The Elevation Controlled Gates is a type of boundary condition that allows the user to adjust the opening and closing of gates based on the water surface elevation at a target location. These gates are commonly used in dams, spillways, flood control channels, and other hydraulic structures where precise water level management is critical. To learn more about boundary conditions, refer to this article in our knowledge base.
In GeoHECRAS software, the user can define the boundary condition data for controlling gate operations in the Elevation Controlled Gates dialog box. This dialog box can be displayed from the Unsteady Flow Data command. To learn more about the Unsteady Flow Data command, refer to this article in our knowledge base.
Note: In order to use the Elevation Controlled Gates boundary condition, the user must define the gate for the inline structure, lateral structure, or SA/2D connection in the model.
Follow the steps below to use the Elevation Controlled Gates dialog box:
- From the Input ribbon menu, select the Unsteady Flow Data command.
- The Unsteady Flow Data dialog box will be displayed.
- In the Boundary Condition column dropdown combo box, select the Elevation Controlled Gates boundary condition type.
- In the Boundary Details column, click on the [Define] button.
- The Elevation Controlled Gates dialog box will be displayed, as shown below.
The following sections describe how to interact with the Elevation Controlled Gates dialog box.
Gate Group Selection
This section allows the user to define both the name of the gate group and the reference used for controlling the gate operations (opening and closing of gates).
This section requires the following data:
- Gate group ID
This dropdown combo box allows the user to select the gate group ID defined in the current scenario. - Gate control reference
This dropdown combo box allows the user to select the reference used to control the opening and closing of gates. The following options are available in this dropdown combo box:
- Upstream WSEL (default) – Control gate operations based on the upstream water surface elevation.
- Location – Control gate operations based on the water surface elevation at a user-defined cross section or storage area.
- Stage Difference – Control gate operations based on the difference in stage between any two user-defined locations.
Upstream Water Surface Elevation Reference
This section allows the user to control the opening and closing of gates based on the water surface elevation upstream of the structure (i.e., inline structure, lateral structure, etc.). Note that this section is enabled when Upstream WSEL is selected in the Gate control reference dropdown combo box of the Gate Group Selection section. Otherwise, this section is disabled (i.e., grayed out).
This section requires the following data:
- Upstream WSEL when gate starts to open
This entry field allows the user to define the water surface elevation upstream of the structure at which the gate will begin to open. - Upstream WSEL when gate starts to close
This entry field allows the user to define the water surface elevation upstream of the structure at which the gate will begin to close.
Location Reference
This section allows the user to control the opening and closing of gates based on the water surface elevation at a user-defined cross section or storage area. Note that this section is enabled when the Location is selected in the Gate control reference dropdown combo box of the Gate Group Selection section. Otherwise, this section is disabled (i.e., grayed out).
This section requires the following data:
- River station
This radio button option allows the user to define the river, corresponding reach, and river station (cross section ID). The user can select the river, reach, and river station (cross section ID) from the dropdown combo boxes next to this option. - Storage area
This radio button option allows the user to define the storage area. The user can select the storage area from the dropdown combo box next to this option. - Reference WSEL when gate starts to open
This entry field allows the user to define the reference WSEL at a user-specified cross section or storage area at which the gate will begin to open. - Reference WSEL when gate starts to close
This entry field allows the user to define the reference WSEL at a user-specified cross section or storage area at which the gate will begin to close.
Stage Difference Reference (First Minus Second)
This section allows the user to control the opening and closing of gates based on the difference in stage between any two user-defined reference locations. Note that this section is enabled when the Stage Difference is selected in the Gate control reference dropdown combo box of the Gate Group Selection section. Otherwise, this section is disabled (i.e., grayed out).
This section requires the following data:
- First reference elevation
This subsection allows the user to define the first reference elevation. The following options are provided:- River station
This radio button option allows the user to define the river, corresponding reach, and river station (cross section ID). The user can select the river, reach, and river station (cross section ID) from the dropdown combo boxes next to this option. - Storage area
This radio button option allows the user to define the storage area. The user can select the storage area from the dropdown combo box next to this option.
- River station
- Second reference elevation
This subsection allows the user to define the second reference elevation. The following options are provided:- River station
This radio button option allows the user to define the river, corresponding reach, and river station (cross section ID). The user can select the river, reach, and river station (cross section ID) from the dropdown combo boxes next to this option. - Storage area
This radio button option allows the user to define the storage area. The user can select the storage area from the dropdown combo box next to this option.
- River station
- Stage difference when gate starts to open
This entry field allows the user to define the stage difference (the difference in water levels between the upstream and downstream of the gate) at which the gate will begin to open. - Stage difference when gate starts to close
This entry field allows the user to define the stage difference at which the gate will begin to close.
Gate Group Opening Specifications
This section allows the user to define the specifications of the gate group.
This section requires the following data:
- Gate opening rate
This entry field allows the user to define the gate opening rate to control how fast the gates can move. - Gate closing rate
This entry field allows the user to define the gate closing rate to control how fast the gates can move. - Maximum gate opening height
This entry field allows the user to define the maximum height up to which the gate can be opened. - Minimum gate opening height
This entry field allows the user to define the minimum height up to which the gate can be opened. - Initial gate opening height
This entry field allows the user to define the initial height of the gate opening. This height will be used during the initial backwater computation. Note that this entry field cannot be left blank.