The Climate Drought Monitoring And Drought Risk Assessment Of Alpine Grassland In The Qinghai-tibet Plateau

Drought is one of the major natural hazard in the Qinghai-Tibet Plateau,with wide range influence and long duration on ecosystem as well as human society.It is necessary to do the drought risk assessment in the Qinghai-Tibet Plateau.The standardized precipitation evapotranspiration index(SPEI)was calculated basing the Penman-Menteith model,By using the meteorological data of 120 meteorological stations in the Qinghai Tibet Plateau in the past 60 years(1955-2014).After analyzing the spatial and temporal characteristics of drought,conclusions are as follows:1)Comparing the different time scales of the SPEI,the 5-9 month time scale SPEI is good of application in this area.2)On the time sequence change,the period of the wet and dry change in Qinghai-Tibet Plateau alpine grassland was 5-9 years or 25-30 years.3)On the spatial distribution characteristics,Qinghai-Tibet Plateau alpine grassland in arid areas are mainly concentrated in the West and Southeast of Tibet autonomous region,at the junction of the northern part of Qinghai province and Gansu Province,in the western region of Sichuan Province.In the past 15 years,drought in the West and Southeast of Tibet autonomous region showed increasing trend,while showing a decreasing trend of drought in other regions.4)In the past 15 years,in the southwest and northern of Qinghai-Tibet plateau region,as well as the eastern edge of the area and the southeast region,the value of drought assessment of risk possibility is lager.Besides,the change trend of the southwest region is increasing.