NDWI (Normalized Difference Water Index) USING ARCGIS

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The Normalized Difference Water Index (NDWI) is a spectral index used in remote sensing and geographic information systems (GIS) to identify and analyze the presence of water in satellite or aerial imagery. NDWI is particularly valuable for various applications, including environmental monitoring, land cover classification, and water resource management. 

Here's a brief overview of NDWI:

NDWI can be calculated using Sentinel-2 data by utilizing the bands available in its multispectral sensors. Specifically, NDWI is typically computed using the following bands:

  •  NIR (Near-Infrared): Sentinel-2 band 8 (approximately 842-872 nm)
  • Green: Sentinel-2 band 3 (approximately 534-564 nm)


Key Characteristics:

  1. Water Detection: NDWI is effective in identifying the presence of water because water absorbs and scatters light differently than other surfaces. As a result, NDWI values tend to be higher in areas with water bodies.
  2. Scale Independence: NDWI can be applied at different spatial resolutions, making it suitable for a wide range of remote sensing data, from satellite imagery to aerial photographs.
  3. Value Range: NDWI values typically range from -1 to 1, where higher values indicate a higher likelihood of water presence.
  4. Applications: NDWI is used in various applications, including the mapping of water bodies, wetland delineation, drought monitoring, and assessing changes in water resources over time.
  5. Data Sources: NDWI can be calculated using multispectral or hyperspectral imagery from various remote sensing platforms, such as Landsat, MODIS, Sentinel, and more.
  6. Thresholding: To classify areas as water or non-water, specific NDWI thresholds are applied. These thresholds can vary based on the study area and objectives.
  7. Limitations: NDWI is sensitive to atmospheric conditions, and its accuracy can be affected by factors like cloud cover or sensor calibration issues.

The below map shows the NDWI of serampore tehsil of Hoogly District of year 2023.






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