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
Article first published online: 27 MAR 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 6, March 2007
How to Cite
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., , , and (
- Issue published online: 27 MAR 2007
- Article first published online: 27 MAR 2007
- Manuscript Accepted: 28 FEB 2007
- Manuscript Revised: 16 FEB 2007
- Manuscript Received: 18 DEC 2006
- MODIS NDVI and NDWI;
- drought assessment
 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.