Hard Bed Option

The hard bed option will prevent erosion from occurring below the initial bed elevation in the designated sections. If required, a HARD BED data block can be specified in any location after the General System Parameters within the sediment module datafile.

Note that where a hard bed prevents erosion, it will also prevent an armour layer forming when the SORTED algorithm is selected in the General System Parameters at the top of the datafile.

If method 2 or 3 is selected for updating the bed, then the channel shape may change. The hard bed option will then prevent erosion below the original elevation at the minimum bed level at the section, but erosion of the banks may occur. An example of the structure of this section of the file is shown in Figure 7.

Datafile Format - Hard Bed Option

Line 1                                                      keyword 'HARD BED'

Line 2                                                      n₁

Line 2                                                      label_i

where

n₁= number of ensuing node labels

label_i= node labels of hard bed sections