Tutorial: Automate Stream & Catchment Delineation using the Graphical Modeler

1. Introduction

QGIS has some great ways to automate your processes. You can use PyQGIS to build scripts. But if you're looking for a more graphical way, the Graphical Modeller is a great way to automate your processes using the tools from the Processing Toolbox.

After this tutorial you're able to:

  • Define input layers and variables for your graphical model
  • Add processing tools to your graphical model
  • Save results of your graphical model
  • Save your graphical model to the Processsing Toolbox
  • Create a graphical model for stream delineation
  • Create a graphical model for catchment delineation
In this tutorial we'll make two models that you can apply to any area for which you have downloaded SRTM data and created a bounding box polygon of the study area. For this tutorial the data is provided.

Here we use QGIS 3.14 Pi, but the procedure is similar in 3.10 LTR.