Temporal and Spatial Distribution of Multi-scale Drought in North China

Abstract

The North China is located in the East Asian monsoon region. The uneven spatial and temporal distribution of water resources leads to frequent drought disasters, and drought has increasingly become a limiting factor for regional development. In this paper, the intrinsic evolution characteristics of multi-scale spatial and temporal distribution of meteorological drought in the past 57 years in North China are analyzed by using standardized precipitation evapotranspiration index and ensemble empirical mode decomposition with multi-time scale features. The results show that the North China region was generally humid in the 1960s and 1970s. Drought in the 1980s and 1990s increased relatively. The interannual SPEI of North China changed in 1991, and entered a relatively dry period in the late 1990s and 2000s. From the SPEI index sequence, the scale characteristics of each scale were extracted. It was found that the SPEI sequence of the three-month time scale in North China mainly existed in the three scale ranges of monthly, interannual and intergenerational, At the same time, through the comparison of the temporal and spatial distribution characteristics of the summer drought in june and august 2002 in North China, it was found that the severe drought in august 2002 was caused by the temporal and spatial overlap of short-term scale and long-term drought events.