Guidance on updating calibrated parameters after land Use change in SWAT model

[Rafia Sarfaraz]

I am currently working on the SWAT modeling component of my research. The model has been calibrated using the historical land-use map, and I have already updated the calibrated parameters obtained from SWAT-CUP into the SWAT model.

For my scenario analysis, I plan to replace the historical land-use map with future land-use map to evaluate the impact of land-use change on groundwater recharge. However, I understand that when the land-use map is changed in SWAT, the HRUs are regenerated, which modifies the HRU structure.

In this situation, I would like to seek your guidance on the best approach. My main question is whether I should reapply the same calibrated parameter set from the historical calibration to the model after regenerating the HRUs.

If so, I am unsure how to properly handle parameters that were calibrated as relative changes (e.g., r__ parameters in SWAT-CUP) and land-use–dependent parameters such as CN2, since the HRU composition changes with the new land-use map.

My intention is to ensure that any differences in simulated groundwater recharge reflect the effect of land-use change itself, rather than differences caused by recalibration or inconsistent parameter updates.

I would greatly appreciate your guidance on the most appropriate methodology to follow in this case.

[Rafia Sarfaraz]