Abstract: According to daily rainfall records in 41 consecutive years (1970-2010) at twelve stations of Longhe River watershed in the Three Gorges Reservoir Region, we calculated and analysed the intra-annual distribution and inter-annual variation of rainfall erosivity by using a simplified model of rainfall erosivity. During 1970-2010, the annual rainfall erosivity (R-factor) of Longhe river watershed varied from 2031.47 to 10 927.5 MJ·mm/(hm²·h), with an average of 4 662.00 MJ·mm/(hm²·h). The spatial distribution of erosive rainfall and rainfall erosivity were in accordance with the elevation, decreasing from northeast to southwest. The rainfall and rainfall erosivity of wet season were highly concentrated, accounting for 78.43% and 78.56%, respectively. Erosive rainfall concentrated in May-July. The Mann-Kendall statistical value Z of annual rainfall erosivity at all stations were inconsistent and insignificant (α=0.05) over 41 years, only at three stations such trend was deceasing, at the other four stations the trend was increasing at the same time. For the whole watershed, the change of R value was incompatible with the variation of rainfall, and showed an insignificant trend of decreasing over 41 years.

Key words: rainfall erosivity, daily rainfall, spatio-temporal distribution, Longhe River watershed, Three Gorges Reservoir Region