Single porosity with immobile water

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Kathrine
Posts: 5
Joined: Mon Nov 12, 2018 6:42 pm
Location: Spain

Single porosity with immobile water

Post by Kathrine » Fri Jul 05, 2019 9:44 pm

Dear Prof. Jirka,

I am trying to simulate solute transport using different approaches in HYDRUS-2D. I have seen that there is also the option to use dual-permeability with immobile water. I was wondering if i can use modified single porosity (by Vogel and Cislerova) with immobile water as well? Because I tried to set the parameter ThImob for that model too and I have seen that the results change as well as for the dual permeability with immobile water content. However, i have read your paper about the different approaches (Šimůnek and van Genuchten, 2008), and the Hydrus manual and there is nothing about the single porosity with immobile water. I have read the manual for Hydrus and it is clear that ThImob is used only for non-equilibrium but I was wondering If i can use it for the modified single porosity since somehow I consider preferential flow as well.

I guess I can use the same equations as for the dual-permeability with immobile water content but now only for the matrix domain, and about the mass transfer terms, I will have only the mass transfer term between the mobile and immobile region of the matrix domain since I didn't consider macropore domain.

Thank you in advance

Jirka
Posts: 4712
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Single porosity with immobile water

Post by Jirka » Sat Jul 13, 2019 3:30 pm

To be frank, I do not understand what the question is.
1. Yes, you can use the modified single porosity model (by Vogel and Cislerova; as well as all the other single porosity models) with a constant immobile water content. However, only the standard VGM single porosity model can be used with a transient immobile water content.
2. If I recall correctly (I'm traveling in Tanzania and do not have time to check it), the dual-permeability model with immobile water in the matrix is implemented only in HYDRUS-1D. I do not recall implementing it for HYDRUS-2D. In any case, you would need the DualPerm module to be able to use the dual-permeability model with HYDRUS-2D.

J.

Kathrine
Posts: 5
Joined: Mon Nov 12, 2018 6:42 pm
Location: Spain

Re: Single porosity with immobile water

Post by Kathrine » Sun Jul 14, 2019 9:10 am

Thank you very much for your reply.

I have the DualPerm module for HYDRUS-2D and I am using the dual-permeability approach with constant immobile water content (ThImob.M) and It works fine as well as the single porosity (ThImob).

Thank you again.

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