Analysis of seasonal water discharge and sediment load data for major tributaries of the Upper Yangtze indicates significant changes from 1957 to 1987. Discrimination between land use–induced and climatic variation–induced changes was attempted using the systematic shift in the seasonal sediment load relative to the seasonal water flow. Available evidence suggests that most of these changes were caused by human activities such as deforestation, water use, and construction of reservoirs rather than by decadal climatic variations. The changes identified in water flow and sediment flux in both wet and dry seasons for some tributaries had significant implications with respect to flooding and water shortages.
