Search found 5203 matches

by Jirka
Tue May 11, 2021 5:15 pm
Forum: HYDRUS (2D/3D)
Topic: Horizontal flow of solute in a flow cell using Hydrus 2D
Replies: 1
Views: 16

Re: Horizontal flow of solute in a flow cell using Hydrus 2D

You cannot have solute outflow at the atmospheric BC. Atmospheric BC assumes that outflow is due to evaporation, and solutes do not leave the soil profile with evaporation (they stay behind in the soil). J.
by Jirka
Tue May 11, 2021 5:12 pm
Forum: Hydrus 1D
Topic: Conditions determining type flux across the soil surface
Replies: 3
Views: 1124

Re: Conditions determining type flux across the soil surface

Once the critical pressure (e.g., hCritS for infiltration and hCritA for evaporation) is reached, we switch from the Neuman (flux) BC to the Dirichlet (head) BC. The code then calculates the flux for a given flow field. We do not use any other equations than the Richards equation. This is described ...
by Jirka
Tue May 11, 2021 5:02 pm
Forum: Hydrus 1D
Topic: Exclusion effects in model
Replies: 17
Views: 13980

Re: Exclusion effects in model

Looking at your BTC, it does not seem to me that you need the physical-nonequilibrium model (i.e., immobile water). The model predicts earlier solute arrival than the data. I would drop it and work with a “two kinetic site” model. J. 
by Jirka
Mon May 10, 2021 10:03 pm
Forum: HYDRUS (2D/3D)
Topic: Overland runoff
Replies: 6
Views: 723

Re: Overland runoff

It is highly unlikely that I will have time to look at this in the coming days/week. That’s more like a long-term project. J.
by Jirka
Mon May 10, 2021 9:56 pm
Forum: Hydrus 1D
Topic: Exclusion effects in model
Replies: 17
Views: 13980

Re: Exclusion effects in model

The model that is available in HYDRUS is called in the GUI “Dual-Porosity Model with Two-Site Sorption”. In the manuscript (S+VG, 2008), it is called “Dual-Porosity Model with One Kinetic Site”. This model has one kinetic and one instantaneous site in the mobile zone (i.e., a two-site sorption model...
by Jirka
Fri May 07, 2021 7:40 pm
Forum: HYDRUS (2D/3D)
Topic: Overland runoff
Replies: 6
Views: 723

Re: Overland runoff

If I recall, there should be several output files (Profile.out. Breakth.out, BalanceO.out) related to overland flow. They should be explained in the text about this special module. What you suggest is something you could do with the current version. Alternatively, I could provide you with an updated...
by Jirka
Thu May 06, 2021 5:57 pm
Forum: HYDRUS (2D/3D)
Topic: Inverse Modeling Subregion
Replies: 1
Views: 21

Re: Inverse Modeling Subregion

1. I assume that here you use Type=2 and Pos=-iSubReg (NLay), i.e., the average water content in a subregion. I think that by mistake the number of outputs is limited to nObs (the number of observation nodes; initially, we had this output only for observation nodes and not for subregions - NLay). If...
by Jirka
Mon May 03, 2021 7:35 pm
Forum: HYDRUS (2D/3D)
Topic: Variable boundary head at variable boundary fluxes
Replies: 3
Views: 1330

Re: Variable boundary head at variable boundary fluxes

Did you read the last sentence of my answer? J.
by Jirka
Fri Apr 30, 2021 8:25 pm
Forum: Hydrus 1D
Topic: dual porosity conc. flux bc
Replies: 1
Views: 1088

Re: dual porosity conc. flux bc

1. I do not see how this could happen, unless you use the Concentration BC at the upper surface, which is almost always physically incorrect.
2. 'sum(cvtop)' is not the sum of the individual concentration fluxes from the first column ('cvtop'), but its integration over time.

J.
by Jirka
Fri Apr 30, 2021 8:10 pm
Forum: HYDRUS (2D/3D)
Topic: Positive pressure head in hydrus
Replies: 7
Views: 1269

Re: Positive pressure head in hydrus

I used the pressure head at the source of 100 cm, and got positive pressure heads at the surface in 6 minutes and a fully saturated profile in about 10 minutes. Your setup does not make much sense to me. J.
by Jirka
Fri Apr 30, 2021 8:02 pm
Forum: HYDRUS (2D/3D)
Topic: Variable boundary head at variable boundary fluxes
Replies: 3
Views: 1330

Re: Variable boundary head at variable boundary fluxes

The results are exactly as I would expect them to be for the conditions you specified. Note that the surface pressure head starts increasing at the time when you keep the evaporation flux constant (after its dramatic decrease), i.e., the soil can bring moisture to the surface faster than it evaporat...
by Jirka
Thu Apr 29, 2021 10:57 pm
Forum: Hydrus 1D
Topic: Hydrus-1D Horizontal flow
Replies: 1
Views: 473

Re: Hydrus-1D Horizontal flow

Well, conductivity is a material property, which is independent of the direction of flow. You may want to revisit Darcy’s law. Direction flow will always depend on the imposed boundary conditions, i.e., it can be both to the left or to the right. J.
by Jirka
Thu Apr 29, 2021 7:01 pm
Forum: HYDRUS (2D/3D)
Topic: Overland runoff
Replies: 6
Views: 723

Re: Overland runoff

The special Overland flow module of HYDRUS associates overland flow only with an Atmospheric boundary condition (Kode=-4). While the code allows treating the time-variable flux BCs (i.e., Kode=-3, -7, -8, and -9) as atmospheric BCs (i.e., with limited pressure head hCritA and hCritS), overland flux ...
by Jirka
Thu Apr 29, 2021 6:45 pm
Forum: HYDRUS (2D/3D)
Topic: Positive pressure head in hydrus
Replies: 7
Views: 1269

Re: Positive pressure head in hydrus

You realize that if you apply pressure of 6 m 15 cm below the soil surface in a sandy soil, you will likely create a geyser at the surface above the dripper, right? J.
by Jirka
Wed Apr 28, 2021 4:32 am
Forum: HYDRUS (2D/3D)
Topic: Positive pressure head in hydrus
Replies: 7
Views: 1269

Re: Positive pressure head in hydrus

Before I look at it, you will need to explain me why do you think it is reasonable to apply the pressure head of 6 meters on a dripper, which is 15-20 cm below the ground. Also, have you look at the retention curve (for sand) before you applied the initial pressure of -30 m? J.