The Variation of Meteorological Drought with the Probabilities of Rainfall and Temperature Under the Impact of Climate Change on the South Central Coast Region of Vietnam

This study aimed to evaluate meteorological drought in the South Central Coast region of Vietnam using the Standardized Precipitation Evapotranspiration Index (SPEI) at both 3- and 12-month timescales for the period of 1986-2005 and the future period of 2040-2059. Rainfall and temperature data were collected at ten meteorological stations in the region. The modified Mann-Kendall trend test and Theory Runs were used to analyze drought characteristics. Future meteorological datasets were obtained from the Vietnam Surrogate Mixed Model Ensemble (SMME_VN) dataset, considering two climate change scenarios: RCP4.5 and RCP8.5. These scenarios were developed using probabilistic models with the SMME method to assess potential impacts on future regional drought focused on the 5, 17, 50, 83, and 95% probabilities of occurrence of rainfall and temperature. The results suggest a projected increase in rainfall of 5.5-6.5% and a rise in the maximum and minimum temperatures ranging from 0.40 to 2.28 degrees C. We compared future drought characteristics for the period 2040-2059 to the period of 1986-2005 under the RCP4.5 and RCP8.5 scenarios. The results of SPEI3 index indicate a decrease in drought deficit from - 27.45 to - 32.67, which implies an increase in drought intensity. Drought frequency increased from 9.61 to 10.55%, and the drought episodes rose from 3 to 5. In contrast, using the SPEI12 index, the number of drought episodes and drought frequency fluctuated from 1 to 2 and 6.99% to 5.68%, respectively. The drought deficit decreased from - 22.66 to - 23.67 across all probabilities of occurrence of rainfall and temperature.