1. Retain sediment (including boulders )) to regulate the water-sediment balance in the channel, avoiding harm to downstream areas and facilitating the management of downstream river channels. 2. Raise the erosion benchmark at the dam site, slow down the riverbed slope of the upstream accumulation section, widen the riverbed, and reduce flow velocity, thereby decreasing the erosive capacity of the water flow. 3. Stabilize bank collapses and landslides, reduce the scouring and impact force of debris flows, prevent upstream erosion, and inhibit the development scale of debris flows. 1. Retain sediment (including boulders )) to regulate the water-sediment balance in the channel, avoiding harm to downstream areas and facilitating the management of downstream river channels. 2. Raise the erosion benchmark at the dam site, slow down the riverbed slope of the upstream accumulation section, widen the riverbed, and reduce flow velocity, thereby decreasing the erosive capacity of the water flow. 3. Stabilize bank collapses and landslides, reduce the scouring and impact force of debris flows, prevent upstream erosion, and inhibit the development scale of debris flows. 1. Retain sediment (including boulders )) to regulate the water-sediment balance in the channel, avoiding harm to downstream areas and facilitating the management of downstream river channels. 2. Raise the erosion benchmark at the dam site, slow down the riverbed slope of the upstream accumulation section, widen the riverbed, and reduce flow velocity, thereby decreasing the erosive capacity of the water flow. 3. Stabilize bank collapses and landslides, reduce the scouring and impact force of debris flows, prevent upstream erosion, and inhibit the development scale of debris flows.