The sediment sources and yield of the Jinshajiang basin, the largest tributary in the upper Yangtze basin are of major significance for the exploitation of the water resources of China's largest river. At Pinshan, the outlet gauging station, the area of the Jinshajiang catchment is 485,500 km2 and the mean annual discharge is 4430 m3 s- I or 32.1 % of that at Yichang, just below the Three Gorges Dam site. The mean annual sediment load at Pinshan of 247 million tonnes is 47.1 % of that at Yichang. The sources and delivery of sediment in the Jinshajiang are assessed in the framework of a catchment system which looks at the interplay of hydrometeorological, terrain, vegetation, and human land use factors. The key factors in the present pattern of soil erosion and sediment delivery are: rainfall, topography, slope characteristics, vegetation cover, land use, soil properties and the duration and areas of storm cover. The main sediment sources are in the lower sector of the Jinshajiang, particularity - the reach from Dukou to Pinshan, with a local catchment area of 61,897 km2 : L" , an average annual runoff of 25.88xlO9 m3 and an average annual sediment load of 54.6 million tonnes. These quantities mean that this reach representing only 12.8 % of the area above Pinshan, supplies 18.1 % of the runoff and 62.6 % of the sediment load. The high sediment load comes from both the steepness of the terrain and the intensity of agricultural land use. No clear time trend in the sediment yield of the Jinshajiang emerges. Some tributaries have decreasing yields, perhaps due to sediment deposition in reservoirs, while others exhibit an increasing trend, in some cases due to increased agricultural pressure on the land, and also to construction and engineering activities which cause high sediment yields for short periods of time at individual localities. The pattern of change sediment discharge has been modelled using a distributed rainfall: runoff and runoff: sediment model using data on precipitation, evaporation and proportion of forest cover (land use). The model has been tested against the daily discharge and sediment yield of the 3074 km2 Heishuihe catchment and the 1607 kM2 Meigu catchment.