Technical data

Chapter 3 Performing Hydrologic Studies
54
To calculate the required storage volume for ponds (continued)
Steps
Use
to look up
6 Select the applicable rainfall distribution from
the Rainfall Distribution list.
7 Specify the drainage area.
Type a value for the area in the edit box, or, if
you created a watershed with the Terrain Model
Explorer, select the polyline from your drawing
by clicking Select and selecting the polyline.
You can also draw a new polyline for selection.
Specify the Drainage Area
8 Specify the peak inflow value if you did not load
an Inflow file in step 4.
Load an Existing
Hydrograph File
9 Specify the peak outflow value.
Type a value for the peak outflow, or click Select
and enter values in the Pond Outflow Design
dialog box. You can add outflow structures to
control the flow, such as weirs, culverts, or
gravity pipes.
If you have a defined pond, you can click Pond
and choose the pond you want to use for these
calculations.
Specify the Peak Outflow
10 Specify the runoff flow value.
11 Click the Save button to display the Save Basin
Data dialog box. Enter the file name, and click
Save to return to the Detention Basin Storage
dialog box.
When you have entered all the values, the runoff volume and the
computed storage volume for the detention basin is displayed at the
bottom of the dialog box. If you have a currently defined pond, then
the maximum storage elevation for the currently defined ponds is
listed as well.