Saltation is a mode of sediment transport in which particles, typically sand-sized materials, move along a surface through a series of short, intermittent jumps or bounces caused by the force of flowing water. In stormwater management and fluvial systems, saltation occurs when flow conditions are strong enough to lift particles off the bed briefly, but not sufficient to keep them fully suspended in the water column.
During saltation, a particle is dislodged from the bed by hydraulic forces and lifted into the flow, travels a short distance downstream, and then falls back to the surface. Upon impact, it may dislodge other particles, causing a chain reaction that contributes to continued sediment movement. This process results in a stepwise transport pattern that is more dynamic than simple rolling or sliding but less continuous than suspension.
Saltation typically occurs under moderate flow velocities where shear stress exceeds the threshold required to move sediment but is not high enough to maintain finer particles in suspension. It is most commonly associated with bed load transport and plays an important role in the movement of coarse sediment within channels, ditches, and stormwater conveyance systems.
In stormwater management, saltation contributes to channel erosion and sediment redistribution, particularly in areas with exposed soils or unprotected channel beds. It also influences how sediment is deposited in downstream locations, such as culverts, basins, and low-velocity zones. Understanding saltation is important for designing stable channels and effective sediment control measures, as it helps predict how and when particles will begin to move under varying flow conditions.