石羊河流域西大河干旱指数演变规律分析OA

The drought index,as an important indicator reflecting the degree of climate drought,is a key parameter for revealing regional climate drought changes.This study takes the main tributary of the Shiyang River in the inland river basin of Hexi,Gansu Province,as the research object.Based on the measured data of the Xida River Reservoir hydrological station,using time series theory,multiple trend and mutation testing methods,and combined with power spectral density method,the evolution law of drought index from 1981 to 2022 was systematically analyzed.The research results indicate that the drought index showed an overall downward trend from 1981 to 2022,with a significant mutation occurring in 2010.The study period can be divided into two characteristic stages:1981-2009(high value period)and 2010-2022(low value period);The change in drought index follows a main cycle of about 10 years,and after 2020,the drought situation in the Xihe River Basin has entered a new cycle of change.