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Northwest A&F University (2020)

Spatio-temporal Evolution of Drought and Future Projections under Climate Change


Titre : Spatio-temporal Evolution of Drought and Future Projections under Climate Change

Auteur : 姚宁;

Grade : Doctoral Dissertation 2020

Université : Northwest A&F University

Drought is a kind of disaster with strong destructive power and serious economic loss.In order to better prevent and control drought disaster and effectively manage water resources,it is of great significance to study the spatial and temporal distribution and predict drought in different climatic regions.In this study,the meteorological observation data of precipitation(P),minimum temperature(Tmin),maximum temperature(Tmax),average temperature(Tave),wind speed at 2m high(U2),relative humidity(RH),sunshine hours(n) the 552 selected weather stations(which belonged to different climatic regions in mainland China)since 1961 were collected.Based on the improved Mann-Kendall method,the annual trend of each meteorological element was tested.The FAO56 Penman-Monteith formula was used to calculate the of reference crop evapotranspiration(ET0),and the change characteristics of ET0 and its sensitivity to the meteorological elements were analyzed when the single,double and multiple meteorological elements were changing at the same time.Based on above analysis,ET0 was estimated by different methods(including the Irmak et al.(2003),Berti et al.(2014),Priestley-Taylor(1972),Doorenbos-Pruitt,and Valiantzas formulae,respectively)and further used to calculate the standardized precipitation evapotranspiration index(SPEI).The periodic variation characteristics of SPEI was analyzed by combining the spectral characteristics and the wavelet variance obtained by the wavelet analysis,and the drought evolution characteristics of SPEI in different climatic zones in China was further evaluated.In addition,the observed daily precipitation data were bias-corrected and the differences in SPEI calculated based on observed precipitation(Pm)and bias-corrected precipitation(Pc)were compared.Different drought indexes(including precipitation anomaly percentage,standardized precipitation index-SPI,standardized precipitation evapotranspiration index-SPEI and evaporation demand index-EDDI)were used to study the drought severity and spatiotemporal variations at different timescales from 1 to 12 months.Finally,the statistical downscaled data from 28 global climate models(GCM)in CMIP5 during the period 2020-2100 were used to predict SPEI at the 12-month timescale with 2 representative concentration paths(RCP4.5 and RCP8.5 scenarios),and the future drought evolution characteristics in 7 climate zones and mainland China was analyzed.The main conclusions based on the above analysis are as follows :(1)Under the condition that single meteorological element changed,the reference crop evapotranspiration(ET0)was more sensitive to Tmax,U2 and n.As the two meteorological elements changed simultaneously,the sensitivity of ET0 to the simultaneous changes of Tmin and Tmax was greater than that of the combination of other elements.However,with the simultaneous change of(-U2)&(-n),ET0 decreased more than other conditions.When three or more meteorological elements changed at the same time,the increase of Tmin,Tmax,Tave and RH and the decrease of U2 and n led to the actual decrease of ET0.

Mots clés : drought index; reference crop evapotranspiration; bias correction of precipitation; GCM; projection;

Présentation (CNKI)

Page publiée le 5 juin 2021