The various regression associations between runoff and sediment yield are related to the characteristics of both rainstorms and soil erosion on the Loess Plateau. Generally, the storms in the north of Shaanxi Province mostly appear at a single station and single time, indicating that the most storms in this region are usually local ones with short duration47. Both rill and shallow gully erosion are very serious on the Loess Plateau, and gully erosion is also very active. The sediment yield of gully erosion accounts for >70% of total sediment yield in the watershed. Although the rills and shallow gullies are small, they are numerous, and dense networks cover all loess slopes. During periods of infiltration-excess rainstorms, overland flow always flows along the direction of minimum resistance, because of the spatial difference of soil erosion resistance, and forms a small stream of relatively concentrated runoff on the slope, and then develops into different erosion types. The rill, shallow gully, dissected valley and gully in Zhifanggou Watershed form a dense network, and play very important roles in the formation of pulsed runoff-erosion events. The weak erosion resistance of loess soil is the fundamental reason for the severe erosion. Under the action of water flow, the stability of sediment particles is determined by the size of sediment particles and the cohesive forces between them48. For coarse-grained sediment, size plays a major role in stability, and the larger the particle size, the greater the starting velocity. When the particle size is less than a certain value, fine particles are also difficult to move, and the smaller the particle size, the larger the starting velocity. In general, fine and silt sand particles are most easy to erode, and the content of silt sand particle is the highest and more than >50% of the loess soil, but the starting velocity of clay soil particles is slightly larger.