Abstract: Drought is one of the major natural hazards in Hebei province.Based on standard precipitation index(SPI),the spatial-temporal characteristics of drought-flood in Hebei province during 1965-2005 were studied by empirical orthogonal function method.The results showed that drought-flood varies with time,in total.Drought was more severe in the periods of 1965-1972 and 1997-2005,and flood was more frequent in 1970s and early 1990s.Occurrence of drought in spring and autumn tends to decrease,while in summer tends to be more severe.There was no obvious change for winter.However,extreme drought and water logging hazards were frequent in Hebei province since 1990s.Hebei could be divided into four sub-regions(east,north,south and west) in terms of the spatial distribution of drought and water logging.There was a consistence among these regions and the whole province,though there were north-south gaps and east-west gaps.The most drastic drought-flood changes had occurred in the 1990s.These Changes were also obvious in the early 1970s,but lest obvious in the 1980s.But,the change rate had been high in the south part since 2000.

Key words: Standard precipitation index(SPI), Standard precipitation index(SPI), Drought-flood, Spatial-temporal characteristics, Hebei province