Entering positive matric potentials in RETC, too

A discussion forum for RETC users. RETC is a program which can be used to analyze the soil water retention and hydraulic conductivity functions of unsaturated soils.
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mfd
Posts: 13
Joined: Wed Oct 21, 2020 8:32 am
Location: Germany

Entering positive matric potentials in RETC, too

Post by mfd » Wed May 11, 2022 1:01 pm

Dear everyone,

what happens when I enter positive matric potential values into RETC? I have some and was hoping they may contribute to the determination of Qs.

So I tried entering them in conjunction with other "normal" retention data, and it produces a retention curve without displaying and error, but a different one from the curve generated without the positive values. I thought the retention curve is inly defined for negative matric potential values?

I wonder whether the software takes them into account for the regression of a retention curve correctly, or whether it causes errors.

Kind regards
MFD

Jirka
Posts: 5495
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Entering positive matric potentials in RETC, too

Post by Jirka » Wed May 11, 2022 5:08 pm

In the RETC, users can enter the pressure head values both as positive or negative numbers. The code will always convert these numbers into positive values, and uses those in fitting the VG model.

do 12 i=1,NR
read(5,*,err=901) XX,YY,WW
X(i)=abs(XX)
Y(i)=YY
W(i)=WW
12 continue

The full saturation should be entered with XX=0.

J.

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