For slopes without rill or shallow gully erosion, the final destination of filling water in the early excess infiltration rainstorm is infiltration. After overflow develops on slopes, sheet overflow will finally enter the channel. Therefore, in this case, the confluence speed is small, the flood duration is long, and the ratios of flood peak and discharge amount are reduced49. On the slope with rill or shallow gully erosion, the filling water in the early period of infiltration-excess rainstorm appears as a ‘dam break effect’ after appearance of the rill or gully erosion during the rainstorm. It suddenly releases by way of ‘installment time deposit’, and rapidly changes into centralized and strong channel flow50. This phenomenon reduces infiltration of rainwater into soil, increases the surface runoff coefficient, and makes the flood show features of “high peak and small volume, less runoff and much sand, peak with rising and dropping steeply, sudden coming and rapid going away”51. The characteristics of rainstorm erosion have important influences on relationships between runoff and sediment yield.