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Assessment of 2006 and 2007 drought patterns in the vegetation drought response index across Nebraska

Jesslyn F. Brown·Brian D. Wardlow·Md Shahriar Pervez·Tsegaye Tadesse
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Abstract

The Vegetation Drought Response Index (VegDRI) is a hybrid geospatial drought indicator and monitoring tool that provides timely drought severity information with relatively higher spatial resolution (1-km2) than the traditional drought monitoring maps. The VegDRI model integrates climate-based drought index data, satellite-based vegetation index information, and several biophysical parameters. During the 2008 growing season, VegDRI was produced in near-real time for 22 states in the central and western United States. Coverage will expand across the conterminous United States in 2009. Validating the results of large-area, operational monitoring tools such as VegDRI requires extensive ground truth information across space and time and to date, only a limited number of assessments of this index have been conducted. This study initiates a comprehensive assessment of historical VegDRI for two summer row crops identified using crop and irrigation masks in an effort to better characterize the accuracy and performance of this index for agricultural drought monitoring. The assessment evaluated drought severity information provided by VegDRI for Nebraska in 2006 and 2007, which represented drought and non-drought conditions over much of the state in those years, respectively. Spatial and statistical comparisons of VegDRI and U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) crop yield data were conducted for both years. For this initial study, comparisons were restricted to Nebraska’s two predominant crops, corn and soybeans. Irrigated and non-irrigated row crops were analyzed separately. Preliminary results showed that non-irrigated corn yields had a stronger relationship to late-season VegDRI than non-irrigated soybeans. Moderate drought impacts in 2006 were also highlighted by this analysis.

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Jesslyn F. Brown, Brian D. Wardlow, Md Shahriar Pervez, Tsegaye Tadesse. 2008. Assessment of 2006 and 2007 drought patterns in the vegetation drought response index across Nebraska. https://pubs.usgs.gov/publication/70201048

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