In GeoSTORM, the Import Cross Section Geometry command is used to import surveyed cross section geometry from a wide variety of file formats. The software will automatically determine where the next cross section starts within the selected file based upon either blank lines contained within the file or a sudden change in direction from one geometry point to the next.
Follow the steps below to use the Import Cross Section Geometry command:
- From the Input ribbon menu, click the Cross Sections dropdown menu and select the Import Cross Section Geometry command.
- The Import Cross Section Geometry dialog box will be displayed.
The following sections describe how to use the Import Cross Section Geometry command and interact with the above dialog box.
Selecting Cross Section File
The Select Cross Section File section allows the user to select the survey point cross section file. The file must be in ASCII text format, with either commas, tabs, or spaces delimiting the data fields within each row of the file.
The first row within the file that contains 3 floating point numbers is used to start the import cross section process. Whenever a blank line is encountered within the data file or the direction between three adjacent points changes too much, the software interprets this as the start of a new cross section.
The Point file format dropdown combo box is used to select the file format into which the survey points data will be imported. The following survey point file formats are supported:
- ENZ (Easting, Northing, Elevation)
- ENZD (Easting, Northing, Elevation, Description)
- LLZ (Lat-Long, Elevation)
- LLZD (Lat-Long, Elevation, Description)
- NEZ (Northing, Easting, Elevation)
- NEZD (Northing, Easting, Elevation, Description)
- PENZ (Point, Easting, Northing, Elevation)
- PENZD (Point, Easting, Northing, Elevation, Description)
- PLLZD (Point, Lat-Long, Elevation, Description)
- PNEZ (Point, Northing, Easting, Elevation)
- PNEZD (Point, Northing, Easting, Elevation, Description)
- PNT (XYZ Survey Alignment Data)
- PTS (XYZ Survey Alignment Data)
The software will attempt to determine the file format based on the file extension. However, the user can change the file format to be used after the file is selected.
For reference, Easting = X coordinate and Northing = Y coordinate.
Note: The cross section points must overlay only one river reach for this command to operate. In addition, cross sections should not already exist for the river reach that is being used to construct cross sections from the imported points.
Point File Preview
This section shows the first 100 lines contained within the survey point file. It allows the user to view the contents of the survey point file and to change the file format to be used for importing based on a preview of the contents. After changing the file format, the column headings in the Point File Preview section are updated accordingly. For example, changing the file format from ENZ (Easting, Northing, Elevation) to PENZD (Point, Easting, Northing, Elevation, Description) displays the additional column header(s) in the table as shown below.
Elevation Data Adjustment
This section allows the user to adjust the survey point data elevation values if the elevation data are in a different unit system or needs to have a datum adjustment.
The user can select one of the following options to modify the elevation values:
- No change
This is the default option. This radio button option will not make any changes to the elevation values.
- Convert feet to meters
This radio button option converts the elevation values from feet to meters. After selecting this option, click the [Apply] button. The software will then update the converted values in the Elevation column of the Point File Preview table.
- Datum adjustment
This radio button option allows the user to add a constant value to the existing elevation values. After selecting this option, the entry field adjacent to this option is enabled, allowing the user to enter the constant value. After entering the value, click the [Apply] button. The software will then update the values in the Elevation column of the Point File Preview table. The new elevation values are the sum of the original value and a constant value provided by the user.
Cross Section Naming Specifications
This section is used to specify the cross section ID for each of the constructed cross sections.
The following naming formats are available in this section:
- Use corresponding reach numerical ID portion: This option extracts the numerical ID from the corresponding reach ID and applies it to the cross section ID. Selecting this option will disable (i.e., grayed out) the following options:
- Cross section ID digits
- Next available cross section ID
- Cross section ID increment
- Cross section ID prefix: This option allows a prefix to be added to the cross section ID.
- Cross section ID digits: This option permits the specification of a set number of digits to use for the cross section ID. For example, using 3 digits causes the cross section ID to be of the format 001, 002, etc.
- Next available cross section ID: This option identifies the next cross section ID number to be used.
- Cross section ID increment: This option identifies the increment to use when numbering cross sections. The default value is 1.
- Cross section ID suffix: This option allows a suffix to be added to the cross section ID.
- Cross section ID preview: This read-only field provides a preview of the cross section naming specifications defined above.
Assign Bank Stations
This section is used to construct channel bank locations based upon an assumed normal flow depth and a maximum channel width search distance. The software will first determine where the thalweg location is on a cross section by assuming the lowest elevation is the thalweg. It will then move outward from the thalweg until the requested channel depth is reached within the maximum channel width specified. Note: The contents of the Assign Bank Stations section will only be enabled if the checkbox at this section header is checked.
Assignment of Manning’s Roughness and Flow Lengths
During the construction of the cross sections, the software will automatically assign a default Manning’s roughness for the left overbank, channel, and right overbank areas. In addition, the cross section flow lengths are automatically determined.
Once all the options have been defined, click the [OK] button. The software will then construct cross sections based upon the imported geometry data.