Bedform

A bedform is a geometrical feature of a sediment bed, such as a ripple or dune, shaped by flowing water or wind. Its form reflects interactions among flow, sediment, and the bed.

Sediment transport: The movement of sediment by fluids, gravity, or other processes. Transport supplies the grains that build bedforms and carries them across the bed.
Wave ripple: A sediment ripple shaped by oscillatory water motion beneath surface waves. Its commonly near-symmetrical profile contrasts with current ripples.
Bedform roughness: The resistance to flow produced by the size, shape, and arrangement of bedforms. Bedform geometry contributes to drag and sets water levels and flow energy.
Antidune: A bedform that travels upstream in phase with surface waves in rapid flow. Its upstream migration contrasts with the usual downstream motion of dunes.
Shields parameter: A dimensionless measure comparing fluid forces on sediment grains with the grains’ submerged weight. It helps predict when flow can mobilize grains and initiate bedform development.
Dune (bedform): A large-scale sediment ridge formed by wind or flowing water. Dunes are larger bedforms whose migration can strongly influence flow resistance.
Dune tracking: The measurement of moving dunes to estimate sediment transport and landscape change. Observed migration rates turn bedform motion into estimates of sediment flux.
Current ripple: A small, asymmetrical sediment ridge produced by a unidirectional current. Its scale and formation conditions distinguish ripples from larger dunes.
Bedload: Sediment transported along or close to a bed by rolling, sliding, or short hops. Bedload grains accumulate and migrate to form many ripples and dunes.
Upper-stage plane bed: A nearly flat sediment bed under strong flow, often marked by grain-scale transport. It marks a high-flow condition in which organized dunes may disappear.

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