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Analysis of PDSI and Vegetation Condition Index (VCI) and Their Links to Streamflow

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2018 ASABE Annual International Meeting  1801344.(doi:10.13031/aim.201801344)
Authors:   Devon Ali Bandad, Vahid Rahmani
Keywords:   Drought, Iowa, Kansas, Missouri, Nebraska, Palmer Drought Severity Index, Streamflow, Vegetation Condition Index


Abstract. This study assesses whether the metrological Palmer Drought Severity Index (PDSI) and a remote sensing drought indicator, the Vegetation Condition Index (VCI), can predict streamflow changes. The region of interest is the four states of Missouri, Iowa, Nebraska, and Kansas (MINK region) using information from 2003 to 2017. Data for each of the 32 climate divisions within the region was evaluated on a monthly basis for the warm season of April through September. Monthly data were then averaged over the warm season to generate annual values. VCI monitors vegetation health which is derived from MODIS satellite data. This index was compared to the in-situ drought indicator PDSI, spatially and temporally. Results show that VCI and PDSI are significantly correlated in all Kansas and western divisions of Nebraska and Missouri. The percentage of discharge anomaly (PDA) was used to compare to PDSI and VCI over the time frame for each climate division. Trend analysis show that PDSI and PDA are slightly increasing (getting wetter) over time for most regions with most relationships being statistically significant. VCI trends followed an annual cycle of low values (less vegetation) in April and high values (more vegetation) in August-September. This leads to a neutral VCI trend for most climate divisions as PDA either increases or decreases. Results suggest that PDSI can reasonably (statistically significant) predict streamflow changes in a majority of divisions particularly in western parts of the region including Kansas, western Nebraska, and a few divisions in Missouri within the MINK region, respectively. VCI also showed significant but weaker correlations with PDA in the same divisions.

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