Evolution characteristics of drought in the Weihe River Basin based on CanESM2.

[Objective] The frequency, intensity and spatio-temporal variation of drought events in the Weihe River Basin under climate change were analyzed and the occurrence and development of future regional droughts were predicted to provide references for drought prevention and water security in future. [Method] This study selected the historical recorded data and modeled data from CanESM2 global climate model provided by the CMIP5 statistical downscaling dataset NEX-GDDP. The quadrant transformation method was employed to calibrate these data, and SPEI and the run theory were used to analyze the spatio-temporal evolution characteristics of drought in historical period (1966-2005) and under two emission scenarios (RCP4.5 and RCP8.5) in future (2021-2060). Finally, the spatial and continuous variations of drought frequencies were discussed. [Result] SPEI in both periods showed a decreasing trend at annual scale. Spring droughts were significantly aggravated in the Weihe River Basin under RCP8.5 scenario. The occurrence frequencies of future droughts showed a trend of decreasing at ends and increasing in middle with reduction in light and extreme droughts and increase in medium and severe droughts. The frequencies of short-duration drought events would decrease in future, while the frequencies of medium-and long-duration drought events would increase at watershed scale. The frequencies of long duration drought events in the northern part and the headwater region of the basin would decrease significantly. Drought events would remain the intervals of 1-6 months in future, with certain differences in some areas. [Conclusion] Spring and winter would be the critical periods for preventing drought risks in the Weihe River Basin and the western part would be the key areas for drought risk prevention in future. Light and medium droughts would still be the most important types of droughts, and attention should be paid to the potential disaster risks caused by medium and severe droughts. In addition, measures for reducing adverse effects of long-lasting drought events are suggested. [ABSTRACT FROM AUTHOR]