WMS:GSSHA Storm Drain

The "GSSHA Storm Drain" coverage in WMS is used to hold feature arcs, nodes, and polygons related to subsurface drainage network or agricultural tile drain modeling.

GSSHA Storm Drain Coverage

In WMS 10.0 and later, Pipe arc types are no longer defined in a GSSHA coverage. They are defined in a GSSHA Storm Drain coverage so pipes drawn inside of WMS do not impact stream elevations in the GSSHA coverage.

File:GsshaStormDrainCoverageFig1.png

The GSSHA Storm Drain coverage has been separated from the GSSHA Coverage

If there is an existing GSSHA project with pipe arcs in a GSSHA coverage, WMS converts these arcs to generic arcs in the GSSHA coverage and copies the pipes into a GSSHA Storm Drain coverage. This transition should work seamlessly, without needing to do any work. Existing files with a GSSHA storm drain coverage can be read and should be able to be re-written and run in GSSHA from the WMS interface. It may be desirable to delete the generic arcs that were pipes and are left in the GSSHA coverage, or leave them there. WMS does not put up any messages when converting a file from the single coverage to the GSSHA and GSSHA Storm Drain coverage model.

Pipe Junction

The following data required for modeling storm/tile drain systems is entered at pipe junction nodes.

Super Junction Number

The super junction number is computed by WMS by using the GSSHA | Number Storm Drain menu command in the 2D Grid module, but can also be manually edited at any time.

Invert Elevation

Enter the invert elevation in meters of the pipe at this location.

Manhole Area

Enter the manhole area in m².

Inlet Type

The inlet type is used to account for flow into or out of the pipe network. Select 0-9 grate inlets to specify the amount of flow into the pipe network. Choose Empty to grid cell or Empty to channel to indicate that flow from the pipe network will be routed either back to the grid cell or into the 1D stream network.

Storm/Tile Drain Dialog

The GSSHA Storm/tile drain dialog.

The GSSHA Storm/tile drain dialog is accessible by clicking the Edit parameters... button to the right of Storm/tile drain in the list of other parameters in the GSSHA Job Control Parameters dialog. It has three options:

• Allow GSSHA to redistribute Superlink Vertices – Turn on to allow GSSHA to redistribute superlink vertices.
• Groundwater flow computation method section
  • "Cooke Method (default)" – Uses the Cooke Method for computing groundwater flow.
  • "Drainmod Method" – Uses the DRAINMOD method developed by R.W. Skaggs.