MNDWI
The modified normalized difference water index from green and shortwave-infrared reflectance, which separates water from built-up surfaces better than NDWI.
Experimental: not yet fully verified. How results are checked
MNDWI is 0.6.
Provenance
- Computed by
- raster.index.mndwi 1.0.0, core 0.1.0
- Model
- MNDWI = (Green - SWIR1) / (Green + SWIR1) on surface reflectance (Xu 2006)
- Accuracy
- Exact arithmetic on the reflectance given.
- Notes
- 1 shown with the answer
- Cites
- Xu, H., International Journal of Remote Sensing, Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: MNDWI = (Green - SWIR1) / (Green + SWIR1) on surface reflectance (Xu 2006)
Accuracy: Exact arithmetic on the reflectance given.
When to use this: Use this where NDWI struggles: in towns and cities, built-up surfaces come out positive under the McFeeters index and get mapped as water. Swapping near-infrared for shortwave-infrared pushes them negative, so water is cleaner to threshold in an urban scene.
Limitations: It still needs a threshold chosen for the scene, and shadow from buildings and terrain remains a source of false water. The shortwave band is coarser than the visible bands on some sensors, so a resampled MNDWI is softer at the shoreline than its pixel size suggests.
Worked example: MNDWI. Source: Xu 2006: green 0.12 and SWIR1 0.03 give 0.6.
You enter
- Green reflectance
- 0.12
- Shortwave-infrared reflectance
- 0.03
You get
- MNDWI
- 0.6
Review: Not yet independently reviewed by a GIS professional.
Last verified: 2026-09-22, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 10 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery, Xu, H., International Journal of Remote Sensing, Volume 27, issue 14, pages 3025-3033. MNDWI = (Green - SWIR1) / (Green + SWIR1).
Terms
- MNDWI: modified normalized difference water index
- Water index using green and shortwave-infrared reflectance. It separates water from built-up surfaces better than NDWI does. Source: Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.