Mouth bar

[1] River mouth bars form because the cross-sectional area of the expanding sediment-laden outflow increases, and consequently, the sediment transport rate down the jet centerline decreases basinward as flow progresses from confined to unconfined.

[1] Sediment erosion and deposition dynamics in estuarine region, consequently the formation and growth of mouth bars, are affected by several natural and artificial factors.

On the other hand, since fine sediments are generally transported in a suspended form, they can be carried further and disperse widely, and most of the time, lead to levee construction.

When tidal energy is much higher than the fluvial one, hydrodynamics of the jet exiting the river mouth, dominating the sediment deposition, are highly affected.

[9][10][11] River discharge, tides and waves can also simultaneously affect the outflow dynamics depending on buoyancy, which play an important role on the evolution of mouth bars.

[10] Lateral spreading of turbulent jet enhanced by increasing frictional resistance in shallow inshore waters, also associated with high bed load, produces almost triangular “middle ground bar” in the mouth of the river causing the channel to bifurcate.

Flood and ebb-dominated sediment transports generate a broad, discontinuous, radial mouth bar dominated by large tidal ridges separated by deep channels.

[24][25] On the Mississippi Delta, in order to eliminate land loss and mitigate coastal erosion, artificial diversions, reconnecting river to the deltaic wetland, have been constructed.

[6][28][29][30] This example shows how extremely essential is to understand the dynamics of river mouth bars and the physics behind their formation for future discussions of new land development, estuary restoration, as well as mitigation measures for loss of deltaic wetlands.