In which units do I have to calculate Slope to use as an input for the LS Factor tool in SAGA (degrees, %, radians)?
I couldn't find anything in the documentation.
Use Slope in radians as input raster.
Some hints are in the code, for instance:
Line 567: if( Slope < 0.08975817419 ) // < 9% Steigung := atan(0.09), ca. 5 Degree
To be more precise, please also check out any one of the reference paper. For instance:
Moore, I.D., Grayson, R.B., Ladson, A.R. (1991): Digital terrain modelling: a review of hydrogical, geomorphological, and biological applications. Hydrological Processes, Vol.5, No.1
The unit is understood when you see the Equation.(8)
And you can confirm how it is implemented in the LS calculation:
Line 536: LS = (0.4 + 1) * pow(Area / 22.13, 0.4) * pow(sin(Slope) / 0.0896, 1.3)
beta in the above.
You may already know SAGA's default output unit of the Slope is radians. (It is less intuitive if you are using the tool through QGIS, which default unit is degrees.)