Error: initial water content condition is lower than Qr
Error: initial water content condition is lower than Qr
Dear Hydrus community,
I'm using HYDRUS1D version 4.14 in the dual porosity model (mobileimmobile, water content mass transfer).
I'm modeling water flow, upper BC: atmospheric BC with surface runoff, 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
I'm using HYDRUS1D version 4.14 in the dual porosity model (mobileimmobile, water content mass transfer).
I'm modeling water flow, upper BC: atmospheric BC with surface runoff, 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
Re: Error: initial water content condition is lower than Qr
It would be good to see the project when this happens. For a uniform flow model, this is pretty straightforward, but for a dualporosity model it is more complicated. J.
Re: Error: initial water content condition is lower than Qr
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.
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 49 times
Re: Error: initial water content condition is lower than Qr
This is not particularly useful. Can you just post the entire project (with the inverse file)? J.
Re: Error: initial water content condition is lower than Qr
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.
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.
Re: Error: initial water content condition is lower than Qr
No problem. Also, I usually simply zip the project and post it; and I have not encountered any problems with that. J.
Re: Error: initial water content condition is lower than Qr
Hi Jirka,
I haven't zipped before
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.
I haven't zipped before
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 40 times
Re: Error: initial water content condition is lower than Qr
You are using a dualporosity 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.
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.
Re: Error: initial water content condition is lower than Qr
Dear Jirka,
Thanks a lot for your elucidation.
Indeed, the first mistake was obvious. I didn't pay attention to that as I was used to model only with single porosity.
The second thing I didn't know that the initial water content is proportionally divided into mobile and immobile (which makes sense).
Where can I find those equations that you sent? I haven't found them in HYDRUS1D  4.17 manual.
Thank you very much,
Rita
Thanks a lot for your elucidation.
Indeed, the first mistake was obvious. I didn't pay attention to that as I was used to model only with single porosity.
The second thing I didn't know that the initial water content is proportionally divided into mobile and immobile (which makes sense).
Where can I find those equations that you sent? I haven't found them in HYDRUS1D  4.17 manual.
Thank you very much,
Rita
Re: Error: initial water content condition is lower than Qr
Hi Jirka,
I'd like to know if this equation of partitioning of the initial water content in the mobile and immobile region is in any HYDRUS manual or where I could find it.
Best,
Rita
I'd like to know if this equation of partitioning of the initial water content in the mobile and immobile region is in any HYDRUS manual or where I could find it.
Best,
Rita
Re: Error: initial water content condition is lower than Qr
I have written the following sentence in the manual:
"When the dualporosity model is used, the water content given in 2.69 is divided into the mobile and immobile domains proportionally to the ratios of porosities (saturated water contents) of the two domains (as this is the equilibrium state for the dualporosity model with the water contentbased mass transfer)."
"When the dualporosity model is used, the water content given in 2.69 is divided into the mobile and immobile domains proportionally to the ratios of porosities (saturated water contents) of the two domains (as this is the equilibrium state for the dualporosity model with the water contentbased mass transfer)."