PLAPS value extremely low

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Osman Furkan TOKGÖZ

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Dec 8, 2025, 8:30:37 AM (9 days ago) Dec 8

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The basin I’m working on is fed by snowfall and has a high, rugged terrain. According to the literature and calibrations done using snow water equivalent, the PLAPS value is typically between 20–40 mm/km, and in some cases it can even reach 150 mm/km. However, in the editor, even when I increase the PLAPS value from 2 to 3, the peak flows increase dramatically—almost like a tsunami. I’m wondering if there is a unit discrepancy in SWAT+ calculations?

Choosing Penman–Monteith or Hargreaves as the PET method does not significantly change the results.
Where could the problem be?

I also later learned that the model interprets a positive TLAPS value as a decrease with elevation, and a positive PLAPS value as an increase. That part was my mistake. However, having one interpreted as a decrease while the other is interpreted as an increase is quite confusing.