I am trying to use the Saga toolbox (2.2.3) in QGIS (2.18) to create a channel network from SRTM data using this tutorial 1.
It works, but the result I get when using the DEM that comes with the tutorial are much better than what I get when using SRTM DEMs. The channels are mostly not connected to each other, no matter what I try. Is there a way to fix this, or is it because of the SRTM data being not good enough for this analysis?
So far, I am using the following workflow:
- Catchment area (recursive): Step: 1, Method: Deterministic, Convergence: 1,100000
2: Channel network: Initiation theshold: Greater than 100000. I have also tried Less than 100000 and other values, but that does not help.
Do I need to prepare the SRTM data first before this analysis works?