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Inverse solution

Posted: Tue Aug 07, 2007 3:18 am
by Srilert
Dear all,
I just have one question about inverse solution in CXTFIT and HYDRUS 2D. when I perform column experiment but I cannot get BTCs because heavy metal have a lot of sorption capacity. However, I can know the varied depth concentration in column by sectioning column extraction. Therefore, I know concentration in each depth. How can I get the retardtion factor from these 2 models? I am not sure I saw in "Data structure Input code", it shows Z(I), C(I) for a fixed time. Can I use this option for input my data for estimating sorption parameters (retardation factor) ? In addtion, I don't know in case of HYDRUS 2D?

Could anyone please suggest to solve this problem?

Thank you very much.

Srilert

Posted: Thu Aug 09, 2007 3:01 pm
by ntoride
Srilert

Yes, Z(I), C(I) for a fixed time is designed for concentration vs. depth. In order to estimate R, it is necessary to know v in advance. If you know exact theta, v can be estimated from water flux. We generally use nonreactive tracer to determine v based on a BTC or concentration profile. Please also note that you need to choose resident concentration c_r or total resident concentration c_t = Rc_r depending on your measurement.

Nobuo

Posted: Fri Aug 10, 2007 10:20 am
by Srilert
Dear Sir,
Can CXTFIT used for unsaturated zone like HYDRUS 1D or 2D ?

Thank you
Srilert

Posted: Fri Aug 10, 2007 1:29 pm
by ntoride
Srilert
CXTFIT is based on analytical solutions for the equilibrium and
nonequlibrium CDEs and HYDRUS uses numerical techniques to solve
Richards eq. and CDE. I would strongly recommend you to read CXTFIT and HYDRUS manuals.
Nobuo

Re: Inverse solution

Posted: Thu Apr 20, 2017 3:10 pm
by LoSrn
Dear Nobuo,
I'm not well known with these two form of model, and even reading the two manuals, I don't really see difference between hydrus and stanmod . Could you please explain me the difference between numerical and analytical solutions, thus between the 2 models ?
Thanks a lot for your help,
Sincerely,
Laura

Re: Inverse solution

Posted: Thu Apr 27, 2017 10:06 am
by LoSrn
Dear all,
I trie to model nonreactive bromide transport in a saturated sand column with stanmod. I trie to use the example 7 provided with the file but I don't manage to model transport of my tracer (fitted stay to 0 ...) could you help me with the set of transport parameters I should use ?
Thanks,
Laura