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Table Of Contents
Chapter 5 Working with Hydrology Commands
610
Sampling the Cross Sections from the Current
Surface and Output in the HEC-2 Format
Use the HEC2-Single command to sample cross sections from a surface and
output the information to an ASCII file in the HEC-2 format. The HEC2-Single
command provides functionality not found in the Plot Single command.
TIP
You can use the Entity option to create skewed sections. This is useful when
dealing with stream, river, and floodplain cross sections, or any condition
in which the cross sections are usually not perpendicular to the central
channel.
To sample cross sections from the current surface for output in HEC-2 Format
1 From the Hydrology menu, choose HEC2 Output ä HEC2  Single.
NOTE
If no current surface is in use, then the Select Surface dialog box is
displayed. Select the surface on which to base the cross sections in the
Select Surface box, and then click OK to continue.
The following prompt is displayed:
First point (or Entity):
2 Do one of the following to select the cross section sampling line:
n
Select two cross section sampling line endpoints in your drawing.
n
Type Entity to display the following prompt:
Select (Entity/POints) <Entity>:
3 Press ENTER, and then select the entity from the drawing to use as the cross
section sampling line.
When you use the Entity option, only one entity per cross section is allowed. If
you select a polyline, then the sampling for the cross section starts from the end
closest to the initial polyline selection point.
For a skewed cross section, you must select a two-segment, three-vertex
polyline. When using this type of polyline, the second or middle vertex
becomes the midpoint of the defined section. Depending on how it is drawn,
you can have left and right reaches at different distances from the center. In this
case, the cross section is not sampled from the start point to the endpoint, but
instead is sampled from vertex to vertex. You can define the angle between the
first and second segment of the polyline to create a skewed section of any
configuration.
NOTE
If you need to create perpendicular sections that have varying reach
distances on the left and right, make sure the angle between the segments
is 180 degrees.
After you select the cross section sampling line, the following message is
displayed:
Line added successfully.