scholarly journals Can Soil Electrical Resistivity Measurements Aid the Identification of Forest Areas Prone to Windthrow Disturbance?

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 234
Author(s):  
Marián Homolák ◽  
Erika Gömöryová ◽  
Viliam Pichler
Keyword(s):  
Electrical Resistivity ◽  
Soil Properties ◽  
Clay Content ◽  
Field Measurements ◽  
Beech Forest ◽  
Root Penetration ◽  
Predictive Tool ◽  
Entire Study ◽  
Resistivity Measurements ◽  
Soil Electrical Resistivity

This study investigates how certain forest soil properties influence the propensity of beech forests to windthrow disturbances. The field measurements of soil electrical resistivity were carried out in an old-growth natural beech forest where the soil has developed from Cainozoic sedimentary rock with mudstone–claystone stratigraphy. In 2014, the forest was hit by a severe windstorm, and dispersed windthrow occurred at certain plots. Apparent electrical resistivity measurements were performed to investigate whether some soil properties could influence the forest trees’ predisposition to windthrow. The increases in the clay content and soil bulk density below 30 cm were associated with weathered claystone and mudstone, which created a physiological barrier for deeper root penetration. The result of the χ 2 test suggested that the windthrown spots were not distributed evenly over the entire study area. They were mainly concentrated over approximately 50% of the area, and their positions coincided with low resistivity values, indicating low soil skeleton content, high clay content and soil moisture. Therefore, electrical resistivity tomography could be considered a useful predictive tool for reducing the risk of natural disturbances by preventive forest management.

scholarly journals The Behaviour of Laboratory Soil Electrical Resistivity Value under Basic Soil Properties Influences

2015 ◽  
Vol 23 ◽  
pp. 012002 ◽  
Author(s):  
Z A M Hazreek ◽  
M Aziman ◽  
A T S Azhar ◽  
W D Chitral ◽  
A Fauziah ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Soil Properties ◽  
Soil Electrical Resistivity

scholarly journals Electrical Resistivity Measurements On The Ross Ice Shelf

1977 ◽  
Vol 18 (78) ◽  
pp. 15-35 ◽  
Author(s):  
Charles R. Bentley
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Seismic Velocity ◽  
Sea Water ◽  
Field Measurements ◽  
Ice Shelf ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Ross Ice Shelf ◽  
The North

AbstractElectrical resistivity measurements were made along two perpendicular profiles on the Ross Ice Shelf, Antarctica, in 1973–74. Apparent resistivities are generally well determined at electrode separations from 10 m out to 600 m, where the effect of the highly conducting sea-water beneath the shelf becomes strongly fell. Schlumberger and equatorial-dipole data are in excellent agreement on each profile; apparent resistivities on the two profiles, however, differ by about 12% at separations greater than about 30 m. This apparent anisotropy is attributed to a presumed inhomogeneity at a few tens of meters depth, rather than to true anisotropy in the bulk resistivity.A computer program has been developed to calculate apparent resistivities on an ice shelf in which the density and temperature, and thus the resistivity, vary continuously with depth. Temperatures have been calculated according to the analysis of Crary (1961 [b]) for a steady-state ice shelf; densities have been calculated from seismic velocity data. Several different models of the dependence of resistivity on density have been tested—one appears to fit the observations very closely, but it must be accepted only with great caution because the assumptions on which it is based are violated in the ice shelf.The activation energy and the rate of bottom melting or freezing upon which the temperature-depth variations depend have been treated as variable parameters in the modeling. The most satisfactory model corresponds to a melt/freeze rate close to zero, and an activation energy, 0.25 eV (24 kJ mol−1), in agreement with laboratory measurements on Antarctic ice samples, although less than that suggested by previous field measurements. However, since the actual temperatures in the ice shelf are unknown, models that combine a substantial melt rate with a higher activation energy, or a substantial freeze rate with a lower activation energy, cannot be ruled out at present. Future measurements in places where the temperature profile is known should resolve this uncertainty.The actual resistivity in the solid ice at a depth of about 100 m (temperature about —23°C), lies within ±10% of 70000 Ω m, thus once again confirming the very low resistivities typical of polar glacial ice. The resistivity is, in fact, only about half that found near Roosevelt Island to the north and “Byrd” station to the east. That difference is believed to be real, but its cause is not known and probably will not be known until the basic cause for the generally low resistivity of polar ice is better understood.

scholarly journals Correlation of electrical resistivity and groundwater arsenic concentration, Nawalparasi, Nepal

2004 ◽  
Vol 30 ◽  
Author(s):  
Tom H. Brikowski ◽  
Linda S. Smith ◽  
Tai-Chyi Shei ◽  
Suresh Das Shrestha
Keyword(s):  
Electrical Resistivity ◽  
Arsenic Concentration ◽  
Clay Content ◽  
High Resistivity ◽  
Great Promise ◽  
Ganges River ◽  
Predictive Tool ◽  
Groundwater Arsenic ◽  
Chemical Conditions ◽  
High Arsenic

The Asian Arsenic Crisis has expanded into the headwaters of the Ganges River, now including the plains (Terai) of Nepal. This study seeks a non-invasive predictive tool to estimate groundwater arsenic concentration prior to drilling, enabling "arsenic avoidance" in contaminated areas. Detailed chemical studies indicate that in Himalayan-sourced aquifers arsenic is released by microbially-mediated redox reactions. Likely hydrogeological settings for oxidizing chemical conditions (immobile arsenic) should be more porous (higher in filtration rate for oxygenated waters) and contain fewer fine organic sediments (oxygen-consuming material). Both conditions should yield higher electrical resistivity, and such aquifer heterogeneity effects should be most prominent in head water regions such as Nepal. To test this approach, a series of vertical electrical resistivity soundings were made near Parasi, Nepal, constituting a profile extending 2 km across a known high-arsenic area. Correlation of the horizontal and vertical distribution of measured resistivity and ENPHO groundwater arsenic measurements demonstrated a distinct inverse relationship between these variables. Out of 240 arsenic sample points, 75% of those extracted from high resistivity zones (>100 ohm-m, inferred lower clay content) exhibited arsenic <150 ppb. Conversely, 7S% of samples from low resistivity zones exhibited arsenic >150 ppb. Given these preliminary results, the resistivity technique appears to hold great promise as a predictive tool for finding low-arsenic groundwater zones within contaminated areas, thereby allowing "well-switching" from highly toxic to new safe or more readily treatable wells. The method should be applicable in most circum- Himalayan high-arsenic areas.

scholarly journals Application of Electrical Resistivity Method to Site Characterisation for Construction Purposes at Institute of Agriculture Research and Training Moor Plantation Ibadan

2021 ◽  
Vol 1 (2) ◽  
pp. 49-62
Author(s):  
Babatunde A. Adebo ◽  
Oladipupo Emmanuel Makinde ◽  
Stephen Olubusola Ilugbo
Keyword(s):  
Electrical Resistivity ◽  
Clay Content ◽  
Site Investigation ◽  
Geophysical Investigation ◽  
Weak Zone ◽  
Southwestern Nigeria ◽  
Entire Study ◽  
Resistivity Method ◽  
Electrical Imaging ◽  
And Training

This research was carried out within Institute of Agriculture Research and Training Moor Plantation Ibadan, Southwestern Nigeria, with the aim to ascertain suitability of the proposed site for building construction and usage. The geophysical investigation involved three electrical resistivity techniques; Vertical Electrical Sounding (VES) using the Schlumberger configuration, 2D ERT and 2-D electrical imaging using Dipole-dipole electrode configuration. Two traverses were established E–W direction cutting across geologic strike with a distance of 80 m and of varying inter-traverse spacing. Eight (8) VES stations were occupied covering the entire study area for layer stratification and geoelectric parameters. The results were qualitatively and quantitatively interpreted and are presented as sounding curves and geoelectric sections. The 2-D imaging gave information on the subsurface characteristic in the area with generally low apparent resistivity indicating low competence material. The results obtained from the VES delineate three geoelectric units which comprise of the topsoil, weathered layer and fresh basement. The results from the VES were used to determine the second order parameters. The entire results correlate well with one another showing that all the techniques used were complemented. This study has further justified the need for geophysical site investigation as pre-condition before any construction to avoid problems of differential settlement. In determining of foundation material, topography elevation, clay content and the depth of weak zones should be put into consideration, since the depth of the weak zone is appreciably high.

scholarly journals Electrical Resistivity Measurements On The Ross Ice Shelf

1977 ◽  
Vol 18 (78) ◽  
pp. 15-35 ◽  
Author(s):  
Charles R. Bentley
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Seismic Velocity ◽  
Sea Water ◽  
Field Measurements ◽  
Ice Shelf ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Ross Ice Shelf ◽  
The North

AbstractElectrical resistivity measurements were made along two perpendicular profiles on the Ross Ice Shelf, Antarctica, in 1973–74. Apparent resistivities are generally well determined at electrode separations from 10 m out to 600 m, where the effect of the highly conducting sea-water beneath the shelf becomes strongly fell. Schlumberger and equatorial-dipole data are in excellent agreement on each profile; apparent resistivities on the two profiles, however, differ by about 12% at separations greater than about 30 m. This apparent anisotropy is attributed to a presumed inhomogeneity at a few tens of meters depth, rather than to true anisotropy in the bulk resistivity.A computer program has been developed to calculate apparent resistivities on an ice shelf in which the density and temperature, and thus the resistivity, vary continuously with depth. Temperatures have been calculated according to the analysis of Crary (1961 [b]) for a steady-state ice shelf; densities have been calculated from seismic velocity data. Several different models of the dependence of resistivity on density have been tested—one appears to fit the observations very closely, but it must be accepted only with great caution because the assumptions on which it is based are violated in the ice shelf.The activation energy and the rate of bottom melting or freezing upon which the temperature-depth variations depend have been treated as variable parameters in the modeling. The most satisfactory model corresponds to a melt/freeze rate close to zero, and an activation energy, 0.25 eV (24 kJ mol−1), in agreement with laboratory measurements on Antarctic ice samples, although less than that suggested by previous field measurements. However, since the actual temperatures in the ice shelf are unknown, models that combine a substantial melt rate with a higher activation energy, or a substantial freeze rate with a lower activation energy, cannot be ruled out at present. Future measurements in places where the temperature profile is known should resolve this uncertainty.The actual resistivity in the solid ice at a depth of about 100 m (temperature about —23°C), lies within ±10% of 70000 Ω m, thus once again confirming the very low resistivities typical of polar glacial ice. The resistivity is, in fact, only about half that found near Roosevelt Island to the north and “Byrd” station to the east. That difference is believed to be real, but its cause is not known and probably will not be known until the basic cause for the generally low resistivity of polar ice is better understood.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

scholarly journals Electrical Resistivity Measurements and Soundings on Glaciers: Introductory Remarks

1967 ◽  
Vol 6 (47) ◽  
pp. 599-606 ◽  
Author(s):  
Hans Röthlisberger
Keyword(s):  
Electrical Resistivity ◽  
Resistivity Measurements ◽  
Resistivity Method

A brief description of the resistivity method is given, stressing the points which are of particular importance when working on glaciers. The literature is briefly reviewed.

scholarly journals Predicting Excavation-Induced Tunnel Response by Process-Based Modelling

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Linlong Mu ◽  
Jianhong Lin ◽  
Zhenhao Shi ◽  
Xingyu Kang
Keyword(s):  
Soil Properties ◽  
Urban Areas ◽  
Field Measurements ◽  
Inverse Modelling ◽  
Machine Learning Techniques ◽  
Interaction Patterns ◽  
Support Structures ◽  
Interaction Processes ◽  
Excavation Support ◽  
Artificial Neural Network Ann

Potential damages to existing tunnels represent a major concern for constructing deep excavations in urban areas. The uncertainty of subsurface conditions and the nonlinear interactions between multiple agents (e.g., soils, excavation support structures, and tunnel structures) make the prediction of the response of tunnel induced by adjacent excavations a rather difficult and complex task. This paper proposes an initiative to solve this problem by using process-based modelling, where information generated from the interaction processes between soils, structures, and excavation activities is utilized to gradually reduce uncertainty related to soil properties and to learn the interaction patterns through machine learning techniques. To illustrate such a concept, this paper presents a simple process-based model consisting of artificial neural network (ANN) module, inverse modelling module, and mechanistic module. The ANN module is trained to learn and recognize the patterns of the complex interactions between excavation deformations, its geometries and support structures, and soil properties. The inverse modelling module enables a gradual reduction of uncertainty associated with soil characterizations by accumulating field observations during the construction processes. Based on the inputs provided by the former two modules, the mechanistic module computes the response of tunnel. The effectiveness of the proposed process-based model is evaluated against high-fidelity numerical simulations and field measurements. These evaluations suggest that the strategy of combining artificial intelligence techniques with information generated during interaction processes can represent a promising approach to solve complex engineering problems in conventional industries.

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