Determination of SWRC by WRB/FAO texture

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.
Post Reply
MatBacher
Posts: 2
Joined: Fri Jul 22, 2016 1:55 pm
Location: Ireland

Determination of SWRC by WRB/FAO texture

Post by MatBacher » Fri Jul 22, 2016 2:42 pm

Good Afternoon!

I am using RetC for solving "retention data only" and "no fitting(Forward Problem)" using USDA texture data. Now I have also textural data with a different threshold for sand and silt(Sand 0.2-0.063 mm; Silt 0.063-0.002 mm, WRB/FAO classification). As I figured out there is no setting in Rosetta lite for different textural classifications, Is RetC any good for this input data?

I assume I need alternative PTF to estimate the vanGenuchten parameters which I can, in turn, then enter into RetC?

Thanks for your time!
Matthias

Jirka
Posts: 4790
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Determination of SWRC by WRB/FAO texture

Post by Jirka » Fri Jul 22, 2016 3:50 pm

Correct. Rosetta has its own fixed limits for textural data. RETC does not really have anything to do with that. It can only use Rosetta, to provide you with the initial estimate of soil hydraulic parameters, before you start fitting the actual retention data. J.

MatBacher
Posts: 2
Joined: Fri Jul 22, 2016 1:55 pm
Location: Ireland

Re: Determination of SWRC by WRB/FAO texture

Post by MatBacher » Mon Jul 25, 2016 8:59 am

Hello Jirka,

thank you for the answer. I guess the faulty estimate of the initial soil hydraulic parameters when actual retention data are available should not have significant influence on the results.

However if I am picturing the problem correctly, for proper parameter estimation I would need PTF based on the FAO/WRB 63um sand/silt limit. If anybody has seen these, please give me a hint here.

However it might also be worth a try to use the soil texture wizard by Julien Moeys to convert from one system into the other
https://cran.r-project.org/web/packages ... gnette.pdf

Post Reply