Geophysical Evaluation of the Inner Structure of a Historical Earth-Filled Dam

Small earth dams usually lack the detailed seepage monitoring system that would provide high resolution data on changes in seepage flow. Alternative solution is monitoring of the temperature and electrical resistivity in the body of the dams. Geophysical methods are useful techniques for a non-destructive exploration of the subsurface. We have utilized the combination of electrical resistivity tomography (ERT), ground penetrating radar (GPR) and multi-depth electromagnetical conductivity meter (CMD) techniques to observe the inner structure, especially internal failures, of the historical earth-filled dams. Longitudinal and transversal profiles of four typical fishpond dams in the Czech Republic were measured within this research. The dams were constructed as early as in the 15th century, some of them went through minor reconstruction. The aim of the application of geophysical methods for investigation of old fishpond dams was to detect and localize the boundary of the dam foundation, new earth material from the reconstruction works, cone of water depression, technical objects location, potential internal erosion, cavities, inhomogeneity in the water content pattern and any other anomalies. The primary results show that the ERT is suitable to observe the dam stratification, dam foundation, bedrock below the dam and large anomalies. GPR is suitable for small objects and anomalies detection in the shallow depths.

Download Full-text

Geophysical characterization of inactive/active rock glaciers in the semi-arid Andes using seismic, geoelectrics and GPR

10.5194/egusphere-egu2020-11808 ◽

2020 ◽

Author(s):

remi valois ◽

Nicole Schafer ◽

Giulia De Pasquale ◽

Gonzalo Navarro ◽

Shelley MacDonell

Keyword(s):

Electrical Resistivity ◽

Seismic Velocity ◽

Seismic Refraction ◽

Geophysical Methods ◽

Late Summer ◽

Relevant Information ◽

Refraction Tomography ◽

Rock Glaciers ◽

Ice Content ◽

Ground Penetrating

<p>Rock glaciers play an important hydrological role in the semiarid Andes (SA; 27&#186;-35&#186;S). They cover about three times the area of uncovered glaciers and they are an important contribution to streamflow when water is needed most, especially during dry years and in the late summer months. Their characteristics such as their extension in depth and their ice content is poorly known. Here, we present a case study of one active rock glacier and periglacial inactive geoform in Estero Derecho (~30&#730;S), in the upper Elqui River catchment, Chile. Three geophysical methods (ground-penetrating radar and electrical resistivity and seismic refraction tomography) were combined to detect the presence of ice and understand the internal structure of the landform. The results suggest that the combination of electrical resistivity and seismic velocity provide relevant information on ice presence and their geometry. Radargrams shows diffraction linked to boulders presence but some information regarding electromagnetic velocity could be extracted. These results strongly suggest that such landforms contain ice, are therefore important to include in future inventories and should be considered when evaluating the hydrological importance of a particular region.</p><p>&#160;</p>

Download Full-text

Joint inversion of full-waveform ground-penetrating radar and electrical resistivity data: Part 1

Geophysics ◽

10.1190/geo2019-0754.1 ◽

2020 ◽

Vol 85 (6) ◽

pp. H97-H113 ◽

Cited By ~ 1

Author(s):

Diego Domenzain ◽

John Bradford ◽

Jodi Mead

Keyword(s):

Electrical Conductivity ◽

Electrical Resistivity ◽

Ground Penetrating Radar ◽

Joint Inversion ◽

Geophysical Methods ◽

Data Types ◽

Full Waveform ◽

Electrical Permittivity ◽

Ground Penetrating ◽

Subsurface Geometry

We have developed an algorithm for joint inversion of full-waveform ground-penetrating radar (GPR) and electrical resistivity (ER) data. The GPR data are sensitive to electrical permittivity through reflectivity and velocity, and electrical conductivity through reflectivity and attenuation. The ER data are directly sensitive to the electrical conductivity. The two types of data are inherently linked through Maxwell’s equations, and we jointly invert them. Our results show that the two types of data work cooperatively to effectively regularize each other while honoring the physics of the geophysical methods. We first compute sensitivity updates separately for the GPR and ER data using the adjoint method, and then we sum these updates to account for both types of sensitivities. The sensitivities are added with the paradigm of letting both data types always contribute to our inversion in proportion to how well their respective objective functions are being resolved in each iteration. Our algorithm makes no assumptions of the subsurface geometry nor the structural similarities between the parameters with the caveat of needing a good initial model. We find that our joint inversion outperforms the GPR and ER separate inversions, and we determine that GPR effectively supports ER in regions of low conductivity, whereas ER supports GPR in regions with strong attenuation.

Download Full-text

Experimental and Numerical Analysis for Earth-Fill Dam Seepage

Sustainability ◽

10.3390/su12062490 ◽

2020 ◽

Vol 12 (6) ◽

pp. 2490 ◽

Cited By ~ 2

Author(s):

Ahmed Mohammed Sami Al-Janabi ◽

Abdul Halim Ghazali ◽

Yousry Mahmoud Ghazaw ◽

Haitham Abdulmohsin Afan ◽

Nadhir Al-Ansari ◽

...

Keyword(s):

Physical Model ◽

Numerical Models ◽

Seepage Flow ◽

Water Levels ◽

The Body ◽

Silty Sand ◽

Internal Erosion ◽

Dam Failure ◽

Seepage Analysis ◽

Earth Fill

Earth-fill dams are the most common types of dam and the most economical choice. However, they are more vulnerable to internal erosion and piping due to seepage problems that are the main causes of dam failure. In this study, the seepage through earth-fill dams was investigated using physical, mathematical, and numerical models. Results from the three methods revealed that both mathematical calculations using L. Casagrande solutions and the SEEP/W numerical model have a plotted seepage line compatible with the observed seepage line in the physical model. However, when the seepage flow intersected the downstream slope and when piping took place, the use of SEEP/W to calculate the flow rate became useless as it was unable to calculate the volume of water flow in pipes. This was revealed by the big difference in results between physical and numerical models in the first physical model, while the results were compatible in the second physical model when the seepage line stayed within the body of the dam and low compacted soil was adopted. Seepage analysis for seven different configurations of an earth-fill dam was conducted using the SEEP/W model at normal and maximum water levels to find the most appropriate configuration among them. The seven dam configurations consisted of four homogenous dams and three zoned dams. Seepage analysis revealed that if sufficient quantity of silty sand soil is available around the proposed dam location, a homogenous earth-fill dam with a medium drain length of 0.5 m thickness is the best design configuration. Otherwise, a zoned earth-fill dam with a central core and 1:0.5 Horizontal to Vertical ratio (H:V) is preferred.

Download Full-text

Magnetic resonance tomography constrained by ground-penetrating radar for improved hydrogeophysical characterization

Geophysics ◽

10.1190/geo2020-0052.1 ◽

2020 ◽

Vol 85 (6) ◽

pp. JM13-JM26

Author(s):

Chuandong Jiang ◽

Jan Igel ◽

Raphael Dlugosch ◽

Mike Müller-Petke ◽

Thomas Günther ◽

...

Keyword(s):

Electrical Resistivity ◽

Magnetic Resonance ◽

Ground Penetrating Radar ◽

Geophysical Methods ◽

Magnetic Resonance Tomography ◽

Aeolian Deposits ◽

Aquifer Systems ◽

Resolution Limits ◽

Depositional Architecture ◽

Ground Penetrating

Geophysical methods can characterize aquifer systems noninvasively and are particularly helpful to image the complex depositional architecture of the subsurface. Among these, ground-penetrating radar (GPR) is an effective tool for detailed investigations of shallow subsurface geometry, but it provides only limited information on hydraulic properties. Magnetic resonance tomography (MRT) provides parameters such as water content (porosity) and relaxation time/hydraulic conductivity, but it suffers from resolution limits. Furthermore, it requires knowledge of subsurface electrical resistivity, which can be obtained by electrical resistivity tomography (ERT) also suffering from resolution limits. To overcome the limitations in resolution, we have incorporated GPR reflectors as structural information into the ERT and MRT data inversion. We test the methodology on a synthetic example and find improved imaging properties compared to standard inversion, particularly at greater depths, where the resolution is limited. We apply the methodology to a test site that is characterized by a complex depositional architecture. The Quaternary deposits consist of interbedded meltwater deposits (aquifers) and till (aquitards), overlain by aeolian deposits. To image the subsurface depositional architecture in three dimensions, a [Formula: see text] area was surveyed by GPR. The use of GPR constraints clearly improves the resolution and zonation of the subsurface image, which is validated by drill-core analyses. We develop a workflow to combine GPR, MRT, and ERT, leading the way to high-resolution hydrogeologic models that can be used for groundwater studies.

Download Full-text

NON-DESTRUCTIVE MEASUREMENTS OF UNSATURATED SEEPAGE FLOW BY USING GROUND-PENETRATING RADAR

Doboku Gakkai Ronbunshuu C ◽

10.2208/jscejc.65.943 ◽

2009 ◽

Vol 65 (4) ◽

pp. 943-950

Author(s):

Yuji TAKESHITA ◽

Shinya MORIKAMI ◽

Syuzo MORITA ◽

Seiichiro KURODA ◽

Mitsuhiro INOUE

Keyword(s):

Ground Penetrating Radar ◽

Seepage Flow ◽

Ground Penetrating ◽

Non Destructive ◽

Unsaturated Seepage

Download Full-text

Ground penetrating radar and electrical resistivity tomography for locating buried building foundations: A case study in the city centre of Thessaloniki, Greece

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.10946 ◽

2016 ◽

Vol 47 (3) ◽

pp. 1355

Author(s):

G. Vargemezis ◽

N. Diamanti ◽

I. Fikos ◽

A. Stampolidis ◽

Th. Makedon ◽

...

Keyword(s):

Electrical Resistivity ◽

Ground Penetrating Radar ◽

Electrical Resistivity Tomography ◽

Geophysical Methods ◽

Geological Structure ◽

City Centre ◽

High Resistivity ◽

Resistivity Tomography ◽

Ground Penetrating ◽

The City

Ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys have been carried out in the city centre of Thessaloniki (N. Greece), for investigating possible locations of buried building foundations. Geophysical survey has been chosen as a non-destructive investigation method since the area is currently used as a car parking and it is covered by asphalt. The geoelectrical sections derived from ERT data in combination with the GPR profiles provided a broad view of the subsurface. Regarding ERT, high resistivity values can be related to buried building remains, while lower resistivity values are more related to the surrounding geological materials. GPR surveying can also indicate man-made structures buried in the ground. Even though the two geophysical methods are affected in different ways by the subsurface conditions, the processed underground images from both techniques revealed great similarity. High resistivity anomalies and distinct GPR signals were observed in certain locations of the area under investigation, which are attributed to buried building foundations as well as the geological structure of the area.

Download Full-text

Determining geophysical responses from burials in graveyards and cemeteries

Geophysics ◽

10.1190/geo2016-0440.1 ◽

2017 ◽

Vol 82 (6) ◽

pp. B245-B255 ◽

Cited By ~ 10

Author(s):

Henry C. Dick ◽

Jamie K. Pringle ◽

Kristopher D. Wisniewski ◽

Jon Goodwin ◽

Robert van der Putten ◽

...

Keyword(s):

Electrical Resistivity ◽

Magnetic Susceptibility ◽

Target Detection ◽

High Frequency ◽

Geophysical Methods ◽

Low Frequency ◽

Coarse Sand ◽

Detection Methods ◽

Surface Data ◽

Ground Penetrating

Graveyards and cemeteries around the world are increasingly designated as full. Therefore, there is a requirement to identify vacant spaces for new burials or to identify existing ones to exhume and then reinter if necessary. Geophysical methods offer a potentially noninvasive target detection solution; however, there has been limited research to identify optimal geophysical detection methods against burial age. We have collected multifrequency (225–900 MHz) ground-penetrating radar (GPR), electrical resistivity, and magnetic susceptibility surface data over known graves with different burial ages and soil types in three UK church graveyards. Results indicate that progressively older burials are more difficult to detect, but this decrease is not linear and is site specific. Medium- to high-frequency GPR and magnetic susceptibility was optimal in clay-rich soils, medium- to high-frequency GPR and electrical resistivity in sandy soils, and electrical resistivity and low-frequency GPR in coarse sand and pebbly soils, respectively. A multigeophysical technique approach should be used by survey practitioners where grave locations are not known to maximize target detection success. Grave soil and grave cuts are important grave position indicators. Grave headstones were not always located where burials were located. We have determined the value of these techniques in grave detection and could potentially date burials from their geophysical responses.

Download Full-text

Spatial relationship between clay content and geophysical data

Clay Minerals ◽

10.1180/claymin.2010.045.2.197 ◽

2010 ◽

Vol 45 (2) ◽

pp. 197-207 ◽

Cited By ~ 15

Author(s):

D. de Benedetto ◽

A. Castrignanò ◽

D. Sollitto ◽

F. Modugno

Keyword(s):

Geophysical Methods ◽

Spatial Relationship ◽

Clay Content ◽

Geophysical Data ◽

Mathematical Function ◽

Non Invasive ◽

Soil Features ◽

Ground Penetrating ◽

Soil Surveys ◽

Non Destructive

AbstractAn important attribute for soil use is clay content, because it affects the water-holding capacity and hydraulic properties of a soil. Soil surveys are time-consuming, labour-intensive and costly, while geophysical methods, such as Electromagnetic Induction (EMI) and Ground Penetrating Radar (GPR), offer a non-invasive and non-destructive approach to mapping soil features. The objective of this paper is to assess the spatial relationship between clay content and geophysical data. The EMI and GPR data and soil cores were collected and analysed in a field of about 3 ha size in Rutigliano, Bari, in SE Italy. The EMI data and clay contents were interpolated using ordinary cokriging. The GPR data were pre-processed and the envelope of the filtered GPR data was used to produce 3Dmaps of the kriged estimates. The correlation with clay content was large and positive for EMI, whereas it was negative for the GPR measurement. In this work, a combination of geostatistical and statistical analysis has shown a significant correlation between the EMI and GPR observations. Estimation of the mathematical function relating these two groups of variables requires a multivariate approach of non-stationary geostatistics.

Download Full-text

Ground penetrating radar and electrical resistivity tomography for locating buried building foundations: A case study in the city centre of Thessaloniki, Greece

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.10930 ◽

2016 ◽

Vol 47 (3) ◽

pp. 1355

Author(s):

G. Vargemezis ◽

N. Diamanti ◽

I. Fikos ◽

A. Stampolidis ◽

Th. Makedon ◽

...

Keyword(s):

Electrical Resistivity ◽

Ground Penetrating Radar ◽

Electrical Resistivity Tomography ◽

Geophysical Methods ◽

Geological Structure ◽

City Centre ◽

High Resistivity ◽

Resistivity Tomography ◽

Ground Penetrating ◽

The City

Download Full-text

Soil exploration using ground penetrating radar

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/889/1/012009 ◽

2021 ◽

Vol 889 (1) ◽

pp. 012009

Author(s):

Zehra Khan ◽

Tarun Sharma ◽

Naiyara Khan ◽

Adil Ahmad Magray

Keyword(s):

Electromagnetic Waves ◽

Geotechnical Engineering ◽

Geophysical Methods ◽

Ground Surface ◽

Destructive Testing ◽

Electromagnetic Pulses ◽

Subsurface Structures ◽

Attenuation Rate ◽

Ground Penetrating ◽

Non Destructive

Abstract Geophysical methods are extensively utilized in the field of geology and in geotechnical engineering such as seismic, gravitational, magnetic and electromagnetic fields. These methods are used to locate or to understand conditions below the ground surface, and the physical properties of subsurface. GPR also known as Radio Detecting and Ranging is based on the electromagnetic waves. It is a specially designed radar unit for transmitting electromagnetic pulses below the ground instead of air. In GPR the medium is soil which is heterogeneous and has higher attenuation rate than air. This method is used to measure the length, depth or to locate the soil layers and its deposits. GPR is one of the most versatile sensors; it provides high resolution profiles for shallow depth. GPR has been used in diverse fields such as archaeology, non-destructive testing, probing underground caves, detecting landmines, mapping pipes and conduits, investigating the reinforcement and conditions of roads, bridges and airport runways, to name a few. Use of this technique/method is being extensively adopted from recent years because of its properties and vast applications. The main applications of GPR in subsurface mapping are: mapping of subsurface utility structures, detection and mapping of unexploded ordnance and mines, extraction of hazardous waste containers or unexploded ammunitions, maintenance or repair of subsurface structures. This paper presents an understanding of the concept or the need of GPR dedicated to civil engineering applications in general and in the field of geotechnical engineering in particular.

Download Full-text