Error: initial water content condition is lower than Qr

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ritadg
Posts: 6
Joined: Fri Sep 20, 2019 12:37 am
Location: Australia

Error: initial water content condition is lower than Qr

Post by ritadg » Wed Jan 15, 2020 12:06 am

Dear Hydrus community,

I'm using HYDRUS-1D version 4.14 in the dual porosity model (mobile-immobile, water content mass transfer).
I'm modeling water flow, upper BC: atmospheric BC with surface run-off, lower BC: free drainage.

I run Hydrus through Matlab. I'm generating parameter sets, by giving the lower and upper limit for each of the nine paramters, plus LAI.
My initial water content is: 0.266. I gave the lower and higher limits for theta r (mob and imm) equal to 0.01 and 0.1.
So the residual water content is always lower than the initial water content.
But I keep getting the error message(not in all of the runs):

'Initial water content condition is lower than Qr !'

Which is not true, from what I can understand.

I appreciate a lot if someone could help me.

Thank you very much,
Rita

Jirka
Posts: 4824
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Error: initial water content condition is lower than Qr

Post by Jirka » Wed Jan 15, 2020 4:11 am

It would be good to see the project when this happens. For a uniform flow model, this is pretty straightforward, but for a dual-porosity model it is more complicated. J.

ritadg
Posts: 6
Joined: Fri Sep 20, 2019 12:37 am
Location: Australia

Re: Error: initial water content condition is lower than Qr

Post by ritadg » Wed Jan 15, 2020 10:42 pm

Thanks Jirka,

Yes, it is weird.
I gave a close look into the parameters from the runs with this error but I couldn't find a relationship between them.
For example, I thought maybe high theta r from both mob and immobile parts combined with a high LAI could be generating this error.
Or maybe high theta with high K (because as it's free drainage below, it could mean that the water percolates to lower layers of the soil).
But I couldn't find anything that explained it, because the runs that worked had similar cases to the ones with error. :?

I attached 3 runs that failed (in .docx) so you can have a look if you want. I'm not sure if that helps.

Thank you very much for your attention,

Rita.
Attachments
SELECTOR1,2,3.docx
(13.37 KiB) Downloaded 2 times

Jirka
Posts: 4824
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Error: initial water content condition is lower than Qr

Post by Jirka » Wed Jan 15, 2020 11:19 pm

This is not particularly useful. Can you just post the entire project (with the inverse file)? J.

ritadg
Posts: 6
Joined: Fri Sep 20, 2019 12:37 am
Location: Australia

Re: Error: initial water content condition is lower than Qr

Post by ritadg » Wed Jan 15, 2020 11:38 pm

Hi Jirka,

Again, I thank you for your prompt reply.
I tried to attach the project but I'm not able to attach this kind of extension here.
How do you think I could send it to you?

Best,
Rita.

Jirka
Posts: 4824
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Error: initial water content condition is lower than Qr

Post by Jirka » Thu Jan 16, 2020 12:01 am

No problem. Also, I usually simply zip the project and post it; and I have not encountered any problems with that. J.

ritadg
Posts: 6
Joined: Fri Sep 20, 2019 12:37 am
Location: Australia

Re: Error: initial water content condition is lower than Qr

Post by ritadg » Fri Jan 17, 2020 3:13 am

Hi Jirka,

I haven't zipped before :shock:
Now I'm sending my Hydrus run that is having this error: "Initial water content condition is lower than Qr ! "
I also included three more files with the .txt inputs (changing only soil parameters - thr, ths, Alfa, n, Ks, l, thrIm, thsIm, Omega - and LAI), that are generating the same error.

I really appreciate your help.

Thank you,
Rita.
Attachments
S2_DRY_DUALPOR_water.zip
(86.42 KiB) Downloaded 1 time

Jirka
Posts: 4824
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Error: initial water content condition is lower than Qr

Post by Jirka » Fri Jan 17, 2020 5:15 pm

You are using a dual-porosity model and specify the saturated water content of the immobile (Ths_im) and mobile (Ths_m) domains equal to 0.806 and 0.428, respectively. That is obviously possible since then the porosity would be larger than 1 (Ths_im + Ths_m = 1.334). That's the first problem.
Second: The initial water content condition (ThInitTotal) is 0.266. This gets distributed proportionally into the mobile and immobile domains: TheInitM=ThInitTotal* Ths_m / (Ths_im + Ths_m ) = 0.092, while TheInitIm = ThInitTotal - TheInitM =0.174. TheInitM is smaller than Ths_m.
J.

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