A COMPARISON OF MEASURED AND MODELLED SOIL WATER RETENTION DATA

1987 ◽  
Vol 67 (3) ◽  
pp. 697-703 ◽  
Author(s):  
R. DE JONG ◽  
J. A. MCKEAGUE
Keyword(s):  
Organic Carbon ◽  
Soil Water ◽  
Water Retention ◽  
Organic Carbon Content ◽  
Retention Data ◽  
Soil Water Retention ◽  
Extreme Caution ◽  
High Potentials ◽  
Measured Water ◽  
Water Contents

Soil water retention data, predicted from texture, organic carbon content and bulk densities, were compared to measured values. Although significant correlations were obtained, the differences between predicted and measured water contents were large, especially at high potentials, and suggest that extreme caution must be exercised in employing the models under conditions other than those for which they were developed. Key words: Soil water retention, modelling, texture

scholarly journals Studying Unimodal, Bimodal, PDI and Bimodal-PDI Variants of Multiple Soil Water Retention Models: I. Direct Model Fit Using the Extended Evaporation and Dewpoint Methods

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 900 ◽  
Author(s):  
Amir Haghverdi ◽  
Mohsen Najarchi ◽  
Hasan Sabri Öztürk ◽  
Wolfgang Durner
Keyword(s):  
High Resolution ◽  
Soil Water ◽  
Water Retention ◽  
The United States ◽  
Retention Data ◽  
Soil Water Retention ◽  
Retention Models ◽  
Direct Model ◽  
Free Parameters ◽  
Measured Water

This study focuses on the reliable parametrization of the full Soil Water Retention Curve (SWRC) from saturation to oven-dryness using high resolution but limited range measured water retention data by the Hydraulic Property Analyzer (HYPROP) system. We studied the performance of five unimodal water retention models including the Brooks and Corey model (BC model), the Fredlund and Xing model (FX model), the Kosugi model (K model), the van Genuchten constrained model with four free parameters (VG model), and the van Genuchten unconstrained model with five free parameters (VGm model). In addition, eleven alternative expressions including Peters–Durner–Iden (PDI), bimodal, and bimodal-PDI variants of the original models were evaluated. We used a data set consisting of 94 soil samples from Turkey and the United States with high-resolution measured data (a total of 9264 measured water retention data pairs) mainly via the HYPROP system and supplemented for some samples with measured dry-end data using the WP4C instrument. Among unimodal expressions, the FX and the K models with the Mean Absolute Error (MAE) values equal to 0.005 cm3 cm−3 and 0.015 cm3 cm−3 have the highest and the lowest accuracy, respectively. Overall, the alternative variants provided a better fit than the unimodal expressions. The unimodal models, except for the FX model, fail to provide reliable dry-end estimations using HYPROP data (average MAE: 0.041 cm3 cm−3, average r: 0.52). Our results suggested that only models that account for the zero water content at the oven dryness and properly shift from the middle range to dry-end (i.e., the FX model and PDI variants) can adequately represent the full SWRC using typical data obtained via the HYPROP system.

A review of fractal, prefractal and pore-solid-fractal models for parameterizing the soil water retention curve

2011 ◽  
Vol 91 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Behzad Ghanbarian-Alavijeh ◽  
Humberto Millán ◽  
Guanhua Huang
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Physical Models ◽  
Water Retention Curve ◽  
Retention Data ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Fractal Models ◽  
Water Contents

Ghanbarian-Alavijeh, B., Millán, H. and Huang, G. 2011. A review of fractal, prefractal and pore-solid-fractal models for parameterizing the soil water retention curve. Can. J. Soil Sci. 91: 1–14. The soil water retention curve is an important hydraulic parameter for characterizing water flow and contaminant transport in porous media. Therefore, many empirical, semi physical, and physical models of the soil water retention curve have been proposed. Among them, fractal models appear to be a useful approach for modeling soil as a heterogeneous porous medium and its hydraulic characteristics. Fractal models are mathematically based, and their parameters have physical meanings. In this study, we review published fractal, prefractal and pore-solid-fractal models for soil water retention curves including Tyler and Wheatcraft, Rieu and Sposito, Perrier et al., Perfect, Bird et al., Millán and González-Posada, and Cihan et al. models. In the pore-solid fractal (PSF) approach the pore phase and matrix phase have a finite volume even for an infinite number of iterations. The results of fitting the PSF model to measured soil water retention data indicate that this model works well, particularly at lower water contents.

scholarly journals Prediction of soil water retention properties using pore-size distribution and porosity

2013 ◽  
Vol 50 (4) ◽  
pp. 435-450 ◽  
Author(s):  
Christopher T.S. Beckett ◽  
Charles E. Augarde
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Soil Water ◽  
Water Retention ◽  
Adsorbed Water ◽  
Retention Data ◽  
Soil Water Retention ◽  
Pore Size Distributions ◽  
Water Retention Properties

Several models have been suggested to link a soil's pore-size distribution to its retention properties. This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties. Mechanisms are suggested for the determination of both the main drying and wetting paths, which incorporate an adsorbed water phase and retention hysteresis. Predicted results are then compared with measured retention data to validate the model and to provide a foundation for discussing the validity and limitations of using pore-size distributions to predict retention properties.

Effect of soil organic carbon on soil water retention

Geoderma ◽  
2003 ◽  
Vol 116 (1-2) ◽  
pp. 61-76 ◽  
Author(s):  
W.J. Rawls ◽  
Y.A. Pachepsky ◽  
J.C. Ritchie ◽  
T.M. Sobecki ◽  
H. Bloodworth
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Water ◽  
Water Retention ◽  
Soil Water Retention

scholarly journals Investigation into water retention behaviour of deformable soils

2013 ◽  
Vol 50 (2) ◽  
pp. 200-208 ◽  
Author(s):  
Simon Salager ◽  
Mathieu Nuth ◽  
Alessio Ferrari ◽  
Lyesse Laloui
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Void Ratio ◽  
Degree Of Saturation ◽  
Retention Data ◽  
Soil Water Retention ◽  
Retention Behaviour ◽  
Wide Range ◽  
Water Retention Behaviour

The paper presents an experimental and modelling approach for the soil-water retention behaviour of two deformable soils. The objective is to investigate the physical mechanisms that govern the soil-water retention properties and to propose a constitutive framework for the soil-water retention curve accounting for the initial state of compaction and deformability of soils. A granular soil and a clayey soil were subjected to drying over a wide range of suctions so that the residual state of saturation could be attained. Different initial densities were tested for each material. The soil-water retention curves (SWRCs) obtained are synthesized and compared in terms of water content, void ratio, and degree of saturation, and are expressed as a function of the total suction. The studies enable assessment of the effect of the past and present soil deformation on the shape of the curves. The void ratio exerts a clear influence on the air-entry value, revealing that the breakthrough of air into the pores of the soil is more arduous in denser states. In the plane of water content versus suction, the experimental results highlight the fact that from a certain value of suction, the retention curves corresponding to different densities of the same soil are convergent. The observed features of behaviour are conceptualized into a modelling framework expressing the evolution of the degree of saturation as a function of suction. The proposed retention model makes use of the theory of elastoplasticity and can thus be generalized into a hysteretic model applicable to drying–wetting cycles. The calibration of the model requires the experimental retention data for two initial void ratios. The prediction of tests for further ranges of void ratios proves to be accurate, which supports the adequacy of formulated concepts.

scholarly journals Modelling of soil-water retention curve considering the effects of existing salt solution in the pore fluid

2021 ◽  
Vol 337 ◽  
pp. 02001
Author(s):  
Hamed Sadeghi ◽  
Ali Golaghaei Darzi
Keyword(s):  
Soil Water ◽  
Osmotic Potential ◽  
Water Retention ◽  
Pore Fluid ◽  
Water Retention Curve ◽  
Model Parameters ◽  
Retention Data ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve

Soil-water retention curve (SWRC) has a wide application in geoenvironmental engineering from the predication of unsaturated shear strength to transient two-phase flow and stability analyses. Although various SWRC models have been proposed to take into account some influencing factors, less attention has been given to consider the effects of pore fluid osmotic potential. Therefore, the key objective of this study is to extend van Genchten’s model so that osmotic potential is considered as an independent factor governing the SWRC behavior. The new model comprises only six variables, which can be calibrated through minimal experimental measurements. More importantly, most of the model parameters have physical meaning by correlating macroscopic volumetric behavior and general trends of SWRC to osmotic potential. The results of validation tests revealed that the new osmotic-dependent SWRC model can predict the retention data in terms of both total and matric suction for two different soils and various molar concentrations very good. The proposed modeling approach does not require any advanced mercury intrusion porosimetry (MIP) tests, yet it can deliver excellent predictions by calibrating only six parameters which are far less than those incorporated into similar models for saline water permeating through the pore structure.

WATER RETENTION EQUATIONS AND THEIR RELATIONSHIP TO SOIL ORGANIC MATTER AND PARTICLE SIZE DISTRIBUTION FOR DISTURBED SAMPLES

1983 ◽  
Vol 63 (2) ◽  
pp. 291-302 ◽  
Author(s):  
R. DE JONG ◽  
C. A. CAMPBELL ◽  
W. NICHOLAICHUK
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Water Retention Curve ◽  
Organic Carbon Content ◽  
Soil Water Retention ◽  
Canadian Prairies ◽  
Functional Relationships ◽  
Straight Line

Functional relationships between soil water content and water suction were examined and related to textural and organic carbon content data. Soil water retention curves between 5 and 10 000 kPa were determined on disturbed samples of 18 soils representing various soil Great Groups in the Canadian prairies. The best fit was obtained with a two-straight-line regression model. Correlation and regression analysis showed that texture was the main soil property influencing the shape and position of the water retention curve. Organic matter influenced primarily the water content at which a break in the curve occurred. Soil zone and cultivation history had little effect on water retention. Key words: Water retention, texture, organic matter, two-straight-line regression

scholarly journals Studying Unimodal, Bimodal, PDI and Bimodal-PDI Variants of Multiple Soil Water Retention Models: II. Evaluation of Parametric Pedotransfer Functions Against Direct Fits

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 896 ◽  
Author(s):  
Amir Haghverdi ◽  
Hasan Sabri Öztürk ◽  
Wolfgang Durner
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Organic Matter Content ◽  
Pedotransfer Functions ◽  
Model Parameters ◽  
Retention Data ◽  
Soil Water Retention ◽  
Data Set ◽  
Free Parameters

A high-resolution soil water retention data set (81 repacked soil samples with 7729 observations) measured by the HYPROP system was used to develop and evaluate the performance of regression parametric pedotransfer functions (PTFs). A total of sixteen soil hydraulic models were evaluated including five unimodal water retention expressions of Brooks and Corey (BC model), Fredlund and Xing (FX model), Kosugi (K model), van Genuchten with four free parameters (VG model) and van Genuchten with five free parameters (VGm model). In addition, eleven bimodal, Peters–Durner–Iden (PDI) and bimodal-PDI variants of the original expressions were studied. Six modeling scenarios (S1 to S6) were examined with different combinations of the following input predictors: soil texture (percentages of sand, silt and clay), soil bulk density, organic matter content, percent of stable aggregates and saturated water content (θs). Although a majority of the model parameters showed low correlations with basic soil properties, most of the parametric PTFs provided reasonable water content estimations. The VGm parametric PTF with an RMSE of 0.034 cm3 cm−3 was the best PTF when all input predictors were considered. When averaged across modeling scenarios, the PDI variant of the K model with an RMSE of 0.045 cm3 cm−3 showed the highest performance. The best performance of all models occurred at S6 when θs was considered as an additional input predictor. The second-best performance for 11 out of the 16 models belonged to S1 with soil textural components as the only inputs. Our results do not recommend the development of parametric PTFs using bimodal variants because of their poor performance, which is attributed to their high number of free parameters.

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

2018 ◽  
Vol 22 (2) ◽  
pp. 1193-1219 ◽  
Author(s):  
Raneem Madi ◽  
Gerrit Huibert de Rooij ◽  
Henrike Mielenz ◽  
Juliane Mai
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Minor Effect ◽  
Residual Water ◽  
Retention Data ◽  
General Criterion ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Soil Hydraulic

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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