Variations Of Meteorological Drought Characteristics And Drought Tendency In The Upper And Middle Reaches Of Huai River Basin Based On CMIP6

As an important grain production base in China,Huai River Basin is prone to drought due to its unique geographical location and climate characteristics.In the past century,with the significant climate change,drought disaster and its risk become more prominent.Therefore,the study of drought under the climate change is helpful to improve the drought prevention and drought resistance ability of the basin,guarantee the food production in China,and promote the sustainable development of society,economy and ecology.Based on the observation data of 19 meteorological stations in the Upper and Middle Reaches of Huai River Basin(UMHRB),NCEP reanalysis data and HadGEM3-GC3-LL model data,combined with Statistical Downscaling Model(SDSM)to simulate the precipitation and temperature of SSP2-4.5 and SSP5-8.5 scenarios in the future.Based on SPEI,analyzing the historical and future drought trend,drought cycle,drought station frequency ratio,drought frequency,drought characteristics and the causes of drought and wet events from the perspective of time and space by using linear regression,Mann Kendall trend test,Morlet wavelet analysis,run length theory and IDW interpolation.The main conclusions are as follows:(1)SDSM can simulate the trend of precipitation and temperature,and the simulation effect of temperature is better than precipitation.Precipitation and temperature in the future would increase(except spring temperature of SSP2-4.5),the annual and four seasons precipitation and temperature basically show a strong upward trend(except winter precipitation of SSP2-4.5),and the upward trend of high emission scenario is more obvious.(2)The dry and wet trend of the basin has changed significantly in the future.In history,there was a trend of drought in spring and autumn,and a trend of wetness in summer and winter.In the future of SSP2-4.5 scenario,the annual and four seasons showed a trend of drought.In the future of SSP5-8.5 scenario,the annual,spring and summer showed a trend of drought,while the autumn and winter showed a trend of wetness(3)In history,the distribution of annual drought trend is uneven,the drought trend in spring is mainly concentrated in the south of the basin;summer is mainly concentrated in the northeast of the basin and near Zhumadian and Kaifeng;autumn is mainly concentrated in the west of the basin,winter is mainly concentrated in the north and southwest of the basin.In the future,the trend of drought is stronger in the east and southeast of the basin,especially under the high emission scenario(4)The first major cycle of dry or wet under historical observation scenario,SSP 2-4.5 scenario and SSP5-8.5 scenario is 29a,12a and 27a respectively in annual,9a,7a and 26a respectively in spring,32a,12a and 31a respectively in summer,20a,32a and 26a respectively in autumn and 19a,12a and 29a respectively in winter.(5)Except for the severe drought and extreme drought station times ratio in history and the light drought station times ratio under SSP5-8.5 scenario show a downward trend,others show an upward trend.The spatial distribution of drought frequency is uneven,and the frequency of severe drought and extreme drought in the basin is less,the location distribution is more scattered.(6)The drought characteristics are all showed an increasing trend.In history,the drought degree in ZhuMaDian,HuoShan,DangShan and XuYi is relatively high,84%of the stations' drought months were more than 4 months,the maximum drought intensity is mainly concentrated in the northern,western and southern edge of the basin.In the future,the drought degree and drought months in the southeast of the basin are relatively large,the maximum drought intensity in the west of the basin is relatively large under the SSP2-4.5 scenario,and in the middle of the basin is concentrated under the SSP5-8.5 scenario(7)Climate change would cause the change of precipitation and temperature.Less precipitation and higher temperature would promote the formation of drought.In the future,the rising trend of temperature is significantly greater than that of precipitation,temperature plays a dominant role in the change of drought or wet.At the same time,there is a close relationship between temperature and potential evaporation,so the impact of potential evaporation can not be ignored in drought analysisThe results of the characteristics and evolution trend of meteorological drought in the UMHRB are helpful to further deepen the understanding of the characteristics of drought change in the basin,and have a certain reference value for improving the drought monitoring level and forecasting and early warning ability of the basin.