Hydraulic conductivity of undeformed soil columns by gamma ray transmission

2001 ◽  
Vol 61 (3-6) ◽  
pp. 693-695 ◽  
Author(s):  
A.C. Moreira ◽  
F.H. de M. Cavalcante ◽  
M.C. da Rocha ◽  
O. Portezan ◽  
M.M. Coimbra ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Gamma Ray ◽  
Soil Columns

scholarly journals Gamma ray transmission for hydraulic conductivity measurement of undisturbed soil columns

2007 ◽  
Vol 50 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Anderson Camargo Moreira ◽  
Otávio Portezan Filho ◽  
Fábio Henrique Moraes Cavalcante ◽  
Melayne Martins Coimbra ◽  
Carlos Roberto Appoloni
Keyword(s):  
Hydraulic Conductivity ◽  
Gamma Ray ◽  
Conductivity Measurement ◽  
Nondestructive Method ◽  
Soil Density ◽  
Soil Columns ◽  
Undisturbed Soil ◽  
Transmission Technique ◽  
Homogeneous Soil

This work had the objective to determine the Hydraulic Conductivity K(theta) function for different depth levels z, of columns of undisturbed soil, using the gamma ray transmission technique applied to the Sisson method. The results indicated a growing behavior for K(theta) and a homogeneous soil density, both in relation to the increase of the depth. The methodology of gamma ray transmission showed satisfactory results on the determination of the hydraulic conductivity in columns of undisturbed soil, besides being very reliable and a nondestructive method.

Influence of sodium adsorption ratio on sodium and calcium breakthrough curves and hydraulic conductivity in soil columns

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 586 ◽  
Author(s):  
Oagile Dikinya ◽  
Christoph Hinz ◽  
Graham Aylmore
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Soil Aggregates ◽  
Breakthrough Curves ◽  
Sodium Adsorption Ratio ◽  
Threshold Concentration ◽  
Critical Threshold ◽  
Soil Columns ◽  
Clay Particles ◽  
The Matrix

The paper examines the effects of electrolyte concentration and sodium adsorption ratio (SAR) on the relative saturated hydraulic conductivity (RHC) and the ionic behaviour of calcium (Ca) and sodium (Na) ions in the Na–Ca exchange complex. Batch binary exchange and saturated column transport experiments were carried out to quantify these effects using an agricultural Balkuling soil and a mining residue. Generally, RHC has been found to decrease with time, with increasing SAR, and with decreasing electrolyte concentration. The more rapid decrease in RHC in the mining residue, particularly at the lowest concentration (1 mmol/L), was consistent at all SAR values. The decreases in RHC were likely to be caused by partial blocking of pores by dispersed clay particles, as evidenced by the appearance of suspended clay particles in the effluent during leaching. Significant differences in RHC were observed in the passage of fronts of decreasing electrolyte concentrations for CaCl2 and SAR 15 solutions through the soil columns. These differences were attributable to structural alterations (slaking) of the media and the nature of the particles released and mobilised within the porous structure at any given point in the column. Measurements at the critical threshold concentration and turbidity concentration at SAR 15 revealed structural breakdown of the pore matrix system as evidenced by decreased RHC. The increase in SAR to 15 is initially accompanied by erratic RHC, presumably due to the break up of soil aggregates under the increased swelling forces. The less coherent mining residue soil was substantially more vulnerable to blockage of pores than the Balkuling soil in which clay particles are likely to be more readily mobilised, and hence available to re-deposit and occlude the matrix pores.

Plant-soil interactions can enhance earth barrier systems in urban spaces 

2021 ◽  
Author(s):  
David Boldrin ◽  
Anthony Glyn Bengough ◽  
Jonathan Knappett ◽  
Kenneth Loades ◽  
Anthony Kwan Leung
Keyword(s):  
Climate Change ◽  
Hydraulic Conductivity ◽  
Urban Environment ◽  
Water Loss ◽  
Matric Suction ◽  
Recycled Concrete ◽  
Soil Columns ◽  
Plant Soil ◽  
Fallow Soil ◽  
Water Holding

<p>Climate change is expected to introduce increasing threats to human health and the urban built environment, due to extreme events such as heavy precipitation. In the urban environment, impermeable hard-engineered surfaces may exacerbate climate change effects and increase the risk of floods. Adaptation solutions are essential to limit the climate change impacts on the urban environment. Research is needed to design new environmentally friendly multi-layer earthen barrier systems that can mimic the natural hydrological processes (e.g., plant-soil interaction) removed by urbanization.</p><p>In this study, potential barrier materials were selected from both natural soils and recycled waste materials (e.g., recycled concrete aggregates). Contrasting herbaceous species (legumes, grasses and forbs) were selected and grown for five months in compacted soil columns and saturated hydraulic conductivity (<em>K</em><sub>sat</sub>) was tested for each soil column. Following <em>K</em><sub>sat</sub> tests, all soil columns were saturated and left for evapo-transpiration. Plant water uptake, matric suction and soil strength (penetration resistance) were measured.</p><p>Among the materials tested in this study, recycled concrete aggregate (RCA) was the most suitable material for the barrier drainage layer, having a <em>K</em><sub>sat</sub> equal to natural gravel, but with 14% lower dry density (2.3 Mg/m<sup>3</sup>) and seven-fold greater water holding capacity (0.08 g/g). However, a portion of the water stored in the RCA was strongly bound to micropores and not available for plants. Plant growth in soil columns increased <em>K</em><sub>sat</sub>. On average <em>K</em><sub>sat</sub> of four-month old vegetated soil (3.2e<sup>-5</sup> ± 2.0e<sup>-6</sup> m/s) was four times larger than that of control fallow soil (6.9e<sup>-6</sup> ± 1.4e<sup>-6</sup> m/s). However, tested species differed in their effect on <em>K</em><sub>sat</sub>, ranging from 9.9e<sup>-6</sup> ± 1.3e<sup>-6</sup> m/s of <em>Festuca ovina</em> (Grass) to 4.1e<sup>-5</sup> ± 3.7e<sup>-6</sup> of <em>Lotus pedunculatus</em> (Legume). In the fallow soil, daily evaporation led to an average water loss of 0.49 ± 0.04 g per 100 g of soil, evapo-transpiration led to a daily water loss up to 2.58 ± 0.10 g per 100 g of soil in<em> Lotus corniculatus</em> columns. Thus, soil drying and induced matric suction strengthened the vegetated soil and further increased its ability to store water. For instance, soil vegetated with <em>L. corniculatus</em> had seven times faster water absorption and twenty-five times greater strength compared with control fallow soil. Plants affected the hydraulic conductivity and water relation of the barrier system. Root systems can increase soil hydraulic conductivity through root-induced channels. This may enable faster drainage during floods, but we found large differences between species. Transpiration restored the water holding capacity of barrier systems after heavy rain events and induced strengthening of soil.</p><p>We suggest that vegetation should not be simply selected for aesthetically “greening” the barrier system, but specifically selected for its role in improving soil engineering function. There is a substantial scope to choose species to manipulate hydrological properties of the barrier system and improve its performance during extreme climate events.</p>

Ability of Beijerinckia indica to degrade phenanthrene and reduce hydraulic conductivity

2010 ◽  
Vol 62 (12) ◽  
pp. 2953-2960 ◽  
Author(s):  
Dong-Hee Lim ◽  
Jai-Young Lee ◽  
Christian M. Lastoskie
Keyword(s):  
Hydraulic Conductivity ◽  
Electron Acceptor ◽  
Landfill Leachate ◽  
Rigid Wall ◽  
Soil Columns ◽  
Two Phase ◽  
Recovery Test ◽  
Phase Partitioning ◽  
Partitioning Bioreactor ◽  
Beijerinckia Indica

This study evaluates the ability of Beijerinckia indica (B. indica) as a biomaterial for aerobic biofilm barriers. B. indica's ability to remove phenanthrene was measured using a two-phase partitioning bioreactor. Approximately 500 mg/L of phenanthrene was gradually removed over a two week period under aerobic conditions of the bioreactor. B. indica's ability to reduce hydraulic conductivity was evaluated using rigid wall soil columns inoculated with the bacteria. B. indica formed a large quantity of strongly adhesive biofilm among soil particles, reducing the hydraulic conductivity in the soil columns by 2 or 3 orders of magnitude. To assess recovery of the biofilm, the formed biofilm was purposely destroyed by introducing landfill leachate into the soil columns. The biofilm recovery test showed that the hydraulic conductivity increased after leachate introduction. However, re-permeation of nutrient solution restored the permeability to its original lower value, which suggests a full recovery of the damaged biofilm. This study suggests that B. indica may be used as a possible biomaterial for aerobic biofilm barriers for the removal of phenanthrene from groundwater, provided that sufficient substrate and electron acceptor are provided to the treatment system.

scholarly journals Prediction of biopore- and matrix-dominated flow from X-ray CT-derived macropore network characteristics

2016 ◽  
Vol 20 (10) ◽  
pp. 4017-4030 ◽  
Author(s):  
Muhammad Naveed ◽  
Per Moldrup ◽  
Marcel G. Schaap ◽  
Markus Tuller ◽  
Ramaprasad Kulkarni ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Preferential Flow ◽  
Air Permeability ◽  
Saturated Hydraulic Conductivity ◽  
Soil Columns ◽  
Macropore Flow ◽  
Matric Potential ◽  
X Ray ◽  
Network Characteristics ◽  
Gas Diffusivity

Abstract. Prediction and modeling of localized flow processes in macropores is of crucial importance for sustaining both soil and water quality. However, currently there are no reliable means to predict preferential flow due to its inherently large spatial variability. The aim of this study was to investigate the predictive performance of previously developed empirical models for both water and air flow and to explore the potential applicability of X-ray computed tomography (CT)-derived macropore network characteristics. For this purpose, 65 cylindrical soil columns (6 cm diameter and 3.5 cm height) were extracted from the topsoil (5 cm to 8.5 cm depth) in a 15 m  ×  15 m grid from an agricultural field located in Silstrup, Denmark. All soil columns were scanned with an industrial X-ray CT scanner (129 µm resolution) and later employed for measurement of saturated hydraulic conductivity, air permeability at −30 and −100 cm matric potential, and gas diffusivity at −30 and −100 cm matric potential. Distribution maps for saturated hydraulic conductivity, air permeability, and gas diffusivity reflected no autocorrelation irrespective of soil texture and organic matter content. Existing empirical predictive models for saturated hydraulic conductivity and air permeability showed poor performance, as they were not able to realistically capture macropore flow. The tested empirical model for gas diffusivity predicted measurements at −100 cm matric potential reasonably well, but failed at −30 cm matric potential, particularly for soil columns with biopore-dominated flow. X-ray CT-derived macroporosity matched the measured air-filled porosity at −30 cm matric potential well. Many of the CT-derived macropore network characteristics were strongly interrelated. Most of the macropore network characteristics were also significantly correlated with saturated hydraulic conductivity, air permeability, and gas diffusivity. The predictive Ahuja et al. (1984) model for saturated hydraulic conductivity, air permeability, and gas diffusivity performed reasonably well when parameterized with novel, X-ray CT-derived parameters such as effective percolating macroporosity for biopore-dominated flow and total macroporosity for matrix-dominated flow. The obtained results further indicate that it is crucially important to discern between matrix-dominated and biopore-dominated flow for accurate prediction of macropore flow from X-ray CT-derived macropore network characteristics.

MEASURING WATER CONTENT OF SOIL COLUMNS IN THE LABORATORY: A COMPARISON OF GAMMA RAY ATTENUATION AND TDR TECHNIQUES

1983 ◽  
Vol 63 (1) ◽  
pp. 37-43 ◽  
Author(s):  
J. C. W. KENG ◽  
G. C. TOPP
Keyword(s):  
Error Analysis ◽  
Water Content ◽  
Time Domain ◽  
Gamma Ray ◽  
Time Domain Reflectometry ◽  
Soil Columns ◽  
Total Uncertainty ◽  
Single Beam ◽  
Sampling Volume ◽  
Γ Ray

Volumetric water content was measured by time domain reflectometry (TDR) and by a single-beam γ-ray attenuation at eight positions on each of three soil columns. Both methods measured equally well at single locations and both showed some position dependence, which was greater for γ-ray attenuation than for TDR. An error analysis showed the major contributor to variance in the γ-ray measurement was the unknown variability of bulk density which gave rise to uncertainty of ± 0.05 cm3∙cm−3 for three soils. For the TDR technique all sources of variance resulted in a total uncertainty of ± 0.02 cm3∙cm−3. The greater sampling volume of the TDR as used in this experiment was advantageous with the naturally structured heterogeneous soils. Key words: Soil structure, error analysis, γ-ray attenuation, time domain reflectometry.

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