Search found 4827 matches

by Jirka
Tue Oct 22, 2019 6:21 pm
Forum: Hydrus 1D
Topic: Improving Obs_Node water content/observed water content adjustment
Replies: 2
Views: 250

Re: Improving Obs_Node water content/observed water content adjustment

You should try the inverse mode of HYDRUS-1D, which allows you to calibrate the soil hydraulic parameters against the observe data. J.
by Jirka
Tue Oct 22, 2019 6:18 pm
Forum: Hydrus 1D
Topic: estimate actual evaporation
Replies: 1
Views: 221

Re: estimate actual evaporation

The evaporation process is usually assumed to have two stages (sometimes also the third, when flow towards the soil surface is only in the vapor phase). During the first stage, actual and potential evaporations are the same (enough water in the soil profile to satisfy the atmospheric demand), during...
by Jirka
Sun Oct 20, 2019 11:04 pm
Forum: HYDRUS (2D/3D)
Topic: Scaling factors for water retention properties over space
Replies: 4
Views: 241

Re: Scaling factors for water retention properties over space

The scaling factors are superimposed on whatever soil hydraulic properties you specify for the domain. If you specify only one material, then this material will give you reference hydraulic functions, which will be scaled by scaling factors. However, nothing prevents you to have multiple layers, and...
by Jirka
Sun Oct 20, 2019 8:31 pm
Forum: HYDRUS (2D/3D)
Topic: Scaling factors for water retention properties over space
Replies: 4
Views: 241

Re: Scaling factors for water retention properties over space

The scaling factors implemented into HYDRUS are based on the linear variability concept of Vogel et al. (1991). In general, there are three scaling factors, one for the hydraulic conductivity (a_K), one for the pressure head (a_h), and one of the water content (a_theta). These scaling factors can be...
by Jirka
Fri Oct 18, 2019 5:50 pm
Forum: Hydrus 1D
Topic: Numerical convergence problem
Replies: 13
Views: 1339

Re: Numerical convergence problem

I wish I knew how to do it in the Intel compiler. J.
by Jirka
Wed Oct 16, 2019 7:04 pm
Forum: HYDRUS (2D/3D)
Topic: Dual porosity model
Replies: 1
Views: 193

Re: Dual porosity model

While on the Data Tab of the Navigator bar you can choose only "Water Content", on the View Tab of the Navigator bar, you can choose in the "Results" section, which "Water Content" to display, either "Mobile", "Immobile", or "Total". If you want to convert the ThIm.out file, which is binary, into an...
by Jirka
Wed Oct 16, 2019 5:04 pm
Forum: Hydrus 1D
Topic: Numerical convergence problem
Replies: 13
Views: 1339

Re: Numerical convergence problem

You like use some unrealistic combination of parameters, which somewhere apparently leads to a division by zero, which leads to NaN (standing for not a number, is a member of a numeric data type that can be interpreted as a value that is undefined or unrepresentable, especially in floating-point ari...
by Jirka
Tue Oct 15, 2019 6:34 pm
Forum: Hydrus 1D
Topic: Electric conductivity and solute concentration
Replies: 2
Views: 248

Re: Electric conductivity and solute concentration

I suggest that you read the following two papers, where we discuss these issues. Note that some simulations from these papers are posted on the HYDRUS website. J. Ramos, T. B., J. Šimůnek, M. C. Gonçalves, J. C. Martins, A. Prazeres, N. L. Castanheira, and L. S. Pereira, Field evaluation of a multic...
by Jirka
Mon Oct 14, 2019 3:43 pm
Forum: Hydrus 1D
Topic: Cumulative root water uptake per subregion
Replies: 1
Views: 186

Re: Cumulative root water uptake per subregion

No. HYDRUS does not keep track of that. Such option would need to be newly coded. You could get actual uptake from different subregions for a particular print time if you integrate the sink term in the Nod_inf.out file. J.
by Jirka
Fri Oct 11, 2019 5:10 pm
Forum: Hydrus 1D
Topic: inquiry about water flow parameters
Replies: 2
Views: 220

Re: inquiry about water flow parameters

The parameter α (denoted as h0 in Kosugi [1996]) has units of [L] and should be entered as such in GUI. J.
by Jirka
Wed Oct 02, 2019 4:07 pm
Forum: Hydrus 1D
Topic: Inverse model in HYDRUS - Water Content Profile
Replies: 4
Views: 356

Re: Inverse model in HYDRUS - Water Content Profile

The results look reasonable to me for the conditions that you described. I assume that the saturated water content is about 0.27 (the water content of the bottom node). Further I would assume that precipitation is smaller than Ks, and as a result, the profile will only reach the water content corres...
by Jirka
Wed Oct 02, 2019 12:57 am
Forum: Hydrus 1D
Topic: Inverse model in HYDRUS - Water Content Profile
Replies: 4
Views: 356

Re: Inverse model in HYDRUS - Water Content Profile

I do not think that it is possible to comment on your project without knowing more details, at the minimum the boundary conditions. J.
by Jirka
Tue Oct 01, 2019 3:21 pm
Forum: HYDRUS (2D/3D)
Topic: Change boundary condition form Atm.BC to Head BC
Replies: 3
Views: 260

Re: Change boundary condition form Atm.BC to Head BC

I do not see how it could be done in one run with the existing model. J.
by Jirka
Tue Oct 01, 2019 3:14 pm
Forum: Hydrus 1D
Topic: Root length input
Replies: 1
Views: 217

Re: Root length input

The Beta function describing the root distribution with depth (in the GUI denoted as "Root [1/cm]") is a function that describes the proportional distribution of potential root water uptake (root distribution) over depth. It does not have any actual values, i.e., it is a relative function. The progr...
by Jirka
Mon Sep 30, 2019 7:19 pm
Forum: HYDRUS (2D/3D)
Topic: How to change an air-entry value
Replies: 2
Views: 222

Re: How to change an air-entry value

You need to use the modified van Genuchten model. This model then has additional parameters Qa (<Qr) and Qm (>Qs). Different values of the Qm parameter will give you different values of the air-entry value. The larger the difference between Qm and Qs, the larger the air-entry value. J.