Dynamics of River Mouth Deposits

Bars and subaqueous levees often form at river mouths due to high sediment availability . Once t hese deposits emerge and develop into islands, they become important elements of the coastal landscape, hosting rich ecosystems. Sea - level rise and sediment starvation are jeopardizing these landforms , motivating a thorough analysis of the mechanisms responsible for their formation and evolution . H ere we present recent studies on the dynamics of mouth bars and subaqueous levees. The rev iew encompasses both hydrodynamic and morphological results. We first analyze the hydrodynamics of the water jet exiting a river mouth. We then show how this dynamics coupled to sediment transport leads to the formation of mouth bars and levees. Specifical ly, we discuss the role of sediment eddy diffusivity and potential vorticity on sediment redistribution and related deposits. The effect of w aves, tides, sediment characteristics , and vegetation on river mouth deposits is included in our analysis, thus acc ounting for the inherent complexity of the coastal environment where these landforms are common . Based on the results presented herein, we discuss in detail how river mouth deposits can be used to build new land or restore deltaic shorelines threatened by erosion.