Now you can find your new model in the Processing Toolbox.
Before running the model, we first need to digitize an outlet.
1. Install the QuickMapServices plugin and add OSM Standard to the map canvas.
2. Find the outlet of the Rur (Roer in Dutch) on the map, where it enters the Meuse (Maas) river.
3. Click the to create a new temporary scratch layer.
4. In the dialogue call the layer Outlet with a Point Geometry type. Set the projection to EPSG: 32632.
5. No need to define attributes. Click OK.
6. The layer is automatically set to editing mode. Click to add a point feature at the outlet.
7. Toggle off editing by clicking and click Save.
Now we can use our Stream delineation model from the Processing Toolbox.
12. In the Processing Toolbox double click Models | Hydrology | Stream delineation.
13. In the Stream Delineation dialogue choose the boundingbox layer as Bounding box, choose the 4 SRTM tiles as DEM Tiles, choose Outlet as Outlet on map, keep the default Strahler order threshold and set the snapping Tolerance to 500 m. Save the Snapped outlet to snapped_outlet.shp, save the Streams to streams.shp and save the Filled DEM to filled_DEM.tif.
14. Click Run. Close the dialogue after processing.