The bed material load is the portion of the sediment that is transported by a stream that contains material derived from the bed. Bed material load typically consists of all of the bed load, and the proportion of the suspended load that is represented in the bed sediments. Its importance lies in that its composition is that of the bed, and the material in transport can therefore be actively interchanged with the bed. For this reason, bed material load exerts a control on river channel morphology. Bed load and wash load (the sediment that rides high in the flow and does not extract non-negligible momentum from it) together constitute the total load of sediment in a stream.
^R.J. Garde, K.G. Ranga Raju. (2000). Mechanics of sediment transportation and alluvial stream problems. New Delhi: New Age International. p. 262. ISBN978-81-224-1270-3.
^Belperio, A (1979). "The combined use of wash load and bed material load rating curves for the calculation of total load: An example from the Burdekin River, Australia". CATENA6 (3-4): 317. doi:10.1016/0341-8162(79)90027-4.