| With the rapid development of society and economy,the impact of extreme climate events on human society in the context of global warming is increasing.How to prevent and respond to the adverse effects of extreme precipitation events is an issue that needs to be solved urgently.The Yangtze River Basin accounts for one-fifth of China's total area,but it has a one-third population of all.The evolution of extreme precipitation directly affects the socio-economic development of the entire basin and even the country.Therefore,a study on characteristics and evolution of extreme precipitation in the Yangtze River Basin is necessary,and the impact of extreme precipitation to the population is analyzed quantitatively.it is particularly important to minimize the loss.In this paper,knowledge of geography,climatology,and disaster science are synthesized.Based on the measured precipitation data and the regional climate model COSMO-CLM simulation data over the Yangtze River basin,the evolution characteristics of extreme precipitation at 1961-2014 and different global warming level(the global warming of 1.5?and 2.0? relative to the industrial revolution before)are analyzed by percentile extreme precipitation threshold and Intensity-Area-Data duration extreme event identification method.At the same time,combined with population data under the shared socio-economic paths(SSPs),the population characteristics exposed to previous extreme precipitation events are analyzed quantitatively.The main conclusions of this paper are as follows:(1)From 1961 to 2014,the total amount of extreme precipitation in the Yangtze River basin increased,the frequency and intensity decreased first and then increased.The extreme value centers of extreme precipitation are mainly located in the Dongting Lake and Poyang Lake.Most of the extreme precipitation events lasted for 1 day,and the single event affects the area will up to 96 million km2,the maximum intensity up to 366.7mm.The extreme precipitation events with large intensity and area are mainly located in the mid-lower reaches of the Yangtze River basin,and mostly occurred in 1967-1970,1983-1996 and 1999.(2)Under the different scenarios of warming,the total precipitation,frequency,and intensity of extreme precipitation in the Yangtze River Basin will increase relative to the reference period(1986-2005).In the 1.5? warming period,the total precipitation,frequency,and intensity of extreme precipitation will increase separately by 18mm-28mm(5.2%-12.0%),0.3-1.9 times(10.5%-21.7%),and 1.3mm-6.8mm(3.2%-8.1%).In the 2.0?warming period,the total precipitation,frequency,and intensity of extreme precipitation will increase separately by 35mm-68mm(7.6%-33.8%),0.7-3.9 times(29.9%-93.5%),and 1.7mm-9.0mm(12.4%-17.8%).The increase centers of extreme precipitation are mainly located in the Dongting Lake and Jinsha River.The extreme precipitation with global warming of 2.0? is significantly higher than the global warming of 1.5?.(3)Under the global warming of 1.5 ? and 2.0 ?,the average annual extreme precipitation events which all over the base level will occurred 1478 times and 1534 times.In the 1.5? warming period,the increase rate relative to the reference period for the total precipitation,frequency,and intensity of extreme precipitation events will up to 39.1%,8.6%and 3.8%.The maximum intensity and influence area of extreme precipitation events are 381.9mm and 0.9 million km2.In the 2.0?warming period,the increase rate relative to the reference period for the total precipitation,frequency,and intensity of extreme precipitation events will up to 44.2%,12.1%and 5.1%.The maximum intensity and influence area of extreme precipitation events are 412.5 mm and 1 million km2.The extreme precipitation events over the base period of maximum intensity will occurred mostly in the Dongting Lake,Poyang Lake,middle and lower reaches of the mainstream and Taihu Lake.The intensity and impact area of extreme precipitation events under the global warming scenario of 2.0? are higher than the global warming of 1.5?(4)The population of the Yangtze River basin will peak in 2025-2030 under the combination of 5 RCPs-SSPs scenarios.In the 1.5?warming period,the total population under the SSP1 and SSP4 routes increased by 11 million compared to 2010,and the elderly population aged over 65 will increase nearly 2 times.The population of most provinces will increase,and the proportion of elderly people in each province will be between 20%and 25%.In the 2.0?warming period,compared with 2010,the total population of the SSP3 route will increase by 25 million people,while the SSP2 and SSP5 routes will decrease by 5 million people and 32 million people.Under the SSP2 and SSP5 routes,more than 80%of the province's population will be decrease,and the proportion of elderly people in each province will be more than 25%.Compared with the global warming of 1.5?,the ageing trend in the scenario of global warming of 2.0? will be on the increase,and the aging in the Sichuan and Chongqing province will be the most serious.(5)Under the five combination scenarios of global warming level and SSPs,there will be 11.77 million people be exposed to extreme precipitation events in the Yangtze River Basin each time.The population exposure will show the distribution pattern of east and west less than the Hu Huanyong line.In the 1.5? warming period,the most people affected by extreme precipitation events will be in the SSP1 rout(11.97 million people),the proportion of elderly people aged 65 or above affected by extreme precipitation events will be about 20.0%which of the total population exposed.In the 2.0? warming period,the most people affected by extreme precipitation events will be in the SSP3 rout(12.32 million people),the proportion of elderly people aged 65 or above affected by extreme precipitation events will be equal 1.5 times than the global warming of 1.50?.The centers of extreme precipitation events that affect the most people will be located in Jiangsu,Zhejiang and Shanghai province.The global warming of 2.0? will have more people affected by extreme precipitation events than global warming of 1.5?.The larger population exposure of extreme precipitation events also have greater intensity and influence area. |
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