snowfall and effective precipitation in SWAT

[Tracy Baker]

For those who have experience using SWAT in areas receiving snowfall, I have a question: In areas where it is very dry and snows in the mountains in the winter, a good portion of that moisture sublimates and never contributes to infiltration nor runoff. Does anyone know if there is correction used in SWAT to account for the sublimation effect when determining “effective precipitation” in such areas? Can you suggest any SWAT literature or guidance on this?

Tracy Baker

[Steven Jepsen]

Hi Tracy,

I once found it instructive for this question to examine daily HRU outputs of SWE and potential ET during times of zero precipitation, finding daily decreases in SWE that tracked potential ET. So I think SWAT does apply a sublimation correction, using potential ET. It may be the soil evaporation form that is used (?), i.e. the Penman-Monteith with canopy resistance (r_s) set to zero. Also note that like snowmelt, evaporation from snowpack is areally weighted by snow covered area using the the depletion curve.

Steve

[Ameer Muhammad]

Hello  Steve/Tracy,

Where you can find simulated SWE? which SWAT output file give you SWE?

Thanks,

Ameer

[Soufiane TAIA]

Swe in swat is simulated by default at hru level. You can find it in output.hru. Also swat simulates swe at the level of elevation band. You have to activate the writing of elevation band outputs in file.cio. 

[summera khan]

Hi

anyone can please confirm, whether the sno_hru in output.hru file is the same thing as SWE?

[summera khan]

according to stehr et.al SWEday = SWE (day-1) - Snowfall-Snowmelt-Sublimation

But Sublimation is not available in hru output file

So PET can be used instead?

Please respond