การประเมินการเกิดภัยแล้งระดับตำบลภายใต้การเปลี่ยนแปลงสภาพภูมิอากาศด้วยดัชนีความแห้งแล้งมาตรฐานค่าการระเหยและการคายน้ำ กรณีศึกษาลุ่มน้ำชีส่วนที่ 4 Assessment of Sub-district Scale Drought under Climate Change using Standardized Precipitation Evapotranspiration Index: A Case Study of Chi River Basin Part 4

Abstract

Climate change has been affecting the frequency and severity of droughts worldwide, particularly in Chi River Sub-basin 4, which is a crucial agricultural area in northeastern Thailand. This study aims to analyze the impacts of climate change on drought occurrence at the sub-district level in Chi River Sub-basin 4 using the Standardized Precipitation Evapotranspiration Index (SPEI) at 3-, 6-, 9-, and 12-month timescales. The study utilizes bias-corrected climate data from CESM2, GFDL-ESM4, and CanESM5 models, analyzing four time periods: the historical period and future projections under medium (SSP2.45) and high (SSP5.85) greenhouse gas emission scenarios for near-, mid-, and far-future periods. Results show that under SSP2.45 in the near future, drought frequency increases by 4-6%, intensity decreases by 1-3%, duration increases by 4-6%, and severity increases by 12-15%. The SSP5.85 scenario shows more pronounced changes, particularly by the end of the 21st century, with drought frequency increasing by 8-15%, intensity decreases by 3-5%, duration increasing by 8-15%, and severity increasing by 6-39%. The most significant changes are observed in SPEI9 and SPEI12 indices, indicating that long-term droughts are likely to become more severe in the future. The study also identifies that the most severely affected areas are mainly located in Roi Et, Kalasin and Maha Sarakham provinces. These findings can be effectively applied to water management planning and climate change adaptation strategies at the local level.