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<ol>
=Introduction=
In this section we will deactivate the 2D cells where the 1D Flood Modeller component is replacing the 2D solution.<br> 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.
 
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.
 
=Method=
<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 and save as <b>2d_bc_hxi_FMT_001_R.shp</b>. </li>
<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>Open the <b>Inactive_area.shp</b> GIS layer from '''Module_Data\Module_01\gisshp''' folder. Select all objects from within this layer, copy and paste into <b>2d_bc_hxi_FMT_001_R2d_bc_FMT_M01_HX_001_R.shp</b>. </li>
<li> For all polygons assign a 'type' attribute of 'CD'. A 2D BC type of 'CD'This designates the digitised polygon as a code polygon. Thewhere codethe polygon2D definescells ifwithin theit 2Dmay cellsbe areeither 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>
[[File:FMT QGIS 1D2D Code attribute.JPG|800px700px]]
 
<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 embankmentatembankment at this location has been represented in the 1D Flood Modeller component of the model.</li>
[[File:FMT QGIS 1D2D Code Polygon Digitisation.JPG|500px400px]]
 
<li> Observe how the code polygon has been digitised downstream of node FC01.11. In this case, no code polygon has been defineddigitised over the embankment. This is because overtopping of the embankment will be modelled in the 2D TUFLOW component of the model. ThisThe is'''2d_bc_FMT_M01_HX_001_L.shp''' layer whycreated therepreviously arecontains additional HX boundary polylines at the upstream and downstream faces of the embankment to allow for overtopping.</li>
[[File:FMT QGIS 1D2D Code Bank Digitasation.JPG|600px400px]]
 
<li>Save the file</li>
 
<div style="background-color: #D6E9E0; margin: 20px; text-align: center;
border: 5px solid #1ABDC9">
<p style="font-weight: bold; color: #E20177">Key Tip!</p>
<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>
</div>
 
Please return to the [[Flood_Modeller_Tutorial_Module01#Modify_Simulation_Control_Files|Flood Modeller Tutorial Model]].
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