2.0

Outputting Hydrology Data
605
5 Double-click a value in the Offset Time column to change the offset time. This
is the time it takes for the flow from the hydrographs drainage area to arrive at
the point of concern.
The Hydrograph Offset dialog box is displayed.
6 Enter the offset time, and then click OK.
7 In the Time Increment box, type the time increment to use for the combined
hydrograph.
8 If you want to include base flow in the hydrograph (flow from previous storms
that is not accounted for in the current storm event), then type the base flow
value in the Base Flow box. This base flow could be used to represent a constant
flow in a stream that was occurring before the storm event. For example, if you
enter a base flow of 5 cfs, then this amount is added to each time increment on
the hydrograph.
9 Click View to view the combined hydrographs in the Combine Hydrograph
Display dialog box.
Use the following options to change the appearance, output, or plot the data:
If you want to} Then click}
change the graphing settings Settings to open the Graph Settings
dialog box.
plot the hydrograph in the drawing Plot to open the Graphing Utility dialog
box.
output the data to an ASCII text file Output.
10 Click Close to return to the Combined Hydrograph Display dialog box.
11 Click Save to display the Save Hydrograph File dialog box.
12 Type a name for the combined hydrograph file, and then click Save. The
hydrograph is saved as .hdc file.
13 Click Close to end the command.
Outputting Hydrology Data
You can use the HEC2 Output commands on the Hydrology menu to define,
create, and plot cross sections based on elevations extracted from existing
AutoCAD Land Development Desktop surfaces. Commonly used for analyzing
stream or channel sections, the cross sections take advantage of the graphing
utility, which lets you customize the graphing output options. You can plot the
cross sections to a file in the standard HEC-2 file format, then perform post-
processing in programs designed for HEC-2 calculations.
You can create sections that are perpendicular to the stream or channel
centerline, or skewed sections. You can generate single and multiple HEC-2
sections, including sections at specific station increments ahead, and left and
right of the centerline. You can then view the post-processed HEC-2 output files
and generate graphs.