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FM Tute M01 QGIS 1D2D Code: Difference between revisions

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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.<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.</li>
<li>Import in an empty 2d_bc_empty_r.
shp<li>Save the layer fromas within<b>2d_bc_FMT_M01_HX_001_R.shp</b> in the '''FMT_tutorial\FMT_M01\TUFLOW\model\gis\empty''' folder and save as 2d_bc_hxi_FMT_001_R.shp. </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 2d_bc_hxi_FMT_001_R<b>2d_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 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>
[[File:FMT QGIS 1D2D Code attribute.JPG|800px700px]]
 
<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>
[[File:FMT QGIS 1D2D Code Polygon Digitisation.JPG|500px]]▼
 
<li> Observe how the code polygon has been digitised downstreambetween ofnodes FC01.35 and FC01.1134. InThe thispolygon case,covers nothe codearea polygonbetween hasthese beentwo definedFlood overModeller the embankmentnodes. This is because overtopping of the embankment willat bethis modelledlocation inhas thebeen 2Drepresented TUFLOW component ofin the model.1D ThisFlood isModeller why there are additional HX boundary polylines at the upstream and downstream facescomponent of the embankmentmodel.</li>
[[File:FMT QGIS 1D2D Code BankPolygon DigitasationDigitisation.JPG|600px400px]]
 
<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>
<li>Save the file in preparation for reading in TUFLOW.</li>
▲[[File:FMT QGIS 1D2D Code PolygonBank DigitisationDigitasation.JPG|500px400px]]
 
<li>Save the file</li>
 
<div style="background-color: #D6E9E0; margin: 20px; text-align: center;
Please return to the Flood Modeller Tutorial Model module 1 page [[Flood_Modeller_Tutorial_Module01#Modify_Simulation_Control_Files|here]].
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>
</oldiv>▼
 
Please return to the [[Flood_Modeller_Tutorial_Module01#Modify_Simulation_Control_Files|Flood Modeller Tutorial Model]].
▲</ol>
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