Hydraulic Conductivity Curves Research Articles

Relation between flow through and volumetric changes in natural expansive soils

Geology and climate govern the evolution and behavior of natural expansive soils in the semi-arid Canadian Prairies. The Regina clay deposit has a flat topography, a homogenous composition, and contains hair-line fissures. This research focuses on understanding the relation between flow through and volumetric changes in the natural expansive soil. Based on analysis of test data, it is concluded that flow occurs through macro-pores or fissures (5 × 10−8 m/s) during structural volume change and through micro-pores or matrix (10−9 m/s) during normal and residual volume changes. The hydraulic conductivity decreases by several orders of magnitude and becomes asymptotic vapor flow (2 × 10−14 m/s) during residual volume change. A complete assessment of soil behavior requires water retention, swell-shrink, and hydraulic conductivity curves. The proposed straight-line representation of the functions' components is useful for predicting field response of expansive soils.

HYPROP measurements of the unsaturated hydraulic properties of a carbonate rock sample

The unsaturated hydraulic properties provide important theoretical and practical information about fluid flow in soils and rocks for a range of soil, environmental and engineering applications. In this study we used the evaporation (HYPROP) and chilled-mirror dew point (WP4C) methods to estimate the water retention and unsaturated hydraulic conductivity curves of an Indiana Limestone carbonate rock sample. The obtained data were analyzed in terms of unimodal and bimodal VG (van Genuchten, 1980) and PDI (Peters et al., 2015) type functions. Bimodal functions were found to produce excellent descriptions for the unsaturated hydraulic data we measured, slightly better than the standard unimodal formulations. For our particular test using an Indiana Limestone rock sample, we did not find much improvement when accounting for film and corner flow using the PDI formulation, relative to the VG model. As far as we know, this is the first time the HYPROP methodology was applied to a rock sample.

A hysteretic hydraulic constitutive model for unsaturated soils and application to capillary barrier systems

Unsaturated soils exhibit water retention hysteresis, with different water retention behaviour during drying and wetting paths. Water retention hysteresis has often been modelled using expressions for the main drying and main wetting water retention curves that are unsatisfactory at low values of degree of saturation. In addition, the effect of retention hysteresis on the unsaturated hydraulic conductivity behaviour has typically not been explicitly considered. This paper presents a new hysteretic hydraulic constitutive model for the water retention and hydraulic conductivity behaviour of unsaturated soils, which is effective and easy to apply. The model includes: (i) main wetting and main drying water retention curves modelled with a modified version of the van Genuchten model, improved at low degree of saturation; (ii) hysteretic scanning water retention curves modelled using a bounding surface approach; (iii) the effect of hydraulic hysteresis on a soil hydraulic conductivity curve (SHCC) model improved at low degree of saturation and including the effect of liquid film conductivity. The new hysteretic hydraulic model is then validated against experimental data. After implementation in the finite element software Code_Bright, the new hydraulic constitutive model is applied in a numerical study of the impact of hydraulic hysteresis on the behaviour of capillary barrier systems (CBSs). Water retention hysteresis, which has typically been neglected in the modelling of the hydraulic behaviour of CBSs, is shown to have a significant impact on: (i) movement and redistribution of water within the finer layer of a CBS; (ii) the phenomenon of water breakthrough across the interface between the finer and coarser layers of a CBS and the subsequent restoration of the CBS after infiltration at the ground surface ceases; (iii) the prediction of evaporation from a CBS into the atmosphere.

Effective hydraulic conductivity of stony soils: General effective medium theory

Despite a longstanding interest in understanding the effects of rock fragments on soil hydraulic properties, physically-based models to describe the effective hydraulic conductivity of stony soils are still rare. The conductivity of stony soils is mostly described by simple scaling approaches, assuming impermeable rock fragments. We present a model based on the general effective medium (GEM) theory to calculate the effective hydraulic conductivity of stony soils. The model accounts for the volumetric content, shape, and orientation of rock fragments in the main direction of water flow. Rock fragments can either be permeable or impermeable in the model which allows to calculate the effective unsaturated hydraulic conductivity curve of stony soils over the full range of soil matric potentials. Existing models assume rock fragments to be isolated and their application is therefore limited to low to moderately stony soils. In GEM model interaction between rock fragments is allowed, which makes it applicable in stony soils with high contents of rock fragments. The mathematical simplicity of the model makes it suitable for practical applications and provides a strong theoretical basis for improving predictions of flow and transport in hydrological models applied in forested and agricultural watersheds and mountainous areas.

Estimation of vineyard soil structure and preferential flow using dye tracer, X-ray tomography, and numerical simulations

The appearance and distribution of soil pores have a significant influence on water flow and solute transport in the soil vadose zone. The pore system is highly variable in arable soils where crop rotation, tillage, trafficking, soil amendments, and various management practices are commonly implemented. The aim of this study was to assess the porous system and preferential flow pathways in a vineyard soil using undisturbed soil columns, and by combining laboratory and numerical methods with dye staining and X-ray imaging. It was hypothesized that the integration of various methods could reveal more information about soil structure, and flow and transport behavior of structured arable soil. Soil water retention and hydraulic conductivity curves were obtained using the evaporation method, while water flow was assessed using intermittent leaching experiments. Water flow and the transport of Brilliant Blue were simulated using HYDRUS-1D. A single-porosity model of soil hydraulic properties provided a good description of data collected during the evaporation experiments. Data collected during leaching experiments did not provide enough experimental evidence for the occurrence of nonequilibrium flow patterns and the differentiation between the single- and dual-permeability models of soil hydraulic properties. However, dye staining and X-ray imaging revealed a complex pore-architecture network with large vertical and horizontal biopores. The staining patterns (Brilliant Blue FCF) within the vertical column sections documented the extent of preferential flow. The study showed that the bi-modal character of pore structure could often be hidden when a limited number or non-adequate methods are applied for its quantification from water flow behavior. The impact of preferential pathways on dye transport can be investigated with observations and simulations. A combination of various methods enabled us to adequately assess vineyard soil structure and fine-tune the description and extent of preferential water flow.

Comparison of the inverse modeling approach and traditional methods to estimate the unsaturated hydraulic properties in a sandy loam soil

The aim of this work is to compare the use of the inverse solution approach in the estimation of soil hydraulic properties with traditional tension disk infiltrometer (TDI) data analysis, field retention data and commonly used pedotransfer functions (PTFs). Field data were collected in an experimental plot located at Bahía Blanca, Argentina. Field infiltration under saturated conditions was measured by the inverse auger hole method and infiltration under unsaturated conditions were carried out with TDI. Field retention data (θ(h)) were also collected periodically. The HYDRUS 2D/3D software was used to optimize soil hydraulic parameters by inverse solution according to TDI data. The saturated hydraulic conductivity measured by inverse auger hole method (5.53 cm.h-1) and calculated by Wooding analytical approach (5.35 cm.h-1) and inverse numerical simulations (5.36 cm.h-1) showed very close values. According to macroporosity estimates infiltrated water is mainly conducted through soils micro and mesopores. Macropores only channeled 15.9% of total infiltrated flow. Soil water retention curves (SWRC) predicted by PTFs did not represented correctly field retention data. The best adjustment between water content at specific pressure heads predicted by SWRCs and field measured water content was reached by the TDI inverse solution approach (RMSE: 0.050 cm3.cm-3). The inverse solution approach probed to be a simple and practical method to obtain an accurate estimate of both, SWRC and hydraulic conductivity curve.

Estimation and mapping of field capacity in Brazilian soils

Modeling soil water dynamics is important to support decision in planning and management policies. Field capacity (FC) is an important parameter in this context and its proper determination allows the use of simple models to assess soil water balance components. In this study we aimed estimation and mapping of FC in Brazilian soils based on available soil global data and pedotransfer functions (PTF). Soil basic data were obtained from the SoilGrids system in a 0.05 × 0.05° spatial grid covering the Brazilian territory, with a resolution of approximately 5 km. Soil saturated hydraulic conductivity (Ks) and water retention curve (SWRC) were estimated by PTFs and used as input in the agro-hydrological model SWAP to simulate an internal drainage experiment without evapotranspiration, until the drainage at the bottom profile reached negligible flux density values (qfc) of: 0.25, 1.0 and 4.0 mm d−1, considered to correspond to FC. Simulations were performed considering three soil depths (zfc) of 30, 60 and 100 cm. FC was classified according to major soil textural and pedological classes. Uncertainty was evaluated by the sensitivity of the model to the soil hydraulic properties and the grid cell size. The highest soil matric potential at FC (hfc) was observed for loam texture while the lowest hfc was observed for sandy loam texture. Between soil pedological classes, Gleysols presented the lowest hfc. The results showed that FC estimation is sensitive to zfc and qfc. Spatial agreement between patterns of Ks, FC and soil class were observed according to the evaluated database. The qfc value of 4.0 mm d−1 presented reasonable results for estimating FC in Brazilian soils, in agreement with expected drainage time following saturation, with average values below 4 days for the evaluated depths and hfc around −30 cm. Estimation of FC with PTF showed underestimation of hfc varying from double to almost fourfolds times. The usually adopted hfc of −330 cm does not represent the FC for Brazilian soils. Furthermore, a qfc lower than 1.0 mm d−1 did not yield usable values for FC.

Utilizing Splintex 2.0 for estimating the soil hydraulic conductivity curve measured with instantaneous profile method

Soil hydraulic conductivity curve (SHCC) is a key-physical-function in hydrological and environmental studies. Measuring SHCC is a difficult and onerous task and often unfeasible in large-scale monitoring. Therefore, pedotransfer functions (PTFs) have been an alternative way for estimating SHCC. In this study, the novel version of Splintex model (Splintex 2.0) is analyzed to estimate the unsaturated soil hydraulic conductivity (K) as a function of water content (θ). Splintex 2.0 estimates the function K(θ) assuming that soil pores can be represented by equivalent capillary tubes and that the water flow rate is a function of pore size distribution. Then, the estimates of K(θ) data are fitted to the SHCC described by the van Genuchten (1980); Mualem (1976) (VGM) equation. In this study, the goodness-of-fit of K(θ) estimation was evaluated with selected 198 measured SHCCs by the instantenous profile method. Each data set contains measured information of textural composition, solid and bulk densities, total porosity, and K(θ) data. Estimated and measured SHCCs were compared dividing the analyzed soil data in four textures and computing Pearson correlation coefficient (r), mean error (ME), and root mean square error (RMSE) measures. The estimation using Splintex 2.0 revealed a mean RMSE of log10[K(θ)] of 1.17, ranging from 0.77 to 1.22, pointing for an acceptable performance for PTFs purposes.

Comportamento da infiltração de água no solo em parque urbano

The objective of this work is to evaluate the infiltration capacity and to determine the hydrodynamic parameters of three surfaces (community use, children's recreation and gardens) in an urban park in Recife/PE. The Beerkan methodology was used to determine the parameters of the water retention curve and the hydraulic conductivity curve from 24 infiltration tests. Besides that, the surfaces’ water balance subjected to 365 days of rainfall was simulated with the aid of the Hydrus 1D model. The garden areas presented the higher values for maximum infiltration rates (553.58 mm.h-1), followed by children's recreation areas (116.70 mm.h-1) and and community use area (18.75 mm.h-1). The areas’ predominant textures had no direct correlation with the saturated hydraulic conductivity (Ks), presenting values between 25.38 and 306.65 mm.h -1 for sandy loam soils (gardens); 7.67 and 542.2 mm.h-1 for sandy clay loam (gardens and community use); and 4.07 and 256.86 mm.h -1 for loamy sand (recreation). The water retention capacity was lower in the gardens, with opposite behavior in the community use areas. The Hydrus’ simulations resulted in higher values of runoff and evaporation in the gardens. They showed that there is no difference in the values of cumulative infiltration in the three areas.

Utilização de métodos de campo e laboratoriais para estimação de propriedades hidrodinâmicas do solo

O solo é de suma importância na drenagem urbana, pois auxilia na retenção da água proveniente das chuvas, através da infiltração, e reduz o escoamento superficial que tem como consequência as inundações urbanas. Determinar as propriedades hidrodinâmicas do solo é essencial para compreender esses processos. As propriedades hidrodinâmicas do solo são determinadas pela curva de retenção da água no solo e a curva de condutividade hidráulica. A determinação das propriedades hidrodinâmicas do solo requer ensaios de campo e de laboratório bastante dispendiosos, oneram e demandam um longo tempo de execução. Desse modo, o objetivo desse trabalho é determinar as propriedades hidrodinâmicas do solo pelos métodos Beerkan e Função de Pedotransferência. O estudo foi realizado no Instituto Federal de Pernambuco, Campus Recife, constituindo-se das etapas de coleta de amostras, ensaios de campo e ensaios de laboratório. O perfil do solo dos pontos amostrais do local de estudo foi classificado como franco arenoso. As propriedades hidrodinâmicas do solo obtidos pelo método da Função de Pedotransferência estão coerentes com os observados na literatura e as curvas de retenção do solo e de condutividade hidráulica, apresentaram comportamento semelhante em todos os pontos analisados. Para o método Beerkan, foram determinados os parâmetros de forma e de normalização, apresentando valores aceitáveis comparados aos da literatura e além disso, as curvas de infiltração ajustadas, as curvas de retenção e condutividade hidráulica nos pontos analisados tiveram comportamentos semelhantes entre elas.

Estimation of tropical soils’ hydraulic properties with inverse method and tension infiltrometer field data

In the last few years, many studies have been published by authors from several countries offering approximations and use of the inverse method. However, the unique environmental conditions and distinct properties of the tropical soils in Brazil require extra considerations and the need to adjust these methods to tropical soil conditions. Considering the above, this determined the parameters of the van Genuchten (1980) model (θs, θr, α, n) of the water retention curve in the soils. It also determined the parameter (Ks) of the soil’s hydraulic conductivity curve by solving an inverse problem using the HYDRUS-2D model, considering cumulative infiltration data collected in the field by means of an infiltration test using the tension infiltrometer. It then compared the hydraulic properties determined by these methods in relation to the standard laboratory method. The inverse method was able to efficiently determine the water retention curves in the soils here studied; however, it was not possible to reliably determine the unsaturated hydraulic conductivity curve.

Splintex 2.0: A physically-based model to estimate water retention and hydraulic conductivity parameters from soil physical data

Soil water retention curve (SWRC) and hydraulic conductivity curve (SHCC) are functions that contribute to the understanding and modeling of hydraulic processes in the vadose zone of the soil. However, their measurement is often difficult and expensive becoming impractical the large-scale monitoring. Pedotransfer functions (PTFs) are, therefore, an alternative to estimate SWRC and SHCC data. Most PTFs are usually calibrated with data from local soils and may be uncertain when applied to soils with different morphological properties. On the other hand, PTFs with a physico-empirical basis have as advantage their wide application. Splintex 1.0 is a physico-empirical model developed in BASIC language that is based on the particle size distribution and other basic soil information. This model estimates the parameters of the van Genuchten-Mualem equation that compose the SWRC without requiring prior calibration and the saturated hydraulic conductivity (Ks) using a texture-PTF. A second version with a user-friendly computational interface is presented to improve the estimates of the SWRC parameters and to introduce the estimation of the SHCC parameters with different PTFs, which are based on two physically-based models that can be applied universally. Computational procedures and equations of Splintex 2.0 were written in C++ language and the performance of both model versions was tested for different soil texture classes. The performance analysis was carried out using the Pearson correlation coefficient and the mean absolute and root mean square errors. Splintex 2.0 yielded good performance in the quantification of water retention data, showing its application to any soil class. As an advantage, the conductivity data can be estimated without the need of Ks and SWRC parameters.

The effect of solid‐phase composition on the drying behavior of Markermeer sediment

AbstractWe studied the drying behavior of slurries of Markermeer sediments in the Netherlands having different solid compositions. Natural processes such as sand–mud segregation and oxidation of organic matter were mimicked to analyze the effect of changes in sediment composition. Evaporation experiments were performed with soft slurry samples using the Hyprop setup. Soil water retention curves (SWRCs) and hydraulic conductivity curves (HCCs) were determined as a function of the water ratio (WR, defined as volume of water/volume of solids). The sediment remained close to saturation until the end of the experiments. The Atterberg limits reduced significantly after sediment treatment involving drying at 50 °C, rewetting, and chemical oxidation. Furthermore, the oxidized sediment lost capacity to retain water. The SWRCs of sandy and oxidized clays were steeper, and fine‐textured sediments showed large water ratios. At low matric suctions, the water retention capacity of the upper sediment samples containing more labile organic matter was larger than that of the sediment underneath. Clear correlations were found between van Genuchten parameters and the degree of degradation of the organic matter. The hydraulic conductivity of fine‐textured samples with less labile organics was larger. The results give insight into the drying behavior of Markermeer sediment, currently used to build wetlands.

Comparison of soil hydraulic properties estimated from steady-state experiments and transient field observations through simulating soil moisture in regenerated Sphagnum moss

Growing Sphagnum moss for peatland restoration and fibre farming requires the proper moisture regime be maintained; thus, there is a desire to optimize growth by creating ideal hydrological conditions. However, it is uncertain which parameterization method is most suitable to describe field-scale processes and which soil water retention model and hydraulic conductivity curve (approach) is the most acceptable to use. Parameterizations of the van Genuchten – Mualem (VGM) equation were done using RETC, curve fitting to direct measurements of the water retention and unsaturated hydraulic conductivity curves; and Hydrus-1D, inverse modelling to field observations of soil moisture. The acceptability of each parameterization was tested by comparing soil moisture estimates based on forward simulations to observed soil moisture in two regenerated moss profiles, established in 1970 and 2006 cases, respectively. The transient field model simulated soil moisture well, and had an RMSE of 0.05 and 0.06 for 1970 and 2006, respectively. The most error occurred during the wettest and driest periods of the simulations. Simulated soil moisture was consistently drier than the observed soil moisture, in the steady-state laboratory simulation, and had markedly higher RMSE, 0.14 and 0.27 for the 1970 and 2006 profiles, respectively. The estimate of the VGM α parameter, an approximately the inverse of the air-entry pressure, fit to direct measurements of the retention and unsaturated hydraulic conductivity curves was an order of magnitude higher than that fit to field observation. The results of the simulation suggest that inverse modelling to field soil moisture should be used to estimate VGM parameters to more accurately represent field-scale soil moisture dynamics.

Extension of the Gardner exponential equation to represent the hydraulic conductivity curve

Abstract The relative hydraulic conductivity curve K r (h) = K/K s is a key variable in soil modeling. This study proposes a model to represent K r (h), the so-called Gardner dual (GD) model, which extends the classical Gardner exponential model to h values greater than h o, the suction value at the inflection point of the K r (h) curve in the log-log scale. The goodness of fit of GD using experimental data from UNSODA was compared to that of the MVG [two-parameter (K ro , L) Mualem-van Genuchten] model and a corresponding modified MVG model (MVGm). In 77 soils without evidence of macropore flow, GD reduced the RMSE errors by 64% (0.525 to 0.191) and 29% (0.269 to 0.193) in relation to MVG and MVGm, respectively. In the remaining 76 soils, GD generally was less accurate than MVG and MVGm, since most of these soils presented evidence of macropore flow (dual permeability). GD has three parameters and two degrees of freedom, like MVG. Two of them allow the calculation of the macroscopic capillary length, a parameter from the infiltration literature. The three parameters are highly dependent on the K r (h) data measurement in a short wet suction range around h o, which is an experimental advantage.

Temperature Dependence of Soil Hydraulic Properties: Transient Measurements and Modeling

The modeling of the water flow in soils under non‐isothermal conditions requires consideration of the temperature influence on the soil hydraulic properties (SHPs). The surface‐tension‐viscous‐flow (STVF) theory considers the influence of temperature on viscosity, density and surface tension and provides a conceptual framework for the temperature dependence of the water retention and hydraulic conductivity curves. Previous research has shown discrepancies between observed temperature effects on SHPs and the STVF theory. Furthermore, experimental investigations, which investigate the temperature effects on both the retention and conductivity curves in a combined manner, are still rare. To overcome this limitation, we measured the SHPs of three different soils at three different temperatures (5, 20, and 35°C) with the evaporation method, which yields highly resolved retention data in the suction range between saturation and 100 kPa, and conductivity data in the range of ∼6 to 100 kPa. The classic STVF‐based model and two alternative models were tested. Results showed that the temperature dependence of SHP was larger than predicted by the STVF theory and depends on the soil. The effect was strongest for the silt loam, followed by the sand and smallest for the sandy loam. Fits of the Grant and Stoffregen models to the experimental data were excellent, but required soil‐specific parameters. This indicates that the surface properties of the soil matrix might contribute to the effects of temperature on SHPs.

Soil physical and hydraulic properties in the Donato stream basin, RS, Brazil. Part 2: Geostatistical simulation

ABSTRACT Geostatistical simulation has been the most promising and used technique for the analysis of uncertainties of soil physical and hydraulic properties, with high spatial heterogeneity. This study carried out a stochastic analysis of saturated hydraulic conductivity (Ksat) and soil water retention curve parameters in the Donato stream basin, located in the municipality of Pejuçara, in the state of Rio Grande do Sul, Brazil, with geographic coordinates between 28º 25’ 34” S and 53º 40’ 30” W, and 28º 24’ 50” S and 53º 41’ 30” W, 590 m of altitude. Soil samples were collected during the period from August to November of 2012. Sequential Gaussian simulation technique was used to generate 100 random fields of each variable. The results showed great uncertainties for Ksat and the parameter α of the soil water retention curve. The uncertainties between the percentiles 5 and 95% for Ksat indicated values from 24 to 44 cm d-1, and for the parameter α, the uncertainties could be estimated from 0.622 to 1.122 cm-1.

Estimation of Unsaturated Hydraulic Conductivity of Granular Soils from Particle Size Parameters

Estimation of unsaturated hydraulic conductivity could benefit many engineering or research problems such as water flow in the vadose zone, unsaturated seepage and capillary barriers for underground waste isolation. The unsaturated hydraulic conductivity of a soil is related to its saturated hydraulic conductivity value as well as its water retention behaviour. By following the first author’s previous work, the saturated hydraulic conductivity and water retention curve (WRC) of sandy soils can be estimated from their basic gradation parameters. In this paper, we further suggest the applicable range of the estimation method is for soils with d10 > 0.02mm and Cu < 20, in which d10 is the grain diameter corresponding to 10% passing and Cu is the coefficient of uniformity (Cu=d60d10). The estimation method is also modified to consider the porosity variation effect. Then the proposed method is applied to predict unsaturated hydraulic conductivity properties of different sandy soils and also compared with laboratory and field test results. The comparison shows that the newly developed estimation method, which predicts the relative permeability of unsaturated sands from basic grain size parameters and porosity, generally has a fair agreement with measured data. It also indicates that the air-entry value is mainly relative to the mean grain size and porosity value change from the intrinsic value. The rate of permeability decline with suction is mainly associated with grain size polydispersity.

Simulation of Water Infiltration Process into a Porous Unsaturated Soil: Application on Tangier’s Bay Region-Morocco

The study is focused on numerical simulation of the infiltration process of polluted water originating from a wadi into the unsaturated soil of a bay. This study addresses the linkage between unsaturated zone and groundwater and it discusses the ability of the unsaturated soil to receive the water dried at once by the wadi and the bay. The simulation requires a number of trials, something that is experimentally expensive and sometimes impossible. The infiltration process is governed by the Richard’s equation. To solve this later, the knowledge of soil water properties such as pressure head, water content and hydraulic conductivity is needed. Hence, the water retention and unsaturated hydraulic conductivity curves near saturation have been established for a range of water content going from h = (− 25 m; 25 m) to h = (− 175 m; 175 m). These curves are obtained using the simulating computer program Hydrus 2D/3D. Numerical results have been calibrated with the Musy and Soutter (Physique du sol (soil physics), Universite de Technologie Compiegne, Lausanne, 1991) type relationships. It has been explained that the infiltration process from the saturated zones to the unsaturated zone is relatively slow depending on the soil structure.

Multi-step outflow and evaporation experiments – Gaining large undisturbed samples and comparison of the two methods

The aim of the study was the comparison of the soil hydraulic properties determined based on two different experimental methods of four large and macroporous soil samples. An undisturbed cylindrical soil column (h = 60 cm and d = 30 cm) was obtained at a natural slope and quartered horizontally in the laboratory. The four sub-samples were saturated and subsequently drained using the extended multi-step outflow method (XMSO). Retention curves and unsaturated hydraulic conductivity curves were derived via inverse modeling based on the measured drainage and corresponding pore water pressure. After resaturation the evaporation method (EVA) was used on the same four samples. The samples were exposed to evaporation and the effective water contents and the average pore water pressures were recorded over time to determine soil hydraulic functions.While both methods yielded similar results in the medium moisture range, the advantage of the XMSO-method is its higher information content with respect to the hydraulic conductivity close to water saturation whereas the advantage of the EVA-method is its fast execution. Moreover, the EVA-method is easier to handle and has significantly lower computational requirements than the XMSO-method.Furthermore, since the four soil samples represent a soil profile in the field, a depth dependent characterizing of the soil profile was possible and showed that the soil properties near saturation are greatly dominated by the ratio of macropores in the sample and that a decrease in the macropore ratio with soil depth was clearly reflected in the hydraulic functions.