Decadal Variations of Arid and Semi-Arid Boundary in China

Decadal variations of arid and semi-arid boundary in China during last 100 years have been analyzed by using Thornthwaite's method. The results indicate that, during the last 50 years, there is a distinguished periodic variation of arid and semi-arid boundary in their locations in the middle part of northeast China and northern part of North China, and an obvious trend moving to the east. In the southern part of Shannxi province and North China, the boundaries between arid and semi-arid areas have been moving to the south, with a periodic variation for the locations, and the boundary of semi-arid area reaches to the largest extent to the south. During the last 100 years, there is a trend of the boundaries moving to the south or east. And in the southern part of North China and the central part of northeast China in the 1920s, the range of arid and semi-arid area was the largest and the intensity was the severest. The location variation of arid and semi-arid boundaries is closely related to regional warming and precipitation reduction.