Comment:

If it is desirable to model the protective effects of dikes, an additional raster layer must be specified that indicates whether each cell is protected by dikes or not. This can be derived from NWI special modifier “h=Diked/Impounded.” As noted above, in the section on Levee and Dike inputs, this raster can also be set up to specify dike locations and elevations, or a combination of the two dike-modeling options may be used. It is possible to input the elevation of the dikes layer to more realistically model water flows as function of sea level. In the traditional model, if a cell is defined as protected by a dike or levee it is not permitted to change. The existence of these dikes can severely affect the ability of wetlands to migrate onto adjacent shorelines. Diked wetlands are assumed to be subject to inundation when relative sea-level change is greater than 2 m, although that assumption can be changed. In SLAMM 6.7 it is also possible to enter the elevation of the levees or dikes on a cell by cell basis or to use a connectivity algorithm along with cell elevations to determine when a dike is overtopped.