How to add a new urban subcatchment

Note: If you want the area of your subcatchment to be automatically calculated based on the shape you draw on the map, you must first set the area equal to zero in the Model Defaults. Recall how to do this from the Urban Networks section.This must be done before adding a subcatchment. Once your subcatchment has been drawn, you cannot set the area equal to zero in the node properties to use this functionality. We also recommend confirming the Infiltration model set at this point, as this must be consistent for all Subcatchment nodes in the network.

To add a new Subcatchment, on the 1D Urban Build tab, initially confirm you are in 1D Urban selection mode by ensuring the toggle is coloured blue.

On the 1D Urban Build tab, locate the Subcatchment icon.

Click the Subcatchment icon and it will be highlighted. If you have your 1D Urban Network panel visible, you will also notice this becomes greyed out. On the map view, click the location you would like to add the first vertex of your Subcatchment.

Click again in the location you would like to add the second vertex. A straight line will join these points. Continue clicking to add more vertices. We recommend drawing in the clockwise direction. Double-click to add the final vertex and the tool will automatically add a Subcatchment node icon inside the polygon drawn.

Enter the properties of this node in the same way as other nodes, for example by double-clicking the node icon in the Map view.