How to Calculate the Slope of a DEM in 3 Steps:
- Open the DEM in QGIS
- Fill Sinks
- Run The Slope Tool
Open the DEM in QGIS
Note: In this example, we use a DEM exported from the Equator Data Menu.
Open your DEM shapefile in QGIS by dragging and dropping the file into the map space.
Image of our DEM in QGIS
Note: DEMs from Equator automatically fill sinks when exported.
If you did not get your DEM from Equator, follow the instructions below:
Use Fill sinks (wang & liu) tool.
Processing → Toolbox → SAGA → Terrain Analysis – Hydrology → Fill sinks (wang & liu)
Match the settings in the screenshot below and click Run.
Using the fill sinks tool to generated a Filled DEM layer
Run The Slope Tool
Now that we have projected our DEM onto our project, we will run the Slope tool:
Processing → Toolbox → Taster Terrain analysis → Slope
Set the input layer as your DEM, and adjust the other input settings as you deem appropriate (in this case we elected to leave the default settings):
Using the Slope tool to generate the final layer
You now have a layer with the slope of your DEM calculated in degrees!
We hope this helped, and feel free to take a look at some of Equator’s other blogs and “How-to tutorials”!