Ground‐penetrating radar responses of dispersive models

Geophysics ◽  
1997 ◽  
Vol 62 (4) ◽  
pp. 1127-1131 ◽  
Author(s):  
Zonghou Xiong ◽  
Alan C. Tripp
Keyword(s):  
Environmental Management ◽  
Electrical Properties ◽  
Ground Penetrating Radar ◽  
Dispersive Media ◽  
Efficient Tool ◽  
Target Region ◽  
High Frequencies ◽  
Ground Penetrating ◽  
Dispersive Models ◽  
Depth Of Investigation

Ground‐penetrating radar (GPR) has been a very efficient tool for mapping shallow targets for applications such as those in geological engineering and environmental management (Fisher et al. 1992). Since the application of GPR depends on the complex electrical properties of the ground, it is important to study this dependence in all its manifestations. The depth of investigation for GPR applications depends strongly on the conductivity of the ground. If the ground is very conductive, GPR waves will be absorbed before they reach the target region. Earth materials can be dispersive, i.e., the conductivity and permittivity of rocks are frequency dependent (Levitskaya and Sternberg, 1994). This is especially true at high frequencies. GPR waves will also be absorbed in dispersive media. Hence modeling the GPR response in dispersive materials can reveal behaviors of importance in understanding field responses.

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

Measurement of Bulk Electrical Properties Using GPR with a Variable Reflector

2018 ◽  
Vol 23 (4) ◽  
pp. 489-496
Author(s):  
J. David Redman ◽  
A. Peter Annan ◽  
Nectaria Diamanti
Keyword(s):  
Electrical Properties ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Arrival Time ◽  
Wood Chip ◽  
Direct Wave ◽  
Trace Data ◽  
Ground Penetrating ◽  
Prototype Instrument

Bulk electrical properties of media are important inherently for ground penetrating radar (GPR) applications and for providing a means to determine indirectly other physical properties such as moisture content. We have developed a reflector whose reflectivity can be controlled electronically. This variable reflector controlled by a GPR provides an effective method to measure bulk electrical properties of media. For sample measurements, the GPR is placed on one side of a sample and the variable reflector on the opposite side. GPR trace data are then acquired with the reflector in an on-state and in the off-state. By differencing these measurements, we improve the ability to detect the specific reflection event from the variable reflector. This process removes both the direct wave and clutter from the trace data, improving the quality of the refection event and our ability to accurately pick its arrival time and amplitude. We describe the variable reflector, a prototype instrument based on the reflector and numerical modeling performed to understand its response. We also show the results of testing applications to the measurement of wood chip moisture content and monitoring of the electrical properties of concrete during the curing process.

Pitfalls in near-surface geophysical interpretation: Challenging paradigms and misconceptions

2018 ◽  
Vol 6 (4) ◽  
pp. SL1-SL9 ◽  
Author(s):  
David C. Nobes ◽  
Estella Atekwana
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Ground Penetrating Radar ◽  
Nonaqueous Phase Liquids ◽  
Potential Fields ◽  
Near Surface ◽  
Geophysical Interpretation ◽  
Occam’S Inversion ◽  
Ground Penetrating

Too often, ideas become so well-established that they take on the roles of paradigms, and challenging those paradigms can be difficult, even if they are flawed. Similarly, misconceptions can take root and become firmly entrenched and again are difficult to dislodge. Both of these situations are fundamentally unscientific. Science makes progress when established theories are shown to be incorrect or at least incomplete. To do that, we have to let the data that we collect tell their stories. We should not impose models upon the data, but rather allow the data to yield those models that best represent those features that are absolutely necessary to fit the data, an approach often called “Occam’s inversion.” We also should not impose nonphysical and unscientific limits on our interpretation models. We evaluate several examples from our own experiences: the electrical properties of faults, nonuniqueness in potential fields, the influence of nonaqueous phase liquids and water on ground-penetrating radar and electrical resistivity, and the geophysical response of seafloor mineralization. In each case, a reviewer or another scientist questioned the conclusions using unscientific or incorrect arguments or assumptions. We must let the data speak.

scholarly journals GEOPHYSICAL FORENSIC FOR ARCHAEOLOGICAL EXPLORATION IN MUAROJAMBI, INDONESIA

2020 ◽  
Vol 5 (3) ◽  
pp. 221-230
Author(s):  
Bambang Sugiarto ◽  
Dicky Muslim ◽  
Iyan Haryanto ◽  
Zufialdi Zakaria ◽  
Emy Sukiyah ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ground Penetrating Radar ◽  
High Frequency ◽  
Rock Magnetism ◽  
Physical Parameters ◽  
Time Data ◽  
Travel Time Data ◽  
Ground Penetrating ◽  
First Time ◽  
Archaeological Objects

In July 2011, archaeological exploration tried to apply the physics method for the first time in Muarojambi, Indonesia. We combined physics with geosciences and called it geophysical forensic. Our method is known as Ground Penetrating Radar (GPR). GPR used high-frequency electromagnetic (EM) waves between 10-3000 MHz to imaging subsurface based on dielectric permittivity’s physical parameters. Changes in the electrical properties, rock magnetism, and water content of the material under the surface will provide a response recorded on the radargram as a function of distance to time (two-way travel time). Data processing performs to reduce the noise recorded when collecting data. We have successfully obtained four GPR lines; three lines gathered near Gumpung Temple and one line at Telago Rajo Pool. The GPR method succeeded in giving a subsurface image and possibility of the archaeological objects near the Gumpung Temple and Telago Rajo Pool.

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