Bed Forms (Fluvial)

Bed form can be defined as the feature developed on the bed of an alluvial channel due to the flow of water. Bed forms are structures that are molded on beds where deposition takes place due to flowing water. Natural channels rarely have flat beds. When water carries loose grains across a horizontal bed of unconsolidated sediment, regular geometric patterns develop on the surface of the bed. Any particle that is larger than approximately 0.7-mm diameter will form visible topographic features on the riverbed or streambed. Shear stresses above the critical for transport will mold cohesion-less beds into discernible forms whose geometry depends on flow characteristics which in turn are influenced by those forms, resulting in complex feedback relationship (Knighton, 1998). Various concealed bed forms most commonly associated with sand bed are ripples, dunes, plane bed, and antidunes. Pebble clusters, transverse ribs, riffle-pool sequence, and step-pool systems are some of the bed forms...