LSU ID and SWAT+Toolbox multi-site calibration

[Fereshteh]

Hello all, 

I am trying to calibrate the SWAT+ model using both streamflow (Q) and evapotranspiration (ET). For ET, I would like to calibrate at the LSU level. In the SWAT+ Toolbox, I selected Level = LSU; for the LSU number, I opened lsus2.shp to find the correct LSU identifier.

I have 2 questions: 

1. Which field should I use, the LSU ID field or the FID as the LSU number in SPT? In my watershed, the total number of LSUs is 1009, but the LSU ID values are like 5162, 5161, etc., which seems confusing to me (the photo is attached).

2. Should I check the Multi-Site Calibration option when I want to calibrate both Q and ET? Or is this option only intended for calibrating Q using several gauge stations?

Thanks,

Fereshteh