Hydrology and Land Surface Studies

A five-year analysis of MODIS NDVI and NDWI for grassland drought assessment over the central Great Plains of the United States

  1. Yingxin Gu1,
  2. Jesslyn F. Brown1,
  3. James P. Verdin2,
  4. Brian Wardlow3

Article first published online: 27 MAR 2007

DOI: 10.1029/2006GL029127

Issue

Geophysical Research Letters

Geophysical Research Letters

Additional Information

How to Cite

Gu, Y., J. F. Brown, J. P. Verdin, and B. Wardlow (2007), A five-year analysis of MODIS NDVI and NDWI for grassland drought assessment over the central Great Plains of the United States, Geophys. Res. Lett., 34, L06407, doi:10.1029/2006GL029127.

Author Information

  1. 1

    Science Applications International Corporation, US Geological Survey Center for Earth Resources Observation and Science, Sioux Falls, South Dakota, USA

  2. 2

    US Geological Survey Center for Earth Resources Observation and Science, Sioux Falls, South Dakota, USA

  3. 3

    National Drought Mitigation Center, University of Nebraska at Lincoln, Nebraska, USA

Publication History

  1. Issue published online: 27 MAR 2007
  2. Article first published online: 27 MAR 2007
  3. Manuscript Accepted: 28 FEB 2007
  4. Manuscript Revised: 16 FEB 2007
  5. Manuscript Received: 18 DEC 2006

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Keywords:

  • MODIS NDVI and NDWI;
  • drought assessment

[1] A five-year (2001–2005) history of moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) data was analyzed for grassland drought assessment within the central United States, specifically for the Flint Hills of Kansas and Oklahoma. Initial results show strong relationships among NDVI, NDWI, and drought conditions. During the summer over the Tallgrass Prairie National Preserve, the average NDVI and NDWI were consistently lower (NDVI < 0.5 and NDWI < 0.3) under drought conditions than under non-drought conditions (NDVI>0.6 and NDWI>0.4). NDWI values exhibited a quicker response to drought conditions than NDVI. Analysis revealed that combining information from visible, near infrared, and short wave infrared channels improved sensitivity to drought severity. The proposed normalized difference drought index (NDDI) had a stronger response to summer drought conditions than a simple difference between NDVI and NDWI, and is therefore a more sensitive indicator of drought in grasslands than NDVI alone.

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