Tutorial: Delineate Multiple Subcatchments

4. Delineate multiple subcatchments for pour points

Now we're ready to calculate the catchments of the snapped pour points. We'll use plugin, which is not in the official repository.

1. In the main menu go to Settings | User Profiles | Open Active Profile Folder.
2. Browse to the subfolder python\plugins so you end up in e.g. C:\Users\hansa\AppData\Roaming\QGIS\QGIS3\profiles\subcatchments\python\plugins

3. Now go to this GitHub repository: https://github.com/jvdkwast/PyQGIS_Hydro
4. Click the green Code button and then choose Download ZIP.
5. Open the downloaded zipfile. 7Zip is a great open source tool to use. Browse in the zip file and extract the points_to_catchments subfolder to your plugins folder, which you have identified in step 2.

6. In QGIS go to the main menu and choose: Plugins | Manage and install plugins...

7. Go to the Settings tab and click Reload Repository.

8. Go back to the All tab and check the box before the Points to Catchments plugin and Close the dialogue.
Points to Catchments Plugin

The tools is now added to the Processing Toolbox (Note that this doesn't work in QGIS 3.14).

9. In the Processing Toolbox go to IHE Delft | Hydrology | Calculate catchments from points.

10. In the Calculate Catchments From Points dialogue select the Snapped Pour Points layer as Outflow point layer. Choose the Filled DEM as DEM layer. Choose a new Output Folder where the tool will save a shapefile for each point.

11. Click Run and Close the dialogue after processing.

12. Go to the Browser panel and drag the shapefiles to the map canvas to style and visualise them.


In the next section we'll do this for all subcatchments in the catchment.