Tutorial: Visualise Flow Direction with Arrows

This tutorial will guide you through the steps of visualising the output of the SAGA flow direction algorithm as a mesh with arrows using the Crayfish plugin.

3. Convert SAGA Flow Direction raster to mesh

When you have calculated the flow direction using the SAGA tools from the Processing Toolbox, you can convert it to a mesh format using the Crayfish plugin.

First we're going to install the Crayfish plugin.
1. In the main menu go to Plugins | Manage and Install Plugins...

2. Search for Crafish and install the plugin. Click Close to continue.

3. Open the Processing Toolbox: in the main menu choose Processing | Toolbox.

4. Choose Crayfish | Conversions | SAGA Flow to GRIB

5. Choose flowdir as Input raster and save the output as flowmesh.grb and click Run. Close the dialogue after processing.

GRIB is a mesh format supported by QGIS.

6. Now you can drag the flowmesh.grb layer to the map canvas from the Browser panel. You can recognise the mesh format from the icon before the layer name.

After a while you'll see a yellow rectangle covering the study area. In the next section we're going to style the flow direction mesh layer that we have created now.