Tutorial: Stream and Catchment Delineation

10. Clipping layers to the catchment boundary

For visualization, it is nicer to clip the layers to the boundary of the catchment.

1. Let’s first clip the channels vector layer to see only the streams that are inside the catchment. Go to the main menu and select Vector | Geoprocessing Tools | Clip...

Clip Vectors Menu

2 .Fill in the dialog as in the figure below to use the catchment layer as a "cookie cutter" to clip the Input layer channels to the boundary of the Overlay layer Rur_catchment. Call the Clipped layer Rur_channels.shp. Click Run to run the tool. Click Close to return the main screen.

If you get an error related to the geometry, you can fix it. Go to the Processing Toolbox and choose Vector geometry | Fix geometries. The geometric errors are caused by the vectorisation process.

We can easily copy the styles from channels to Rur_channels.

4. Right-click on the channels layer and choose Styles | Copy Style | All Style Categories.

5. Now right-click on Rur_channels and choose Styles | Paste Style | All Style Categories.

6. Remove channels from the layers list and make sure that Rur_channels layer is at the top of the list.

We can clip the DEM in the same way as we did in Section 6. The only difference is that we have to give a no data value that is out of the range of elevations—we often use -9999 for that. Here we don’t need the clipped DEM, because we are going to apply a styling technique to create a nice effect to highlight our study area.

Watch this video to check the steps of this section: