An easily installable groundwater lysimeter to determine waterbalance components and hydraulic properties of peat soils

Schwaerzel, Kai; Bohl, H. P.

doi:10.5194/hess-7-23-2003

Cited by 27 publications

(33 citation statements)

References 17 publications

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“…The water content was determined by using a site‐specific calibration between the dielectric constant, e , and the water content (standard error of calibration = 0.022 m 3 m −3 , Schwärzel and Bohl, 2003):

\begin{matrix} θ = 0.0393 + 0.0284 e - 0.000419 e^{2} + 0.00000277 e^{3} \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Estimation of the Unsaturated Hydraulic Conductivity of Peat Soils: Laboratory versus Field Data

Schwärzel

Šimůnek

Stoffregen

et al. 2006

Vadose Zone Journal

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As compared with mineral soils, there are few in situ measurements of the unsaturated hydraulic properties of peat soils available. We used parameter estimation (inverse) methods to estimate the water retention and hydraulic conductivity functions of drained peat soils from both laboratory and field data. The laboratory data were obtained on small cores using the traditional evaporation method, while the field data were obtained by means of evaporation experiments using groundwater lysimeters with and without vegetation. The field experiments without vegetation produced highly uncertain parameters and were limited to a relatively small pressure head range. Better results were obtained for the lysimeter with a grass cover that caused the peat soil to dry out more. However, a physically realistic minimum in the objective function for the plant‐covered lysimeter could be found only when prior information about several parameters was included in the optimization. Good agreement was obtained between the laboratory and field measurements. The hydraulic functions were subsequently tested by comparing forward simulations with independently measured pressure heads and water contents of an additional lysimeter experiment under grass. The dynamics of the drying process was described well using the optimized soil hydraulic properties.

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\begin{matrix} θ = 0.0393 + 0.0284 e - 0.000419 e^{2} + 0.00000277 e^{3} \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Estimation of the Unsaturated Hydraulic Conductivity of Peat Soils: Laboratory versus Field Data

Schwärzel

Šimůnek

Stoffregen

et al. 2006

Vadose Zone Journal

View full text Add to dashboard Cite

show abstract

“…Disconnecting the capillary connection with deeper soil affects the drainage and prevents capillary rise. Several studies have shown that upward directed water fluxes from shallow groundwater tables and deeper soil layers serve as an additional water supply for evapotranspiration processes (Schwaerzel and Bohl, 2003; Yang et al, 2007; Luo and Sophocleous, 2010; Karimov et al, 2014). A seepage‐face boundary condition may lead to a bias in the drainage (Stenitzer and Fank, 2007) and in the solute transport processes (Abdou and Flury, 2004; Boesten, 2007) so that lysimeter observations are not directly transferable to field‐scale conditions (Vereecken and Dust, 1998; Flury et al, 1999).…”

mentioning

confidence: 99%

How to Control the Lysimeter Bottom Boundary to Investigate the Effect of Climate Change on Soil Processes?

Groh

Vanderborght

Pütz

et al. 2016

Vadose Zone Journal

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A dynamic tension-controlled bottom boundary of lysimeters allows observing water and matter fluxes in lysimeters that are close to natural field conditions, as pressure heads at the lysimeter bottom are adjusted to measured pressure heads at the same depth in the surrounding field. However lysimeters are often transferred from their sampling location for practical reasons or to study, for example, the effect of climate change on soil functions. This transfer can be accompanied by a change aboveground but also in subsurface conditions that are used to control the bottom boundary and that may affect the soil water balance of lysimeters. This issue is also relevant for lysimeter stations which use a tension-controlled bottom boundary and are not directly installed near the site of excavation. The potential impact of different bottom boundary conditions on the water balance of lysimeters that were transferred in a climate impact experiment (SOILCan) was investigated exemplarily by a numerical study. Results showed that by using nonappropriate pressure heads, which were measured in soil profiles with a different texture and water table depth than the profile where the lysimeter was taken from, had partially large impacts on soil water fluxes, especially when the water table was located within a specific critical range. Different climate conditions between sampling and installation site were buffered by the soil and did not show a strong influence on the bottom boundary control of lysimeters when the groundwater table depth was assumed to remain constant. Considering a change in groundwater table depths due to changing climate tempered the effects of climate change on the soil water balance terms. In general, results demonstrate the importance of a proper control of the lysimeters bottom boundary conditions in studies that investigate the influence of climate change on soil functions and ecosystem variables by transferring lysimeter along climate gradients.

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“…However, the water table is not constant but can be changed at high resolution by iteratively filling or emptying the compensation tank, which is usually done by pumping water to or from the tank while the connection between the lysimeter and tank is temporarily interrupted by closing the corresponding valve. These systems allow the groundwater level to be adjusted more flexibly, up to an intra-day basis, thus enabling a more natural groundwater behavior to be simulated (Abtew and Melesse, 2013;Bethge-Steffens et al, 2004;Meissner et al, 2008;Rupp et al, 2007;Schwaerzel and Bohl, 2003).…”

Section: Established Types Of Groundwater Lysimetersmentioning

confidence: 99%

Behavior of water balance components at sites with shallow groundwater tables: Possibilities and limitations of their simulation using different ways to control weighable groundwater lysimeters

Dietrich

Fahle

Seyfarth³

2016

Agricultural Water Management

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An easily installable groundwater lysimeter to determine waterbalance components and hydraulic properties of peat soils

Cited by 27 publications

References 17 publications

Estimation of the Unsaturated Hydraulic Conductivity of Peat Soils: Laboratory versus Field Data

Estimation of the Unsaturated Hydraulic Conductivity of Peat Soils: Laboratory versus Field Data

How to Control the Lysimeter Bottom Boundary to Investigate the Effect of Climate Change on Soil Processes?

Behavior of water balance components at sites with shallow groundwater tables: Possibilities and limitations of their simulation using different ways to control weighable groundwater lysimeters

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