Ein Verfahren zur Messung der ungesättigten Wasserleitfähigkeit

Becher, H. H.

doi:10.1002/jpln.19711280102

Cited by 32 publications

(12 citation statements)

References 4 publications

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“…For fine soils the grain size distribution smaller than 63 µm was analyzed by sieving and sedimentation [42]. Soil hydraulic properties, that is, water retention parameters and saturated as well as unsaturated conductivities, were obtained using the evaporation method [43][44][45] and subsequent fitting of retention curves with the software ROSETTA [46]. Saturated conductivity was also examined in the field using a double-ring infiltrometer.…”

Section: Laboratory Analysismentioning

confidence: 99%

Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia

Beyer

Gaj

Hamutoko

et al. 2015

Isotopes in Environmental and Health Studies

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The stable water isotope deuterium ((2)H) was applied as an artificial tracer ((2)H2O) in order to estimate groundwater recharge through the unsaturated zone and describe soil water movement in a semi-arid region of northern central Namibia. A particular focus of this study was to assess the spatiotemporal persistence of the tracer when applied in the field on a small scale under extreme climatic conditions and to propose a method to obtain estimates of recharge in data-scarce regions. At two natural sites that differ in vegetation cover, soil and geology, 500 ml of a 70% (2)H2O solution was irrigated onto water saturated plots. The displacement of the (2)H peak was analyzed 1 and 10 days after an artificial rain event of 20 mm as well as after the rainy season. Results show that it is possible to apply the peak displacement method for the estimation of groundwater recharge rates in semi-arid environments via deuterium labelling. Potential recharge for the rainy season 2013/2014 was calculated as 45 mm a(-1) at 5.6 m depth and 40 mm a(-1) at 0.9 m depth at the two studied sites, respectively. Under saturated conditions, the artificial rain events moved 2.1 and 0.5 m downwards, respectively. The tracer at the deep sand site (site 1) was found after the rainy season at 5.6 m depth, corresponding to a displacement of 3.2 m. This equals in an average travel velocity of 2.8 cm d(-1) during the rainy season at the first site. At the second location, the tracer peak was discovered at 0.9 m depth; displacement was found to be only 0.4 m equalling an average movement of 0.2 cm d(-1) through the unsaturated zone due to an underlying calcrete formation. Tracer recovery after one rainy season was found to be as low as 3.6% at site 1 and 1.9% at site 2. With an in situ measuring technique, a three-dimensional distribution of (2)H after the rainy season could be measured and visualized. This study comprises the first application of the peak displacement method using a deuterium labelling technique for the estimation of groundwater recharge in semi-arid regions. Deuterium proved to be a suitable tracer for studies within the soil-vegetation-atmosphere interface. The results of this study are relevant for the design of labelling experiments in the unsaturated zone of dry areas using (2)H2O as a tracer and obtaining estimations of groundwater recharge on a local scale. The presented methodology is particularly beneficial in data-scarce environments, where recharge pathways and mechanisms are poorly understood.

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Section: Laboratory Analysismentioning

confidence: 99%

Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia

Beyer

Gaj

Hamutoko

et al. 2015

Isotopes in Environmental and Health Studies

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“…Starting with the early studies by Becher (1971) and Wind (1968), the evaporation method is now widely used to estimate the water retention and the unsaturated hydraulic conductivity curves simultaneously. The method has seen many improvements over the years (e.g., Halbertsma, 1996; Wendroth et al, 1993; Peters and Durner, 2008; Schindler and Müller, 2006; Peters et al, 2015), leading to a semi‐automated version (referred to here as the HYPROP measurement system, HMS) that is now being commercialized by Decagon Devices and UMS AG.…”

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confidence: 99%

Analysis of the Hysteretic Hydraulic Properties of Unsaturated Soil

Zhuang

Coelho

Hassanizadeh

et al. 2017

Vadose Zone Journal

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Core Ideas We devised a setup to measure hydraulic properties using the multistep flux method. Results showed good agreement with the data obtained with the hanging water column. However, they deviated slightly from independent data obtained with the HYPROP. Knowledge of the unsaturated soil hydraulic properties is essential for modeling water flow and solute transport processes in variably saturated subsurface systems. Various experimental setups have been developed over the years to measure the hydraulic properties. We devised a relatively simple setup for simultaneous measurement of the water retention and unsaturated hydraulic conductivity curves using multistep flux (MSF) and hanging water column (HWC) experiments. Our focus was especially on medium‐ and coarse‐textured sands having relatively narrow particle‐size distributions as reflected by the van Genuchten–Mualem (VGM) hydraulic parameter n. Values of the VGM parameter n for some of the sands we used were as high as 15. We also measured the hydraulic properties using the HYPROP evaporation method. The MSF and HWC results showed excellent agreement, but deviated slightly from independent data obtained with the HYPROP measurement system.

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“…Measurements of the evaporation rate and tension at multiple depths in the sample permitted the simultaneous direct estimation of the water retention and hydraulic conductivity. Key contributions have been by Halbertsma (1996), Klute and Dirksen (1986), Becher (1970), Plagge (1991), Wendroth et al (1993), Bertuzzi and Voltz (1997), and many others, including analyses of the data using parameters estimation approaches (Šimůnek et al, 1998b, Iden and). An increasingly popular version of the evaporation method is the HYPROP © measurement system (further referred to here as HMS), which allows semi-automated direct measurements of water retention and conductivity pairs over a relatively wide range of pressure head values (Peters and Durner, 2008;Schindler et al, 2010a, b, and others).…”

Section: Introductionmentioning

confidence: 99%

Further tests of the HYPROP evaporation method for estimating the unsaturated soil hydraulic properties

Bezerra-Coelho

Zhuang

Barbosa

et al. 2018

Journal of Hydrology and Hydromechanics

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Many soil, hydrologic and environmental applications require information about the unsaturated soil hydraulic properties. The evaporation method has long been used for estimating the drying branches of the soil hydraulic functions. An increasingly popular version of the evaporation method is the semi-automated HYPROP © measurement system (HMS) commercialized by Decagon Devices (Pullman, WA) and UMS AG (München, Germany). Several studies were previously carried out to test the HMS methodology by using the Richards equation and the van-Genuchten-Mualem (VG) or Kosugi-Mualem soil hydraulic functions to obtain synthetic data for use in the HMS analysis, and then to compare results against the original hydraulic properties. Using HYDRUS-1D, we carried out independent tests of the HYPROP system as applied to the VG functions for a broad range of soil textures. Our results closely agreed with previous findings. Accurate estimates were especially obtained for the soil water retention curve and its parameters, at least over the range of available retention measurements. We also successfully tested a dual-porosity soil, as well as an extremely coarse medium with a very high van Genuchten n value. The latter case gave excellent results for water retention, but failed for the hydraulic conductivity. In many cases, especially for soils with intermediate and high n values, an independent estimate of the saturated hydraulic conductivity should be obtained. Overall, the HMS methodology performed extremely well and as such constitutes a much-needed addition to current soil hydraulic measurement techniques.

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Ein Verfahren zur Messung der ungesättigten Wasserleitfähigkeit

Cited by 32 publications

References 4 publications

Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia

Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia

Analysis of the Hysteretic Hydraulic Properties of Unsaturated Soil

Further tests of the HYPROP evaporation method for estimating the unsaturated soil hydraulic properties

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