Reservoir Outlet Mismatch Between SWAT+ Editor and reservoir.con File

[Swetasree Nag]

Hello all,

I am currently working on a watershed model using SWAT+ Editor v3.0.8 (rev.61.0.1) and have come across a discrepancy involving automatically added reservoirs and their outlet channel connections.

In my case, I added a reservoir shapefile to the model. The SWAT+ Editor automatically assigned outflow channels for each reservoir. When I check in the Editor interface, the outlet connection (e.g., to cha33) appears to be correctly assigned for reservoir 1(attached screenshots).

However, when I open the corresponding reservoir.con file (from the TxtInOut folder), the obj_id listed for that reservoir is different from what is shown in the Editor (Screenshot attached). The mismatch between the channel displayed in the SWAT+ Editor and the one reflected in the .con file is causing confusion, and I am unsure which one is actually used in the model execution.
Same happened for other reservoirs also.

I have tried the following steps to troubleshoot:

• Verified that there are no duplicate reservoir entries or naming conflicts.

• Used “Save Changes” and “Write Input Files” after confirming the connections.

• Deleted the existing reservoir.con file and re-generated it.

• Cross-checked the channel IDs using QGIS attribute tables.

Despite these efforts, the mismatch remains.

Could you please advise if this is a known issue, or if there's something additional I need to do to ensure consistency between the SWAT+ Editor interface and the .con file output?

I would greatly appreciate your guidance.

Best regards,
Swetasree

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[Jaclyn Tech]

This is because the SWAT+ text files require sequential numbers, basically like the line number minus the headers in the file. So check your channels connection file and see if #30 matches with cha33.

[Swetasree Nag]

Thank you for the response.
But it is not clear to me. Here I am attaching my channel connection file for your reference.

Please let me know how to get clarification on this.

Regards
Swetasree

[Jaclyn Tech]

The ID numbers in QGIS are not the same as the ID numbers in SWAT+ input files due to the requirements of the model inputs. Though I think your last screenshot does not match up with what you previously showed, so you might double check or send a zip of your project files.

But, generally, when looking at the SWAT+ input files, the obj_id values refer to the id column there which is the first, leftmost column, not the column labeled gis_id which refers to the QSWAT+ ID number. 

[Swetasree Nag]

Thank you for your prompt response.
I could now understand it clearly. The ID number does not match with SWAT+ ID because I think some streams are got merged or skipped during delineation process due to less stream length may be.