View source for FM Tute M01 QGIS GPKG 1D2D Code

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=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=
<li>Import in an empty <b>2d_bc_empty_R.gpkg</b> layer from within the '''FMT_tutorial\FMT_M01\TUFLOW\model\gis\empty''' folder.</li>
<li>Save the layer as <b>2d_bc_FMT_M01_HX_001_R.gpkg</b> in the '''FMT_tutorial\FMT_M01\TUFLOW\model\gis''' folder. </li>
<li>Move the empty 2d_bc layer <b>2d_bc_FMT_M01_HX_001_R.gpkg</b>  into the project GeoPackage file <b>M02_5m_002.gpkg</b> in the Browser Panel. Load the empty layer <b>2d_bc_FMT_M01_HX_001_R</b> into QGIS from <b>M02_5m_002.gpkg</b>.</li>
<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</b>. </li>
<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. 
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.</li>

<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>

<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> 

<br>{{Video|name= Deactivate 2D cells GPKG.mp4 |width=1123}}<br>

<li>Save the file</li>

<br>Please return to the [[Flood_Modeller_Tutorial_Module01_Provisional_Files#Modify_Simulation_Control_Files|Flood Modeller Tutorial Model]]</br>.
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