Dredging

A dredging source can be used to control the maximum bed level in the domain area. By specifying the maximum allowed bed level in each element, the model will automatically remove the excess volume. The removed excess volume can be discarded or redistributed in the domain using a distribution map.

Maximum allowed bed level

The maximum allowed bed level can be specified as

·         Constant (in time and domain)

·         Constant in time, varying in domain

·         Varying in time and domain

If the maximum allowed bed level is specified by a constant the value is spec­ified directly.

For the case with constant in time but varying in domain you have to prepare a data file containing the maximum allowed bed level. 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 piecewise constant inter­polation is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data.

For the case with varying in time and domain you have to prepare a data file containing the maximum allowed bed level. 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 piecewise constant interpola­tion is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data. The data must cover the complete simulation period. The time step of the input data file does not, however, have to be the same as the time step of the hydrodynamic simulation. A linear interpolation will be applied if the time steps differ.

Distribution factor

By specifying a distribution map you can redistribute the removed excess vol­ume from the bed level source to other places in the domain. The resulting amount of material in each element is controlled by a distribution factor. The distribution factor can be specified in three ways:

·         Constant (in time and domain)

·         Constant in time, varying in domain

·         Varying in time and domain

If the distribution factor is specified by a constant the value is specified directly.

For the case with constant in time but varying in domain you have to prepare a data file containing the distribution factor. 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 piecewise constant interpolation is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data.

For the case with varying in time and domain you have to prepare a data file containing the distribution factor. 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 piecewise constant interpolation is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data. The data must cover the complete simulation period. The time step of the input data file does not, however, have to be the same as the time step of the hydrodynamic simulation. A linear interpolation will be applied if the time steps differ.

NOTE: The distribution factors within the distribution map do not need to sum up to 1 (or 100). The total excess volume of sediment is redistributed in the domain according to a weighted distribution factor in each element.