scholarly journals Enhanced Biogeochemical Cycling and Subsequent Reduction of Hydraulic Conductivity Associated with Soil-Layer Interfaces in the Vadose Zone

2011 ◽  
Vol 40 (6) ◽  
pp. 1941-1954 ◽  
Author(s):  
David J. Hansen ◽  
Jennifer T. McGuire ◽  
Binayak P. Mohanty
Keyword(s):  
Hydraulic Conductivity ◽  
Vadose Zone ◽  
Soil Layer ◽  
Biogeochemical Cycling ◽  
Subsequent Reduction

The effect of subsurface military detonations on vadose zone hydraulic conductivity, contaminant transport and aquifer recharge

2013 ◽  
Vol 146 ◽  
pp. 8-15 ◽  
Author(s):  
Jeffrey Lewis ◽  
Jan Burman ◽  
Christina Edlund ◽  
Louise Simonsson ◽  
Rune Berglind ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Contaminant Transport ◽  
Vadose Zone ◽  
Aquifer Recharge

scholarly journals Salinity Status of Lajas Valley Soils

1969 ◽  
Vol 41 (1) ◽  
pp. 25-34
Author(s):  
Juan A. Bonnet ◽  
Eduardo J. Brenes
Keyword(s):  
Electrical Conductivity ◽  
Hydraulic Conductivity ◽  
Soil Layer ◽  
Soil Surface ◽  
Exchangeable Sodium Percentage ◽  
Exchangeable Sodium ◽  
Surface Layers ◽  
Alkali Soils ◽  
The World ◽  
Sodium Percentage

1. The area of soils surveyed in Lajas Valley was 24,656 acres. 2. The soils were classified into normal, saline, saline-alkali, and non- saline-alkali at depths of 0 to 8, 8 to 24, 24 to 48, and 48 to 72 inches, respectively. 3. A large percentage of normal soils was found in the upper soil layer and of saline-alkali soils in the lower layers. 4. Normal soils occupied about 86 percent of the surface area to a depth of 8 inches and about 63 percent at a depth of 8 to 24 inches. 5. Soils with a salinity problem increased from 9 percent at a depth of 8 inches to 28.3, 58.8 and 68.5 percent, respectively, at depths of 8 to 24, 24 to 48, and 48 to 72 inches. 6. The soils with a salinity problem were largely of the saline-alkali class. 7. In four soil-profile samples taken from Lajas Valley, the saturation percentage varied from 58 to 191, the electrical conductivity from 0.8 to 28.4 millimhos per centimeter, the exchangeable-sodium percentage from 2.2 to 46.0, the soil pH from 8.1 to 8.9, the content of gypsum from 0 to 21.9 tons per acre-foot, the gypsum requirement from 0 to 23.8 tons per acre-foot, and the hydraulic conductivity from less than 0.005 to 6.24 inches of water per hour. Higher gypsum contents were found in the deep subsoil layers of two soils (profiles 1 and 4). Amounts of gypsum varying from 9.9 to 20.3 tons per acre-foot of depth, are required for the reclamation of the surface layers of these two profiles. In general, the hydraulic- conductivity values show that the soil-surface layers are more permeable than the subsoil layers. 8. The procedure and methods used in this paper were found to be accurate, simple, rapid, and practical. They are recommended for the coordination of data related to the classification and reclamation of soils affected by salinity problems in the different countries of the world.

scholarly journals Impact of Soil Amendments on the Hydraulic Conductivity of Boreal Agricultural Podzols

Agriculture ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 133 ◽  
Author(s):  
Dinushika Wanniarachchi ◽  
Mumtaz Cheema ◽  
Raymond Thomas ◽  
Vanessa Kavanagh ◽  
Lakshman Galagedara
Keyword(s):  
Hydraulic Conductivity ◽  
Vadose Zone ◽  
Hydraulic Properties ◽  
Soil Amendments ◽  
Dairy Manure ◽  
Soil Hydrology ◽  
Inorganic N ◽  
Infiltration Rates ◽  
Agricultural Setting ◽  
Properties Of Soil

Hydraulic properties of soil are the basis for understanding the flow and transport through the vadose zone. It has been demonstrated that different soil amendments can alter the soil properties affecting soil hydrology. The aim of this study was to determine the effect of soil amendments on hydraulic conductivity (K) of a loamy sand podzolic soil under both unsaturated (Kunsat) and near-saturated (near Ksat) conditions in an agricultural setting. A field experiment was conducted with two common soil amendments: Dairy manure (DM) in 2016 and 2017 and biochar (BC) once only in 2016. DM and BC were incorporated up to a depth of 0.15–0.20 m at a rate of 30,000 L ha−1 and 20 Mg ha−1, respectively. A randomized complete block experimental design was used and the plots planted with silage corn (Zea mays L.) without irrigation. The treatments were: Control without amendment (0N), inorganic N fertilizer (IN), two types of DM (IN+DM1 and IN+DM2), and two treatments with BC (IN+BC and IN+DM1+BC). Infiltration data were collected using a mini disk infiltrometer under three tension levels in which −0.04 and −0.02 m was ascribed as unsaturated (at the wet end) and −0.001 m as near-saturated condition. Based on the measured infiltration rates, Kunsat and near Ksat hydraulic conductivities were calculated. There were no significant effects of DM and BC on bulk density and near Ksat. Treatments IN+DM1, IN+DM2, and IN+DM1+BC significantly reduced the Kunsat compared to the control. Since these soil amendments can influence soil hydrology such as reduced infiltration and increased surface runoff, carefully monitored application of soil amendments is recommended.

scholarly journals Modeling subsurface transport in extensive glaciofluvial and littoral sediments to remediate a municipal drinking water aquifer

2011 ◽  
Vol 8 (1) ◽  
pp. 1729-1764
Author(s):  
M. Bergvall ◽  
H. Grip ◽  
J. Sjöström ◽  
H. Laudon
Keyword(s):  
Drinking Water ◽  
Hydraulic Conductivity ◽  
Contaminant Transport ◽  
Vadose Zone ◽  
Transport Processes ◽  
Zone Model ◽  
Macropore Flow ◽  
Subsurface Transport ◽  
Littoral Sediments ◽  
Sandy Aquifers

Abstract. Few studies have been carried out that cover the entire transport process of pesticides, from application at the soil surface, through subsurface transport, to contamination of drinking water in esker aquifers. In formerly glaciated areas, such as Scandinavia, many of the most important groundwater resources are situated in glaciofluvial eskers. The purpose of the present study was to model and identify significant processes that govern subsurface transport of pesticides in extensive glaciofluvial and littoral sediments. To simulate the transport processes, we coupled a vadose zone model at the point scale to a regional groundwater flow model. The model was applied to a municipal drinking-water aquifer, contaminated with the pesticide-metabolite BAM (2,6-dichlorobenzoamide). A sensitivity analysis revealed that hydraulic conductivity and infiltration rate accounted for almost half of the model uncertainty. For a ten-meter-deep vadose zone of coarse texture, macropore flow was found to be of minor importance for contaminant transport. The calibrated model was applied to optimize the location of extraction wells for remediation, which were used to verify the predictive modeling. Running a worst-case scenario, the model showed that the establishment of two remediation wells would clean the aquifer in four years, compared to nine years without them. Further development of the model would require additional field measurements to assess the importance of macropore flow in deep, sandy aquifers. We also suggest that future research should focus on characterization of the variability of hydraulic conductivity and its effect on contaminant transport in eskers.

scholarly journals Significance of Pyrolytic Temperature, Particle Size, and Application Rate of Biochar in Improving Hydro-Physical Properties of Calcareous Sandy Soil

Agriculture ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1293
Author(s):  
Abdulaziz G. Alghamdi ◽  
Abdulrasoul Al-Omran ◽  
Arafat Alkhasha ◽  
Zafer Alasmary ◽  
Anwar A. Aly
Keyword(s):  
Particle Size ◽  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Sandy Soil ◽  
Tap Water ◽  
Soil Layer ◽  
Application Rate ◽  
Saturated Hydraulic Conductivity ◽  
Medium Temperature ◽  
Application Rates

Water management and irrigation conservation in calcareous sandy soil are of significant importance for sustaining agricultural production, especially in arid and semi-arid region that facing scarcity of water resources. The changes in hydro-physical characteristics of calcareous sand soil were investigated after date palm waste-derived biochar application in column trials. Significance of pyrolysis temperature (300 °C, 500 °C, and 700 °C), particle size [<0.5 mm (D0.5), 0.5–1 mm (D1), and 1–2 mm (D2)], and application rate (1%, 2.5%, and 5%) were studied. Variations in infiltration rate, intermittent evaporation, and saturated hydraulic conductivity as a function of aforementioned factors were investigated. After amending the top 10-cm soil layer with different biochar and application rates, the columns were subjected to six wetting and drying cycles by applying 25 cm3 tap water per week over a 6-week period. Overall, biochar application resulted in decreased saturated hydraulic conductivity, while improved cumulative evaporation. Specifically, biochar produced at 300 °C and 500 °C demonstrated 10.2% and 13.3% higher cumulative evaporation, respectively., whereas, biochar produced at 700 °C with 5% application rate resulted in decreased cumulative evaporation. Cumulative evaporation increased by 5.0%, 7.7% and, 7.8% for D0.5, D1 and D2 (mm) on average, respectively, as compared with the untreated soil. Thus, biochar with particle size 0.5–1 mm significantly improved hydro-physical properties when applied at 1%. Generally, using biochar produced at medium temperature and small particle size with appropriate application rates could improve the soil hydro-physical properties.

Re-mobilization of pile shaft friction after an earthquake

2013 ◽  
Vol 50 (9) ◽  
pp. 979-988 ◽  
Author(s):  
M.E. Stringer ◽  
S.P.G. Madabhushi
Keyword(s):  
Hydraulic Conductivity ◽  
Load Distribution ◽  
Axial Load ◽  
Soil Layer ◽  
Pile Group ◽  
Excess Pore Pressure ◽  
Vertical Loading ◽  
Soil Settlement ◽  
Excess Pore Pressures ◽  
Excess Pore

During strong earthquakes, significant excess pore pressures can develop in saturated soils. After shaking ceases, the dissipation of these pressures can cause significant soil settlement, creating downward-acting frictional loads on piled foundations. Additionally, if the piles do not support the full axial load at the end of shaking, then the proportion of the superstructure’s vertical loading carried by the piles may change as a result of the soil settlement, further altering the axial load distribution on piles as the soil consolidates. In this paper, the effect of hydraulic conductivity and initial post-shaking pile head loading is investigated in terms of the changing axial load distribution and settlement responses. The investigation is carried out by considering the results from four dynamic centrifuge experiments in which a 2 × 2 pile group was embedded in a two-layer profile and subjected to strong shaking. It is found that large contrasts in hydraulic conductivity between the two layers of the soil model affected both the pile group settlements and axial load distribution. Both these results stem from the differences in excess pore pressure dissipation, part of which took place very rapidly when the underlying soil layer had a large hydraulic conductivity.

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