The researchers analyzed 50 years of data on the Yangtze River to understand changes in water flow and sediment levels. They found that while annual water flow stayed steady, sediment levels decreased over time. This decrease was mainly due to the construction of a reservoir that trapped sediment. Water and sediment levels were highest during the flood season from May to October. The researchers also discovered a 12-year cycle in water flow changes. Overall, the upper Yangtze River currently has low water flow, but this is expected to increase in the future. The reservoirs in the upper river will keep sediment levels low in the middle and lower river reaches.