Difference between revisions of "FM Tute M01 QGIS 1D2D Code"

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<ol>
 
<ol>
 
=Introduction=
 
=Introduction=
In this section we will deactivate the 2D cells where the 1D Flood Modeller component is replacing the 2D solution. The deactivated 2D area should be the same as the area modelled in 1D. This is to ensure that the storage removed from the 2D component of the model is equal to the storage modelled in the 1D component of the model.
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In this section we will deactivate the 2D cells where the 1D Flood Modeller component is replacing the 2D solution. The width of the deactivated 2D area should be approximately equal to the width of the 1D cross-sections. This step essentially replaces the conveyance of the deactivated 2D area with an equivalent 1D conveyance.
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=Method=
 
=Method=
<li>Import in an empty 2d_bc_empty.shp layer from within the TUFLOW\model\gis\empty folder and save as 2d_bc_hxi_FMT_001_R.shp. </li>
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<li>Import in an empty <b>2d_bc_empty_R.shp</b> layer from within the '''FMT_tutorial\FMT_M01\TUFLOW\model\gis\empty''' folder.</li>
<li>Open the Inactive_area.shp GIS layer from Module_Data\Module_01\gis folder. Select all objects from within this layer, copy and paste into 2d_bc_hxi_FMT_001_R.shp. </li>
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<li>Save the layer as <b>2d_bc_FMT_M01_HX_001_R.shp</b> in the '''FMT_tutorial\FMT_M01\TUFLOW\model\gis''' folder. </li>
<li> For all polygons assign a 'type' attribute of 'CD'. A 2D BC type of 'CD' designates the digitised polygon as a code polygon. </li>
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<li>Open the <b>Inactive_area.shp</b> GIS layer from '''Module_Data\Module_01\shp''' folder. Select all objects from within this layer, copy and paste into <b>2d_bc_FMT_M01_HX_001_R.shp</b>. </li>
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<li> For all polygons assign a 'type' attribute of 'CD'. This designates the digitised polygon as a code polygon where the 2D cells within it may be either active or inactive. </li>
 
<li> For all polygons assign a 'f' attribute of '-1'. A cell code of '-1' deactivates all cells within the digitised code polygons. </li>
 
<li> For all polygons assign a 'f' attribute of '-1'. A cell code of '-1' deactivates all cells within the digitised code polygons. </li>
<li> Observe how the code polygon has been digitised between FC01.35 and FC01.34. The polygon covers the area between these two Flood Modeller nodes. This is because overtopping of the embankmentat this location has been represented in the 1D Flood Modeller component of the model.</li>
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[[File:FMT QGIS 1D2D Code attribute.JPG|700px]]
<li> Observe how the code polygon has been digitised downstream of FC01.11. In this case, no code polygon has been defined over the embankment. This is because overtopping of the embankment will be modelled in the 2D TUFLOW component of the model. This is why there are additional HX boundary polylines at the upstream and downstream faces of the embankment.
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<li>Save the file in preparation for reading in TUFLOW.</li>
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<li> Observe how the code polygon has been digitised between nodes FC01.35 and FC01.34. The polygon covers the area between these two Flood Modeller nodes. This is because overtopping of the embankment at this location has been represented in the 1D Flood Modeller component of the model.</li>
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[[File:FMT QGIS 1D2D Code Polygon Digitisation.JPG|400px]]
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<li> Observe how the code polygon has been digitised downstream of node FC01.11. In this case, no code polygon has been digitised over the embankment. This is because overtopping of the embankment will be modelled in the 2D TUFLOW component of the model. The '''2d_bc_FMT_M01_HX_001_L.shp''' layer created previously contains additional HX boundary polylines at the upstream and downstream faces of the embankment to allow for overtopping.</li>  
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[[File:FMT QGIS 1D2D Code Bank Digitasation.JPG|400px]]
  
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<li>Save the file</li>
  
Please return to the Flood Modeller Tutorial Model module 1 page [[Flood_Modeller_Tutorial_Module01#Modify_Simulation_Control_Files|here]].
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<div style="background-color: #D6E9E0; margin: 20px; text-align: center;
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border: 5px solid #1ABDC9">
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  <p style="font-weight: bold; color: #E20177">Key Tip!</p>
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  <p> Cells may also be deactivated within a model by using a cell code of '0' instead of '-1'. A value of 0 removes these cells from the computation entirely which has the benefit of reducing computation time and output file sizes. </p>
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</div>
  
</ol>
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Please return to the [[Flood_Modeller_Tutorial_Module01#Modify_Simulation_Control_Files|Flood Modeller Tutorial Model]].

Latest revision as of 23:39, 7 December 2018

    Introduction

    In this section we will deactivate the 2D cells where the 1D Flood Modeller component is replacing the 2D solution. The width of the deactivated 2D area should be approximately equal to the width of the 1D cross-sections. This step essentially replaces the conveyance of the deactivated 2D area with an equivalent 1D conveyance.


    Method

  1. Import in an empty 2d_bc_empty_R.shp layer from within the FMT_tutorial\FMT_M01\TUFLOW\model\gis\empty folder.
  2. Save the layer as 2d_bc_FMT_M01_HX_001_R.shp in the FMT_tutorial\FMT_M01\TUFLOW\model\gis folder.
  3. Open the Inactive_area.shp GIS layer from Module_Data\Module_01\shp folder. Select all objects from within this layer, copy and paste into 2d_bc_FMT_M01_HX_001_R.shp.
  4. For all polygons assign a 'type' attribute of 'CD'. This designates the digitised polygon as a code polygon where the 2D cells within it may be either active or inactive.
  5. For all polygons assign a 'f' attribute of '-1'. A cell code of '-1' deactivates all cells within the digitised code polygons.
  6. FMT QGIS 1D2D Code attribute.JPG
  7. Observe how the code polygon has been digitised between nodes FC01.35 and FC01.34. The polygon covers the area between these two Flood Modeller nodes. This is because overtopping of the embankment at this location has been represented in the 1D Flood Modeller component of the model.
  8. FMT QGIS 1D2D Code Polygon Digitisation.JPG
  9. Observe how the code polygon has been digitised downstream of node FC01.11. In this case, no code polygon has been digitised over the embankment. This is because overtopping of the embankment will be modelled in the 2D TUFLOW component of the model. The 2d_bc_FMT_M01_HX_001_L.shp layer created previously contains additional HX boundary polylines at the upstream and downstream faces of the embankment to allow for overtopping.
  10. FMT QGIS 1D2D Code Bank Digitasation.JPG
  11. Save the file
  12. Key Tip!

    Cells may also be deactivated within a model by using a cell code of '0' instead of '-1'. A value of 0 removes these cells from the computation entirely which has the benefit of reducing computation time and output file sizes.

    Please return to the Flood Modeller Tutorial Model.