PC-Progress Discussion Forums

Dear all, I noticed that the forum for STANMOD has been inactive for a while, so I am posting my question here instead. I hope that's okay. I am using the CXTFIT model to simulate a soil column where the top 5 cm layer is initially contaminated with arsenic. Free-arsenic water continuously infiltrat...

Dear all, I am using the CXTFIT model to simulate a soil column where the top 5 cm layer is initially contaminated with arsenic. Free-arsenic water continuously infiltrates through the soil column from the top. I want to observe how the arsenic concentration changes over time at a depth of 100 cm in...

Thank you so much for your reply, Jirka.

Have a good day.

Dear Jirka, Thank you so much for your reply. 1/With ML algorithm, with a certain initial guess, we might only get the local minimum, not the global one. That means if we tried different initial guesses and got different results, that means we have various local minimums, right? 2/Thank you for your...

Dear all, I am running the inverse mobile-immobile model for determining some parameters including (mass transfer between mobile and immobile water, and theta_immobile). as the nature of least square estimation, the model gives the best optimized results for those variables (as fas as I understand)....

Dear Jirka,

Thank you so much for your reply.

Best regards

Dear all, I am using an inverse Mobile and Imobile water model in HYDRUS 1-D. I forced HYDRUS to calculate theta_r and theta_im. Is there any relationship or correlation between these two? Should theta_r be less than theta_im? Indeed, they are two different concepts but not so sure about their relat...

Dear Jirka,

Thank you so much for your reply ^.^

Have a good day~

Dear Jirka, I have one question not directly regards to HYDRUS 1-D. But I am using HYDRUS 1-D for inversely fitting model using Mobile-Immobile water model to obtain several parameters and aimed to calculate the retardation factor of solute. I crossed several manuscripts and found that we can calcul...

Dear Jirka,

Thank you so much for your quick and helpful response. It does help me a lot.

Have a good day!

Best regards,

Tho Tran

Dear Jirka, Thank you for your reply. It is very helpful. Can I have one more question please? Under such condition, when we consider the Freundlich absorption, there is a term of "Fraction of sorption site in contact with mobile zone" - known as f. I crossed several papers, some assumes that as the...

Dear Jirka, I crossed by this post. and have one question please? "In the system with macropores, the dual-porosity model (which requires two domains – mobile and immobile) likely interprets the entire matrix as being immobile, since the flow is dominated by macropores." You stated this. Could you e...

Dear sir, Thank you so much for your quick response. I got it now. I have one more question, please. The Dual-Permeability Model with the two-site sorption model is inactivated in my HYDRUS 1-D version (which I downloaded from PC-progress website). Could you tell me how to activate it or which versi...

Dear Sirs, I have two questions regarding to Chemical and Physical Nonequilibrium Models in HYDRUS 1-D. Currently, I only see the Dual-Porosity Model with two-site sorption in the Mobile zone in the HYDRUS 1-D version that I am using. The "Modeling Nonequilibrium Flow and Transport Processes using H...

Dear all, My study is about the transport of As(V) through the vadose zone. I conducted the tracer test (with Cl-) and found that the two-region physical nonequilibrium model fitted well. Normally people used the equilibrium model for the tracer test and then use fitted v and D for modeling reactive...