Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

Amer, Abdelmonem Mohamed

doi:10.1080/03650340.2011.572877

Cited by 11 publications

(10 citation statements)

References 21 publications

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“…i b = aKs). Amer (2011) proved that the matching factor a (dimensionless) as a function between i b and Ks, is:…”

Section: Infiltration and Hydraulic Conductivity Into Non-capillary Pmentioning

confidence: 99%

Water flow and conductivity into capillary and non-capillary pores of soils

Amer

2012

J. Soil Sci. Plant Nutr.

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Downward water flow in the vadose zone occurs principally through the non-capillary pores, while the redistribution and lateral and upward flow occurs in the capillary pores. The purpose of this study was to propose equations to estimate water flow, Q(θ), and hydraulic conductivity, K(θ), in the capillary and non-capillary soil pores. The equations related K(θ) to soil pore radius (r) were based on soil hydraulic data, including water retention h(q), field basic infiltration rate, water sorptivity (S) and distribution density function f(r) of the soil pore size. Calcareous sandy loam and alluvial clay soils located at the Nile Delta were used to test the validity of the assumed equations. Data showed that the values of K(θ) calculated by the proposed equations were in the common ranges for such soils. The equations are therefore expected to be applicable for both coarse and fine textured soils. Also, an equation was derived to estimate the sorptivity at steady state infiltration. It was observed that S is decreased in going from the un-saturation condition to steady state infiltration by 15.1% and 45.9% in sandy loam and clay soils, respectively.

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“…i b = aKs). Amer (2011) proved that the matching factor a (dimensionless) as a function between i b and Ks, is:…”

Section: Infiltration and Hydraulic Conductivity Into Non-capillary Pmentioning

confidence: 99%

Water flow and conductivity into capillary and non-capillary pores of soils

Amer

2012

J. Soil Sci. Plant Nutr.

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“…The corresponding Δθ values of water filled pore classes can be derived from soil-moisture retention curve. Thus, the equation 17 can be developed (Amer, 2011b) into:…”

Section: Theoretical Development Saturated Hydraulic Conductivity Andmentioning

confidence: 99%

Hydraulic conductivity and sorptivity at unsaturated and saturated conditions as related to water infiltration in soils

Amer¹

2020

Eurasian Journal of Soil Science (Ejss)

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Sorptivity (S) has been defined in terms of the horizontal infiltration equation. At unsaturated conditions (at a very short time) S represents "maximum sorption capacity", but in saturated conditions the sorption capacity decreases with the time. Over a long time of infiltration, sorptivity was not studied as a soil water parameter that could be determined. The purpose of this study is to apply derived equations depending on the infiltration functions to predict (1) soil water sorptivity (S) at infiltration capacity (unsaturated conditions) and at basic infiltration rate (Ib) (saturated conditions), (2) the hydraulic conductivity (Saturated Ks and unsaturated K(θ)) into capillary-matrix and noncapillary macro pores of soils. Five alluvial (saline and non-saline clay) and calcareous soil profiles located in the Nile Delta were investigated for applying the assumed equations. A decrease in S value was observed with an increase in soil water content. At steady infiltration rate (Ib), S decreased from 1.04 to 0.647cm.min-0.5 (i.e. S decreased by 37.79%) in average in calcareous soils and from 0.537 to 0.251cm.min-0.5 (53.25%) in alluvial clay soils. The steady Sw parameter was used in prediction of the hydraulic conductivities and the basic infiltration rate Ib , whereas, Sw is a suggested term at steady infiltration rate. The calculated values of Ib were corresponding to those obtained by infiltration experiment. This confirmed the significance of steady Sw as a new functional infiltration parameter. A matching factor u was calculated as a ratio between predicted Ib and the measured saturated hydraulic conductivity, Ks. The mean values of u were 0.895, 0.685 and 0.360 for calcareous, clay and saline clay soils respectively. Unsaturated K(θ) has been discriminated into saturated macro-pore K(θ)RDP and matrix unsaturated K(θ)h. The values of K(θ)RDP for macro pores remained higher than those for soil matrix pores (K(θ)h) in the studied soils. The highest value of K(θ) was obvious in calcareous soil profiles, while the lowest value was existed in saline clay soil. In conclusion, the predicted values of hydraulic conductivities of soil matrix (capillary) and macro (non-capillary) pores were reasonable and existed in the normal ranges of the investigated soils, indicating that the proposed equations are applicable and can be recommended to be used in coarse and fine textured soils with large scale of different properties.

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“…Parameter Equation UnitValue 2 and 24 h draining, which roughly represented the matrix capillary water content (10 kPa) and field capacity (33 kPa) (Armer, 2011). The shape parameters n and α h (see Eq.…”

Section: Parameterization Of Vegetation and Soil Texturementioning

confidence: 99%

Modelling the diurnal and seasonal dynamics of soil CO2 exchange in a semiarid ecosystem with high plant-interspace heterogeneity

Gong¹,

Wang²,

Jia³

et al. 2017

Preprint

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Abstract. This study represents a first attempt to model the diurnal and seasonal dynamics of soil CO2 exchange (FS) in a dryland ecosystem with a high plant-interspace heterogeneity. The modelling used an integrated process-based approach, in which the CO2 production, transport and surface exchanges (e.g. biocrust photosynthesis, respiration and photodegradation) are considered simultaneously. The model was parameterized and validated with multivariate data measured during year 2013&#8211;2014 in a semiarid shrubland ecosystem in Yanchi, northwestern China. We also investigated the sensitivity of simulated FS to a set of stand-specific parameters and investigated the relative contribution of different flux components. The model explained reasonably well the two-year dynamics of FS measured from a non-crusted and two lichen-crusted plots. Simulations showed that the temporal pattern of FS could deviate from that of the total CO2 production from rooting-zone soil. Such deviations could be explained by the variations of CO2 dissolution and the CO2 exchanges of biocrust during wetting-drying cycles, and the root uptake and transport of dissolved CO2. Moreover, the FS was spatially sensitive to the plant-interspace differences and the variations in root biomass, soil organic matter and pH. These results emphasized that, the processes beyond autotrophic and heterotrophic respirations and the heterogeneities of soil at plant-interspace can strongly affect the FS dynamics and their climatic sensitivities. Such variability should be carefully considered in extrapolation of findings from chamber to ecosystem level and from seasonal to inter-annual scales. Based on this work, our model can serve as a useful tool to simulate FS dynamics in dryland ecosystems.

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Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

Cited by 11 publications

References 21 publications

Water flow and conductivity into capillary and non-capillary pores of soils

Water flow and conductivity into capillary and non-capillary pores of soils

Hydraulic conductivity and sorptivity at unsaturated and saturated conditions as related to water infiltration in soils

Modelling the diurnal and seasonal dynamics of soil CO<sub>2</sub> exchange in a semiarid ecosystem with high plant-interspace heterogeneity

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Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

Cited by 11 publications

References 21 publications

Water flow and conductivity into capillary and non-capillary pores of soils

Water flow and conductivity into capillary and non-capillary pores of soils

Hydraulic conductivity and sorptivity at unsaturated and saturated conditions as related to water infiltration in soils

Modelling the diurnal and seasonal dynamics of soil CO&lt;sub&gt;2&lt;/sub&gt; exchange in a semiarid ecosystem with high plant-interspace heterogeneity

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Modelling the diurnal and seasonal dynamics of soil CO<sub>2</sub> exchange in a semiarid ecosystem with high plant-interspace heterogeneity