Particles in a flowing fluid that are transported along the bed
The term bed load or bedload describes particles in a flowing fluid (usually water) that are transported along the stream bed. Bed load is complementary to suspended load and wash load.
Bed load moves by rolling, sliding, and/or saltating (hopping).
Generally, bed load downstream will be smaller and more rounded than bed load upstream (a process known as downstream fining). This is due in part to attrition and abrasion which results from the stones colliding with each other and against the river channel, thus removing the rough texture (rounding) and reducing the size of the particles. However, selective transport of sediments also plays a role in relation to downstream fining: smaller-than average particles are more easily entrained than larger-than average particles, since the shear stress required to entrain a grain is linearly proportional to the diameter of the grain. However, the degree of size selectivity is restricted by the hiding effect described by Parker and Klingeman (1982),[1] wherein larger particles protrude from the bed whereas small particles are shielded and hidden by larger particles, with the result that nearly all grain sizes become entrained at nearly the same shear stress.[2][3]
Experimental observations suggest that a uniform free-surface flow over a cohesion-less plane bed is unable to entrain sediments below a critical value of the ratio between measures of hydrodynamic (destabilizing) and gravitational (stabilizing)
forces acting on sediment particles, the so-called Shields stress . This quantity reads as:
,
where is the friction velocity, s is the relative particle density, d is an effective particle diameter which is entrained by the flow, and g is gravity. Meyer-Peter-Müller[4] formula for the bed load capacity under equilibrium and uniform flow conditions states that the magnitude of the bed load flux for unit width is proportional to the excess of shear stress with respect to a critical one . Specifically, is a monotonically increasing nonlinear function of the excess Shields stress , typically expressed in the form of a power law.
^Parker, Gary; Klingeman, Peter C. (2010). "On why gravel bed streams are paved". Water Resources Research. 18 (5): 1409–1423. doi:10.1029/WR018i005p01409.
^Ashworth, Philip J.; Ferguson, Robert I. (1989). "Size-selective entrainment of bed load in gravel bed streams". Water Resources Research. 25 (4): 627–634. Bibcode:1989WRR....25..627A. doi:10.1029/WR025i004p00627.
^Parker, Gary; Toro-Escobar, Carlos M. (2002). "Equal mobility of gravel in streams: The remains of the day". Water Resources Research. 38 (11): 1264. Bibcode:2002WRR....38.1264P. doi:10.1029/2001WR000669.
^Meyer-Peter, E; Müller, R. (1948). Formulas for bed-load transport. Proceedings of the 2nd Meeting of the International Association for Hydraulic Structures Research. pp. 39–64.
complementary to suspended load and wash load. Bedload moves by rolling, sliding, and/or saltating (hopping). Generally, bedload downstream will be smaller...
segregated into bedload, suspended load, and wash load. They may sometimes also be segregated into bed material load and wash load. Bedload moves by rolling...
are included in the load of a river system are the following: dissolved load, wash load and bed material load. The bed material load is the portion of the...
load during transportation due to the very similar process. The wash load never touches the bed even outside of a current. The boundary between bed load...
Stream load is a geologic term referring to the solid matter carried by a stream (Strahler and Strahler, 2006). Erosion and bed shear stress continually...
Wash load is similar to a suspended load, but wash load sediment never interacts with the bedload. All of the sediment in the wash load stays suspended...
Albert obtained a doctorate in technical science. His doctoral thesis "BedLoad Transport as a Probability Problem" (Der Geschiebetrieb als Wahrscheinlichkeitsproblem)...
sediment to move (see Initiation of motion), it will move along the bed as bedload by rolling, sliding, and saltating (jumping up into the flow, being...
exceptions. Despite the size and engine displacement, most kei trucks have a bedload capacity of nearly 350 kg (770 lb). For export markets, kei trucks are...
rocks and particles in sediment transport, whether in suspension or as bedload, and in sediment deposits. Clastic sedimentary rocks are rocks composed...
The sediment particles within foreset beds consist of larger and more variable sizes, and constitute the bedload that the river moves downstream by rolling...
plane bed" features are flat and characterized by a unidirectional flow with high rates of sediment transport as both bedload and suspended load. Upper...
level 'bed' with no sides or roof. This allows for quick and easy loading of goods, and consequently they are used to transport heavy loads that are...
sediments are picked up by run off and carried as suspended matter or bedload. Localized flooding may be caused or exacerbated by drainage obstructions...
minerals. The sediment that makes up these rocks was transported as bedload, suspended load, or by sediment gravity flows. Siliciclastic sedimentary rocks...
contains little organic matter and sediment and is generally very clear. The beds of the rivers are generally composed of clean, compacted gravel and flints...
the fluid. The required Rouse numbers for transport as bedload, suspended load, and wash load, are given below. Sediment transport Sediment Dimensionless...
in grams)/ mL of sample * 1,000,000 Bedload – Particles in a flowing fluid that are transported along the bed Settleable solids – Process by which particulates...
(2004). "A mechanistic model for river incision into bedrock by saltating bedload" (PDF). Water Resources Research. 40 (6): W06301. Bibcode:2004WRR....40...
A sofa bed or sofa-bed (in the US often called a sofabed, hide-a-bed, bed-couch, sleeper-sofa, or pullout sofa) is a multifunctional furniture typically...
Sediments are picked up by the run-off and carried as suspended matter or bed-load. Muddy floods are typically a hill-slope process, and should not be confused...
2nd episode of The Batman Traction (geology), a process which transports bedload through a channel Tracktion This disambiguation page lists articles associated...
sediment load or slope is reached. On timescales long enough for the river to evolve, a sustained increase in sediment load will increase the bed slope of...
process: dissolved load, suspended load, and bedload. The process that most affects a bedrock river is the suspended load. Suspended load is the grains that...
detached from the overlying bed, resulting in apparently isolated masses of the overlying material floating in the lower bed. Load casts were scientifically...