Geographia Technica, Vol 16, Special Issue, 2021, pp. 70-81
SPATIOTEMPORAL ANALYSIS OF VEGETATION DROUGHT VARIABILITY IN THE MIDDLE OF THE NORTHEAST REGION OF THAILAND USING TERRA/MODIS SATELLITE DATA
Nanthawat JOMSREKRAYOM, Pattanapol MEENA 
, Teerawong LAOSUWAN
ABSTRACT: Drought is one of Thailand’s most common catastrophes and causes a considerable amount of damage, especially to farming, in the northeast of the country. The objective of this study is to analyze vegetation drought variability from a vegetation phenology perspective using the vegetation condition index (VCI( from Terra/MODIS satellite data in the middle of the northeast region of Thailand. The MOD09A1 dataset from Terra/MODIS satellites was analyzed using the normalized difference vegetation index (NDVI(, and the results were analyzed with the VCI to examine vegetation drought variability in July, August, and September 2009–2019. The study found that in August 2013, the drought was most severe and accounted for 47.71% coverage (22,456.76 km2(, and in September 2013, the drought was the least severe at 55.55% coverage )17,456.42 km2.( Moreover, using simple linear regression analysis, the VCI results for each month of the 11-year period were used to find the statistical correlation with rainfall data from ground monitoring stations. It found that July, August, and September showed a coefficient of determination) r2(equal to 0.835, 0.834, and 0.849, respectively. The r2 value showed that this method was reliable. Furthermore, the analyzed VCI averages can be used as a very good indicator of drought in the middle of the northeast region of Thailand.
Keywords: Remote sensing, Vegetation drought variability, NDVI, VCI
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