SWAT-CUP Calibration and Manual Calibration Feasibility AND new_par error

[Sefa Nur Yeşilyurt]

Dear All,

I hope this email finds you well.

I have recently developed my first model using ArcSWAT and calibrated it with SWAT-CUP. The calibration yielded the following results: NSE = 0.81, R² = 0.87, and P-factor = 0.56. Interestingly, the validation results were even better. However, when I input the best parameters obtained from SWAT-CUP into SWAT for evaluation, the NSE dropped significantly to 0.3. Suspecting an underlying issue, I decided to rebuild the model.

For the new model, I initially performed a manual calibration, achieving NSE = 0.79 and R² = 0.8. While these results are promising, I encountered a persistent issue when attempting to calibrate the new model in SWAT-CUP: the "new_par not found" error.

The files I input into SWAT-CUP are identical to those used in the previous model, and the model outputs are also very similar. However, SWAT-CUP consistently fails to generate the necessary files and gives the aforementioned error. Despite numerous attempts, I have been unable to resolve this issue.

Given the critical role of calibration in my study—where I aim to evaluate the performance of raw satellite data (e.g., GPM) and conduct climate scenario simulations using this calibrated model—it is imperative for me to achieve consistent results in both SWAT and SWAT-CUP.

I have two specific questions:

1. How can I resolve the "new_par not found" error? Despite testing various parameter ranges, no new files are generated, and the current outputs are unusable for scenario analysis.


2. Would it be problematic to rely solely on SWAT for manual calibration instead of using SWAT-CUP?



I would greatly appreciate any insights, suggestions, or similar experiences you may share to help address these issues.

Best regards,
Sefa Nur