Tutorial Module03

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    Introduction

    In this module we add some breaklines to the model to ensure that the 5m cell size model correctly represents the key hydraulic controls. We will add break-lines to represent the following features:

    • Road crests
    • Creek centre line (thalweg)

    The only new GIS layer that is introduced is the 2d_zshape (2d Z Shape), it is recommended that the user reads section 4.4.9 of the 2010 TUFLOW manual. The 2d_zsh layer is commonly used, and will be also used in later modules.
    Note: As per module 2, instructions are given for the following four GIS platforms:

    • MapInfo
    • ArcGIS
    • QGIS
    • SMS

    GIS Inputs

    For this module you have been provided road crest and creek centreline (thalweg) survey in a text file format (.xyz). This will involve importing the data into a GIS package and then manipulating it into a format suitable for input into TUFLOW. To import the data and manipulate into a TUFLOW format, please select your GIS package from the list below.

    Modify Simulation Control Files

    With the new GIS layers created it is time to update the control files. The two files we need to change are the geometry control file (.tgc) and the TUFLOW control file (.tcf), the changes for each are described below.

    TGC File

  1. Save a copy of the geometry control file used in module 2 (TUFLOW\model\M01_5m_002.tgc) as M03_5m_001.tgc (this should be kept in the TUFLOW\model\ directory.
  2. Note: There was no M02 (module 2) version of the geometry control file, there we no changes to the 2D geometry in this run so the latest version is the one we created in module 1.
  3. Open the M03_5m_001.tgc in your text editor and add the following lines after the base DEM has been input. The DEM will be read in using one of the following commands: Read Grid Zpts, Read TIN Zpts or Read RowCol Zpts command.
    For MapInfo users add:
    Read GIS Z Shape == mi\2d_zsh_M03_Thalweg_001.MIF
    Read GIS Z Shape == mi\2d_zsh_M03_Rd_Crest_001.MIF

    For ArcGIS or QGIS users add:
    Read GIS Z Shape == gis\2d_zsh_M03_Thalweg_001_L.shp | gis\2d_zsh_M03_Thalweg_001_P.shp
    Read GIS Z Shape == gis\2d_zsh_M03_Rd_Crest_001_L.shp | gis\2d_zsh_M03_Rd_Crest_001_P.shp
    As the points and lines are in separate shapefiles, we need to read both of these files in, the points (_P) and lines (_L) are part of the same breaklines so they need to be inputted on the same line. The vertical bar "|" operator tells TUFLOW that there is another input file.
    For TUFLOW modelling the convention is that:
    • Points are stored in a filename_P.shp file;
    • Lines are stored in a filename_L.shp; and
    • Regions or polygons in a filename_R.shp
    Up to nine separate files can be inputted on a single line using the "|" operator. This works for both MapInfo or Shapefiles.

    For SMS users, you do not need to modify these files manually, it is automatically done when you export TUFLOW files from SMS. Follow the instructions on page "Export TUFLOW Simulation"

    TCF File

  4. Save a copy of the simulation control file M02_5m_001.tcf as M03_5m_001.tcf
  5. Open the file in M03_5m_001.tcf in a text editor and make the following changes:
    Change the output folder for the 2D results to:
    Output Folder == ..\results\M03\2D\
    The 1D output folder command occurs within the Start 1D Domain .... End 1D Domain block of commands. Change the output folder for the 1D results to:
    Output Folder == ..\results\M03\1D\
    Finally, update the geometry control file to the newly created M03_5m_001.tgc:
    Geometry Control File == ..\model\M03_5m_001.tgc


    For SMS users, you do not need to modify these files manually, it is automatically done when you export TUFLOW files from SMS. Follow the instructions on page "Export and Run TUFLOW Simulation"

    Run the Simulation

    Using your preferred method for starting TUFLOW, run the recently created M03_5m_001.tcf. Please refer to module 1 for a detailed description of the various methods for running a TUFLOW simulation.
    If the model fails to start correctly please refer to the troubleshooting section at the end of this page.

    Review Check Files

    While the model is running, now is a good time to open the check files to review the changes to the topography caused by the breaklines. As the modifications are to the 2D topography, the check files are written to the TUFLOW\check\2d\ folder.

  6. In your GIS package open the M03_5m_001_zsh_zpt_check file, for shapefile users this is M03_5m_001_zsh_zpt_check_P.shp for MapInfo users this is M03_5m_001_zsh_zpt_check.mif.
  7. This layer contains the Zpts that have been modified by the 2d_zsh layers. The layer contains the following information:

    • Elevation after modification;
    • Change in elevation (dZ);
    • Source layer.
  8. Open the grid check file (M03_5m_001_grd_check_R.shp / M03_5m_001_grd_check.mif) from the same check folder location.
  9. Make the check files visible and zoom into the road breakline at the north of the site. In this case a shape_width_or_dMax attribute of 5 (metres) was specified, a "thick" breakline formulation has been used, with the entire cells being raised. This can be seen in the image below.
    In this image, the black squares are the TUFLOW cells, the red line the breakline and the purple triangles, the points that have been raised by the breakline.
  10. Tute M03 checks thick breakline.png


  11. The road to the east of the model had a shape_width_or_dMax attribute of 0 and a "thin" breakline formulation has been used in TUFLOW. The cell sides have been raised (this prevents water from flowing across the breakline until the elevation is overtopped. However, the cell centres (ZC) have not been modified, this means the storage in the model has not been altered.
  12. Tute M03 checks thin breakline.png


  13. In the creek, the "MIN" or "Gully" shape option was used, this lowers a continual flowpath in the direction of the line. TUFLOW does not allow water to flow diagonally between cells, therefore, the gully line formulation lowers cell sides and cell centres to form a flow path. This is shown in the image below.
  14. Tute M03 checks gully breakline.png


  15. The above images are provided as it is important to set the correct breakline type. For example if a creek was represented with a "thick" gully line, the changes to the model elevations (Zpts) might not necessarily provide a continual flow path. In the example below, the "thick" breakline is shown, however as flow cannot move diagonally between cells, this would be unsuitable for a creek centre line.
  16. Tute M03 checks thick breakline2.png

    The check files should show the changes shown above, if they do not please see the troubleshooting section at the bottom of this page.

    Review the Results

    The 1D and 2D results can be reviewed using the methods outlined in Module 1 and Module 2.
    Some suggestions for things to check are:

    • Does the flooding still overtop the roads?
    Tip: check the maximum 2D results.
    • What is the difference in peak water level at the upstream of the roads compared to the previous run?
    Tip: the mmH layer (1D results) could be useful here.

    Conclusion

    Point data from survey was provided in text files as x,y,z format data. GIS software was used to import the data and manipulate into a 2d Z Shape format (2d_zsh), the model was simulate with breaklines to represent the creek centre line and road crests.

    Check files were used to confirm the changes to the elevation points (Zpts). "Thin", "thick" and "gully" breaklines were described.

    The 2D Z Shape can also be used for more complex modifications, using polygons and TIN lines, these will be introduced in later modules.

    In Tutorial Module 4 the setup of 1D open channel will be introduced.

    Troubleshooting

    This section contains links to some possible issue that may occur when progressing through the second tutorial module. If you experience an issue that is not detailed please detail the issue on the discussion page.

    If you are unsure of why the model has failed to start, check the TUFLOW Log File (this is in the TUFLOW\runs\log\ folder and has the name M02_5m_001.tlf. This can be opened in a text editor, the error is generally at the end of the file, however you can search for "Error" if you can not see the error.