors and retaining structures.
- 2021Mains GS3 · Q18Causes and effects of landslides; components of national landslide risk strategy.
- 2019Mains GS3 · Q18How landslide hazard zonation mapping aids disaster mitigation and preparedness.
- 2016Mains GS1 · Q14Causes of Himalayan landslide proneness and suitable mitigation measures.
UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Disaster management is on the syllabus and InSAR monitoring is a lasting concept. The release gives few testable facts, so no question is likely.
Worth revising until Prelims 2028: most news questions come within two years of the event.