Creating a Spillway

A common practice when creating a detention basin is to create a spillway or a similar channel to control the location and release of water.  In the following, I will show how to add a spillway to the basin design.

As you can see from the screen capture above, here is a detention basin with a high water elevation of 176.  Now we need to create a feature line that represent the location of our spillway.  It is important that this feature line is in a different site from the detention basin, that way it will not react with the pond grading.

In the capture above, you can see that an elevated feature line representing the spillway has been created.  We will then create a grading group for the spillway, and use the grade to surface method and target the proposed detention basin.

In the two screen captures above, you can feature line has created the spillway,  The bottom capture shows the spillway in a 3d perspective.  It is important to note, that the infill option needs to be used to close the bottom of the spillway.  Also, if for some reason the spillway needs to change location, we simply move it to its new area, and the spillway will be updated.

Finally, now that the spillway and detention basin are created, we simply need to make a new surface and paste both surfaces together.