Tuanshangou unit watershed was selected to be the sediment yield source. The ratio of transported sediment modulus from a medium or small watershed to erosion modulus of the unit watershed was defined as sediment delivery ratio. Temporal and spatial variations of sediment delivery ratio from a single rainstorm and integrated effects of rainfall hydrological factors and topography factors were studied systematically. Re-sults showed that from a long-term perspective

soil erosion and sediment yield of watersheds may reach a balance

but from a single rainstorm or one year perspective

watersheds were characterized by alternative deposition

erosion and transportation of sediment. Rainfall

runoff coefficient

rainfall duration and average sediment content in runoff can well express sediment delivery ratio for a single rainstorm in Chabagou water-shed. After topographic factors were incorporated

an integrated expression of rainfall hydrological factors and topographic factors was founded for sediment delivery ratio from a single rainstorm in Chabagou water-shed.