Background Severe soil erosion in the Weihe River basin has attracted much attention due to its impact on land degradation, river bed siltation and sedimentation in reservoirs. Investigations on variations of sediment load and its response to climate change and human activities may provide good reference for river basin management.

Methods The present study applied the Mann-Kendell non-parametric test, double cumulative curve method and Kriging interpolation to analyze the dynamic variations of rainfall erosivity and sediment load by using daily precipitation data from 23 climate stations and annual sediment load time series at 3 hydrological stations in Weihe River basin from 1961 to 2015.

Results 1) Average annual rainfall erosivity was 1 685.67 MJ·mm/(hm²·h·a) in the past 55 years in Weihe River basin. The annual rainfall erosivity showed an insignificant increasing trend of 1.94 MJ·mm/(hm²·h·a). The lowest value was 1 507.23 MJ·mm/(hm²·h·a), occurring in 1990s, which was 10% lower than the annual average. In the 1960s, the rainfall erosivity was 1 685.67 MJ·mm/(hm²·h·a), which was similar to the average rainfall erosivity in the last 55 years. The average rainfall erosivity in the 1970s was slightly lower than the average. In the 1980s and the first 15 years of the 21st century, the average annual rainfall erosivity was almost the same. 2) The rainfall erosivity ranged from 292.9 to 4 098.9 MJ·mm/(hm²·h·a) in the Weihe River basin with high spatial heterogeneity. The average annual rainfall erosivity in the basin decreased from southeast to northwest. High values occurred in Huashan and Foping station, which were 2 980 and 4 098.9 MJ·mm/(hm²·h·a). 3) Sediment load exhibited significant decrease during the past 55 years in the Weihe River basin. Human activities had a greater impact on sediment load at Zhangjiashan and Xianyang stations after 1990s and the contribution was higher than 100%, which resulted from increasing rainfall erosivity, as well as the vegetation restoration and soil and water conservation. From 1980 to1994, human activities accounted for 58% of sediment load reduction at Zhuangtou station, and increased up to 67% during 2000-2015.

Conclusions This study investigated the spatial and temporal changes in rainfall erosivity and sediment load, as well the causes of variation in sediment load in the study area. The results may provide scientific bases for the future soil and water conservation in the Weihe River basin.