sediment
Large boulders and smaller rocks can be carried by a river. When rocks and sediment are displaced, it's called erosion.
deposition
Sediment is dirt, rocks, and sand carried by a river.
Large boulders and smaller rocks can be carried by a river. When rocks and sediment are displaced, it's called erosion.
The rock material carried away by a river is called sediment.
dredging?
Abrasion. (~the process of scraping or wearing away)
Sediment and small rocks are carried down in the river and are deposited.
Recent deposits by a river are known as alluvium, which can include a mix of rocks, gravel, sand, silt, and clay. These materials are carried by the river's current and eventually deposited along its banks or floodplains.
A river's load refers to the materials, such as sediment, rocks, and organic matter, that the river transports along its course. This load can be carried in several ways: dissolved load (minerals dissolved in water), suspended load (particles carried within the water column), and bed load (larger particles that roll or slide along the riverbed). The river's velocity and flow determine how much and what type of load can be carried, with faster flows able to transport larger particles.
rocks are there
The process you are describing is called erosion. Erosion occurs when rocks or soil are gradually worn away by natural forces such as water, wind, or ice.