The researchers studied sediment deposition and erosion in the upper Yellow River from 1952 to 2010. They found that despite reduced sediment from upstream sources, the area still experienced buildup due to changes in reservoir operations. The reservoirs altered the river's flow patterns, leading to decreased sediment transport capacity during floods. This imbalance between water and sediment caused ongoing sediment accumulation in the study area. The researchers also identified a critical value for sediment input that determines whether the area experiences erosion or deposition.