Normalized Difference Water Index (NDWI)
The Normalized Difference Water Index (NDWI) is a numerical indicator, derived from optical satellite images, using the near-infrared and short wave infrared spectral bands. The latter spectral band is highly associated with changes in vegetation water content and spongy mesophyll structure in the vegetation canopies. The near infrared spectral band response is correlated with the leaf internal structure and the leaf dry matter content, excluding water content.
NDWI is useful in many remote sensing applications. Crop health monitoring, land/water boarding mapping, inland water discrimination from open sea water bodies, are just a few applications where NDWI is used.
To calculate the NDWI with the following formulas (one for each satellite):