Normalized Difference Vegetation Index (NDVI)

The Normalized Difference Vegetation Index (NDVI) gauges the greenery amount and density in a satellite image. The Normalized Difference Vegetation Index (NDVI) measures the difference between red and near-infrared light, which vegetation absorbs, and near-infrared light, which vegetation strongly reflects.

NDVI is that difference expressed as a number – ranging from -1 to 1.

Index Range

Negative values, it’s highly likely that it’s water. On the other hand, if you have an NDVI value close to +1, there’s a high possibility that it's dense green leaves. But when NDVI is close to zero, there aren’t green leaves and it could even be an urbanized area or empty areas of rocks, sand, or snow

?Class?????????????????????????????????? ????????????????????????NDVI Range

Water?????????????????????????????? ??????????????????????????-0.28 to 0.015

Built up or Rocks and Sand??????????????????????? 0.015 to 0.14

Barren land??????????????? ?????????????????????????????????0.14 to 0.18

Shrub and Grassland???? ??????????????????????????????0.18 to 0.27

Sparse Vegetation?????????? ????????????????????????????0.27 to 0.36

Dense Vegetation?????????? ?????????????????????????????0.36 to 0.74

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How do you calculate NDVI?

NDVI is derived from satellite imagery and calculated in accordance with the formula:

NDVI = (NIR - Red) / (NIR + Red)

NIR – Light reflected in the near-infrared spectrum

RED – Light reflected in the red range of the spectrum

NDVI for datasets:

For Sentinel-2, the index will be as follows;

NDVI = (Band 8 - Band 4) / (Band 8 + Band 4) Where, Band 8 is NIR and Band 4 is Red band.

NDVI using Landsat 9, 8, 7 or 5 bands,

Landsat 9 NDVI = (B5-B4) / (B5+B4)

Landsat 8 NDVI = (B5 - B4) / (B5 + B4)

Landsat 5 and 7 NDVI = (B4 - B3) / (B4 + B3)

MODIS NDVI = (B2 - B1) / (B2 + B1)

ENVISAT MERIS NDVI = (B13 - B07) / (B13 + B07)

Application of NDVI:

·???????? NDVI is frequently used to track the productivity and health of crops. It can enhance irrigation and fertilization techniques and assist farmers in identifying fields that may be under stress or have nutrient deficits.

·???????? The density and health of forests can be evaluated using NDVI, and changes in the forest cover over time can be tracked.

·???????? In natural ecosystems like grasslands, savannas, and wetlands, NDVI can be used to track the production and health of vegetation. It can be used to spot modifications in vegetation owing to human activity or uncontrollable natural occurrences including drought, land use change, and deforestation.

·???????? NDVI can also be used to monitor vegetation recovery after disturbances, such as fires or floods.

·???????? The effects of environmental management techniques like reforestation, conservation, or restoration on ecosystem health can also be tracked using NDVI.