Skip to main content
U.S. flag

An official website of the United States government

Analysis of dynamic thresholds for the normalized difference water index

January 1, 2009

The normalized difference water index (NDWI) has been successfully used to delineate surface water features. However, two major problems have been often encountered: (a) NDWIs calculated from different band combinations [visible, nearinfrared, or shortwave-infrared (SWIR)] can generate different results, and (b) NDWI thresholds vary depending on the proportions of subpixel water/non-water components. We need to evaluate all the NDWIS for determining the best performing index and to establish appropriate thresholds for clearly identifying water features. We used the spectral data obtained from a spectral library to simulate the satellite sensors Landsat ETM+, SPOT-5, ASTER, and MODIS, and calculated the simulated NDWI in different forms. We found that the NDWI calculated from (green - swm)/(green + SWIR), where SWIR is the shorter wavelength region (1.2 to 1.8 ??m), has the most stable threshold. We recommend this NDWI be employed for mapping water, but adjustment of the threshold based on actual situations is necessary. ?? 2009 American Society for Photogrammetry and Remote Sensing.

Publication Year 2009
Title Analysis of dynamic thresholds for the normalized difference water index
DOI 10.14358/PERS.75.11.1307
Authors Lei Ji, Li Zhang, Bruce K. Wylie
Publication Type Article
Publication Subtype Journal Article
Series Title Photogrammetric Engineering and Remote Sensing
Index ID 70035636
Record Source USGS Publications Warehouse
USGS Organization Earth Resources Observation and Science (EROS) Center