[663] - Low-field NMR logging sensor for measuring hydraulic parameters of model soils

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Sucre, O., Pohlmeier, A., Miniere, A., Blümich, B., 2011. Low-field NMR logging sensor for measuring hydraulic parameters of model soils. Journal of Hydrology, 406, 30 - 38. DOI: 10.1016/j.jhydrol.2011.05.045.
Title(s):Main Title: Low-field NMR logging sensor for measuring hydraulic parameters of model soils
Description(s):Abstract: Knowing the exact hydraulic parameters of soils is very important for improving water management in agriculture and for the refinement of climate models. Up to now, however, the investigation of such parameters has required applying two techniques simultaneously which is time-consuming and invasive. Thus, the objective of this current study is to present only one technique, i.e., a new non-invasive method to measure hydraulic parameters of model soils by using low-field nuclear magnetic resonance (NMR). Hereby, two model clay or sandy soils were respectively filled in a 2 m-long acetate column having an integrated PVC tube. After the soils were completely saturated with water, a low-field NMR sensor was moved up and down in the PVC tube to quantitatively measure along the whole column the initial water content of each soil sample. Thereafter, both columns were allowed to drain. Meanwhile, the NMR sensor was set at a certain depth to measure the water content of that soil slice. Once the hydraulic equilibrium was reached in each of the two columns, a final moisture profile was taken along the whole column. Three curves were subsequently generated accordingly: (1) the initial moisture profile, (2) the evolution curve of the moisture depletion at that particular depth, and (3) the final moisture profile. All three curves were then inverse analyzed using a MATLAB code over numerical data produced with the van Genuchten–Mualem model. Hereby, a set of values (a, n, hr and hs) was found for the hydraulic parameters for the soils under research. Additionally, the complete decaying NMR signal could be analyzed through Inverse Laplace Transformation and averaged on the 1/T2 space. Through measurement of the decay in pure water, the effect on the relaxation caused by the sample could be estimated from the obtained spectra. The migration of the sample-related average h1/T2,Samplei with decreasing saturation speaks for a enhancement of the surface relaxation as the soil dries, in concordance with results found by other authors. In conclusion, this low-field mobile NMR technique has proven itself to be a fast and a noninvasive mean to investigate the hydraulic behavior of soils and to explore microscopical aspect of the water retained in them. In the future, the sensor should allow easy soil moisture measurements on-field.
Identifier(s):DOI: 10.1016/j.jhydrol.2011.05.045
Responsible Party
Creator(s):Author: Oscar Sucre
Author: Andreas Pohlmeier
Author: Adrien Miniere
Author: Bernhard Blümich
TR32 Topic:Soil
Subject(s):CRC/TR32 Keywords: Low-Field NMR, NMR, Hydraulic Parameters, Soil, Relaxation Analysis, Diffusion
File Details
File Name:2011_Sucre_JoH.pdf
Data Type:Text
Size(s):9 Pages
File Size:947 kB (0.925 MB)
Date(s):Date Accepted: 2011-05-29
Available: 2011-06-22
Mime Type:application/pdf
Data Format:PDF
Download Permission:OnlyTR32
General Access and Use Conditions:For internal use only
Access Limitations:For internal use only
Licence:TR32DB Data policy agreement
North:-no map data
Measurement Region:None
Measurement Location:--None--
Specific Informations - Publication
Article Type:Journal
Source:Journal of Hydrology
Number Of Pages:9
Page Range:30 - 38
Metadata Details
Metadata Creator:Oscar Elías Sucre
Metadata Created:2013-12-02
Metadata Last Updated:2013-12-02
Funding Phase:2
Metadata Language:English
Metadata Version:V40
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