Nguyen Thi-Thu-Ha, Li Ming-Hsu, Vu Tue Minh, Chen Pei-Yuan
Graduate Institute of Hydrological and Oceanic Sciences, National Central University, No. 300, Zhongda Rd., Zhongli District, Taoyuan City 32001, Taiwan.
Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29631, USA.
Sci Total Environ. 2023 Jan 1;854:158589. doi: 10.1016/j.scitotenv.2022.158589. Epub 2022 Sep 7.
Drought may lead to severe and diverse impacts on agriculture, economy, and society across different regions and periods, posing predictive and adaptive challenges. In recent years, severe droughts have affected >60 million people in the Mekong River Basin (MRB). Additionally, El Niño Southern Oscillation (ENSO) episodes had distinct influences on the occurrence and intensity of drought variability in the regions. Understanding the spatiotemporal characteristics of droughts across the MRB is critical to improving management and mitigation actions. This study aims to investigate spatiotemporal drought characteristics in the MRB and their teleconnection with the ENSO. Three multiple drought indices, including the Standardized Precipitation Index (SPI) for meteorological drought, Standardized Soil Water Index (SSWI) for agricultural drought, and Standardized Runoff Index (SRI) for hydrological drought were calculated to quantify drought events, drought frequency, and drought severity. The overall patterns showed more events and larger intensity were identified by the SPI than those by the SRI or the SSWI, while the higher frequency was observed by the SRI. The Middle Mekong basins seem to experience more drought events, while higher levels of frequency and intensity of droughts were observed in the Upper Mekong Basin. The correlation analysis between ENSO index and precipitation suggested that the strongest ENSO events in Dec-Jan-Feb may result in developments of meteorological drought in Mar-Apr-May, and further led to hydrological and agricultural drought in Apr-May-Jun. Such ENSO effects had significant influences on drought variabilities in southern MRB and were insignificant in the north. The multiple drought indices show skills in identifying spatial and temporal drought characteristics from meteorological, agricultural, and hydrological perspectives, and potential for drought outlook further considering their ENSO teleconnections. The results can be applied to the development of drought monitoring methods and adaptive strategies to mitigate drought impacts through scientific and quantitative assessments.
干旱可能在不同地区和时期对农业、经济和社会造成严重且多样的影响，带来预测和适应方面的挑战。近年来，严重干旱已影响湄公河流域（MRB）超过6000万人。此外，厄尔尼诺南方涛动（ENSO）事件对该地区干旱变化的发生和强度有显著影响。了解湄公河流域干旱的时空特征对于改进管理和缓解措施至关重要。本研究旨在调查湄公河流域的时空干旱特征及其与ENSO的遥相关。计算了三个多干旱指数，包括用于气象干旱的标准化降水指数（SPI）、用于农业干旱的标准化土壤水分指数（SSWI）和用于水文干旱的标准化径流指数（SRI），以量化干旱事件、干旱频率和干旱严重程度。总体模式表明，SPI识别出的事件更多、强度更大，高于SRI或SSWI识别出的情况，而SRI观测到的频率更高。湄公河中游流域似乎经历更多干旱事件，而湄公河上游流域观测到更高水平的干旱频率和强度。ENSO指数与降水之间的相关分析表明，12月至次年1月至2月最强的ENSO事件可能导致3月至4月至5月出现气象干旱，并进一步导致4月至5月至6月出现水文和农业干旱。这种ENSO效应在湄公河流域南部对干旱变化有显著影响，而在北部则不显著。多干旱指数在从气象、农业和水文角度识别时空干旱特征方面具有技能，并且进一步考虑其与ENSO的遥相关后具有干旱展望潜力。研究结果可应用于干旱监测方法的开发和适应策略，通过科学定量评估减轻干旱影响。
