Soil Hydraulic Properties

Durner, Wolfgang; Flühler, H.

doi:10.1002/0470848944.hsa077c

Cited by 41 publications

(32 citation statements)

References 127 publications

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“…Numerical solvers of Richards' equation for water flow in unsaturated soils require these curves as descriptors of the soil in which the movement of water should be calculated. Many parametric expressions for the retention curve and fewer for the hydraulic conductivity have been developed for that purpose (see the Supplement, Leij et al, 1997;Cornelis et al, 2005;Durner and Flühler, 2005;Khlosi et al, 2008;Assouline and Or, 2013).…”

Section: Introductionmentioning

confidence: 99%

Parametric soil water retention models: a critical evaluation of expressions for the full moisture range

Madi

Rooij

Mielenz

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Few parametric expressions for the soil water retention curve are suitable for dry conditions. Furthermore, expressions for the soil hydraulic conductivity curves associated with parametric retention functions can behave unrealistically near saturation. We developed a general criterion for water retention parameterizations that ensures physically plausible conductivity curves. Only 3 of the 18 tested parameterizations met this criterion without restrictions on the parameters of a popular conductivity curve parameterization. A fourth required one parameter to be fixed.We estimated parameters by shuffled complex evolution (SCE) with the objective function tailored to various observation methods used to obtain retention curve data. We fitted the four parameterizations with physically plausible conductivities as well as the most widely used parameterization. The performance of the resulting 12 combinations of retention and conductivity curves was assessed in a numerical study with 751 days of semiarid atmospheric forcing applied to unvegetated, uniform, 1 m freely draining columns for four textures.Choosing different parameterizations had a minor effect on evaporation, but cumulative bottom fluxes varied by up to an order of magnitude between them. This highlights the need for a careful selection of the soil hydraulic parameterization that ideally does not only rely on goodness of fit to static soil water retention data but also on hydraulic conductivity measurements.Parameter fits for 21 soils showed that extrapolations into the dry range of the retention curve often became physically more realistic when the parameterization had a logarithmic dry branch, particularly in fine-textured soils where high residual water contents would otherwise be fitted.

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Section: Introductionmentioning

confidence: 99%

Parametric soil water retention models: a critical evaluation of expressions for the full moisture range

Madi

Rooij

Mielenz

et al. 2018

Hydrol. Earth Syst. Sci.

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“…Unfortunately, no general procedure exists for upscaling hydraulic properties of soils. Even the question about the existence of effective soil hydraulic properties at coarser scales has not found a satisfactory answer yet (Durner & Flühler, 2005). The inverse determination of hydraulic parameters directly from field data (Abbaspour et al , 2000) is most desirable, but restricted by an insufficient knowledge of the water flow dynamics across the system boundaries.…”

Section: Introductionmentioning

confidence: 99%

Effective hydraulic properties of layered soils at the lysimeter scale determined by inverse modelling

Durner

Jansen

Iden

2007

European J Soil Science

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The transferability of soil hydraulic properties measured in the laboratory to the field or catchment scale is a key problem in soil hydrology. To narrow the gap between laboratory and field scale we investigated soil water movement at the lysimeter scale. Specific questions of interest are the existence and uniqueness of effective hydraulic properties for lysimeters that are internally heterogeneous. To answer these questions, synthetic measurements of water contents, pressure heads, and fluxes across the system boundaries were generated by forward modelling of water flow, based on the Richards equation, for a variety of homogeneous and layered soils and under varying types of boundary conditions (multistep outflow, evaporation, transient atmospheric). We evaluated the measurements by inverse modelling assuming a homogeneous system. The globally convergent shuffled complex evolution algorithm was applied to avoid parameter estimation problems caused by a rough topology of the objective function. The hydraulic properties of homogeneous soils were always uniquely identified, not only for the classic multistep outflow and evaporation experiments but also under natural atmospheric boundary conditions. Moreover, for the weakly heterogeneous layered soils, the soil water dynamics could be well described with effective homogeneous properties. For highly heterogeneous, layered soils, it was still possible to match the boundary fluxes for all types of experiments. Internal system states could not be matched, however, and the properties identified depended on the type of experiment. For these soils no unique effective soil hydraulic properties exist. We found that for strongly layered soils the simultaneous determination of the hydraulic properties of multiple soil layers by inverse modelling is a practicable alternative to the description with effective parameters.

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“…The parameter n is connected to the width of the pore size distribution of the soil between S and air entry pressure head. The product mn is related to the width of the pore size distribution of the soil between air entry pressure head and R (Durner and Flühler, 2006;Peters and Durner, 2006). Studies of Wösten and van Genuchten (1988) and van Genuchten and Nielsen (1985) analysed the influence of these parameters on the shape of the modelled pF curve in detail.…”

Section: Soil Hydraulic Functionsmentioning

confidence: 99%

Subgrid spatial variability of soil hydraulic functions for hydrological modelling

Kreye

Meon

2016

Hydrol. Earth Syst. Sci.

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Abstract. State-of-the-art hydrological applications require a process-based, spatially distributed hydrological model. Runoff characteristics are demanded to be well reproduced by the model. Despite that, the model should be able to describe the processes at a subcatchment scale in a physically credible way. The objective of this study is to present a robust procedure to generate various sets of parameterisations of soil hydraulic functions for the description of soil heterogeneity on a subgrid scale. Relations between Rosettagenerated values of saturated hydraulic conductivity (K s ) and van Genuchten's parameters of soil hydraulic functions were statistically analysed. An universal function that is valid for the complete bandwidth of K s values could not be found. After concentrating on natural texture classes, strong correlations were identified for all parameters. The obtained regression results were used to parameterise sets of hydraulic functions for each soil class. The methodology presented in this study is applicable on a wide range of spatial scales and does not need input data from field studies. The developments were implemented into a hydrological modelling system.

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Soil Hydraulic Properties

Cited by 41 publications

References 127 publications

Parametric soil water retention models: a critical evaluation of expressions for the full moisture range

Parametric soil water retention models: a critical evaluation of expressions for the full moisture range

Effective hydraulic properties of layered soils at the lysimeter scale determined by inverse modelling

Subgrid spatial variability of soil hydraulic functions for hydrological modelling

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