The study looked at how sediment in the lower Yellow River changes over time. By analyzing data from four river stations, researchers found that sediment concentration follows cycles of 55, 26-34, 17-18, and 6-11 years. The longer cycles are influenced by natural factors, while the shorter ones are affected by human activities. Different types of sediment require different management strategies, with coarse sand being the most impacted by human actions. The study suggests that controlling sediment in the Yellow River should consider these different cycles and types of sediment.