Feature Description
NDWI (Normalized Difference Water Index) is used to extract water body information from imagery. Compared with NDVI, it can effectively monitor water content in vegetation canopies. The NDWI index responds promptly to water stress in vegetation canopies, making it significant for drought monitoring. However, NDWI performs poorly in extracting water bodies with substantial building backgrounds, such as urban water features.
NDWI is a normalized ratio index based on green band and near infrared band, expressed as: NDWI = (G - NIR)/(G + NIR), where G represents green band reflectance and NIR represents near infrared band reflectance.
NDWI can be calculated using various satellite remote sensing data. Users should understand remote sensing data types and band definitions before application. For band descriptions of common satellite imagery, refer to Data Description.
Feature Entry
- Data tab -> Data Processing -> Raster -> NDWI.
- Toolbox -> Data Processing -> Raster -> NDWI.
Parameter Description
- Green Band: Specifies the green band for calculation. Select green band dataset for single-band imagery, or choose green band from multi-band datasets.
- Near Infrared Band: Specifies the near infrared band for calculation. Select NIR band dataset for single-band imagery, or choose NIR band from multi-band datasets.
- Result Data: Sets output data source and dataset. The program will generate a raster result dataset based on the set green band and near infrared band according to the NDWI formula.
Application Example
Using Landsat 8 satellite imagery from June 2013 and June 2018 in a specific region, NDWI indices were calculated for different years to analyze water body changes. The results are shown below.
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| 2013 NDWI Result Map | 2018 NDWI Result Map |
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