Assign River Reaches command

The Assign River Reaches command enables the user to quickly assign a polyline as a river reach.

Follow these steps to use the Assign River Reaches command:

  1. From the Input ribbon menu, select the River Reaches menu item and then choose the Assign River Reaches command.
    How to Assign River Reaches in HEC-RAS
  1. The Assign River Reaches dialog box will be displayed.
    Assign River Reaches command 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 the [Pick] button and the dialog box will temporarily disappear. A prompt will be displayed on the status line, informing the user what to do next. Within the Map View, click on the downstream half of the 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. In addition, the software will display the assumed flow direction arrow on the polyline where the user clicked. If the river reach is assigned an incorrect flow direction, click 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 a 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 River name dropdown combo box listing or click the [New] button. The software will then provide an empty field to define the new river name.

Once the river reach has been defined, click the [Apply] button to assign the river reach data. The river reach ID will display on the Map View adjacent to the assigned river reach.

About the Author Chris Maeder

Chris Maeder

Chris is an experienced civil engineering and software technology leader, with over 30 years industry experience. With proven expertise in global software development, he has built engineering teams that adapt quickly, focus on what’s important and, most importantly, deliver. He is a licensed professional civil engineer with extensive experience in water resource engineering. He has performed and supervised engineering projects in urban stormwater drainage, transportation and roadway drainage, storm sewer design, detention pond design, stormwater quality, green infrastructure, watershed management planning, wastewater sewers, water distribution networks, pump stations, FEMA flood studies, bridge and culvert design, bridge scour and armoring, dam failure analysis, seepage and groundwater modeling, and environmental permits.

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