Hydrology Toolset
For some time TatukGIS has been working on a Hydrology Toolset. This is coming soon feature arrived with version 11.54.0.
The following teaser images illustrate several operation steps: from raw DEM to vectorized rivers (with flow amounts) and drainage basins.

1. Original DEM

Step 2: Flow directions.
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Step 3: Flow accumulation.

Step 4: Watershed.

Step 5: Stream order.

Step 6: Basins and Streams vectorized.
Read documentation.
Data source: publicly available 100m Digital Elevation Model for area around Bytów county, Poland; Head Office of Geodesy and Cartography (GUGiK).