The Input | River Reaches | Assign River Reaches command enables the user to quickly assign an existing polyline as a cross section on the Map View.
Selecting this command will display the Assign River Reaches dialog box.
The following sections are used for defining data in assigning a river reach.
Select River Reach Polyline
This section is used to interactively select a polyline from the Map View for assigning as a river reach. Click on the [Pick] button and the dialog box will temporarily disappear. A prompt will be displayed at the status line, informing the user what to do next. Within the Map View, click on the downstream end of a polyline to assign as a river reach.
After selecting a polyline, the user will be returned to the dialog box showing that a polyline was selected.
The river reach flow direction is defined by clicking on the downstream half of the polyline. A flow directional arrow is shown at the center of the river reach to show the assigned flow direction. If the river reach is accidentally assigned in an upstream direction, click on the [Reverse Direction] button.
River Reach Specifications
This section is used to define the river name and reach name of the river reach polyline that was selected. Note that each river reach must have an unique ID which is formed from the combination of the river name and reach name. This is how the HEC‑RAS software can correctly identify each river reach.
The river name dropdown combo box can be used to select from an existing river name or to create a new river name.
To create a new river name, either select Add New River from the dropdown combo box listing or click the [New] button. The software will then provide an empty field to define the new river name.
Process Selected River Reach Polyline
This section allows the user to optionally delete the previously created polyline once the river reach has been assigned.