The set of mechanisms that operate as a result of water flow within (and at times beyond) a stream channel, bringing about the erosion, transfer, and deposition of sediment. The erosional processes include: the displacement of bed particles through drag and lift forces; corrasion, the wearing away of bed and banks as mobile sediment is dragged against them; and bank collapse, a consequence of hydraulic activity. Transport processes include the transfer of material in solution and suspension, and by saltation. Depositional processes act when the immersed weight of a particle is greater than the force driving it down-channel.