NDWI

Summary

Calculates the Normalized Difference Water Index (NDWI) from a multiband raster object and returns a raster object with the index values.

Discussion

The Normalized Difference Water Index (NDWI) method is an index for delineating and monitoring content changes in surface water. It is computed with the NIR and green bands.

\(NDWI \space = \space (Green \space - \space NIR) \space / \space (Green \space + \space NIR)\)

For information about other multiband raster indexes, see the Band Arithmetic raster function.

The referenced raster dataset for the raster object is temporary. To make it permanent, you can call the raster object's save method.

Syntax

NDWI(raster, {nir_band_id}, {green_band_id})

Parameter	Explanation	Data Type
raster	The input raster.	Raster
nir_band_id	The band ID of the near-infrared band. The ID index uses one-based indexing. The default value is 5.	Integer
green_band_id	The band ID of the green band. The ID index uses one-based indexing. The default value is 3.	Integer

Parameter

Explanation

Data Type

raster

The input raster.

Raster

nir_band_id

The band ID of the near-infrared band. The ID index uses one-based indexing.

The default value is 5.

Integer

green_band_id

The band ID of the green band. The ID index uses one-based indexing.

The default value is 3.

Integer

Return value

Data Type	Explanation
Raster	The output raster object with the NDWI index values.

Code sample

NDWI example

Calculates the Normalized Difference Water Index for a Sentinel-2 image.

import arcpy

NDWI_raster = arcpy.sa.NDWI("Sentinel2.tif", 8, 3)