rRoot (T-level)/Transp (Meteo_out)

A discussion forum for Hydrus-1D users.
Post Reply
elizabeth.ramirez.z
Posts: 8
Joined: Sat Oct 26, 2019 4:03 am
Location: Chile

rRoot (T-level)/Transp (Meteo_out)

Post by elizabeth.ramirez.z » Mon May 18, 2020 11:38 pm

Hello,
I hope you are well. I´m using hydrus1d to simulate pine evapotranspiration. I inserted in the hidrus LAI and meteorological data. Hydrus calculated PET (Penman.Monteith).
My question is: I don't understand why rRoot (T-level) and transpiration (Meteo_out) are so different if they are both potential transpiration. In the case of rRoot, the result is 1900 mm but in the transpiration of Meteo_out it is 1400 mm.

Another question: Is it necessary to use the Julian day? In my case I simulated in hours with hydrus-1d, is it also necessary?

Thanks for your help
Last edited by elizabeth.ramirez.z on Thu May 21, 2020 2:39 am, edited 1 time in total.

Jirka
Posts: 4922
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: rRoot (T-level)/Transp (Meteo_out)

Post by Jirka » Mon May 18, 2020 11:52 pm

First question: I do not see the difference between rRoot (1400 mm) and the transpiration in Meteo_out (1400 mm).

Another question: Unless you use an option when you specify directly net radiation, you need to use Julian days since radiation is then calculated based on that.

J.

elizabeth.ramirez.z
Posts: 8
Joined: Sat Oct 26, 2019 4:03 am
Location: Chile

Re: rRoot (T-level)/Transp (Meteo_out)

Post by elizabeth.ramirez.z » Thu May 21, 2020 2:44 am

Sorry, I was wrong in the Transpiration values.
In the case of rRoot, the result is 1900 mm but in the transpiration of Meteo_out it is 1400 mm. I wanted to understand why the values are different.

Thanks Jirka.

Jirka
Posts: 4922
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: rRoot (T-level)/Transp (Meteo_out)

Post by Jirka » Thu May 21, 2020 5:12 pm

"rRoot" in the T_level.out file and "Trasp" in the Meteo.out file are potential transpiration rates in units of [L/T] and (mm/d). respectively. This means that they should be on the order of few mm/d. I do not see how they can potentially be 1400 or 1900 m (wrong units and wrong values). J.

elizabeth.ramirez.z
Posts: 8
Joined: Sat Oct 26, 2019 4:03 am
Location: Chile

Re: rRoot (T-level)/Transp (Meteo_out)

Post by elizabeth.ramirez.z » Thu May 21, 2020 9:38 pm

The rRoot (1900 mm) and Transp (1400 mm) values ​​are cumulative transpiration for one year. I summed all the transpiration for 1 year and those are the results.

Through Hydrus, I have tried to find out how much water the pine transpires in a year.

But my question is if there can be differences between the potential transpiration of T-level and Meteo_out, or should they be similar?

Thanks.

Jirka
Posts: 4922
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: rRoot (T-level)/Transp (Meteo_out)

Post by Jirka » Fri May 22, 2020 12:32 am

In general, they should be the same. However, they can be different for some special conditions, such as when you consider interception. Meteo.out reports potential transpiration values calculated based on meteo conditions. T_level.out reports potential transpiration values as applied to root water uptake, i.e., after subtracting interception. Interception is part of transpiration, but not root water uptake. J.

Post Reply