Geographia Technica, Vol 19, Issue 2, 2024, pp. 152-163
COMPARISON OF DROUGHT INDICES FOR EVALUATING AGRICULTURAL DROUGHT RISK IN HIGHLAND REGIONS
Teerawong LAOSUWAN 
, Yannawut UTTARUK , Phaisarn JEEFOO , Jumpol ITSARAWISUT
ABSTRACT: The impact of drought on human livelihoods is significant, as it is a natural disaster that affects various aspects of life. This research aims to evaluate suitable drought indices for assessing agricultural drought risk in highland regions, focusing on the Nan Watershed in Northern Thailand. The study analyzed three types of drought indices: Normalized Monthly Precipitation Anomaly Percentage (NPA), Vegetation Health Index (VHI), and Normalized Vegetation Supply Water Index (NVSWI). Rainfall data from the Tropical Rainfall Measuring Mission (TRMM) TRMM 3B42 product was used to assess the suitability of these indices for evaluating agricultural drought risk over a ten-year period (2013-2022). The study found that ground-based rainfall data and TRMM3B42 satellite data have a very high statistical correlation, with a correlation coefficient of 0.8945. Analyzing the statistical correlation of suitable drought indices for assessing agricultural drought risk revealed that NVSWI had the highest statistical correlation with a coefficient of 0.956.VHI had a correlation coefficient of -0.8179, and NPA had a correlation coefficient of 0.867. For evaluating the suitability of drought indices affecting the assessment of agricultural drought risk in high areas, focusing on the Nan Watershed in Northern Thailand, this study concludes that NVSWI is the most suitable index for assessing agricultural drought risk in high areas.
Keywords: Remote Sensing, Drought Indices, NPA, VHI, NVSWI, TRMM
Full article here