关键词: 气候模式, 气象干旱, 标准化降水蒸散发指数, 长江流域, 时空变化

Abstract: The temporal and spatial evolution characteristics of historical meteorological drought in the Yangtze River basin (YRB) were analyzed, and the temporal and spatial variation trend of meteorological drought under different discharge scenarios in the basin in the future was predicted. The standardized precipitation evapotranspiration index is used as the index to classify drought grade according to the observed data of 318 meteorological stations in the basin and its surrounding areas from 1956 to 2018 and the predicted data of CMIP5 global climate model under three typical RCPs. Results show that: 1) In the past six decades, the drought rate in the YRB has changed greatly, with an average drought rate of 18.21%, while in ages scale, drought has had a widespread impact in the past two decades; the drought-prone areas in the YRB were mainly located in the Minjiang River basin, and the number of droughts decreased from the upper to the lower reaches; the high-intensity droughts in the YRB mostly occurred in the middle and lower reaches of the Jinsha River and in the Chengdu Plain, and the average drought intensity followed the trend of drought frequency. 2) Under RCP2.6, RCP4.5 and RCP8.5 scenarios, the annual average drought area of the YRB in 2020-2050 was 741 000 km², 757 000 km² and 1 264 000 km², respectively; the annual average drought frequency of the upper, middle and lower reaches of the basin is 1.1-1.2 per year, 1.0-1.1 per year, and 1.0-1.1 per year, respectively. The frequency of drought in the upper, middle and lower reaches of the YRB increases by 38.4%-50.7%, 33.7%-45.3% and 32.6%-49.6% respectively compared with that in historical period; the average annual drought intensity of the upper, middle and lower reaches of the river basin in the predicted period is -1.68, -1.64, -1.60 respectively, which is not significantly different from that in historical period. The research results offer scientific basis for scientific and reasonable drought disaster prevention measures and countermeasures.

Key words: climate model, meteorological drought, standardized precipitation evapotranspiration index, Yangtze River basin, spatial and temporal variations