Is the gate being operated during the storm, or are you modeling the entire storm with different (fixed) gate positions?

Peter Smart
HydroCAD Software
www.hydrocad.net

It's a combination of uses. In most of our projects, there's a lot of active water level management. Part of what I'm looking at is what the drawdown times (from flat pool) are for various gate positions and then what would happen if a storm hits when the gate is at a particular postion.

If the gate opening was rectangular, you could route the culvert to a rectangular orifice of the appropriate size. But if the opening is semicircular, you will need to create a custom weir/orifice for each configuration.

With a custom weir/orifice you would define the opening by entering the width at various heights. To get a good smooth circular shape takes a number of points, but there's a shortcut that saves a lot of time:

1) On the custom weir/orifice screen, right-click the table and select "Add chamber..." from the context menu.

2) Expand the CMP or CPP sesction and select the desired pipe size. This will automatically load the table with the correct dimensions for a full round opening.

3) To truncate the opening to the desired height (where the gate is set), right-click the line at the desired height and select "Delete rows to end". The adjusted shape is displayed on-screen.

Repeat the process for each gate opening, or duplicate the outlet device with the highest gate setting and trim repeatedly for each desired opening. You can use a separate pond to store each scenario.

Peter Smart
HydroCAD Software
www.hydrocad.net