Context :

• The National Highways Authority of India (NHAI) has released the first annual report of the National Highways Green Cover Index (NH-GCI) 2025–26.

Key Points :

• Institutional Partnership: This report has been prepared in collaboration with the Indian Space Research Organisation (ISRO)’s National Remote Sensing Centre (NRSC).
• Memorandum of Understanding (MoU): This initiative is part of a three-year agreement signed between NHAI and NRSC in January 2024.
• Objective: To scientifically and quantitatively monitor the green cover within the Right of Way (RoW) of National Highways.

Methodology and Technology :

• Satellite Data: For assessment, multi-spectral data with 5-meter resolution from ISRO’s Resourcesat 2 / Resourcesat 2A satellites is used, which is cross-verified with imagery from Cartosat 2S.
• Chlorophyll Detection: High-resolution sensors identify vegetation using chlorophyll signals.
• Index Calculation: NH-GCI is expressed as a percentage value that measures the proportion of green cover within each 1-kilometer stretch inside the highway’s Right of Way (RoW).

Results of the First Assessment Cycle :

• Coverage: In the first cycle (July–December 2024), nearly 30,000 kilometers of National Highways across 24 states were analyzed.
• Top States: According to the report, Assam recorded the highest green cover along National Highways, followed by Gujarat, Telangana, Bihar, and Tamil Nadu.
• States/UTs with Minimum Green Cover: The lowest green cover was found in Himachal Pradesh (13.5%), Delhi (25.37%), Chhattisgarh, Odisha, and Jammu & Kashmir.

Importance and Objectives :

• Year-to-Year Monitoring: The index provides a reliable baseline for managing plantation activities, ranking performance, and enabling timely interventions in the future.
• Policy Alignment: This initiative supports the objectives of India’s Green Highways Policy and helps fulfill climate commitments under the Paris Agreement.
• Public Access: Its results and interactive maps are made available on the open-source Bhuvan Web GIS Portal of NRSC.

State-wise Performance Highlights :

• States are ranked in the index based on the percentage of green cover along National Highways.

Top Performing States (Top 5):

• Assam: Highest green cover (benefiting from rainforest conditions and favorable climate).
• Gujarat: Effective plantation management despite being a dry region.
• Telangana: Positive impact of the state’s “Haritha Haram” program.
• Bihar: Dense plantation in the Gangetic plains.
• Tamil Nadu: Good greenery along coastal and peninsular highways.

Lowest Performing States/UTs:

• Himachal Pradesh (13.5%): Lowest due to difficult geographical conditions and construction activities.
• Delhi (25.37%): Highly urbanized with limited space.
• Jammu & Kashmir: Security and construction-related constraints.

Remote Sensing Technology (The Tech Behind NH-GCI) :

• NHAI and ISRO have used advanced space technology to make this index objective.
• Satellites and Sensors: Mainly Resourcesat 2 / Resourcesat 2A satellites are used. The LISS-IV (Linear Imaging Self-Scanning Sensor) onboard provides a high resolution of 5.8 meters, enabling the identification of even small roadside trees.
• Multi-Spectral Imagery: This technology measures different wavelengths of light. Plants reflect Infra-red (IR) light, which is detected by satellites.
• Use of Cartosat-2S: Its high-resolution data is used for cross-checking micro-level details and accurate demarcation of the highway Right of Way (RoW).
• Bhuvan Portal: All data is hosted on ISRO’s Bhuvan platform, which ensures real-time monitoring through geo-tagging.