Remote sensing is the science of acquiring information about the Earth’s surface without direct physical contact, by detecting and analysing electromagnetic radiation reflected or emitted by objects.
- Different materials such as vegetation, water, soil, and minerals reflect or absorb radiation differently, creating unique spectral signatures.
- For instance, healthy vegetation absorbs red light and reflects near-infrared radiation, enabling assessment of plant health from space.
Working Principles of Remote Sensing:
- Energy Source: The Sun or an artificial source like radar/laser provides electromagnetic energy.
- Interaction with Atmosphere and Target: Radiation interacts with the atmosphere and then with Earth’s surface depending on the target’s physical and chemical properties.
- Detection by Sensors: Sensors onboard satellites or aircraft record the reflected or emitted energy.
- Data Transmission and Processing: Recorded signals are transmitted to ground stations, processed digitally, and converted into usable images.
- Interpretation: Scientists analyse these images to derive information for practical applications.
Significance of Remote Sensing in India:
- Agricultural Monitoring: Remote sensing enables crop acreage estimation, yield forecasting, drought assessment, and soil moisture mapping.
Example: ISRO’s satellite data supports FASAL (Forecasting Agricultural Output using Space, Agro-meteorology and Land-based observations).
- Water Resource Management: Optical indices such as NDWI/MNDWI and SAR imagery help map rivers, reservoirs, floods, and groundwater potential zones.
Example: SAR-based flood mapping during Kerala floods enabled real-time disaster response despite cloud cover.
- Forest and Climate Governance: Satellite-derived vegetation indices help estimate forest biomass and carbon stocks, supporting climate commitments.
Example: India’s forest carbon assessment for UNFCCC reporting relies on IRS and HysIS data.
- Disaster Management: Remote sensing enables early warning, damage assessment, and recovery planning for floods, cyclones, landslides, and droughts.
Example: EOS-01 and RISAT satellites support the National Disaster Management Authority.
- Resource Exploration: Hyperspectral sensors detect mineral signatures, reducing exploratory costs and environmental disturbance.
Example: Remote sensing is used for mapping bauxite, iron ore, and limestone belts in Odisha and Chhattisgarh.
- Environmental Monitoring: Satellite data identifies land-use change, wetland loss, urban heat islands, and greenhouse gas hotspots.
Example: Satellite-based methane detection helps locate emission hotspots from landfills and oil infrastructure.
Conclusion:
Remote sensing has transformed governance by shifting decision-making from reactive to predictive, and from localized to systemic perspectives. By enabling precise monitoring of ecosystems, resources, and disasters, it acts as an enabler of sustainability, resilience, and climate accountability.
‘+1’ Value Addition:
- ISRO oversees satellite missions under the Indian Remote Sensing (IRS) programme.
- National Remote Sensing Centre (NRSC) processes and disseminates satellite data.
- Indian Institute of Remote Sensing (IIRS) provides training and research support.
- IRS satellites form the backbone of the National Natural Resources Management System (NNRMS).
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