i.wi

Calculates different types of water indices.

i.wi winame=type [blue=name] [green=name] [red=name] [nir=name] [band5=name] [band7=name] output=name [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

i.wi winame=lswi output=name

grass.script.run_command("i.wi", winame="lswi", blue=None, green=None, red=None, nir=None, band5=None, band7=None, output, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("i.wi", winame="lswi", output="name")

Parameters

Command linePython (grass.script)

winame=type [required]
    Type of water index
    Allowed values: awei_ns, awei_s, lswi, ndwi_mf, ndwi_x, tcw, wi
    Default: lswi
    awei_ns: Automated Water Extraction Index - No Shadow
    awei_s: Automated Water Extraction Index - Shadow
    lswi: Land Soil Water Index
    ndwi_mf: Normalized Difference Water Index - Mc Feeters
    ndwi_x: Normalized Difference Water Index - Xu
    tcw: Tasseled Cap Water
    wi: Water Index
blue=name
    Name of input blue channel surface reflectance map
    Range: [0.0;1.0]
green=name
    Name of input green channel surface reflectance map
    Range: [0.0;1.0]
red=name
    Name of input red channel surface reflectance map
    Range: [0.0;1.0]
nir=name
    Name of input nir channel surface reflectance map
    Range: [0.0;1.0]
band5=name
    Name of input 5th channel surface reflectance map
    Range: [0.0;1.0]
band7=name
    Name of input 7th channel surface reflectance map
    Range: [0.0;1.0]
output=name [required]
    Name of the output wi layer
--overwrite
    Allow output files to overwrite existing files
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

winame : str, required
    Type of water index
    Used as: type
    Allowed values: awei_ns, awei_s, lswi, ndwi_mf, ndwi_x, tcw, wi
    awei_ns: Automated Water Extraction Index - No Shadow
    awei_s: Automated Water Extraction Index - Shadow
    lswi: Land Soil Water Index
    ndwi_mf: Normalized Difference Water Index - Mc Feeters
    ndwi_x: Normalized Difference Water Index - Xu
    tcw: Tasseled Cap Water
    wi: Water Index
    Default: lswi
blue : str, optional
    Name of input blue channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
green : str, optional
    Name of input green channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
red : str, optional
    Name of input red channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
nir : str, optional
    Name of input nir channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
band5 : str, optional
    Name of input 5th channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
band7 : str, optional
    Name of input 7th channel surface reflectance map
    Range: [0.0;1.0]
    Used as: input, raster, name
output : str, required
    Name of the output wi layer
    Used as: output, raster, name
overwrite: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

i.wi calculates water indices based on biophysical parameters.

AWEI: Automated Water Extraction Index (2 versions: no shadow or shadow
LSWI: Land Surface Water Index
NDWI: Normalized Difference Water Index (2 versions: McFeeters or Xu)
TCW: Tasseled Cap Water
WI: Water Index

NOTES

Requirements (as of Landsat 5TM bands)

awei_noshadow needs greenchan, nirchan, chan5chan
awei_shadow needs bluechan, greenchan, nirchan, chan5chan, chan7chan
ls_wi needs nirchan, chan7chan
ndwi_mcfeeters needs greenchan, nirchan
ndwi_xu needs greenchan, chan5chan
tcw needs bluechan, greenchan, redchan, nirchan, chan5chan, chan7chan
wi needs greenchan, redchan, nirchan, chan5chan, chan7chan

TODO

Find other water indices and add them.

REFERENCES

AWEI: Automated Water Extraction Index
Feyisa, G.L., Meilby, H., Fensholt, R., Proud, S.R. (2014). Automated Water Extraction Index: A new technique for surface water mapping using Landsat imagery. Remote Sensing of Environment, 140, 23-35. https://doi.org/10.1016/j.rse.2013.08.029.

LSWI: Land Surface Water Index
a kind of Normalized Difference Water Index Xiao X., Boles S., Frolking S., Salas W., Moore B., Li C., et al. (2002) Landscape-scale characterization of cropland in China using vegetation and Landsat TM images. International Journal of Remote Sensing, 23:3579-3594.

NDWI McFeeters
McFeeters, S.K. (1996). The use of the Normalized Difference Water Index (NDWI) in the delineation of open water features. International Journal of Remote Sensing, 17, 1425-1432. https://doi.org/10.1080/01431169608948714.

NDWI Xu
Xu, H. (2006). Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery. International Journal of Remote Sensing, 27, 3025-3033. https://doi.org/10.1080/01431160600589179.

TCW
Crist, E.P. (1985). A TM tasseled cap equivalent transformation for reflectance factor data. Remote Sensing of Environment, 17, 301-306.

WI
Fisher, A., Flood, N., Danaher, T. (2016). Comparing Landsat water index methods for automated water classification in eastern Australia. Remote Sensing of Environment, 175, 167-182. ISSN 0034-4257, https://doi.org/10.1016/j.rse.2015.12.055.

AUTHOR

Yann Chemin

SOURCE CODE

Available at: i.wi source code (history)
Latest change: Friday Feb 21 12:27:42 2025 in commit 8fce680