ASSESSMENT THE IMPACT OF DROUGHT IN VEGETATION AREA IN CENTRAL REGION OF THAILAND

Abstract

Many countries in the world against with mainly natural disaster like drought including Thailand. Thailand is an agricultural country.  Especially in the central region that is a corrugated plain area suitable for agriculture. Causing the central region is an important agricultural area (Meteorological Development Bureau, 2015).  Hence, the central region is interesting to assess the impact of drought. The objectives of this research were to obtain maps and compare them together and assess drought in central region. This research aims to assess drought in vegetation area in central region of Thailand by using Normalized Difference Drought Index (NDDI) and Vegetation Health Index (VHI) indexes. NDDI and VHI were created by evaluate the index from satellite images of MODIS09 terra 500 m resolution. Satellite images 10 years from January 2010 to December 2019, Monthly data were used in this research and cloud in every image was removed by using conditional. The calculation of NDDI and VHI was based on Normalized Difference Vegetation Index (NDVI) index. NDDI was calculated by using NDVI and Normalized Difference Water Index (NDWI) indexes while VHI was calculated by using Vegetation Condition Index (VCI) and Thermal Condition Index (TCI) which VCI was calculated from NDVI relationships. NDDI and VHI maps were created to compare with Meteorological map that were created by using meteorological data (rainfall, highest temperature, and lowest temperature) from 26 stations and spatial interpolation technique. The research was shown in the form of map of NDDI and VCI with in last 10 years, the assessment of drought using NDDI shown most of drought are in 2010, 2014 to 2016, and 2018 to 2019. In 2010, there was an abnormally low rainfall due to El Nino especially in May and June. Since 2014, Thailand has had abnormally low rainfall and rainy season was slower than usual, possibly as late as June and lightly than before.