[Qgis-user] Generating rivers from DEM

[j***@south-gis.co.za]

Hi all.



I'm trying to generate rivers from SRTM data in Cameroon.



I've done a few tests using the SAGA tools - Channel Network and Channel
Network and Drainage Basins. However, I'm not getting any useable answers
out. I'm not sure if my parameters are incorrect or what.



The size of the area I am trying to generate rivers for is 110km x 110km
(One SRTM scene).



I am on the latest version of QGIS - 3.4.1.



Many thanks

Jill



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[Nicolas Cadieux]

Hi,

The first thing to do is to fill sink algorithm. Most importantly, do NOT save this output as a tiff. Just leave it as a temporary file. This way, It will keep the SAGA format.

Then use this temporary layer to make the bassins and river channels. It looks like there is a bug when saving the sink free raster as a tiff. Results are very different in the bassin file. If you can reproduce, tell me. We should do a bug report.

Nicolas

Post by j***@south-gis.co.za
Hi all.
I’m trying to generate rivers from SRTM data in Cameroon.
I’ve done a few tests using the SAGA tools – Channel Network and Channel Network and Drainage Basins. However, I’m not getting any useable answers out. I’m not sure if my parameters are incorrect or what.
The size of the area I am trying to generate rivers for is 110km x 110km (One SRTM scene).
I am on the latest version of QGIS – 3.4.1.
Many thanks
Jill
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