WMS:Computing Basin Data (TINs)

After defining basin boundaries, attributes such as basin areas and slope and stream lengths and slopes can be computed using the Compute Basin Data command. These are all geometric parameters used in defining basins and routing networks in HEC-1 and TR-20. If the TIN is edited or sub basin configuration changed, the drainage data must be recomputed using this command.

Once computed, they can be displayed along with the basins in the Graphics Window or written to a file using the Export File command found in the File menu. By default, basin IDs and areas are displayed after computing drainage data. The other attributes can be toggled on for display in the Basin Attributes dialog accessed from within the Drainage Display Options dialog.

Units

When the Compute Basin Data command is given the Model and Parameters Units dialog appears allowing you to specify the current units of the model (TIN vertices) and the units you wish to use for computed parameters. TIN vertices must either be in feet or meters, but the computed areas and lengths can be given separate units. If you wish to change the units of computed parameters at a later point you must recompute the basin parameters with different selections. You may wish to convert the coordinate system prior to computing the basin data.

Related Topics

• Compute Basin Data
• Defining Basins
• Delineation with TINs
• Delineation with DEMs
• Units