The study analyzed data from the headwaters of the Yangtze River to understand the factors influencing changes in runoff. They found that runoff depth, precipitation, and evaporation all increased significantly from 1966 to 2013. The main factor affecting runoff changes was precipitation, with a minor impact from evaporation and land use/cover changes. The study identified a change point in 2004, dividing the period into base and impacted periods. Overall, the research showed that precipitation played the most significant role in historical runoff changes in the basin.