Soil Water Hysteresis Research Articles

Hydraulic properties of co-seismic landslide deposits around the Wenchuan earthquake epicentre: Large-scale column experiments

The co-seismic landslides and rock avalanches caused by the 2008 Wenchuan earthquake generated numerous poorly consolidated deposits over a vast area. Rainfall-induced initiation and remobilization of these deposits have resulted in many post-earthquake disasters, such as rapid erosion, flow slides, and debris flows, threatening the local residents. The hydraulic properties of the deposits dominate the evolution of the soil moisture in the slope during rainfall, consequently affecting the initiation and failure types of these geo-disasters. Thus, laboratory tests and infiltration experiments were conducted with material from co-seismic landslide deposits in the Wenjia Gully near the Wenchuan earthquake epicentre. The soil-water characteristic curve (SWCC) of the co-seismic deposit material was determined by a pressure plate extractor and tensiometers. Then, a series of large-scale soil column experiments were conducted with the materials. The results of the experiments showed a relatively high permeability and low matric suction of the co-seismic deposit compared with other soils. The infiltration characteristics of the deposit material with different initial water contents, compactness, and fine particle contents were also analysed and compared. A linear solution of the Green and Ampt equation was employed to estimate the infiltration rate in the deposit during rainfall events, which fit the results of the experiments well. The influence of matric suction on the water absorption and retention capacity was obvious when the moisture content was less than 5%, resulting in a variable evaporation rate and a soil-water hysteresis phenomenon. The results of this study provide reliable experimental evidence with which to evaluate the distribution and evolution of soil moisture in landslide deposits, which is significant for geo-hazard assessments and mitigation works. • Large-scale soil column experiments were conducted to study the hydraulic properties of co-seismic landslide deposits. • The permeability of co-seismic landslide deposits is relatively high, which results in an infiltration rate of 0.174–2.4 m/h. • An algebraic solution of the Green and Ampt equation is used to estimate the evolution of the wetting front. • The evaporation rate is much lower than the infiltration rate due to the increase in matric suction, which results in a soil-water hysteresis.

Comparative analysis of the apparent saturation hysteresis approach and the domain theory of hysteresis in respect of prediction of scanning curves and air entrapment

Abstract This study theoretically analyzes the concept of apparent saturation hysteresis, combined with the Scott et al. (1983) scaling approach, as suggested by Parker and Lenhard (1987), to account for the effect of air entrapment and release on the soil water hysteresis. We found that the theory of Parker and Lenhard (1987) is comprised of some mutually canceling mathematical operations, and when cleared of the superfluous intermediate calculations, their model reduces to the original Scott et al.’s (1983) scaling method, supplemented with the requirement of closure of scanning loops. Our analysis reveals that actually there is no effect of their technique of accounting for the entrapped air on the final prediction of the effective saturation (or water content) scanning curves. Our consideration indicates that the use of the Land (1968) formula for assessing the amount of entrapped air is in disaccord with the apparent saturation concept as introduced by Parker and Lenhard (1987). In this paper, a proper routine is suggested for predicting hysteretic scanning curves of any order, given the two measured main curves, in the complete hysteretic domain and some verification tests are carried out versus measured results. Accordingly, explicit closed-form formulae for direct prediction (with no need of intermediate calculation) of scanning curves up to the third order are derived to sustain our analysis.

The Effect of Precipitation Pulses on Evaporation of Deeply Buried Phreatic Water in Extra‐Arid Areas

Core Ideas Precipitation may increase deeply buried phreatic evaporation (PE). Soil‐water hysteresis leads to this phenomenon. This study reveals the mechanism of the effect of precipitation pulses on PE. Past research has shown that evaporation of deeply buried phreatic water occurs in extra‐arid areas where the soil surface is very dry. A dry surface layer can suppress the evaporation of capillary water, but it is not clear whether it suppresses deeply buried phreatic evaporation (PE). We deduced that the PE could be suppressed by a dry surface soil. Therefore, as the soil‐water content increases during a precipitation pulse, this can lead to an increase in PE. To investigate the effects of precipitation pulses on PE, a simulated 10‐mm precipitation recycling experiment using a shed–air‐conditioning condensation method was performed on Gobi Desert land at the top of the Mogao Grottoes in 2011 to 2015. The results show that after the 10 mm of precipitation was completely recycled, the PE increased by 28.9% compared with the control during the following 3 yr. In addition, the soil moisture increased in the 10‐ to 20‐cm layer for a long time. We hypothesize that this is a soil‐water hysteresis phenomenon, which is important for the observed differences in the evaporation rate, and it is apparent that the higher water content in the shallow layer is conducive to PE entering into the atmosphere. This preliminary study reveals the effect of precipitation pulses on deeply buried PE; this hysteresis phenomenon must be analyzed in further studies.

Subsoil water available in suction and poor in amount under continuous grassland use

Soil water storage in grassland is critical to regulate herbage yield while it may be threatened by continuous land use without plowing because of the progress of soil compaction associated with worsening soil hydraulic properties. This study aimed at contrasting the quantity and the availability of soil water in a meadow which had not been renovated for 13 years. We monitored matric potentials and mass soil water contents to 100 cm depth from autumn to winter in which plant transpiration was dormant. Soil water capacities were determined with soil water characteristics. The measurements were made in both a harvesting area in which agricultural vehicles had been operated, and a tree cover area which had experienced almost no vehicle loads. The soil layer in the tree cover area had a larger capacity for readily available moisture than that in the harvesting area. The matric potentials in the tree cover area varied in time between 0 and -1000 cm regardless of depth while those in the harvesting area were rather steady. These suggested better pore water continuity in the tree cover area. In the subsoil layers in both the harvesting and the tree cover areas, the soil water contents in terms of actually stored water did not reach as high a level as those expected from the soil moisture characteristics of the matric potential of -1000 cm. On the other hand, the measured matric potentials were consistently readily available for plants during the entire period of measurement. The apparent discrepancy between the matric potentials in readily available vs. actually stored water implied that the subsoil layers had become drier than observed during the study period, and that soil water hysteresis had prevented the full recovery of the water storage.

A contact angle-dependent hysteresis model for soil–water retention behaviour

Hysteresis is common in soil–water phenomena, and the soil–water retention relationship is not a one-to-one relationship between the effective degree of saturation and the matric suction. Existing theoretical soil–water retention models are usually derived by applying a capillary law that does not depend on the contact angle to the cumulative distribution function of soil pores. These theoretical models usually contain equations only for the main drying and wetting branches, so additional empirical scanning laws are needed to model hysteresis behaviour between these branches. This paper proposes a contact angle-dependent model in incremental form to reproduce soil–water hysteresis behaviour. The change in suction during scanning wetting and drying processes leads to a change in both the effective degree of saturation and the liquid–solid contact angle. An allocation proportion function is proposed to divide suction increments into two parts, one of which is allocated to the change in the effective degree of saturation and the other consumed by changing the contact angle. The proposed hysteresis model contains only four parameters that can be conveniently calibrated by the main drying branch and a scanning wetting curve. Test results are included to validate the proposed hysteresis model.

Water flow through unsaturated porous media with hysteresis

The paper is devoted to the investigation of a parabolic equation with the Preisach operator under the time derivative. The model equation appears in the context of soil water hysteresis. Under suitable assumptions an existence result is obtained by using an implicit time discretization scheme, a priori estimates and passage to the limit in the convexity domain of the Preisach operator.

土壌水分ヒステリシスが飽和・不飽和浸透流に及ぼす影響

土壌水分ヒステリシスが飽和・不飽和浸透流に及ぼす影響

A Soil-Water hysteresis model for unsaturated sands based on fuzzy set plasticity theory

The present work is focused on the details of a fuzzy set plasticity theory that was used to model the hysteresis loops in the Soil-Water Characteristic Curves (SWCCs). This study first presents an elasto-plastic stress-strain relationships of capillary hysteresis behavior in unsaturated conditions. The linear evolution equation for the elasto-plastic modulus and the membership function in the fuzzy set plasticity theory are introduced. An implicit integration method is then applied to develop the full set of incremental equations. Experimental and literature-cited data were used to evaluate model accuracy. Qualitative predictions of the proposed model show that incorporating soil-water characteristic equation and membership function into the fuzzy set plasticity model opens a full range of possibilities in modeling hysteretic behavior in unsaturated sands.

Rate-Independent Hysteresis in Terrestrial Hydrology

The goal of this article is twofold. The first objective is to demonstrate the role of hysteresis in hydrology. The second objective is to describe a class of simple and convenient mathematical models of hydrological systems with hysteresis and to briefly discuss methods for the quantitative and qualitative analysis of such models. This article is organized as follows. In the first section we discuss the role of the Preisach model. We then present an explicit expression for analogues of wetting and drying curves in the Preisach model context. The central role in this section is occupied by special one-parameter classes of Preisach operators which are useful as models of soil-water hysteresis for particular soils. Fitting is discussed in the context of the GRIZZLY database of hysteretic soil-water characteristics. The second section introduces a simple but instructive example of a differential equation coupled with a Preisach nonlinearity. This equation serves as a basis for modeling vegetated soil in terrestrial hydrology. The third section is dedicated to the FEST model, where FEST stands for "fully vegetated slab of soil with transpiring plants". This model describes drainage, transpiration, and infiltration flows in a fully vegetated slab of soil. We demonstrate that hysteresis effects are critical, both on qualitative and quantitative levels, for modeling hydrological systems and flows in soil, while theoretical analysis and numerical implementation of the models raise interesting mathematical questions. To demonstrate the application of this model we use rainfall data gathered in the Feale region in County Kerry, Ireland, covering a period of 19 months between July 2002 and February 2004. The FEST model includes a quantitative description of the dynamics of the plant biomass, which depends on the amount and regularity of precipitation and soil type, including details of soil-water hysteresis. Hence, the FEST model can be used as a component of ecological system models. Finally, the qualitative properties of the FEST model are discussed.

Soil Water Hysteresis in Water‐Stable Microaggregates as Affected by Organic Matter

Interaction of water and organic matter (OM) in pores affects the capacity for long‐term C sequestration and water retention in soils. This study investigated the effects of the amount and distribution of OM in microstructures on water retention in soil microaggregates. The focus of the study was on the hysteretic soil water characteristic (i.e., the difference between the main drying and wetting curves), which has been largely ignored in previous studies on water–OM relations. The main drying and wetting branches of the water retention curve were measured using a water activity meter on water‐stable microaggregates (53–250 μm), which were collected from surface soils (0–15 cm) subject to different management practices: tallgrass prairie restoration on a Mollisol, and tillage with and without N fertilization on an Alfisol. The results show that the presence of OM in <5‐μm‐diameter pores increases water retention in microaggregates, while management practices that either increased or decreased the abundance of OM‐filled pore volume in the microaggregates promoted hysteresis of water retention characteristics due to changes in soil pore structure. Comparison of the drying and wetting curves between intact and combusted (OM removed) microaggregates indicated a strong retention of water by pore‐filling OM. This retention suggests that the high water saturation in microaggregates from soils under management practices that increased OM‐filled porosity, which also offered physical protection of the OM, may be a positive feedback mechanism that retards OM decomposition in micropores. The water retention data measured on intact and combusted microaggregates were consistent with results from ultra‐small‐angle x‐ray scattering, and indicated that management practices have a great potential for facilitating the synergistic retention of water and organic C in soils.

Application of the “proportionate partitioning” method suggested by Poulovassilis and Kargas (2000) for determination of the domain distribution function

The soil water hysteresis model proposed by Poulovassilis and Kargas (Soil Sci. Soc. Am. J. 64:1947–1950, 2000) is considered in the present study. According to this model, the bivariate domain density distribution function f can be derived by partitioning the slopes of either of two main curves proportionally to the slopes of another. Accordingly, there are two possible ways of deriving function f. The basic claim of Poulovassilis and Kargas is that both possibilities lead to the same resultant function f, which can be evaluated using integral equation presented by them. The present study shows that the above two ways of determining function f actually lead to two incompatible partitioning models yielding different domain density distribution functions. Moreover, none of these two partitioning models can reproduce the measured hysteresis loop used for calibration. Whether the partitioning of the main wetting curve slopes proportionally to the main drying curve slopes or vice versa is applied, most of the predicted primary scanning curves deviate considerably from the measured ones, cross out the measured boundary loop and do not converge at an appropriate edge of the loop. The present study reveals that the above-mentioned integral equation, presented by Poulovassilis and Kargas, appears to be at variance with both partitioning models. It is shown herein that this integral equation unambiguously follows from Mualem (Water Resour. Res. 9:1324–1331, 1973) similarity hypothesis and, accordingly, the correspondent domain density distribution function derived as the unique analytical solution of this equation is evidently identical to that obtained by Mualem (1973). The predicted curves presented by Poulovassilis and Kargas are not obtained when any of the two partitioning models is applied, but when using the integral equation of Mualem’s (1973) model.

Soil Water Hysteresis at Low Potential

Knowledge of the soil water characteristic curve is fundamental for understanding unsaturated soils. The objective of this work was to find scanning hysteresis loops of two fine textured soils at water potentials below wilting point. This was done by equilibration over NaCl solutions with water potentials of −6.6 to −18.8 MPa at 25 ?C. When cycled repeatedly through a series of potentials in the range noted previously both soils exhibited a hysteresis effect. The experimental differences in water content between the drying and wetting soils at the same water potential were much too large to be accounted for by failure to allow sufficient time to attain equilibrium as predicted by the exponential decay model. The wetting versus drying differences were relatively small, however, at only 4 mg g −1 or less in absolute terms and about 3% of the mean of wetting and drying, in relative terms. Hysteresis should be a consideration when modeling biological and physical soil processes at water contents below the wilting point, where small differences in water content result in large potential energy changes.

Fractal analysis of soil water hysteresis as influenced by sewage sludge application

The impact of three types of surface applied sewage sludge from the same lot (fresh, composted, and thermally dried) on the water retention properties of a loam soil ( Udic Calciustept) and a loamy sand soil ( Typic Haplustalf) from central Catalonia (NE Spain) was investigated using fractal analysis. First, we proposed a composite fractal model that covers both the low and high suction regimes. This model has four fitting parameters: D 1 (the pore-solid fractal dimension), D 2 (the surface fractal dimension), A 1 (a compound parameter that includes D 1, the density of water, bulk density, particle density, and the air/water displacement suction), and A 2 (a compound parameter that includes D 2, and the critical suction and water content separating the low and high suction regimes). This model was fitted to the main wetting and drying branches of soil water retention curves obtained from small-disturbed samples using the chilled mirror dew point method. The equation fitted the data extremely well with adjusted R 2 values ≥ 0.99 ( p < 0.0001). Analysis of variance (ANOVA) was performed on the resulting parameter estimates. Few significant effects were observed for the loamy sand soil. In contrast, all of the model parameters, except D 1, were significantly affected by hysteresis and/or the sludge treatments for the loam soil. Values of A 1 and A 2 from the main drying branch were significantly higher than corresponding estimates from the wetting branch. This trend was reversed for D 2, indicating that pore surfaces are smoother after wetting, as compared to initially dry surfaces. The fresh, composted and thermally dried sludge treatments all significantly increased the A 1 parameter relative to the untreated loam soil, possibly by decreasing bulk density. The fresh and thermally dried sludge treatments also significantly increased the A 2 parameter. All three sludge types increased D 2 relative to the control when this parameter was determined from the main wetting branch of the water retention curve. In contrast, D 2 estimated from the main drying branch was not influenced by any of the sludge treatments. These analyses indicate that the effects of sewage sludge on hysteresis of the soil water retention curve were still present 2 years after surface application in the case of the loam soil.

Modeling the Primary Drainage Curve of Prefractal Porous Media

Fractal models for the soil water retention curve have largely ignored hysteresis. Such models generally require that all pores be connected to the atmosphere via a network of similar‐sized or larger pores. In random mass fractals and natural porous media, however, not all pores of a given size class empty during drainage due to incomplete pore connectivity and/or the presence of surrounding smaller pores. A modification of Rieu and Sposito's (1991a) prefractal water retention equation is proposed to accommodate this hysteresis during monotonic drying. The resulting expression is identical in form to the empirical Brooks and Corey (1964) model and contains three physically‐based parameters: the proportion of nondraining pores (Pd), the scale factor (b), and the apparent fractal dimension of the primary drainage curve (Dd), which is related to the underlying mass fractal dimension (D) of the porous medium by Dd = D + [log(Pd)]/[log(b)]. Model testing consisted of fitting the modified equation to previously published water retention data for 30 randomized Sierpinski carpets and seven soils. Error sums of squares ranged from 0.001 to 0.093 for the carpets, and from 0.015 to 0.047 for the soils. In contrast, the unmodified Rieu and Sposito (1991a) equation performed very poorly. Best fit estimates of Dd ranged from 0.295… to 1.640… for the two‐dimensional carpets, and from 2.467… to 2.902… for the three‐dimensional soils. Prediction of D, based on estimates of Dd derived from the primary drainage curve, will require additional research on how to obtain Pd and b. Based on the analytical approach outlined here, it should also be possible to model the primary wetting curve, thus providing a more complete fractal description of soil water hysteresis.

The FEST model—a test bed for hysteresis in hydrology and soil physics

The purpose of the paper is to develop two new models that capture much of the physics of flow through a slab of vegetated unsaturated soil. The first is a partial differential equation; the second is an ordinary differential equation derived from a simplified case. Both models are intended to serve as the initial test-bed for studying rate-independent soil-water hysteresis using the new concepts and tools.

Application of a Soil Water Hysteresis Model to Simple Water Retention Curves

The Parlange hysteresis model is reformulated as a pair of recurrence relations to provide relationships between wetting and drying phases to any order. The model is applied to the classical van Genuchten model for soil water retention used as the main wetting curve. The nonphysical behaviour of these retention curves is related to the existence of a point of inflection in the van Genuchten model when it is used for the wetting boundary. Where the van Genuchten form is used as the main drying curve, the Parlange hysteresis model provides an ordinary differential equation describing the main wetting curve. A number of simple analytical solutions, relating to particular values of the parameters of the van Genuchten model, then provide forms for the main wetting curve. In general, a numerical integration is required to generate the main wetting curve, for general values of the parameters of the van Genuchten model. The recurrence relations for the hysteresis cycling are still applicable, even when the main wetting curve is only known numerically. The new main wetting curves do not have inflection points and there is no nonphysical behaviour. The model is then applied to the experimental data of Viaene et al. (1994)

A Soil Water Hysteresis Model for Fingered Flow Data

Wetting and drying boundaries of a hysteresis loop were measured for fingered flow in a uniform sand, as well as drying scanning curves within the loop. The data are described by a soil water hysteresis model that uses a Brooks and Corey (1964) type main wetting boundary curve to predict the boundaries and scanning curves. The model requires as input parameters the bulk density, matric potential, water content at the two intersection points between the wetting and drying boundary curves, and one parameter obtained by curve fitting. The analysis is used to explain a fingered flow pattern in an uniform sand with different initial moisture contents.

飽和・不飽和多孔体中の熱移動とヒステリシスを伴う浸透流の連成解析

A two-dimensional mathematical model for simulating coupled problems of water flow and heat transport in saturated-unsaturated porous media is presented. The model is composed of two submodels; that is, a saturated-unsaturated water flow submodel and a heat transport submodel. The saturatedunsaturated water flow submodel can take into consideration thermal convection in saturated zone due to temperature gradient, soil water hysteresis accompanied by unsaturated flow, and temperature effect on the density and viscosity of water together with the typical forced convection. The heat transport submodel can handle heat conduction, heat dispersion, and forced and thermal convection in saturatedunsaturated porous media. The numerical method proposed in this paper is based on the finite elements for water flow and the characteristic finite elements for heat transport.The model was applied to two experimental problems with laboratory and field data. First, water flow in saturated-unsaturated soil column was analyzed under hysteretic and isothermal condition. Then, the model was applied to a problem of coupled transport of water and heat in saturated-unsaturated porous media. The latter problem is accommodated to account for an aquifer thermal energy storage experiment conducted in Sanrihama dune sand area where serial tests of artificial recharge of warm and cold water and recovery for agricultural use have been taken place for several years. Although it was not possible to compare the simulation and experimental results in a strict sense due to the lack of adequate experimental data, it was qualitatively proved that the model can be successfully applied to this type of coupled problems.

Effects of soil water hysteresis and the direction of sampling on aeration and pore function in relation to soil compaction and tillage

Cores of intact soil were taken in vertical and horizontal directions in two tillage experiments from horizons subjected to compaction. Cores from below the plough layer were equilibrated at a range of matric potentials by drainage. Cores from near the soil surface were subjected to hysteresis by drainage to −2 kPa from saturation, further drainage to − 10 kPa and finally re-wetting to − 2 kPa. Air-filled porosity, relative diffusivity, diffusion time delay and air permeability were measured at each potential, and pore continuity and pore organisation indices were calculated. Diffusion time delay is a measure of the time taken for gas to diffuse across a core at the beginning of a measurement of diffusion. Hysteresis influenced both air-filled porosity and the relationships between air-filled porosity and gas diffusivity and air permeability. Soil aeration was generally more favourable after wetting to − 2 kPa from − 10 kPa than after drainage to − 2 kPa from saturation. Hysteresis effects were greater in ploughed than in direct drilled soils. Direction of sampling influenced diffusion and flow properties, mainly in compact direct drilled soil from near the surface. These effects were partly attributed to the sampling method but gave evidence of greater vertical than horizontal orientation of macropores in ploughed soil and greater horizontal than vertical orientation of macropores in direct drilled soil.

Application of a simple soil-water hysteresis model

A simple hysteresis model is reformulated on the basis of the Brooks and Corey equation for the relationship between soil-water content and matric potential. In principle, the method requires the knowledge of a drying curve (boundary or primary) to predict the wetting boundary and all scanning curves. Experimental observations used recently to assess a variety of soil-water hysteresis models show that the present model is simple, accurate and general.