Why did silt reduce the generating capacity of the Sanmenxia Dam?

The Huang He (Yellow River) carries an enormous load of silt, primarily gathered as it flows through the Loess Plateau. Upon the completion of the Sanmenxia Dam, this heavy silt load began to accumulate rapidly within the Sanmenxia Reservoir, significantly reducing the reservoir's capacity.123

This massive accumulation of silt has limited the dam's ability to generate electricity, restricting power production to only a fraction of its total planned capacity. While reconstruction projects in 1965 and 1970 were undertaken to improve the dam's discharge capacity for both floodwater and silt, the ongoing issue of siltation has continued to hamper the project's functional capabilities and its effectiveness as a hydroelectric generator.123