Data

Erosion description
Critical shear stress for erosion
Data format

Erosion description

Hard bed description

For a dense consolidated bed the erosion rate for the j´th layer is described as (Partheniades, 1989).

(7.17)   

where  is a probability ramp function of erosion, E₀ is the erosion coeffi­cient and E_m is the power of erosion.

(7.18)   

Soft bed description

For a soft, partly consolidated bed the erosion rate for the j’th layer is described as (Parchure & Mehta, 1985):

(7.19)   

where a is a coefficient.

Critical shear stress for erosion

The criteria for erosion is that the critical shear stress for erosion is exceeded corresponding to the driving forces exceeding the stabilising forces. The criti­cal shear stress for erosion is constant throughout the simulation.

Data format

The erosion parameters must be specified as a Constant in time for each bed layer.

The critical shear stresses for erosion for each layer can be specified as:

·         Constant (in domain)

·         Varying in domain

For the case with varying in domain you have to prepare a data file containing the critical bed shear stresses before you set up the hydrodynamic simula­tion. The file must be a 2D unstructured data file (dfsu) or a 2D grid data file (dfs2). The area in the data file must cover the model area. If a dfsu-file is used, piecewice constant interpolation is used to map the data. If a dfs2-file is used, bilinear interpolation is used to map the data.

Recommended values