Normalized difference water index

The Normalized Difference Water Index (NDWI) is a way of measuring the amount of water in the environment. It looks at how much sunlight is reflected off a surface (like a river or pond) by using two kinds of light (called near-infrared and green light). The NDWI compares the amount of near-infrared light reflected off the surface to the amount of green light reflected off the surface. Higher NDWI values mean that there is more water in the environment and lower NDWI values mean that there is less water in the environment.