Tute M01 Boundaries SAGA: Difference between revisions
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We will create the 2d_bc boundaries first. These boundaries are external and will "snap" to the edge of our active model area. Both of these boundaries should be aligned perpendicular to flow direction. Care should be taken to digitise these boundaries perpendicular to flow direction (i.e. across the waterways). We will review the flow patterns in the vicinity of the boundaries later in this tutorial.
<li>Load the DEM '''Module_Data\DEMs\SAGA\DEM_M01.sgrd'''</li>
<li>Load the code polygon '''TUFLOW\model\gis\
<li>Create a new map containing these layers, select both of these in the data tab of the workspace window, right click and select "Show".</li>
<li>Load the template 2d bc type layer (2d_bc_empty_L.shp) from '''TUFLOW\model\gis\empty\'''.</li>
<li>Save a copy of the template under the '''TUFLOW\model\gis''' folder as '''
<li>Open the newly saved, '''
The SAGA window should now look something like this:<br>
[[File:Tute M01 Saga 2d bc 1.png|frame|none]]
<br>
<li>The first step is to change the style of the code region to make it a bit easier to work with. Select the '''
* Set the Fill Style to "Transparent", this allows us to see the DEM behind the polygon;
* Set the Outline Size to 2, to make the object more visible;
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Select Apply.</li>
[[File:Tute M01 Saga 2d bc 2.png|frame|none|Modifications above highlighted in bold]]
<li>Before we begin modifying the 2d_bc layer, we need to enable snapping to the 2d_code region. To do this select the '''
[[File:Tute M01 Saga SnapTo1.png|frame|none]]
<br>
<li>In the snap to dialogue, select the
[[File:Tute M01 Saga SnapTo2.png|frame|none]]
<br>
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The type "HQ" designates this as a Water Level ("H") versus Flow ("Q") boundary. This is a stage-discharge boundary condition. If a Name is specified, the user must define this stage-discharge relationship in the boundary database. In this case a water surface slope value is specified via the "b" attribute, this value of 0.01 is in metres per metre and corresponds to a 1% water surface slope. TUFLOW will automatically create a stage-discharge curve flow this location, based on the underlying topography, roughness and specified water surface slope.</li>
[[File:Tute M01 Saga 2d bc 6.png|frame|none]]
<li>In the data tab, right click on the
[[File:Tute M01 Saga 2d bc 7.png|frame|none]]
===2d_sa type boundary===
The next step is to create an internal inflow boundary using a source-area inflow this is done with a 2d_sa type layer.
<li>Load the '''2d_sa_empty_R.shp''' template file from the '''TUFLOW\model\gis\empty\'''. Save a copy of the layer in the '''TUFLOW\model\gis\''' directory as '''
<li>Load the newly created
<li>Add the layer to a map window with the DEM.</li>
<li>Add a new shape and digitise a polygon around the dam in the lower right (south-east) of the screen.</li>
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