Influence of exchangeable sodium and clay mineralogy on soil water retention and hydraulic conductivity

2020 ◽  
Vol 75 (6) ◽  
pp. 755-764
Author(s):  
H.W. Klopp ◽  
F. Arriaga ◽  
W. Bleam
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Clay Mineralogy ◽  
Exchangeable Sodium ◽  
Soil Water Retention

Method for Quick Prediction of Hydraulic Conductivity and Soil-Water Retention of Unsaturated Soils

2018 ◽  
Vol 2672 (52) ◽  
pp. 108-117 ◽  
Author(s):  
Shaoyang Dong ◽  
Yuan Guo ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Characteristic Curve ◽  
Soil Water Retention

Hydraulic conductivity and soil-water retention are two critical soil properties describing the fluid flow in unsaturated soils. Existing experimental procedures tend to be time consuming and labor intensive. This paper describes a heuristic approach that combines a limited number of experimental measurements with a computational model with random finite element to significantly accelerate the process. A microstructure-based model is established to describe unsaturated soils with distribution of phases based on their respective volumetric contents. The model is converted into a finite element model, in which the intrinsic hydraulic properties of each phase (soil particle, water, and air) are applied based on the microscopic structures. The bulk hydraulic properties are then determined based on discharge rate using Darcy’s law. The intrinsic permeability of each phase of soil is first calibrated from soil measured under dry and saturated conditions, which is then used to predict the hydraulic conductivities at different extents of saturation. The results match the experimental data closely. Mualem’s equation is applied to fit the pore size parameter based on the hydraulic conductivity. From these, the soil-water characteristic curve is predicted from van Genuchten’s equation. The simulation results are compared with the experimental results from documented studies, and excellent agreements were observed. Overall, this study provides a new modeling-based approach to predict the hydraulic conductivity function and soil-water characteristic curve of unsaturated soils based on measurement at complete dry or completely saturated conditions. An efficient way to measure these critical unsaturated soil properties will be of benefit in introducing unsaturated soil mechanics into engineering practice.

scholarly journals A numerical study on the effect of salinity on stability of an unsaturated railway embankment under rainfall

2020 ◽  
Vol 195 ◽  
pp. 01004
Author(s):  
Ali Kolahdooz ◽  
Hamed Sadeghi ◽  
Mohammad Mehdi Ahmadi
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Numerical Study ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Unsaturated Hydraulic Conductivity ◽  
Influence Of Water ◽  
Dispersive Soils

Dispersive soils, as one of the main categories of problematic soils, can be found in some parts of the earth, such as the eastern-south of Iran, nearby the Gulf of Oman. One of the most important factors enhancing the dispersive potential is the existence of dissolved salts in the soil water. The main objective of this study is to explore the influence of water salinity on the instability of a railway embankment due to rainfall infiltration. In order to achieve this goal, the embankment resting on a dispersive stratum is numerically modeled and subjected to transient infiltration flow. The effect of dispersion is simplified through variations in the soil-water retention curve with salinity. The measured water retention curves revealed that by omitting the natural salinity in the soil-water, the retention capability of the soil decreases; therefore, the unsaturated hydraulic conductivity of the soil stratum will significantly decline. According to the extensive decrease in the hydraulic conductivity of the desalinated materials, the rainfall cannot infiltrate in the embankment and the rainfall mostly runs off. However, in the saline embankment, the infiltration decreases the soil suction; and consequently, the factor of safety of the railway embankment decreases.

The effect of natural seed coatings of Capsella bursa-pastoris L. Medik. (shepherd’s purse) on soil-water retention, stability and hydraulic conductivity

2014 ◽  
Vol 387 (1-2) ◽  
pp. 167-176 ◽  
Author(s):  
Wenni Deng ◽  
Paul D. Hallett ◽  
Dong-Sheng Jeng ◽  
Geoffrey R. Squire ◽  
Peter E. Toorop ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Soil Water Retention

scholarly journals An Environmentally Friendly Soil Amendment for Enhancing Soil Water Availability in Drought-Prone Soils

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 133
Author(s):  
Ting Yang ◽  
Xuguang Xing ◽  
Yan Gao ◽  
Xiaoyi Ma
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Critical Role ◽  
Saturated Hydraulic Conductivity ◽  
Soil Water Retention ◽  
Semiarid Areas ◽  
Arid And Semiarid Areas ◽  
Relative Change ◽  
Arid And Semiarid

Applying soil amendments plays a critical role in relieving water stress in arid and semiarid areas. The natural clay mineral attapulgite (ATP) can be utilized to adjust the balance of water and soil environment. In this study, we investigated four different particle size distribution typical soils in the Loess Plateau: (1) lou soil (LS), (2) dark loessial soil (DS), (3) cultivated loess soil (CS), (4) sandy soil (SS). Five ATP application rates (0, 1%, 2%, 3%, and 4%) were selected to test the effect of ATP on the soil water retention curve, soil saturated hydraulic conductivity, and soil structure. The results showed that applied ATP significantly increased the soil clay content, and the relative change of SS with 3% ATP applied increased by 53.7%. The field water holding capacity of LS, DS, CS, and SS with 3% ATP applied increased by 8.9%, 9.6%, 18.2%, and 45.0%, respectively. Although applied ATP reduced the saturated hydraulic conductivity, the values of CS and SS were opposite when the amount of ATP applied was >3%. The relative change in the amount of 0.25–1 mm soil water-stable aggregates of SS was 155.9% when 3% ATP was applied. Applied ATP can enhance soil water retention and soil stability, which may improve limited water use efficiency and relieve soil desiccation in arid and semiarid areas or similar hydrogeological areas.

Newly-amended biochar particles decrease erodibility and improve hydraulic soil properties

2021 ◽  
Author(s):  
Steffen Seitz ◽  
Sandra Teuber ◽  
Christian Geissler ◽  
Philipp Goebes ◽  
Thomas Scholten
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Erosion ◽  
Soil Water ◽  
Water Retention ◽  
Early Stage ◽  
Substrate Surface ◽  
Hydrothermal Carbonization ◽  
Future Research ◽  
Small Scale ◽  
Soil Water Retention

<p>Biochar is charcoal obtained by thermal decomposition of biomass through pyrolysis. The amendment of biochar changes chemical, but also physical properties of soils such as aggregation and texture. Thus, it is assumed that it can also affect soil erosion and erosion-related processes like the movement of water within the soil. In this study, we investigated how biochar particles change erodibility by rain splash instantly after application, as well as the initial movement of soil water.</p><p>Therefore, we conducted a small-scale laboratory experiment with two sieved substrates and using hydrothermal carbonization (HTC)-char and Pyrochar. Soil erodibility was determined with Tübingen splash cups under simulated rainfall, soil hydraulic conductivity was calculated from texture and bulk soil density, and soil water retention was measured using the negative and the excess pressure methods.</p><p>Results showed that the addition of biochar significantly reduced initial soil erosion in coarse sand and silt loam immediately after biochar application. Furthermore, biochar particles were not preferentially removed from the substrate surface. Increasing biochar particle sizes partly showed decreasing erodibility of substrates. Moreover, biochar amendment led to improved hydraulic conductivity and soil water retention regarding soil erosion control, with increasing application rates. It became clear that these effects are already detectable in a very early stage, and without long-term incorporation of biochar into soils. We could further show that different biochar types have varying impacts on investigated parameters due to their chemical properties and sizes, and future research should include varying biochars produced with different production methods.</p><p>In conclusion, this study showed that biochar amendments have the potential to reduce soil erosion by water from a very early stage. This mechanism adds a further ecosystem service to the list of useful impacts of biochar application on agriculture.</p>

scholarly journals Influence of crust formation under natural rain on physical attributes of soils with different textures

2011 ◽  
Vol 35 (6) ◽  
pp. 1893-1905 ◽  
Author(s):  
Selene Cristina de Pierri Castilho ◽  
Miguel Cooper ◽  
Carlos Eduardo Pinto Juhász
Keyword(s):  
Particle Size ◽  
Hydraulic Conductivity ◽  
Soil Water ◽  
Soil Degradation ◽  
Water Retention ◽  
Sandy Loam ◽  
Distribution Analysis ◽  
Soil Water Retention ◽  
Crust Formation ◽  
Soil Crusts

One of the main negative anthropic effects on soil is the formation of crusts, resulting in soil degradation. This process of physical origin reduces soil water infiltration, causing increased runoff and consequently soil losses, water erosion and/or soil degradation. The study and monitoring of soil crusts is important for soil management and conservation, mainly in tropical regions where research is insufficient to explain how soil crusts are formed and how they evolve. The purpose of this study was to monitor these processes on soils with different particle size distributions. Soil crusts on a sandy/sandy loam Argissolo Vermelho-Amarelo (Typic Hapludult), sandy loam Latossolo Vermelho-Amarelo (Typic Hapludox) and a clayey Nitossolo Vermelho eutroférrico (Rhodic Kandiudalf) were monitored. The soil was sampled and data collected after 0, 3, 5 and 10 rain storms with intensities above 25 mm h-1, from December 2008 to May 2009. Soil chemical and particle size distribution analysis were performed. The changes caused by rainfall were monitored by determining the soil roughness, hydraulic conductivity and soil water retention curves and by micromorphological analysis. Reduced soil roughness and crust formation were observed for all soils during the monitored rainfall events. However, contrary to what was expected according to the literature, crust formation was not always accompanied by reductions in total porosity, hydraulic conductivity and soil water retention.

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