SWAT+ Check land use summary CN values and channel_sd_day precipitation issue

[Vrashesh Karkar]

1. Software details: 

• Component : QSWAT+/SWAT+ Editor
• Area of Impact: User Input and Model Output

2. Software Version: QGIS 3.40.13, SWAT+ 3.12,  SWAT+ Editor 3.2.1, Rev 61.0.2.61

3. Project Characteristics:

• Watershed: Credit River, Ontario, Canada. approx. 950km2, HRU Threshold 8/9/0%
• Modelling aim: Water balance (Daily)

4. Description

Dear SWAT+ Editor Group,

I am having two related issues with my SWAT+ project and would appreciate any guidance on what might be going wrong.

1. Land use summary CN values are incorrect: I have defined the land use classes and checked the land use management, plant communities, and CN values in the editor; everything appears to be set correctly. However, after running the model, the CN values reported in SWAT+ Check > Land Use Summary are much higher than expected and do not match what I assigned. Could someone please review my txtinout files and suggest what might be causing this discrepancy?

1. Channel_sd_day precipitation is out of bounds: For the second issue, the values in the rainfall gauge station (nasacr1) are correct and match my observed data. However, in the channel_sd_day output the precipitation values for the channels are different and appear to be way out of bounds, especially for Channel 33. I am not sure whether this is related to how subdaily precipitation is being routed, clipped, or assigned to channels, or if there is a setup problem in the climate or routing configuration.

If anyone has encountered similar issues with CN values in the land use summary or unexpected precipitation values in channel_sd_day, I would really appreciate your insights or suggestions on what to check.

5. Supporting Data

Drive link to txtinout: txtinout

Thank you very much for your time and support.

Vrashesh Karkar