water balance

A discussion forum for users of the new HYDRUS 2D/3D. HYDRUS is a software package for simulating water, heat and solute movement in two- and three-dimensional variably saturated media. Happy Posting!
Post Reply
nessrine
Posts: 17
Joined: Sun Jun 28, 2015 9:38 pm
Location: Tunisia

water balance

Post by nessrine » Sun Jun 14, 2020 9:54 am

Dear Jirka

I'm using Hydrus 2D/3D version 3.02

I'm modelling water flow and solute transport under irrigation .
the simulation periode is 271 day , the irrigation is a rotation between a flood irrigation and subsurface irrigation
for this end I selected VARflux2 for subsurface irrigation and c2 for irrigation salinity , and Varflux3 and C3 for flood irrigation and irrigation salinity respectively.
my domaine is 3m*3m

my problem is the incoherence between the input of ATM.Bc and the out.put of fluxes .

for exemple :

I have in the ATM.BC in-put window :
total evaporation = 414 mm
total transpiration =1072 mm
total precipitation=59 mm
total flux2= -655,7722 mm
total flux3= -628,2857 mm
however after simulation the boundary water fluxes output are very different from my in-put.

I summed the evaporation rate from boundary water fluxes in order to get the total in mm and I found 2846,90363 mm ??? and if I took the cumulative evaporation from the cumulative boundary water fluxes I get 0.18 m2( only the last value since it is a cumulative, I did not summed all values) I divided the value by 9 m2(the surafce of my domain) I found 19 mm ??? i can not undersatnd what happened the same for the other (fluxes 2 and 3 and precipitation). I found a very different and huge amounts if I summed them from the boundary water fluxes and very small amounts if I get them from the cumulative boundary water fluxes (m2) and the divided them by the surface.

I'm really confused
note that WatBalR [%] = 0.478

Jirka
Posts: 4961
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: water balance

Post by Jirka » Sun Jun 14, 2020 6:34 pm

The program integrates all fluxes across all boundaries and then uses them in the mass balance calculations. If Hydrus reports an error less than 1% (which it does in your case) then everything should be OK. Note that you cannot simply sum up fluxes from different files. The values there are the rates and thus you need to always multiply them by a time interval before summing them up. That's what HYDRUS does before reporting the cumulative values. Jirka

nessrine
Posts: 17
Joined: Sun Jun 28, 2015 9:38 pm
Location: Tunisia

Re: water balance

Post by nessrine » Wed Jun 17, 2020 1:17 pm

Thank you for your reply

So I should work with the masse balance information out-put file.

Jirka
Posts: 4961
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: water balance

Post by Jirka » Wed Jun 17, 2020 2:22 pm

You can do both. However, if you do that correctly, you need to get the same results as those reported by Hydrus. J.

Post Reply