User:Jcreer/SMS:GSSHA Coverages

The GSSHA model makes use of the simulation based modeling approach. This requires defining coverages in the Map module to build the components for use in the GSSHA simulation.

A GSSHA simulation makes use of the following coverage types:

• Boundary Conditions

Boundary Conditions Coverage

The GSSHA Boundary Condition map coverage allows setting boundary condition properties for feature arcs and feature points.

Arc Properties

To assign boundary conditions properties to arcs, select an arc, then double-click on it.

Example of GSSHA Arc Properties dialog

• Channel – User defines the channel properties here.
  • Channel type – Choose channel type here.
    • "Trapezoidal" – Trapezoidal channels are used to define channel routing in GSSHA models. SMS automatically assigns a link number to trapezoidal channel arcs.
      • Manning's n (MANNINGS_N): – Manning's n roughness coefficient. Enter the Manning's n integer for trapezoidal channels here.
      • Depth (m) (BANKFULL_DEPTH): – The maximum depth of the channel represented by the GSSHA feature arc in meters.
      • Bottom width (m) (BOTTOM_WIDTH): – The width of the bottom of the channel in meters.
      • Side slope (H:V) (SIDE_SLOPE): – The horizontal value to one unit of vertical rise.
    • "Cross-section" – The profile of irregular cross sections are defined using XY coordinate pairs.
      • Manning's n (MANNINGS_N): – Manning's n roughness coefficient. Enter the Manning's N integer for cross-sections here.
      • Cross section: – Click below to define the cross section by inputting or importing data.
        • Edit XY Series – Selecting this bring up the XY Series Editor dialog.
  • Most downstream arc of stream network – Turning this on assigns one arc as the most downstream and directs all flow from other arcs towards the selected arc.
  • Output hydrograph at downstream end – Turning this on will allow creation of a hydrograph at the downstream end.
  • Specify point source at upstream end – Turning this on will specify one
• Overland Flow BC – Set the overland flow boundary conditions for an arc.
  • Overland Flow BC Type: – A drop-down list with the following options:
    • "Constant slope" – Select this to define all channels with the same slope.
      • Constant slope: – Enter decimal value here
    • "Constant stage (water surface elevation)" – Select this to define a constant water surface elevation.
      • Constant stage (water surface elevation): – Enter decimal value here
    • "Variable stage (water surface elevation)" – Define a WSE curve
      • Variable stage (water surface elevation) – Click below to input or import parameters for WSE.
        • Edit XY Series... to bring up the XY Series Editor dialog.
    • "Variable flow (cms discharge)" – Define a discharge curve in cubic meters per second.
      • Variable flow (cms discharge): – Click below to input or import parameters for cms discharge.
        • Edit XY Series... to bring up the XY Series Editor dialog.
    • "Variable flow (cfs discharge)" – Define a discharge curve in cubic feet per second.
      • Variable flow (cfs discharge): – Click below to input or import parameters for cfs discharge.
        • Edit XY Series... to bring up the XY Series Editor dialog.

Point Properties

To assign boundary conditions properties to a point, select a point, then double-click on it.

Example of GSSHA Point Properties dialog

Properties set here apply only to points, not nodes.

• Overland Flow BC – Set the overland flow boundary conditions for an arc.
  • Overland Flow BC Type: – A drop-down list with the following options:
    • "Constant slope" – Select this to define all point with the same slope.
      • Constant slope: – Enter decimal value here
    • "Constant stage (water surface elevation)" – Select this to define a constant water surface elevation for all points.
      • Constant stage (water surface elevation): – Enter decimal value here
    • "Variable stage (water surface elevation)" – Define a WSE curve through a point
      • Variable stage (water surface elevation) – Click below to input or import parameters for WSE.
        • Edit XY Series... to bring up the XY Series Editor dialog.
    • "Variable flow (cms discharge)" – Define a discharge curve in cubic meters per second through a point.
      • Variable flow (cms discharge): – Click below to input or import parameters for cms discharge.
        • Edit XY Series... to bring up the XY Series Editor dialog.
    • "Variable flow (cfs discharge)" – Define a discharge curve in cubic feet per second through a point.
      • Variable flow (cfs discharge): – Click below to input or import parameters for cfs discharge.
        • Edit XY Series... to bring up the XY Series Editor dialog.