Tutorial M02 002 GIS Inputs QGIS: Difference between revisions

= Introduction =

QGIS is used to create, import and view input data.<br>

= Method =

Navigate to the '''Module_02\Tutorial_Data''' folder. Copy and save all the below layers into the ''' Module_02\TUFLOW\model\gis''' folder:

 

Create two polygons, one raises the elevation to a set height and another raises the elevation by a set amount. <br>

:*Shape_Option = NO MERGE (assigns a single elevation to all Zpts falling within the polygon without interpolating the edges to the original topography) <br>

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<li>Zoom to the south west corner of the grid to digitise the second polygon.

<li>Turn off editing to save the edits.<br>

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<li>Turn off editing to save the edits.<br>

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:*Shape_Width = -1<br>

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<li>Add more vertices by holding Shift and double click along the upstream and downstream sides of the polygon. By default TUFLOW uses the merge option and the negative Shape_Width instructs TUFLOW to sample the DEM elevation only at the location of the polygon vertices. <br>

<li>Turn off editing to save the edits.<br>

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:*Select Layer > Add layer > Add Vector Layer and navigate to the ''' Module_02\TUFLOW\model\gis''' folder.

<li>The point layer specifies the elevation with the ‘Z’ attribute. Some of the point are snapped to the line layer setting the elevations along the line.

<li>The region layer sets the area over which the TIN functionality takes place. Without points snapped to the perimeter vertices of the region, the elevations are inserted from the underlying Zpt elevations, it uses the default merge option.<br>

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:*The material attribute associated with each polygon is an integer value based on the underlying land use type.<br>

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