Me! what relationship exists between the speed that water flows and the size of material that it can carry?

The speed of the water flows determines the size of the material that can be carried by it and moved down its flow or deposited. It is very simple really, the bigger the speed of the water flows, the bigger the push force it has, so it can carry bigger size material with it, and vice versa, the smaller the speed of the water flows, the lesser the push force, so it can carry only smaller size material with it.