The HP1 code incorporates modules simulating
(1) transient water flow in variably-saturated media,
(2) transport of multiple components, and
(3) mixed equilibrium/kinetic geochemical reactions.
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Post by jkgeiger » Thu Dec 15, 2022 3:29 pm


I’m attempting to model the evaporative transport and precipitation of minerals (halite) from a column saturated with saline solution using HP1. I’ve successfully modeled the water and solute transport in HYDRUS (w/o PHREEQC). I’ve also successfully modeled the precipitation of minerals as evaporation occurs in PHREEQC (w/o HYDRUS). When I attempt to use HP1, the transport aspects appear to be reasonable. However, I am only seeing precipitation of minerals (halite) in the top cell, despite concentrations reaching levels that I would expect to see precipitation across a third of the column. I believe the issue likely lies in my PHREEQC GUI script, but have done significant troubleshooting and am uncertain of what could be the issue.

My questions are:
1) Is it possible to access the full PHREEQC output? I’ve noticed that the PHREEQC.out file is finalized several minutes before the run finishes. When I open it, I only see the first several iterations in the file. I’m hoping to access the full file for troubleshooting purposes. Is there a limitation on how much HP1 prints for this? Or a specific trigger that stops this file?

2) I’ve included the geochemical model script from the PHREEQC GUI below. At this stage, it is relatively simple, but I’m concerned that I may not be correctly designating the domain over which the reaction should be applied. I believe I am specifying a domain for the equilibrium phases block of the Geochemical Model GUI (cells 1-101). Is this correct?

Any advice on this issue or additional input is greatly appreciated.

Thank you,

Halite 0 0
Fix_H+ -7.0 HCl

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Re: PHREEQC Output

Post by diederik » Fri Dec 16, 2022 8:51 am


Q1: Yes you can for full phreeqc output when the transport simulation starts. Indeed no information is printed anymore in the output when the transport simulation start (sentence "Starting transport calculations" in the output file). To activate also printing after starting, you should change the defaults in the dialogue window "HP Output Information"

Under the headings "Print options", you select "Printing in phreeqc.out". Then you select where and when to print to full phreeqc output in the file.

you could also ask more information in the selected output files (e.g. saturation indices, ...)

Q2: Yes, this is correct. Alternatively, you could write it as:

equilibrium_phases 1001
-material 1


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Re: PHREEQC Output

Post by jkgeiger » Mon Jan 16, 2023 5:36 pm

Hi Diederik,

Thank you for the advice, pointing me in the right direction. I still had some issue with the Location portion, as HP1 didn't seem to identify my HYDRUS observation nodes under that setting. However, I tried inputing them separately in the other nodes option (which isn't an issue) and had success getting a more complete HP1 output script. For the HYDRUS observation nodes, I had them inputed in the soil profile - graphical editor, just to make you more aware of the potential issue. At any rate, I'm now able to obtain what was desired. Thank you again for your assistance.


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