Sediment transport is the movement of inorganic and organic material by water. Within a system, there are 3 sediment load types, each occupying a different part of the water column. The 3 load types are suspended load, dissolved load, and bed load.
Suspended loads are the particles that are fully suspended in the water column. Suspended loads require flow to keep the particles in suspension and off the river bottom. Once flow slows or stops the lack of energy will result in the suspended load settling out. Suspended loads usually consist of very fine-grained sediments such as silts, clays, and depending on the flow, sand.
Dissolved load is the term used to describe dissolved ions. Common dissolved ions include calcium, bicarbonate, potassium, sulfate, and chloride. These ions are dissolved through groundwater and weathering processes.
Bed load is the sediment that never truly stays suspended within the water column but remains on the river or lake bottom. Bed load is often comprised of larger, heavier, and coarser sediments such as sand, gravel, cobble, and boulders. Bed load types are broken down further into specific transportation methods. The two-bed load transportation types are saltation and traction. Saltation is the term used when grains of sediment bounce along the bed floor. They are briefly lifted due to a difference in pressure however gravity quickly returns them back to the bed. Sediment moving via traction is in constant contact with the bed and moves via rolling or sliding, never becoming suspended.
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