Capillary Upflow
Masoud...@dpi.vic.gov.au
Can anybody answer this apparently simple question?
A perched water table has dropped by 100 cm, at the same time the soil
water
potential immediately above it has increased by -10kPa (100cm). Any
indication
of the mm water moved up as capillary upflow? Any information missing?
Thank you
Masoud Edraki
Department of Primary Industries
Mildura, VIC AUSTRALIA
Warren, Jeff
Although capillary upflow may be the underlying process, you should also consider hydraulic redistribution by roots following a water potential gradient as a process to move water in the soil profile. Also, there could be some vapor flow of water based on temperature differences. And to calculate water content in the different layers, you may need to make some assumptions on soil structure - that is soil texture, porosity and organic matter that would underlie the ability of the soils in different layers to hold water at different water potentials - i.e., if one layer is sandy and the other has more clay then the amount of water held and available would be different for the two layers.
Jeff
____________________________________
Jeffrey M Warren
Ecosystem Processes
USDA Forest Service, PNW Research Station
3200 SW Jefferson Way
Corvallis, OR 97331
(541) 758-8766
____________________________________
Masoud...@dpi.vic.gov.au
Hi Jeff
Thanks very much for your response. This is a uniform sandy soil under vineyard. We are almost sure that the rise in matric suction and concurrent drop in water table is as a result of root extraction from perched water table. The vigorous growth of the vines without any irrigation supports this idea. I am hoping to quantify this extraction and there should be a way to relate the drop in height of the water table to the amount reduced from the profile the same as we can relate the amount added to the profile to the rise in water table ( is this called the specific yield?).
Regards
Masoud
Dr. Masoud Edraki
Irrigation Scientist
Soil and Water (Hydrology)
Department of Primary Industries
PO BOX 905 Mildura, VIC 3502
AUSTRALIA
Tel: 03 50514641
Mob: 0428 132 881
Fax : 03 50514534
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Arie Nadler
As we all know the production of the eternal 1502C has been stopped for
several years. Those who own it of course keep enjoying it. I am not sure if
it makes sense to get one (used) now.
Therefore I would ask those of you who have found good, reliable, tested
substitutes to share with us their experience. Of course also negative
evidence is valuable.
I am definitely referring to the "real", research tool, TDR device that
measures permittivity and electrical resistance using 0.5 1.4 GHz
frequencies.
Thanks for your cooperation,
arie nadler
Arie Nadler
Dept. of Soil Physics
Institute of Soil, Water, and the Environment
A.R.O., Volcani Center, Min. of Agriculture
POB 6 Bet Dagan, Israel, 50250
Tel: 972-3-9683865
Fax: 972-3-9604017
Home: 972-8-9404161
Email: vw...@volcani.agri.gov.il
http://www.agri.gov.il/People/ArieNadler.html
-----Original Message-----
From: sow...@googlegroups.com [mailto:sow...@googlegroups.com] On Behalf Of
Masoud...@dpi.vic.gov.au
Sent: Tuesday, March 14, 2006 5:01 AM
To: sowacs: soil water moisture content measurement systems and sensors
Subject: Capillary Upflow
Hi All,
Thank you
This message was scanned against malicious content by the
ARO secure anti-virus and anti-spam system.
Volcani Infrastructure & System Department
bittelli
Campbell Scientific produces the TDR100, which has similar electronics to
the classic Tektronics. The output is identical, a time domain reflected
waveform operating between 0.5 to 1.5 GHz. Moreover, the system incorporates
an algorithm for travel time and amplitude analysis for dielectric
permittivity and electrical conductivity measurement, respectively.
Having used the 1502C for many years and having written an algorithm myself
for travel time analysis, I was skeptical at the beginning, but I have been
pretty happy with the Campbell TDR100 system.
The only problem is that the algorithm for travel time analysis does not
always converge and, especially when the system is multiplexed for field
measurement, there are sometime missing data.
Since one can download the waveform instead, one can then apply its own
algorithms for travel time analysis.
The improvement in recent years in micro-electronics (in terms of size of
the components for wave-generating chips) also makes the system much smaller
in size.
Let me know if I can provide more information,
Best Regards,
Marco Bittelli
-----Messaggio originale-----
Da: sow...@googlegroups.com [mailto:sow...@googlegroups.com] Per conto di
Arie Nadler
Inviato: Tuesday, March 14, 2006 8:02 AM
A: sow...@googlegroups.com
Oggetto: 1502 Cable tester substitute
Hi All,
Thank you
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Raimundo Cosme de Oliveira Junior
I agree completely with Jeff Warren. Hug.
Cosme
Raimundo Cosme de Oliveira Junior
Pesquisador II Embrapa Amazônia Oriental
Fone: 55-93-522.2203
55-93-5234138
55-91-99919275
email: co...@cpatu.embrapa.br
co...@lbaeco.com.br
Warren, Jeff
Schaap, M.G., Leij, F.J., van Genuchten, M.Th. 2001. ROSETTA: a computer program for estimating soil hydraulic parameters with hierarchical pedotransfer functions. Journal of Hydrology 251:163-176.
- publicly available from the US Salinity lab: http://www.ars.usda.gov/Services/docs.htm?docid=8910
van Genuchten, M.Th. 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal 44:892-898.
Saxton, K.E., Rawls, W.J., Romberger, J.S., Papendick, R.I. 1986. Estimating generalized soil-water characteristics from texture. Soil Science Society of America Journal 50:1031-1036.
Wösten, J.H.M., Pachepsky, Y.A., Rawls, W.J. 2001. Pedotransfer functions: bridging the gap between available basic soil data and missing soil hydraulic characteristics. Journal of Hydrology 251:123-150.
Subject: Capillary Upflow
Can anybody answer this apparently simple question?
A perched water table has dropped by 100 cm, at the same time the soil
water
potential immediately above it has increased by -10kPa (100cm). Any
indication
of the mm water moved up as capillary upflow? Any information missing?
Thank you
Masoud Edraki
Department of Primary Industries
Mildura, VIC AUSTRALIA
<FONT face="Times New Roman"
Arie Nadler
Thanks for the fast and detailed response. I'll read it and see if
applicable to me.
One piece of information that I may find already useful is not to chain
muxes.
I wonder why yours was the only response to TDR100 if there are so many
users?
I know about an Israeli user (Shani) who "can't make up his mind" if he will
recommend it or not. This pushed me to look for additional users.
Lets keep in touch.
ciao
arie
(I am working with Dr. Angelo Basile from CNT San Sebastiano.)
Jean-Paul Laurent
PC-TDR (the software delivered by Campbell Scientific) doesn't always work
properly especially when you use other TDR probes than those recommended
(and sold...) by Campbell Scientific. The reason for this is that Campbell
TDR three-rod probes (CS605, 610...) have approximately an 8cm long section
of their rods encapsulated in the probe's head resin. In terms of impedance,
that makes a high impedance section and I suspect that PC-TDR searches for
it to determine the beginning of the TDR waveforms.
Otherwise, the TDR100 electronics come from earlier developments by Agoston
Agoston at Hyperlabs (http://www.hyperlabsinc.com). I don't know if the fact
that Tektronix and Hyperlabs are located in the same city (Bearverton,
Oregon) is purely accidental but, nevertheless, TDR100 printed circuit board
exhibits a good CMS design and realization and its performance are very
similar to those of the regretted Tektro 1502. I purchased mine in 2003, use
it occasionally since either in the field or at the lab and gets no
particular problem with it except the one mentioned above.
Bien cordialement.
Jean-Paul Laurent, Chargé de recherches au CNRS
Laboratoire d'étude des Transferts en Hydrologie et Environnement.
(LTHE, UMR 5564 CNRS-INPG-UJF-IRD)
Bureau G103, ENSHMG
1209 rue de la Piscine
Domaine universitaire de Saint Martin d'Hères
BP53, F-38041 Grenoble-Cedex 09 France
Tel. +33 (0) 4 76 82 50 59, Fax. +33 (0) 4 76 82 52 86
Page Web : http://www.lthe.hmg.inpg.fr/~laurent
Réseau MeDiTE : http://www.lthe.hmg.inpg.fr/medite
-----Message d'origine-----
De : sow...@googlegroups.com [mailto:sow...@googlegroups.com] De la part de
Arie Nadler
Envoyé : mercredi 15 mars 2006 09:22
À : sow...@googlegroups.com
Objet : Re: 1502 Cable tester substitute
Wim Cornelis
being an Tektronics 1502 adept in the past (in combination with Campbell loggers
and multiplexers), we changed about five years ago to TDR100 (because of
malfunctioning of the Tektronics and reparation costs being higher than a new
TDR100). I can only recommend it, with multiplexers!!! We generally work with 5
multiplexers and I don't recall having any problems.
I am actually planning to set up a network with about 50 multiplexers - 360
probes (in case a project proposal is approved). Does anyone has bad experiences
working with 3 levels of multiplexers?
Good luck!
Wim Cornelis
Citeren Arie Nadler <vw...@agri.gov.il>:
--
=========================================================
Wim Cornelis
Dep. Soil Management and Soil Care
Ghent University
Coupure links 653
B-9000 Ghent
Belgium
tel. ++32 9 264 60 40
fax ++32 9 264 62 47
http://soilman.ugent.be
==========================================================
bittelli
I am available to provide additional info if you need it about the TDR100.
I read some of your papers and I would like to meet you sometime in future.
What kind of work are you doing with Dr. Basile ?
Are you going to be in Italy sometime in the future ?
I would be happy to host you in our Department.
Shalom,
Marco
-----Messaggio originale-----
Da: sow...@googlegroups.com [mailto:sow...@googlegroups.com] Per conto di
Arie Nadler
Inviato: Wednesday, March 15, 2006 9:22 AM
A: sow...@googlegroups.com
Oggetto: Re: 1502 Cable tester substitute
Version: 7.1.385 / Virus Database: 268.2.3/281 - Release Date: 3/14/2006
Arie Nadler
>
> I am available to provide additional info if you need it about the TDR100.
Ciao
> Marco
>
> -----Messaggio originale-----
> Da: sow...@googlegroups.com [mailto:sow...@googlegroups.com] Per conto di
Wojciech Skierucha
I am very glad that you, the very experienced TDR user, have raised the TDR
instrumentation problems.
I would like to take part in the discussion about the TDR moisture
measurement of porous bodies and present a little different instrumentation
approach developed in the Institute of Agrophysics, Lublin, Poland.
The measurement devices developed here have been distributed as EasyTest
devices since 1990. More details about them you can find on
www.easytest.lublin.pl
These devices are different from standard Tektronix 1502 and Campbell TDR200
because they use a needle pulse of about 200 ps rise and fall time rather
than a step pulse. The reason for this choice was the less complicated
algorithm to localize the reflections on the waveform. Moreover, we have
found that generation of a needle pulse was easier than a step pulse. The
offered devices give direct readout of calculated dielectric constant of the
medium or its moisture (on the base of our calibration, which is very close
to the one of Topp).
The devices can localize the TDR waveguide at the end of a coax cable (it
can be 1 to 9 m length) and the time window for reflected pulses has 10 ns
(1024 points). Thus the resolution is 10 ps. We consider to introduce a
small change in firmware to give the user the readout in time scale to make
the devices similar to typical reflectometers (like Tektronix 1502). However
we have recently introduced the option to calibrate the TDR probes in
different media, i.e. having dielectric constant values close to the
measured ones. This can decrease the measurement error.
We have abandoned the multi-level multiplexing of the TDR devices because of
signal distortion introduced by cables, new electronics coming from
telecommunication industry that decrease the price of the TDR units and all
general problems with cables in field conditions. Up to 16 8-channel
multiplexed units can be controlled by PC computer of a data logger.
We do not have big production facilities, therefore we are oriented to the
used individual requirements.
Those, who are interested in the TDR measurement developments from the
Institute of Agrophysics, Lublin, Poland are invited for discussion.
Best regards,
Dr. Wojciech Skierucha
Institute of Agrophysics
Polish Academy of Sciences
20-290 Lublin, Doswiadczalna 4
Poland
tel. +48 81 7445061 ext. 125
fax. +48 81 7445067
e-mail. skie...@demeter.ipan.lublin.pl