- Normalized Difference Vegetation Index is a satellite-based vegetation index used to measure plant health, density, and greenness.
- It is one of the most widely used indicators in remote sensing, agriculture, forestry, and climate studies.
- NDVI works on the principle that healthy vegetation absorbs red light and reflects near-infrared (NIR) light.
Formula
- NDVI = (NIR − Red) / (NIR + Red)
- Values range between −1 and +1
Interpretation of NDVI Values
- +0.6 to +1.0 → Dense, healthy vegetation (forests, well-irrigated crops)
- +0.3 to +0.6 → Moderate vegetation (grasslands, crops under growth)
- 0.1 to +0.3 → Sparse vegetation or stressed crops
- 0 to 0.1 → Bare soil, rocks
- Negative values → Water bodies, snow, clouds, urban areas
Why NDVI is Important
- Helps assess crop health and productivity
- Used for drought monitoring and early warning systems
- Tracks deforestation and land degradation
- Supports climate change studies by monitoring vegetation trends
- Assists in food security analysis and yield estimation
Applications
- Agriculture
- Crop condition monitoring
- Identifying water stress and pest impact
- Environment & Ecology
- Forest cover assessment
- Desertification studies
- Disaster Management
- Drought severity mapping
- Post-flood or wildfire vegetation recovery
- Urban & Regional Planning
- Monitoring green cover loss or expansion
NDVI in India
- Used extensively by ISRO, State Agriculture Departments, and research institutions.
- Plays a key role in drought assessment, crop insurance (PMFBY), and monsoon impact analysis.
- Helps monitor vegetation changes in regions like arid Rajasthan, Indo-Gangetic plains, and forest belts.
Limitations of NDVI
- Saturates in very dense forests, reducing sensitivity
- Affected by cloud cover, atmospheric conditions, and soil brightness
- Cannot distinguish between crop types without additional indices
- Less effective in areas with mixed land cover
Advanced Indices Beyond NDVI
- EVI (Enhanced Vegetation Index) – better for dense vegetation
- SAVI (Soil Adjusted Vegetation Index) – reduces soil background effect
- NDWI – focuses on vegetation water content
