Projection of droughts in Amu river basin for shared socioeconomic pathways CMIP6

Abstract

Droughts significantly affect socioeconomic and the environment primarily by decreasing the water availability of a region. This study assessed the changes in drought characteristics in Central Asia’s transboundary Amu river basin for four shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). The precipitation, maximum, and minimum temperature (Pr, Tmx, and Tmn) simulations of 19 global climate models (GCMs) of the coupled model intercomparison project phase 6 (CMIP6) were used to select the best models to prepare the multimodel ensemble (MME) mean. The standard precipitation evapotranspiration index (SPEI) was used to estimate droughts for multiple timescales from Pr and potential evapotranspiration (PET) derived from Tmx and Tmn. The changes in the frequency and spatial distribution of droughts for different severities and timescales were evaluated for the two future periods, 2020–2059 and 2060–2099, compared to the base period of 1975–2014. The study revealed four GCMs, AWI-CM-1–1-MR, CMCC-ESM2, INM-CM4-8, and MPI-ESM1-2-LR, as the most suitable for projections of droughts in the study area. Results revealed a decrease in Pr by 3 to 12% in the near future and by 3 to 9% in the far future in most parts of the basin for different SSPs. However, there is almost no change in PET in the near future while increasing by 10 to 70% in the far future. The changes in Pr and PET would cause a noticeably decrease in drought occurrence in the near future, particularly for moderate droughts by − 50% for SSP5-8.5 and an increase in the far future up to 30% for SSP3-7.0. The increase in all severities of droughts was projected mostly in the center and northwest of the basin. Overall, the results showed a drought shift from the east to the northwest of the basin in the future.