TUFLOW SWMM Tutorial M03: Difference between revisions
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===Update SWMM Hydrology Subcatchments===
The information within '''Hydrology--Subcatchments''' defines the subcatchment parameters (including catchment area, width, slope, percent impervious, outlet specification and infiltration details). All required data entries have been pre-filled in the supplied dataset except the 'Area' information, which we will determine using QGIS.
<ol>
<li>In the QGIS Layers Panel, select (left click) '''Hydrology--Subcatchments''' and toggle on editing.
<li>Right click '''Hydrology--Subcatchments''' and select 'Open Attribute Table'.
<li>Choose 'Area' as the target field and type the calculation expression, '$area / 10000'.
:* '$area ': Extracts the area
:* '/ 10000': Converts the area values into hectares.<br>
'''Note:''' The projection used in these tutorials is measured in meters. Thus, when QGIS extracts the area from a region, it reports the area in m<sup>2</sup>. If using a projection that is measured in feet, QGIS would extract the area in ft<sup>2</sup>.
<li>Click
<li>Turn off editing and save the information.
<li>Inspect the attribute information within '''Hydrology--Subcatchments''' to familiarize yourself with the data. A few demonstration features have been included in the dataset.
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