scholarly journals Field determination of vertical permeability to air in the unsaturated zone

1978 ◽  
Author(s):  
Edwin P. Weeks
Keyword(s):  
Unsaturated Zone ◽  
Vertical Permeability

scholarly journals Effect of Vertical Pressure on Horizontal and Vertical Permeability of Soil and Effect of Surcharge Pressure on 3D Consolidation of Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Arpan Laskar ◽  
Sujit Kumar Pal
Keyword(s):  
Soil Properties ◽  
Three Dimensional ◽  
Vertical Pressure ◽  
Soil Layers ◽  
One Dimensional ◽  
Consolidation Theory ◽  
Vertical Permeability ◽  
Homogeneous Soil ◽  
Soil Changes

Permeability and consolidation of soil are known as the most variable soil properties. The values of permeability and consolidation of soil may vary with depth even in case of homogeneous soil layers, and because of that, the determination of appropriate values of permeability and consolidation is a complex and complicated engineering task. In this study, horizontal and vertical permeability apparatus and a 3D (three-dimensional) consolidation apparatus are developed to determine the effects of vertical pressure on horizontal and vertical permeability and the effects of vertical surcharge pressures on three-dimensional consolidation of soil. A series of horizontal and vertical permeability tests of soil under different vertical pressures and a series of 3D consolidation tests under different surcharge pressures are performed. From the study, it is observed that the horizontal and vertical permeability of soil changes with the changes in vertical pressures, and 3D consolidation of soil also changes with the changes in surcharge pressures. The horizontal and vertical permeability values obtained from the newly developed horizontal and vertical permeability apparatus are used in Terzaghi’s one-dimensional consolidation theory to find out the consolidation characteristics of the soil, and it is compared with the results obtained from the newly developed 3D consolidation apparatus.

scholarly journals Depth to water table correction for initial carbon-14 activities in groundwater mean residence time estimation

2021 ◽  
Vol 25 (10) ◽  
pp. 5415-5424
Author(s):  
Dylan J. Irvine ◽  
Cameron Wood ◽  
Ian Cartwright ◽  
Tanya Oliver
Keyword(s):  
Water Table ◽  
Unsaturated Zone ◽  
Time Estimation ◽  
Carbon 14 ◽  
Depth To Water Table ◽  
Groundwater Samples ◽  
Initial Carbon ◽  
Mean Residence Times ◽  
Depth Relationship

Abstract. Carbon-14 (14C) is routinely used to determine mean residence times (MRTs) of groundwater. 14C-based MRT calculations typically assume that the unsaturated zone is in equilibrium with the atmosphere, controlling the input 14C activity. However, multiple studies have shown that unsaturated zone 14C activities are lower than atmospheric values. Despite the availability of unsaturated zone 14C data, no attempt has been made to generalise initial 14C activities with depth to the water table. We utilise measurements of unsaturated zone 14C activities from 13 studies to produce a 14C–depth relationship to estimate initial 14C activities. The technique only requires the depth to the water table at the time of sampling or an estimate of depth to water in the recharge zone to determine the input 14C activity, making it straightforward to apply. Applying this new relationship to two Australian datasets (113 14C measurements in groundwater) shows that MRT estimates were up to 9250 years younger when the 14C–depth correction was applied relative to conventional MRTs. These findings may have important implications for groundwater samples that suggest the mixing of young and old waters and the determination of the relative proportions of young and waters, whereby the estimated fraction of older water may be much younger than previously assumed. Owing to the simplicity of the application of the technique, this approach can be easily incorporated into existing correction schemes to assess the sensitivity of unsaturated zone 14C to MRTs derived from 14C data.

scholarly journals Research of natural remediation of the subsurface contaminated with petroleum products

2019 ◽  
pp. 49-51
Author(s):  
O. M. Shpak ◽  
O. I. Lohvynenko
Keyword(s):  
Petroleum Product ◽  
Unsaturated Zone ◽  
Petroleum Products ◽  
Soil Samples ◽  
Quality Analysis ◽  
Contamination Source ◽  
Microbiological Methods ◽  
Fuel Storage ◽  
Natural Remediation

Remediation of the subsurface contaminated with petroleum products is the ecological problem on a world scale and a foreground direction of geoecological research in Ukraine. Remediation of contaminated vadose zone can be provided with the activity of microorganisms, mainly micromycets, whose features of location and vital activity depend on a depth, the level of contamination, aerobic conditions, etc. Practically, it is complicated to use artificial microbiological methods and natural remediation of contaminated subsurface due to microorganisms should be taken into consideration. Microorganisms oxidizing hydrocarbons are of particular interest. Field investigations were carried out within the fuel storage of the Boryspil airport where subsurface contamination with petroleum products was revealed in 1998. The research included sampling at contaminated and uncontaminated sites, quality analysis of petroleum product contains in soils and determination of the species composition of micromycets. Soil samples were taken in three wells at different depths – in the center of the contamination source at the depths of 0,1 m and 2,0 m (unsaturated zone) and 4,0 m (saturated zone), in the northern part of the fuel storage in the unsaturated zone at the depths of 0,1 m and 1,0 m, and out of the contamination source in the unsaturated zone at the depth of 3,7 m. Fungus culture determination data in soil samples indicate that variety of their forms depends on a contamination degree, a depth of sampling, lithology and water saturation. Regular monitoring should be carried out including soil sampling and determination of petroleum product contains to specify conclusions about natural remediation of contaminated soils due to life activity of microorganisms oxidizing hydrocarbons.

scholarly journals Physical models for class-room teaching in hydrology

2012 ◽  
Vol 9 (3) ◽  
pp. 4135-4160 ◽  
Author(s):  
A. Rodhe
Keyword(s):  
Unsaturated Zone ◽  
Hydraulic Properties ◽  
Groundwater Table ◽  
Physical Models ◽  
Contaminant Dispersion ◽  
Sand Aquifer ◽  
University Level ◽  
Class Room ◽  
Tracer Experiments

Abstract. Hydrology teaching benefits from the fact that many important processes can be illustrated and explained with simple physical models. A set of mobile physical models has been developed and used during many years of lecturing at basic university level teaching in hydrology. One model, with which many phenomena can be demonstrated, consists of a 1.0 m long plexiglass container containing an about 0.25 m deep open sand aquifer through which water is circulated. The model can be used for showing the groundwater table and its influence on the water content in the unsaturated zone and for quantitative determination of hydraulic properties such as the storage coefficient and the saturated hydraulic conductivity. It is also well suited for discussions on the runoff process and the significance of recharge and discharge areas for groundwater. The flowpaths of water and contaminant dispersion can be illustrated in tracer experiments using flourescent or colour dye. This and a few other physical models, with suggested demonstrations and experiments, are described in this article. The finding from using models in class-room teaching is that it creates curiosity among the students, promotes discussions and most likely deepens the understanding of the basic processes.

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