Transects

Click the Transects button to open the Transects window.

Button	Description
	Add one transect
	Delete selected transects. Please note to use Ctrl and Shift keys for multiple selection.
	Import a group of transects
	Export all the transects

1. Name: The user-assigned name for the transect.
2. Description: An optional comment or description of the transect.
3. Station/Elevation Data Grid: This grid contains pairs of values representing the distance from the left side of the channel and the corresponding elevation of the channel bottom as one moves across the channel from left to right, looking downstream. The elevations can be relative to any reference point, such as the channel bottom, and don’t have to be mean sea level. Up to 1500 data values can be entered.
4. Roughness: Manning’s roughness coefficient (n) values for different sections of the transect:
• Left Overbank
• Right Overbank
• Main Channel Overbank roughness values can be zero if there’s no overbank section.
*5. Bank Stations: *The distance values in the Station/Elevation grid that mark the end of the left overbank and the start of the right overbank. Use 0 to denote the absence of an overbank.
6. Modifiers: These are factors and constants applied to modify transect data during processing by SWMM:
• Stations Modifier: A factor by which the distance between each station is multiplied.
• Elevations Modifier: A constant value added to each elevation value.
• Meander Modifier: The ratio of the length of a meandering main channel to the length of the surrounding overbank area. This modifier is applied to conduits that use this transect for their cross-section. SWMM adjusts calculations for overbank length and main channel roughness based on this modifier. It’s ignored if left blank or set to 0.

To add a group of transects, click the Import button . In the pop-up window, change the file type to csv. Navigate to and add the csv file.

VOSWMM allows users to define the csv file of conduit transects in either of the following two formats.

• Format 1: this format applies to the situation when all the transects share the same stage. The first column is the stage and the following columns are elevations for each transect. The header is the first row. The first cell of the header is the column name of the first column, i.e. stage. The following cells of the header are the NHYD of conduits whose transects are to be assigned.

Download the sample csv file of transects in format 1

• Format 2: this format applies to the situation when each transect has different stage from others. Each transect defines its own stage and its elevation in two separate columns. The header of each elevation column is the NHYD of the conduit.

Download the sample csv file of transects in format 2

After importing the transect curves, the left and right Bank Station will be automatically calculated based on the csv file. The imported transects will be assigned to the conduits based on the elevation headers.