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Draw Reaches Command

A reach is a section of a stream or river along which similar hydrologic routing conditions exist, such as discharge, depth, area, and slope.

In GeoHECHMS, the Draw Reaches command allows the user to interactively draw polylines on the Map View as reaches. After drawing reaches, the user can name an individual reach with a unique ID and can also assign a reach slope and downstream invert elevation.

Follow the steps below to use the Draw Reaches command:

  1. From the Input ribbon menu, select the Routing Reaches menu item and then the Draw Reaches menu command.
  2. The Draw Reaches dialog box will be displayed.

The following sections describe how to use the Draw Reaches command and how to interact with the above dialog box.

Drawing Reach Polylines

Selection of a naming method from the Reach Specifications settings should be considered before drawing reaches. If the Reach ID radio button option is selected, then only one reach can be drawn at a time. By contrast, if the Auto-name reach ID radio button option is selected, the user can interactively and continuously draw reaches on the Map View without having to purposefully interact with the dialog box each time a reach needs to be identified and named.

Drawing Individual Reaches

To draw reaches one at a time—naming each individual reach before drawing the next reach—follow these steps:

  1. From the Reach Specifications settings section, select the Reach ID radio button option.
  2. From the Reach polyline entry, click on the [Draw] button and the dialog box will temporarily disappear.
    The user can turn on the Draw curvilinear polyline check box to add the curvilinear segments or can press the [Ctrl] key to enable the straight segments while drawing the polylines.
  3. The status line (shown under the Map View) will prompt you to draw a reach on the Map View. From the Map View, click on the point to start the reach drawing.
  4. After drawing the reach, the user can either press the [Enter] key or can right-click and select Done from the displayed context menu. The user can press the [Esc] key to abort the draw command.
  5. After completing the reach drawing, the user is immediately returned to the Draw Reaches dialog box, and the Reach polyline read-only field will be changed from Not Drawn to Drawn.
  6. The user can also reverse the direction of the drawn reach using the [Reverse Direction] button.
    The [Ctrl+E] keys can be used to repeatedly draw reaches on the Map View.
  7. After entering the Reach ID, press the [Enter] key or click on the [Apply] button.

Continue this process of drawing one reach at a time until all the reaches have been drawn on the Map View. When finished, click the [Close] button to close the Draw Reaches dialog box.

Drawing Multiple Reaches

To draw multiple reaches continuously and without prompting from the software to name each individual reach, follow these steps:

  1. From the Reach Specifications settings section, select the Auto-name reach ID radio button option.
    The different naming formats present in the Auto-name reach ID option are as follows:

    • Reach ID prefix: This option allows a prefix to be added to the front of the reach ID.
    • Reach ID digits: This option permits specification of a set number of digits to use for the reach ID. For example, using 3 digits causes the reach ID to be of the format 001, 002, etc.
    • Next available reach ID: This entry defines the next element ID number to be used.
    • Reach ID increment: This entry defines the increment to use when numbering elements. The default value is 1.
    • Reach ID suffix: This option allows a suffix to be added to the end of the reach ID.
    • Reach ID preview: This entry provides a preview of the reach naming specifications defined above.
  2. From the Reach polyline entry, click on the [Draw] button and the dialog box will temporarily disappear.
  3. The status line (shown under the Map View) will prompt you to draw a reach on the Map View. From the Map View, click on the point to start the reach drawing.
  4. After drawing the first reach, the status line (shown under the Map View) will prompt you to draw the next reach.
  5. Continue this process of drawing one reach at a time until all the reaches have been drawn on the Map View. When finished, right-click and choose [Done] from the displayed context menu or press the [Enter] or [Esc] key. You will be returned to the dialog box. Click the [Close] button to close the dialog box.
  6. The drawn reaches will be displayed on the Map View.

Assign Reach Slope & Downstream Invert Elevation

This section of the dialog box allows the user to assign an invert elevation using a terrain model while drawing reaches. Define this section before drawing reaches in order to assign invert elevations later.

To assign an invert elevation, the Terrain elevation source dropdown combo box supports the following surface types:

  • Elevation grids
  • LandXML data
  • TIN surfaces

The user can also apply the elevation offset by enabling the Apply elevation offset check box entry. To lower the reaches for specific circumstances—a manhole bottom elevation, for example—define a negative offset value.

About the Author Chris Maeder

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