Simultaneous measurements of tidal straining and advection at two parallel transects far downstream in the Rhine ROFI

This study identifies and unravels the processes that lead to stratification and destratification in the far field of a Region of Freshwater Influence (ROFI). We present measurements that are novel for two reasons: (1) measurements were carried out with two vessels that sailed simultaneously over two cross-shore transects; (2) the measurements...

Do intertidal flats ever reach equilibrium?

Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying...

A finite volume approach for shallow water flow accounting for high-resolution bathymetry and roughness data

This study presents a finite volume hydrodynamic model for shallow water flow that computes on a coarse grid, but accounts for high-resolution bathymetry and roughness variations on a subgrid. The detailed information can be incorporated by using the assumption of a uniform flow direction and a uniform friction slope within a part of a coarse...

Observations and modeling of steep-beach grain-size variability

Novel observations of surface grain-size distributions are used in combination with intra-wave modeling to examine the processes responsible for the sorting of sediment grains on a relatively steep beach (slope?=?1:7.5). The field observations of the mean grain size collected with a digital camera system at consecutive low and high tides for a 2...

A conceptual framework for shear flow–induced erosion of soft cohesive sediment beds

This paper proposes a conceptual framework for erosion of cohesive sediment beds. We focus on cohesive beds, distinguishing between floc erosion, surface erosion, and mass erosion. By (our) definition, surface erosion is a drained soil mechanical process, whereas mass erosion occurs under undrained conditions. The eroding shear stress is modeled...

A stochastic formulation for erosion of cohesive sediments

The linear formulation for erosion E = M(?b??c), often applied in engineering applications, has two properties, which do not always comply with field and laboratory observations, they are as follows: (1) The erosion rate is zero below the critical bed shear stress ?c and increases linearly with bed shear stress ?b, when exceeding the critical...

The Relevance of a Back-Scatter Model for Depth-Averaged Flow Simulation

This study demonstrates the importance of a sophisticated sub-grid model when performing a depth-averaged unsteady RANS simulation of a shallow flow. The reduction of resolution and the spatial dimensions exclude important physical processes as present in three-dimensional turbulence. Especially the effect of the bottom turbulence on the...

A linear approach for the evolution of coherent structures in shallow mixing layers

The development of large coherent structures in a shallow mixing layer is analyzed. The results are validated with experimental data obtained from particle tracking velocimetry. The mean flow field is modeled using the self-similarity of the velocity profiles. The characteristic features of the down-stream development of a shallow mixing layer...