Future projection of seasonal drought characteristics using CMIP6 in the Lancang-Mekong River Basin

Abstract

As the most widespread natural hazard, drought has significant impacts on the livelihood and ecosystems in the Lancang-Mekong River Basin (LMRB). However, few studies focus on the seasonal characteristics of drought in the LMRB, especially under future climate projections by the Sixth Phase of Coupled Model Inter-comparison Project (CMIP6). This study filled the knowledge gap using SPI and SPEI, based on eight GCMs of CMIP6 under three scenarios (i.e., SSP1-2.6, SSP2-4.5, SSP5-8.5). Our results show that the LMRB tends to experience wetter wet season and drier dry season with the rising temperature considered (based on SPEI), while the temporal trend of dry-season SPI is not significant. The future trends of SPEI are -0.006 per year and -0.011 per year under SSP2-4.5 and SSP5-8.5, respectively. The trend magnitudes demonstrate spatial heterogeneities. Our evaluation based on SPEI shows that the most notable increases of dry-season drought (in terms of duration and intensity) are distributed in the middle reaches of LMRB. The upper Lancang and middle Mekong basin will likely experience more wet-season droughts. The dry-season drought accounts for 60% of total drought events in the near future (i.e., 2021–2055) and more than 80% in the far future (i.e., 2061–2095) under SSP2-4.5. Effective strategies are needed to enhance food and drinking water security in the LMRB, especially for the dry seasons under a changing climate.