Variations in runoff and sediment in the Yellow River's middle reaches are influenced by environmental factors like climate and human activities. Research shows that changes in runoff and sediment are due to a combination of natural factors and human actions. In the 1970s, decreased precipitation was the main cause of reduced water and silt flow, while in the 1980s, human activities like reservoir projects played a bigger role. Over time, human activities have become more significant in reducing runoff and sediment, thanks to better soil and water conservation methods. The study found that both natural factors and human actions impact the flow of water and sediment in the Yellow River's middle reaches.