# Generated by scripts/sync_indices.py from Awesome Spectral Indices (MIT).
# DO NOT EDIT BY HAND. Edit overlays (_asi_*.yaml, _folia_*.yaml) and re-run.
# Spec: docs/spec/SPECTRAL_INDICES.md
slug: ndwi
name: Normalized Difference Water Index
short_name: NDWI
formula: (G - N) / (G + N)
bands:
- G
- N
domain: water
theme: hydrology
concepts:
- river-discharge
- groundwater
rank: 3
display:
  colormap: brbg
  range:
  - -1.0
  - 1.0
pedagogy:
  description: 'Normalized Difference Water Index (McFeeters 1996). Uses green and

    near-infrared to enhance open-water features while suppressing

    vegetation and soil. The original surface-water-extraction index;

    MNDWI is its shadow-robust successor.

    '
  use_cases:
  - Open-water body delineation and area change over multi-decadal time series
  - Flood-extent mapping when SWIR bands are unavailable
  - Pre-classification water masking for downstream vegetation indices
  limitations:
  - Misclassifies built-up areas and shadow as water — prefer MNDWI (green vs SWIR1) for urban scenes
  - Confused by turbid or shallow water where bottom reflectance bleeds in
  - Note that Gao 1996's vegetation-water-content NDWI uses the same name but different bands — context matters
  interpretation:
    high: Open water, wet surfaces
    mid: Shallow / turbid water, wet soil
    low: Bare or built surfaces
    negative: Dense vegetation
  authoritative_sources:
  - label: McFeeters 1996
    url: https://doi.org/10.1080/01431169608948714
  - label: NV5 ENVI — Water Features
    url: https://www.nv5geospatialsoftware.com/docs/AlphabeticalListIndices.html
  - label: Index Database · NDWI
    url: https://www.indexdatabase.de/db/i-single.php?id=80
references:
- url: https://doi.org/10.1080/01431169608948714
date_of_addition: '2021-04-07'
contributor: https://github.com/davemlz
platforms:
- Sentinel-2
- Landsat-OLI
- Landsat-TM
- Landsat-ETM+
- MODIS
- Planet-Fusion
source:
  authority: awesome-spectral-indices
  commit_sha: 7f28d3fe68af1287f7449faf0685659e73197212
  upstream_id: NDWI
match_tags:
- difference
- g
- index
- n
- normalized
- water
status: stable