r/Hydrology • u/gummiebe • 21d ago

Delineation of Catchment/Sub-basin Problem

hi everyone, what do u do when hec-hms cant identify streams? i tried to preprocess it in qgis but the strahler order can't seem to connect the streams properly, i edited the channel lines (vector) to manually connect it, but how do you integrate this with the current dem so that hec-hms can recognize it? 🫤 i've read about burning the streams but will it matter once i use it in hec-hms?

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u/OttoJohs 21d ago

1.) I use the terrain preprocessing (burn channels, create walls) internal to HEC-HMS.

2.) If that doesn't work, I do manual terrain modifications in GIS or RasMapper and use that DEM.

3.) If both those don't work, I just do hand edits to the watershed shapefile.

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u/Carbulon 21d ago

Hec has an option to burn streams or delineate basins. You should do that first before using the "fill" option