Wetlands are specified in GSSHA by including the wetland mapping table in the mapping table file. An index map related to the mapping table can be developed as described below.
Wetlands are set up in WMS through creating a wetlands polygon. This polygon is in the same coverage as the stream data for the GSSHA simulation. When creating the polygon, be careful not to click on or very close to any stream arcs. Once the polygon is created, set its attributes to be a wetlands polygon. The following parameters must be defined and are uniform across the polygon extent.
- Initial Depth (mm) - Initial depth of water in the cell, from the bottom of the retention depth.
- Retention Depth (mm) - Depth of the peat layer. This value is actually subtracted from the elevation grid inside of GSSHA.
- Retention Depth Hydraulic Conductivity (m/day) - Lateral seepage hydraulic conductivity through the peat layer.
- Vegetation Height (mm) - Height of the vegetation above the peat layer.
- Vegetation Height Hydraulic Conductivity (m/day) - Lateral seepage hydraulic conductivity through the bottom of the vegetation.
- Inundated Vegetation Manning's Roughness - Manning's roughness value after the vegetation is overtopped (and possibly flattened.)
To visualize the wetland cells that underlie the polygon, turn on the wetland cells option in the 2D Grid Display Options dialog. WMS creates a new wetland mask map consisting of zeros, no wetland, and integer numbers specified from the wetland polygons. Wetland routing occurs whenever GSSHA encounters a specified wetland cell and using the wetland parameters, as specified above, related to the cell wetland mask number.