SMS:TUFLOW Boundary Conditions

TUFLOW Boundary conditions may be defined at nodes, arcs, or polygons in a Boundary Conditions Coverage.

Boundary Condition Locations

1D Boundary Conditions at Nodes

Boundary conditions defined at points are 1D boundary conditions and must be placed at the same location as a 1D boundary node. (See Snapping Feature Objects) The boundary condition information is specified in the BC Node Attributes dialog.

2D Boundary Conditions at Arcs

Arcs can be used to define 2D Boundary conditions applied to the 2D domain. The BC attributes are specified in the BC Arc Attributes dialog.

2D Boundary Conditions for Polygons

Polygons can be used to define rainfall applied to 2D domains or to specify active/inactive information for 2D domains. The BC Polygon Attributes dialog specifies the type of information stored with the polygons.

Convert GIS Rainfall Data to TUFLOW BC Polygons

GIS files containing TUFLOW rainfall data may be imported into SMS and a Boundary Condition coverage with the data assigned to polygons will be created. The data for each polygon should be contained in the following columns: 8 STARTYEAR – year of first data point (integer)

• STARTMONTH – month of first data point (integer)
• STARTDAY – day of first data point (integer)
• STARTHOUR – hour of first data point (integer)
• STARTMIN – minutes of first data point (integer)
• STARTSEC – seconds of first data point (integer)
• TIMESPAN – timespan between data point in minutes (integer)
• NUMRAINPTS – number of data points (integer)
• PT0 – data for the first point (double)
• PT1, PT2,... – data for each point

When converting GIS rainfall data to TUFLOW rainfall polygons, the user will be prompted to set a reference time. Each rainfall data point will be stored as total mm for each interval of time (hrs) from the reference time.

Events

File:TUFLOW BC Events.jpg

TUFLOW BC Event dialog

Every boundary condition should be setup for each event that will be used with the boundary condition. The events can be defined by clicking on the Add/Remove Events button. The list of events is common to all the boundary conditions in the project.

Options

Depending upon the type of boundary condition, there are several additional boundary condition options.

• Override Component Identifier – SMS creates a default unique boundary condition identifier based upon the coverage and id of the arc. You can override this value to more easily find boundary condition information in the TUFLOW check, and log files.
• Spline curve – If this option is on, TUFLOW will smooth the boundary condition curve using a spline algorithm. This should generally only be used for smooth, cyclic boundary conditions such as a tidal boundary.

Boundary Condition Types

The types of boundary conditions available depend upon whether the boundary condition is at nodes, arcs, or polygons.

Boundary Conditions

Type	Available Locations	Description
Not used	Points, Arcs	No boundary condition exists at the location.
Flow vs Time	Points, Arcs	Sets the flowrate as a curve through time.
Flow vs Wse	Points	Sets the flowrate based upon a relationship with the water surface elevation.
Wse vs Time	Points, Arcs	Sets the water surface elevation as a curve through time.
Wse vs Flow	Points, Arcs	Defines a relationship to determine the water surface elevation from a flowrate. The relationship can be specified or TUFLOW can compute it using water surface slope.
1D Flow/2D Water Level Connection (HX)	Arcs	Defines the interface between a 1D and 2D domain. See Combining 1D and 2D Domains.
Non-directional Flow vs Time	Arcs	Defines a flowrate that enters along each cell of the boundary.
Non-directional Flow vs Wse	Arcs	Defines a flowrate that enters along each cell of the boundary based upon a relationship to the water surface elevation.
Flow Source from 1D model (SX)	Arcs	Defines an interface between a 1D and 2D domain which is often useful for curlverts rather than using the 1D Flow/2D Water Level Connection.
Flow/Rainfall over Area	Polygons	Defines either an amount of flow entering the polygon (applies to all wet cells or lowest cell if none) or rainfall amounts (applies to all cells in the polygon).
Cell Codes	Polygons	Specifies whether cells are active or inactive and whether or not they will be included in the mesh output files.

Related Topics

• TUFLOW
• TUFLOW Coverages