The spatiotemporal patterns of rainfall erosivity in Yunnan Province, southwest China: An analysis of empirical orthogonal functions

• R in western YP was higher than in eastern, and in southern R was higher than in northern.
• The annual, summer, and autumn R had a decreasing trend.
• The spring and winter R showed an increasing trend.
• EOF analysis can effectively identify the major space–time features of R.
• Two spatiotemporal patterns of the annual R, and three for seasonal R were identified.

Rainfall erosivity (R) influences the formation mechanisms and succession processes of soil erosion. Knowing of the R factor facilitates the prediction of soil erosion and of the impact of climate change on erosion. However, defining of the R factor is challenging because its spatiotemporal variation can be complex. We combined the Empirical Orthogonal Function (EOF), North criteria, and Mann-Kendall test (M-K) to investigate the spatiotemporal patterns of the R factor for a study area in a typical mountain plateau region of Yunnan Province (YP), China. Daily rainfall records from 1960 to 2012 were collected from 115 national meteorological observation stations in YP. Based on the daily rainfall erosivity estimating model, we determined that the average annual R factor was 4383.85 MJ·mm·ha− 1·h− 1, the seasonal R factor exhibited an order of summer > autumn > spring > winter, and the summer R was significantly higher than winter R. The spatiotemporal variation of the R factor was complex and did not reveal a uniform pattern. The spatial distribution revealed that the annual and seasonal R factors in the west were higher than those in the east, and R in the south were higher than those in the north. The temporal trends of annual, summer, and autumn R factors had decreasing trends from 1960 to 2012. On the contrary, the spring and winter R factors showed an increasing trend. The EOF analysis identified two typical spatiotemporal patterns of the annual R factor in YP, and three for spring, summer, autumn, and winter R factors. These patterns represented the influence of the monsoon, circulation systems, and complex terrain conditions on the rainfall in the YP.