Abstract: Rainfall erosivity is an essential index for soil erosive risk assessment as it reflects the potential of soil erosion driven by rainfall. According to daily rainfall data collected between 1986 and 2015 from 27 rain-gauge stations in the Ganjiang River basin (GRB), we investigated the temporal and spatial variation of rainfall erosivity using Mann-Kendall, accumulative anomaly, and Kriging interpolation. Results showed that average annual rainfall erosivity of the GRB was 9 824.55 MJ·mm/(hm²·h) with the maximum value reaching 13 234.72 MJ·mm/(hm²·h) in 2002 and the minimum value at 6 769.16 MJ·mm/(hm²·h) in 2003. There was a significant linear relationship between rainfall amount and rainfall erosivity, of which the correlation coefficient reached 0.965 (P<0.01). In recent three decades, the annual rainfall erosivity tended to increase insignificantly in majority areas of the GRB, with the high values concentrating in Ji’an, Jinggangshan, and Suichuan, increasing evidently. The trend of rainfall erosivity in seasonal, flood period and non-flood period of the GRB was not significant with their high-value and low-value areas different. The research findings are helpful to further discuss the soil erosion evolution, the assessment of soil erosion risk, and the formulation of reasonable preventive measures in the GRB.

Key words: rainfall erosivity, temporal and spatial variation, Mann-Kendall trend analysis, accumulative anomaly, Ganjiang River Basin