I'm trying to use the calibration files in SWAT+ but I have some questions on that matter. According to the Input Data documentation, several files (e.g., codes.cal, cal_parms.cal, calibration.cal) must be prepared beforehand and set in the file.cio under the section CHG. What is not really clear for me is the number of required files and how to define changes in all or certain HRUs belonging to one or several subbasins. For example, if my project has 34 subbasins and I want to modify the cn2 parameter in all HRUs of subbasins 5,7 and 10, how the files must be prepared in order to accomplish this task?

Thank you!