| Under the influence of global climate change,the occurrence frequency,intensity and impact range of drought are increasing,and the transmission from meteorological drought to hydrological drought also shows the characteristics of aggregation,lag and extension.The two severe droughts in the Lancang-Mekong River Basin in 2016 and 2019 are a true reflection of this problem,causing serious economic losses to the basin and bringing new challenges and opportunities to regional water security and geopolitical cooperation.Predicting the spatiotemporal variation and transmission characteristics of future drought in this basin is the basis of tackling climate change and carrying out Lancang-Mekong water resources cooperation.For this reason,this paper used the SWAT model to simulate the hydrological processes of the Lancang-Mekong River Basin in the past(1960-2005)and in the future(2022-2050,2051-2080)by air-land coupling method,and estimated and analyzed the spatiotemporal variation trend of meteorological and hydrological drought in the basin in the future.The main research results are as follows:(1)Three trend analysis methods,namely Mann-Kendall trend analysis method,5-year moving average method and unary linear regression method,and double cumulative curve abrupt point identification method,were used to analyze the change characteristics of meteorological and hydrological elements in the basin.The results show that the variation of rainfall runoff in the basin from 1960 to 2005 is relatively consistent,and is less affected by climate change and human activities.(2)The Quantile Mapping method was used to correct the deviation of the climate model data,which corrected the frequency distribution of different precipitation intensities and air temperatures,and made up for the shortcoming that the total amount correction could not correct the variability of precipitation and air temperature.The results show that the GFDL-CM3 climate model predicts that under different carbon emission scenarios,the distribution of rainfall in the future will be more uneven,and the spatial distribution of rainfall will be significantly heterogeneous.The mean temperature in the basin will rise by about2??4?.The average annual runoff of the basin showed an increasing trend,and the increase was more in the upper reaches,but less in the lower reaches.(3)Under the influence of increasing precipitation,meteorological drought in the Lancang-Mekong Basin will be somewhat weakened in the future,but the uneven annual distribution of precipitation and the increase of evaporation caused by future temperature rise will aggravate the hydrological drought,and the drought will be strengthened in the process of transmission from meteorological to hydrological.In the future,the frequency of hydrological drought events will decrease,but the proportion of severe drought and extreme drought events will increase significantly,and extreme hydrological drought will be more and stronger.Hydrological drought also has obvious spatial variation rule.The proportion of hydrological drought intensity,severe drought and extreme drought all presents an asymmetric "V" shape change from upstream to downstream.The hydrological drought at Yunjinghong and Qingsheng stations is the most serious,followed by Luang Prabang,Mudahan and Basse stations,and Wanxiang station is the weakest.(4)Considering the uncertainty of climate models,this paper adopts GFDL-CM3,CSIRO-MK3.6.0,FGOLAS-G2 and MIROC5 climate model data respectively to analyze the spatial-temporal variation characteristics of meteorological and hydrological drought in the Lancang-Mekong Basin.The results show that although there are some numerical differences in the prediction results of meteorological and hydrological drought in the four climate models,However,there is a consistent change rule in the trend of spatiotemporal change,and the reliability of the research conclusion is good. |
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