Product(s):	CivilStorm, SewerGEMS, OpenRoads Designer, OpenSite Designer
Version(s):	CONNECT Edition
Area:	Modeling

Problem

How can I model check dams in a channel?

   

Solution

A check dam can be modeled using a start or stop control structure in a conduit or channel element. Control structures can be used to model an inline weir, orifice or depth-flow rating curve, so the weir option can be used to model the top elevation of the check dam that water must flow over. The type of weir could be set to V-notch or rectangular depending on how your check dams look.

For the element layout, you could use either a series of conduits with transition elements in the location of the check dam, or a series of channel elements with cross section nodes at the location of the check dams. The control structure can be placed on the appropriate end of the pipe by using the fields "Has start control structure?" or "has stop control structure?".

Layout

Properties fields

        

Control Structure configuration

   

More information can be found here:

Using Start and Stop Control Structures for conduits and channels

Cross section vs Transition for modeling slope or size change

Results Visualization

After computing the model, advance to the appropriate timestep (if using a dynamic or EPS simulation) and view a profile of the elements that have the check dams modeled as control structures. You will be able to visualize the water pooling up behind the control structure appropriately.

Cascading Check Dam

If your check dams are "cascaded" with a step down between the weirs, you would need to use the conduit/transition approach since you can set the start and stop invert of the conduits that connect to the transition by choosing "false" for "set invert to "start" or "set invert to stop".

Check Dam with Orifice

In some cases you may have a check dam with an orifice to handle low flow. 

In this case, you must first determine the composite rating curve of the weir and orifice in parallel, then paste it in the table for the "depth-flow" control structure type. This can be done easily by using the Composite Outlet Structure tool. Configure a composite outlet structure with the orifice and weir in parallel, compute the rating table within the Composite Outlet editor screen, then use the Data tab on the right side to select the rating table and copy and paste with CTRL+C and CTRL+V.