View source for Tute M01 Materials SAGA

<ol>
== Introduction ==
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 ==

<li>Open the aerial photo from the '''Module_Data\Aerial_Photos\SAGA\Aerial_Photo_M01.sgrd'''</li>

<li>Copy the '''2d_mat_M01_003_R''' files from the '''Module_Data\Module_01\SAGA\''' directory to '''TUFLOW\Model\Saga\'''.  There should be four (4) files, with the extensions dbf, prj, shp and .shx.</li>

<li>Load the '''TUFLOW\Model\Saga\2d_mat_M01_003_R.shp''' file.</li>

<li>In the ''Data'' tab of the Workspace window, select both the '''Aerial_Photo_M01''' and '''2d_mat_M01_003_R''' items, right click on either of them and select show:</li>
[[File:Tute M01 SAGA 2d mat 1.png|frame|none]]

<li>This will have created a new map window, with the material objects (these are regions). By default SAGA will give all of these objects the same style, something like the below.</li>
[[File:Tute M01 SAGA 2d mat 2.png|frame|none]]
<br>
<li>Each of the regions contains an integer value that defines the land use type.  To make this more obvious in SAGA, we can colour using the attribute.  To do this
*Select the 2d_mat_M01_003_R shape in the workspace tab
*In the ''Object Properties'' window select the ''Settings'' tab
*In the '''Colors ''' section set the '''Type'' to '''Lookup Table'''
*In the '''Lookup Table''' that appears, select, table and click on the '''...''' at the right of the prompt.
*Select ''Load'' and at the prompt select the following file '''Module_01\SAGA\2d_mat_M01_003_R_colour_table.txt'''
*This will bring up a list of attributes and colours. Select ''Okay''.
[[File:Tute M01 SAGA 2d mat Lookup.png|frame|none]]
*In the Object Properties window uncheck the '''Outline''' setting in the Display Section and select ''Okay''.
The region objects should now be colour coded based on the material ID attribute.
[[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, to 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>

{| align="center" class="wikitable"

! style="background-color:#005581; font-weight:bold; color:white;"| Material ID
! style="background-color:#005581; font-weight:bold; color:white;" width=50% | Land Use
! style="background-color:#005581; font-weight:bold; color:white;" width=25% | Manning's n
|-
|1|| Pasture|| 0.06
|-
|2|| Roads|| 0.022
|-
|3|| Buildings|| 3.0
|-
|4|| Ponds and other water|| 0.03
|-
|10|| Vegetated Creek|| 0.03
|}
<li> <u>Alternatively</u>, load 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_003_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>

== Conclusion ==
SAGA has been used to view or create a 2d_mat layer which defines the spatial extents of the land use categories.  Please return to the tutorial model module 1 page [[Module1_test#Define_the_Materials_.28Surface_Roughness.29|here]].
</ol>