Spatio-temporal distribution characteristics of meteorological drought in western region of Liaoning Province based on standardized precipitation evapotranspiration index
Drought is one of the frequent natural disasters in the western region of Liaoning Province,and has seriously limited the production and living of people and economic development. In this paper,taking the western region of Liaoning Province as the research object,the daily temperature and precipitation data from 1961 to 2015 were collected to calculate the Standard Precipitation Evapotranspiration Index(SPEI)at different scales in one month,three months and twelve months. Combined with M-K method and ArcGIS spatial visualized analysis, temporal evolution tendency,frequency and intensity of drought occurrence distribution features of the region were revealed. The results show as follows:(1)Drought in western region of Liaoning Province began in 1968, and the drought frequency increased later;there were three times of continuous drought in 1960-2015,and the most serious one happened from 2000 to 2002. SPEI index decreased by 0.12·(10 a)~(-1) in recent 56 years,indicating the increasing trend of drought. At the 0.05 significance level,mutation began in 1995. At seasonal scale, drought occurred in spring and summer were more serious,but the general trend was relatively stable. Autumn linear trend declined significantly,in contrast,it showed a slight rise tendency in winter. Interannual variation of seasonal drought showed fluctuation change.(2)The drought frequency showed different distribution at different scales in the western region of Liaoning Province. The frequency occurred at annual scale(22%-32%)was all less than that at month scale(33%-37%),Jianping was the high value center. Frequency in summer and autumn was higher,and the maximum value was above 35%;both of them decreased progressively from southeast to northwest,the high value center was Jinzhou. The drought intensity was strong in the southwest and weak in the northeast,the strongest place was Jianping(24%). The temporal distribution shows that,Jianping and Chaoyang had the most times of continuous drought,however,the longest time happened in Xingcheng and Suizhong. Large range of durative droughts occurred in 1961,the second half of 1983 and 21st century. SPEI index,which considered the element of warming under global warming,and selected precipitation and evaporation as the indicators, has favorable applicability in the western region of Liaoning Province,it is available to reflect the spatio- temporal distribution characteristic of drought in recent 56 years. This paper can provide a theoretical basis and references for the drought monitoring,assessment and early warning.