Lateral bar (alternate or side bar)

Position: In-channel

 

Form

Bank-attached unit bar developed along low-sinuosity reaches of gravel- and mixed-bed channels. Bar surface is generally inclined gently towards the channel. These bars occur on alternating sides of the channel. They are generally longitudinally asymmetrical, and may or may not have an avalanche face on the downstream side.

 

Process description

Flow along a straight reach of river adopts a sinuous path. Bar length and width are proportional to these flows. Bar height is dictated by flow depth. Bars form by lateral or oblique accretion processes, with some suspended load materials atop (i.e. typically upward fining depositional sequence). They generally migrate in a downstream direction.