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Please use this identifier to cite or link to this item: http://dspace.mediu.edu.my:8181/xmlui/handle/10261/5031
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dc.creatorMoret-Fernández, David-
dc.creatorArrúe Ugarte, José Luis-
dc.creatorLópez Sánchez, María Victoria-
dc.creatorGracia Ballarín, Ricardo-
dc.date2008-06-12T11:12:55Z-
dc.date2008-06-12T11:12:55Z-
dc.date2006-04-
dc.date.accessioned2017-01-31T01:40:15Z-
dc.date.available2017-01-31T01:40:15Z-
dc.identifierJournal of Hydrology, Volume 321, Issues 1-4, 30 April 2006, Pages 163-172-
dc.identifier0022-1694-
dc.identifierhttp://hdl.handle.net/10261/5031-
dc.identifier10.1016/j.jhydrol.2005.07.041-
dc.identifier.urihttp://dspace.mediu.edu.my:8181/xmlui/handle/10261/5031-
dc.descriptionThe definitive version is available at: http://www.sciencedirect.com/science/journal/00221694-
dc.descriptionTime Domain Reflectometry (TDR) has been widely accepted as a reliable technology for the measurement of volumetric water content (θ) in soils. Here, we present a new procedure for the graphical interpretation of TDR waveforms to determine the variation of the apparent dielectric constant (K) along a single TDR probe in non-conducting media and its application for profiling the moisture content in soils. The method is based on the influence of K on the reflection coefficient (ρ) and travel time (t) of the TDR signal along a transmission line. A ρ(t) function is initially defined for a length l of 10 cm and plotted together with the TDR waveform for a three-rod probe of length L (L=nl). The interception point of both lines defines t11 as the reference time to build a second ρ(t) line that intercepts the waveform at time t2l. By repeating this process iteratively, a series of ρ(t) lines intercepting the TDR trace at times t3 l,t4 l,… and tnl is obtained, making it possible to calculate K for apparent probe lengths equal to l,2l,3l… and nl. To test the consistency of the method, two sand column experiments were conducted with two different TDR probe geometries. A total of 144 values of K were measured during a wetting and draining cycle of the sand column with vertical 10-, 20-, 30-, and 40-cm long three-wire uncoated TDR probes (diameter d: 2.8 mm; spacing of the outer conductors s: 32 mm) and 10-, 20-, 40-, and 60-cm long coated TDR probes (d: 10 mm; s: 80 mm) using the standard double reflection waveform analysis. A satisfactory relationship (R2=0.99) was found between these K values and those obtained for the same depths by the proposed method applied to the 40- and 60-cm long probes, respectively. In this case, a probe-specific correction factor was used for the different probe geometries. Likewise, an excellent match was found between the θ profiles measured in the sand column applying the new approach to the 60-cm long probe and the θ profiles measured with horizontal probes placed at 10, 20, 30 and 50 cm depth. The results show that the proposed method is sound and suitable for determining the variation of K at fixed intervals along a single probe and therefore for soil water content profiling.-
dc.descriptionThis work was supported by the Comisión Interministerial de Ciencia y Tecnología of Spain (grants AGF98-0261-CO2-02 and AGL2001-2238-CO2-01).-
dc.descriptionPeer reviewed-
dc.format209007 bytes-
dc.formatapplication/pdf-
dc.languageeng-
dc.publisherElsevier-
dc.rightsopenAccess-
dc.subjectTime domain reflectometry-
dc.subjectDielectric constant-
dc.subjectReflection coefficient-
dc.subjectCharacteristic probe impedance-
dc.subjectSoil water content-
dc.titleA new TDR waveform analysis approach for soil moisture profiling using a single probe-
dc.typeArtículo-
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