Applicability Evaluation Of Five Drought Indices In Southwestern China

Drought is one of the worst natural disasters in the world.It can bring immeasurable loss to social and economic development,ecological environment,and influence the social continuous development due to its long duration,larger influence areas and universality.Based on meteorological data of 90 meteorological stations such as daily precipitation and daily temperature in Southwest China from 1962-2013,and the study region was divided into four sub-regions: Sichuan basin;Yun-Gui plateau;the eastern margin of the Tibetan Plateau;and the arid river valley region.Temporal and spatial variation of precipitation and potential evapotranspiration were investigated with the methods of linear tendency,Mann-Kendall rank correlation and inverse distance weighted interpolation.In order to explore the region applicability between the commonly used drought indices,Drought degree consistency analysis,drought degree difference analysis and combined the records of drought disasters was used to analyze the application of precipitation anomaly percentage(Pa),relative moisture index(M),standardized Precipitation Index(SPI),meteorological drought composite index(CI)and Z index in the Southwestern China.It is better to understand the application of each drought index of different regions.Meanwhile,it has significant theoretical and practical value in improving drought evaluation and monitoring which could provide the important scientific basis for water resources management in Southwestern China.The results were summarized as follows.(1)The mean annual precipitation in whole Southwestern China during recent 52 years was 1198.1mm,the linear changing trend of precipitation in Southwestern China was-2.5mm/a,the decreasing tendency was significant(p<0.01).The highest precipitation was in Sichuan basin(1357.9mm),the lowest was in arid river valley region(916.7mm),and the precipitation of Yun-Gui plateau and the eastern margin of the Tibetan Plateau were 1342.2mm,948.1mm,respectively.(2)The mean annual potential evapotranspiration in whole Southwestern China during recent 52 years was 3209.8mm,the linear changing trend of potential evapotranspiration in Southwestern China was 0.9mm/10 a.Potential evapotranspiration in Yun-Gui plateau was the biggest(3373.3mm),followed by arid river valley region(3341.4mm),the eastern margin of the Tibetan Plateau(2984.8mm)and Sichuan basin(2859.8mm).(3)It showed a good relationship between Pa?SPI?CI?Z,except M.(4)Pa was the most suitable index in Sichuan basin,Yun-Gui plateau,the eastern margin of the Tibetan Plateau,and the arid river valley region.SPI showed the worst performance in Sichuan basin,Yun-Gui plateau,and the arid river valley region.While M showed the worst performance in the eastern margin of the Tibetan Plateau.On the whole,Pa was the most suitable index to evaluate and monitor drought in Southwest China,while SPI showed the worst performance in this region.According to the results,precipitation and potential evapotranspiration had obvious difference between latitudes,but not between longitudes.As well,drought condition changed in spatial distribution.Complex terrain environment and climate characteristics are main reasons which reflected the unique feature of hydrometeorology changes in Southwest China.