Abstract:In the Loess Plateau, as the significant measure for preventing and reducing the sediment into the Yellow River, check dams are playing an essential role in sediment retention and farmland-making. In order to study the effect of check dam on the changes of soil erosion, sediment yield and sources in dam-controlled watershed, a check dam named Yuanzigou in Huangfuchuan watershed of Pisha sandstone area was selected as the research object. The soil samples were collected on the check dam profile and the surface of the slopes including land between gullies and gully region. The sediment deposition records of sediment couplets were analyzed by identifying the relationship between rainfall events and sediment couplets. The sediment sources were assessed and the changes of the sediment yield intensity were analyzed. The particle size analysis indicated that the sediment particle size distribution of the sediment profiles in the check dam mostly concentrated in the range of 0.05~2 mm sand, in which the proportion of very fine sand and fine sand was the most, followed by silt and clay. According to the corresponding relationship between rainfall events and sediment couplets, the minimum daily rainfall corresponding to erosive rainfall events in the dam-controlled watershed was 22.8 mm. And the sediment deposition process was divided into 2007-2013 and 2013-2016. In the early stage, it mainly depended on the dam body to trap sediment, and in the later stage, as more sediment is trapped the effect of erosion reduction was prominent. The results of sediment contribution analysis indicated that 71.4% of the sediment was contributed by the gully region and 28.6% by land between gullies. The erosion and sediment yield of land between gullies were not only affected by vegetation. When the daily rainfall was more than 45.4 mm, topographic factor would limit the the further occurrence of erosion.