Question about soil depth profile

[kookie0616]

Dear Jirka.

I was a student uploading the question in the forum: https://www.pc-progress.com/forum/viewt ... ang#p15669

I appreciate that my modeling works based on your advice.
I really appreciate it. I got the 95% credibility in my modeling.
However, I have one more question.

I uploaded two pictures to this forum.
Based on the Observed and fitted Quantity, the water contents range from 0.27764 to 0.32515.
However, when looking at the basic profile information, the theta starts from 0.315 and ends at 0.34.
I think the values are different: 0.27764 ~ 0.32515 and 0.3315 ~ 0.34..

Why is the range different? Does it normally happen? Or did I do something wrong?

[kookie0616]

Moreover, I have one more question.

Is the number of print time effecting the modeling results?

When I set the number of print time as 5, it works.
However, if I set the number of print time as 1 (2300 second), it doesn't converge.

For specific information, I uploaded the Hydrus 1D project of mine.

[Jirka]

I’m not sure where you see the problem. Your average water content in the entire column varies from 0.2776 at the beginning to 0.32515 at the end of the simulation. Your final water content profile, which corresponds to the final average water content (0.32515), varies from 0.315 to 0.34. I do not see any problem.

Untitled.png (50.32 KiB) Viewed 21455 times

Your data to not have enough information to estimate four soil hydraulic parameters, which is clear from the 95% confidence intervals, which goes from negative to positive values for most parameters (which need to be all positive). And thus, every minor disturbance (even a print time) can send the parameter search in a completely wrong direction.

[Jirka]

You need to think about your problem! You specify the initial conditions in terms of the water content. Then you give the boundary conditions in terms of fluxes at both ends of the column. That means that the amount of water in the column is always defined exactly (and thus also the average water content, which you use in the objective function), and completely independent of any parameters that you try to optimize. This cannot be done. J.

[kookie0616]

Thank you for your reply, now I totally understand!!