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Tute M01 Materials SAGA: Difference between revisions

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This page details the method for using SAGA to create the GIS based material types (land use areas). Once the GIS layers are setup (in this section), surface roughness or bed-resistance values (e.g. Manning's n) are assigned to each of these land use areas (in the main tutorial module, [[Module1_test#Define_the_Materials_.28Surface_Roughness.29|here]]).
 
The '''Module_Data\Module_01\SAGA\''' folder already contains the materials files that we will use.
 
== Method ==
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[[File:Tute M01 SAGA 2d mat 3.png|frame|none]]
 
You may notice that the open pasture land-use that covers most of the study area has not been defined. This will be our default land use type,. toTo save time we only need to define the areas where the land use differs from the default.<br>
'''<u>NOTE:</u>''' The material attribute associated with each polygon is an integer number specific to a type of land-use. In the next step we link the material ID (integer) to a roughness coefficient. A table is provided below for reference.<br>
 
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<ol>
<u>Alternatively</u> if you would like to create your own material inputs rather than using the supplied dataset.
<li> <u>Alternatively</u>, loadLoad the empty (template) file named '''2d_mat_empty_R.shp''' from '''TUFLOW\Model\saga\empty\'''and save this in the '''TUFLOW\model\saga\''' folder as as '''2d_mat_M01_002_R.shp''', add this to a map window with the aerial photo and edit the shape, digitise your own material polygons ensuring to assign a Material ID to each polygon using the land use types in the table above.</li>
</ol>
 
== TUFLOW Geometry Control (TGC) File Updates ==
In order to read in the GIS layer created above. Enter the following text into the TGC file:<br>
<font color="blue"><tt>Set Mat </tt></font> <font color="red"><tt>== 1</tt></font> <font color="green"><tt> ! Set every cell to a material ID of 1 (Pasture)</tt></font><br>
<font color="blue"><tt>Read GIS Mat </tt></font> <font color="red"><tt>==</tt></font><tt> mi\2d_mat_M01_002_R.shp</tt><br><br>
The <font color="blue"><tt> Set Mat </tt></font> command sets all 2D cells to a Material ID of 1, which is used for pasture. The <font color="blue"><tt>Read GIS Mat </tt></font> command updates any 2D cells that fall within the polygons in the 2d_mat layer with the Material attribute value of each polygon. As discussed for the cell code values in the previous section, the order of these Mat commands is important.<br>
 
== Conclusion ==
SAGA has been used to view or create a 2d_mat layer which defines the spatial extents of the land use categories. Material Pleasecommands returnhave been added to the tutorialTGC. model modulePlease 1return to page [[Module1_test#Define_the_Materials_.28Surface_Roughness.29|hereTutorial Module 1]].
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