Characteristics of Annual Rainfall in Arid and Semi-arid Region of China

Through cluster analysis of the normalized annual precipitation data for the 160 stations in China during the period from 1951 to 1992, it is found that there are two big regions—the arid and semi-arid region as well as the non-arid region. On the basis of it the annual rainfall division is made, and the annual rainfall distribution in the arid and semi-arid region is also studied. The results show that the arid and semi-arid region can be divided into 9 subdivisions and there are three distribution patterns for annual rainfall.