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18th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
- Conference date: 03 Apr 2005 - 07 Apr 2005
- Location: Atlanta, Georgia, USA
- Published: 03 April 2005
101 - 120 of 146 results
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Use of Electromagnetic, Geoelectric and Seismic Tomography Refraction Geophysical Methods To Estimate The Water Content In The Subsoil
More LessThe interpretation of combined geophysical methods [Ground Penetrating Radar (GPR),
Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT)] are
proposed to assess the physical properties characterizing the near surface porous formations, and in
particular way the volumetric water content. The search was carried out in semi-controlled
situations. Were considered the variations of several geophysical parameters, (the electromagnetic
(EM) wave velocity, the seismic wave velocity, and the electrical resistivity) in the subsoil to
esteem the fluctuations of the volumetric water content in the same subsoil. Is, in fact, known that
the values of the geophysical parameters, that can be obtained from measures in surface, are
influenced by the presence of water in the pore and in the fractures of the materials in the subsoil.
The esteem of the variations of these parameters can be makes by measures repeated in the time
(i.e. measures realized before and after water's immission in the subsoil). This type of monitoring
can allow the individualization of the principal paths of outflow of the water in the subsoil.
The study conducted in this paper point out as the use of combined geophysical methods providing
models of water outflow from the surface down to some meter deep.
[Key words: Ground penetrating radar, seismic refraction tomography and electrical resistivity
tomography methods, water content, monitoring]
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Geophysical Characterization of Seawater Intrusion In Antigua, West Indies
The Inter-American Agency for Cooperation and Development is currently funding a project
focused on groundwater management in coastal karst environments in the Caribbean. The islands of
Jamaica, Antigua, and Barbados are currently the primary regional participants in this project.
Geophysical characterization of pilot sites on each of these islands is being used to provide input into
conceptual groundwater flow models, which in turn will be used to support the development of
sustainable groundwater management strategies for these coastal aquifers.
Geophysical fieldwork at a pilot site located in the northeast portion of the island of Antigua took
place in April 2004. Data from the survey support mapping the geology and hydrology of the region
and locating the freshwater-seawater interface. Geophysical methods used in the fieldwork included
time-domain electromagnetic (TEM) central-loop soundings, Schlumberger-array resistivity soundings,
EM-31 terrain conductivity profiling, and multi-electrode resistivity profiling. In-field analysis of data
collected at a regional scale led to a conceptual understanding of seawater intrusion into the study area.
This conceptual understanding led to concentrated data collection efforts in specific areas.
The first area surveyed in-depth to confirm our conceptual understanding of seawater intrusion at
the site was Mercers Creek channel that runs from west of the Collins and Potworks reservoirs to
Mercers Creek Bay located along the north coast of the island. TEM soundings, assembled into an eastwest
profile across the channel, reveal a conductive region, thought to represent seawater migrating
inland in response to the reduced freshwater head caused by pumping at the Collins well field. The
second area surveyed in-depth was the Ayres Creek channel that runs by the Collins and Bristol well
fields before draining into the extensive tidal flat at Nonsuch Bay located along the northeast coast of
the island. This channel contains a secondary dam that captures outflow from the Potworks and Collins
dams during periods of high rainfall and flooding, but is otherwise dry. This area was studied in detail
using a high-density geophysical data collection strategy. Subsequent data interpretation led to the
identification of a conductive zone that appears to be the result of seawater intrusion. The extent of the
intrusion in the vicinity of the channel is controlled by the groundwater pumping at the Collins and
Bristol well fields and storm surge/tidal fluctuations. This conceptual model has groundwater
management implications that are being evaluated using groundwater flow models.
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An Archaeological Investigation of The San Marcos Pueblo, New Mexico, Usa
Authors Jacob Hodges, John Ferguson and Louise PellerinAs part of the Summer of Applied Geophysical Experience (SAGE), a field-based educational program in applied geophysical methods, several geophysical surveys were performed at the San Marcos Pueblo for archaeological purposes. The San Marcos Pueblo was a large and significant Tano pueblo in the Galisteo Basin south of Santa Fe, NM. It is a sixty-acre preserve, currently owned by the Archaeological Conservancy, containing the remains of thirty-eight room blocks, up to 5,000 rooms, two springs, and the foundations of a seventeenth-century Franciscan Mission complex. Over two days in June 2004 SAGE students acquired ground penetrating radar (GPR), loop-loop electromagnetic (EM), magnetic, and shallow refraction seismic data to investigate the buried secrets. The seismic GPR, EM and magnetic data proved to be complementary in delineating room block walls and a possible kiva, a chamber used by men for ceremonies and council meetings. The seismic data were definitive in terms of the dimensions of the kiva.
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Geophysical Investigation of The Groundwater Regimes In The Lower Okavango Delta, Northwestern Botswana
Authors Elisha M. Shemang, Loago N. Molwalefhe, Harish Kumar, Tej Bakaya and Joel NtsatsiThe Okavango Delta in the northwestern part of Botswana is unique and it is the largest inland
delta in the world. Instead of flowing into the sea, the annual flood of fresh water from the
highlands flows inland, spreading over 15 000km² of the arid Kalahari environment and forming
several islands and channels that emerge from its waterways. Parts of the Lower Okavango
Delta that have been receiving large and frequent flood events have developed extensive fresh
water aquifers, while other parts that have been receiving intermittently small floods have limited
fresh water aquifers. The present study used aeromagnetic, airborne Electromagnetic
(AEM), ground transient electromagnetic (TEM) soundings, drilling and down-hole geophysical
logging data to map the distribution and geometry of these fresh water aquifer systems. The
results of this study showed that the occurrence of freshwater aquifers in the lower delta are associated
with active drainage channels and are bounded below and on their edges by brackish/
saline groundwater. The geometry of these aquifers provides an insight into the long term
flooding history of the delta. This can be seen from the Gomoti River, which has had only intermittent
flow in recent times, but is one of the largest fresh water aquifers in the lower delta.
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Temenos Estates, Anguilla, Bwi Hydrogeologic Investigation, Geophysical Mapping and Water Supply Development
More LessN. S. Nettles & Associates, Inc. (NSN) was contracted by Flagg Luxury Properties to perform a
hydrogeologic investigation of its Temenos property, the former Sonesta Resort, on the island of
Anguilla, Rendezvous Bay, BWI (Figure 1). Temenos Estates is a $300 million dollar development
comprised of a St. Regis Resort Hotel, Greg Norman Golf Course, private beach estate homes, and
private villas (Figure 2). The project site incorporates nearly one mile of beachfront property with
fringing reefs. Land elevations rise from the beach to elevations of 80 feet above sea level (Figure 3).
The island is of volcanic origin but has in excess of 300 feet of limestone overlying the igneous rocks.
Two large hydric geomorphic features are present on the property that will be modified as part of NSN’s
scope of work. One feature is a 12 acre salt barren (a sea level plain with hyper-salinities) referred to as
the savanna, that was formed by a large sinkhole many thousands of years ago. The second is the 13-
acre Merrywing Salt Pond that was originally used to mine salt and was later used as the disposal site for
the Sonesta Resort septic system. This salt pond is also hyper-saline and very high in nutrients. The
investigation was designed as a three-phase program to define the hydrogeology of the site, construct
water supply wells, drainage wells and flushing channels.
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Geoelectrical Exploration for Groundwater Around The New Communities, East Nile Delta
Authors Abd El Hamid A. Taha, Ahmed S. El Mahmoudi and Islam M. El-HaddadWithin the last couple of decades, the groundwater development in Egypt has become more and
more important. New communities and land reclamation projects have been recently established in the
area to the east of the Nile Delta to overcome the growing population problem in Egypt. Groundwater is
the second source of water in Egypt.
The present paper deals with the hydrogeological investigation using geoelectrical vertical
electrical sounding technique around the new communities, East Nile Delta. A number of 53 vertical
electrical soundings using Schlumberger electrode configuration with maximum current electrode
spacing “AB” = 1400m have been carried out by the authors. Raw data of 92 VES from (Ezz El Din,
1993 and Abd El-Gawad, 1997) are reinterpreted. Records of the water wells drilled in the study area
and chemical analysis for the water samples are been guided.
The interpreted VES data in the form of layer thickness and resistivities presented on the crosssections
are found not to be easily a sequence of continuous sedimentary lithologic layers due to of the
lateral changes in layer resistivities. Therefore, the geoelectrical resistivity layers lumped into three
Litho- resistivity zones with different hydrogeological conditions. Litho-resistivity zone (A) represents
the detrital surface cover. Litho-resistivity zone (B) represents the dry zone. Litho-resistivity zone (C)
represents the saturation zone in the study area.
Geoelectric cross-sections have been constructed. The different aquifers have been recognized
with main structural elements controlling these aquifers.
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A Ground-Bas Ed Squid Magnetometer
Authors W.E. Doll, T.J. Gamey, L.P. Beard and J.R. SheehanOver the past five years, our group has focused on development of airborne magnetic and electromagnetic systems for mapping and detection of unexploded ordnance (UXO). Among these projects is one involving testing and development of a high temperature airborne Superconducting Quantum Interference Device (SQUID) tensor magnetometer. In association with the airborne SQUID development, we are conducting tests of the SQUID as a ground-based instrument for UXO mapping and detection. The ground-based SQUID is mounted on a man-portable litter with ancillary instrumentation mounted on a cart and connected by an umbilical. High-temperature SQUIDs use liquid nitrogen as the cryogen, which is more convenient than the helium-cooled lowtemperature devices. Preliminary data from the ground-SQUID prototype show good agreement with cesium vapor total magnetic field data along a test line. Noise frequencies and levels appear manageable and we anticipate that specialized processing should make it possible to extract more details about UXO items from their tensor magnetic properties.
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Comparison of Laboratory-Based Multi-Frequency Systems for Measuring Magnetic Susceptibility
Authors Ryan E. North, Eric W. Smith and Gary L. CavanoughMagnetic soils can have significant influence on instruments that are used for detecting
unexploded ordnance (UXO) as well as landmines. Magnetic susceptibility is a measure of the degree to
which a material can be magnetized. Magnetic viscosity is the frequency dependence of the magnetic
susceptibility and is normally characterized as the percentage difference of the magnetic susceptibility at
two frequencies separated by one decade (e.g. 465 Hz and 4.65 kHz). This may be too simplified of an
approach. Queensland Magnetic Research has built a prototype magnetic-susceptibility-measurement
system (MAGNASAT) that can measure the magnetic susceptibility of a small soil sample at multiple
frequencies ranging between 10 Hz and100 kHz. The comparison between the Queensland Magnetic
Research MAGNASAT and the Bartington MS2 is the focus of this presentation. Six different chemical
salts with known magnetic susceptibility values were measured multiple times with each system. The
results will demonstrate the accuracy and precision of each instrument. Characterization of a
measurement system is an important first step for collecting quality data.
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Mineralogy of Magnetic Soils at A Uxo Remediation Site In Kaho'Olawe Hawaii
Magnetic characteristics of soils can have a profound influence on electromagnetic sensors for
the detection of unexploded ordnance (UXO) and may cause false alarms in the case of spatially variable
concentrations. In particular, the performance of several electromagnetic sensors is hampered by viscous
remanent magnetism, which is caused by the presence of ferrimagnetic iron oxide minerals of different
sizes and shapes. Tropical soils formed on basaltic substrates commonly have large concentrations of
iron oxide minerals. To improve detection and discrimination of UXO in these soils it is crucial to have
a better understanding of the types of minerals responsible for the magnetic behavior, as well as their
distribution in space. In this paper we present the results of recent field and laboratory studies of soil
magnetic properties and soil mineralogy at the former Naval training range on Kaho’olawe Island,
Hawaii. We discuss the role of environmental controls such as parent material, age and precipitation on
the magnetic properties.
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Examples of The Effect of Magnetic Soil Environments On Time Domain Electromagnetic Data
During September 2004 a field study was carried out on the Hawaiian Island of Kaho’olawe to explore
various aspects of the effect of magnetic soils on time domain electromagnetic (TEM) measurements.
This field work was in support of two Strategic Environmental Research and Development Program funded
research projects (UX1355 and UX1414) whose goals are to investigate the source and spatial variability
of magnetic soil anomalies, to create a methodology for modelling the response of magnetic soils, and
to develop TEM data collection techniques that can better discriminate between the response of magnetic
soils and unexploded ordnance (UXO). Detailed electromagnetic surveys were carried out at a test site on
the island. The data from the surveys verify the commonly held belief that magnetic variations in the soil
can complicate the identification of UXO. However, the data also show that short wavelength variations in
the TEM response due to micro-topographic variations and coil orientation effects can generate responses
that could mask a UXO and/or result in a false positive. An overview of the surveys, a discussion of
preliminary results and some practical recommendations for surveying in magnetic soil environments will
be presented.
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Evaluating The Effectiveness of Varying Transmitterwaveforms for Uxo Detection In Magnetic Soil Environments
More LessMagnetic soils are a major source of false positives when searching for landmines or unexploded ordnance
(UXO) with electromagnetic induction sensors. In adverse areas up to 30% of identified electromagnetic (EM)
anomalies are attributed to geology. The EM phenomena that give rise to the response of magnetically viscous
soil and metal are fundamentally different. The viscosity effects of magnetic soil can be accurately modelled by
assuming a ferrite relaxation with a log-uniform distribution of time constants. The EM response of a metallic target
is due to eddy currents induced in the target and is a function of the target’s size, shape, conductivity and magnetic
susceptibility. In this presentation, we compare the range and variation of time decays of metallic targets (UXO
and scrap metal) with the time domain electromagnetic response of magnetically viscous ground. Electromagnetic
sensor measurements and modelling are used to assess the feasibility of multiple pulse widths to differentiate the
ground response from metallic targets. We present ground and metal responses measured by Geonics EM61-MK2
sensors with differing transmitter waveform characteristics.
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Progress in The Geophysical Delimitation of Fort St. Joseph, Niles, Mi
Authors Laura Smart, William Sauck and Daniel LynchFort St. Joseph was a French trading post built in 1691, later conquered by the English, and used until 1781. The exact location of the Fort was unknown for over a century, until archaeological investigations in 1998 recovered 18th Century artifacts along the southeast bank of the St. Joseph River. The site is located between a mid-20th Century landfill and a reservoir on the Saint Joseph River. Strata overlying the remains include a 0.3m organic surface layer and a 19th century silty gray plow zone approximately 0.25m thick. Cesium-vapor magnetometer/gradiometer, GPR, electrical resistivity, and EM induction surveys were employed in 2002 to guide archaeological excavations. All but one of the excavations oriented by the geophysical surveys yielded evidence of the Fort, as reported in SAGEEP 2003. Deposits associated with the geophysical anomalies include burnt pit features, building stones, and a charcoal layer derived from a burnt structure. The magnetometer survey was greatly expanded over the last two years, and additional excavations were made in 2004. At this time, only the boundary of the Fort facing the river has been defined. The surveys can be expanded in the up-river direction, but the landfill likely covers a significant area of the Fort.
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A Shallow Water Uxo Survey System
Authors Jim R. McDonald, Chester F. Bassani and David J. WrightWith support of the Environmental Security Technology Certification Program (ESTCP), AETC
is developing a UXO survey system for use in shallow water (up to 15 feet deep). The sensor platform
incorporates both an array of Cs-vapor magnetometers and a time domain EMI sensor array. A
performance modeling study defined the platform operational and deployment concepts. An
engineering design study established the performance characteristics of the new time-domain EMI
sensor, which incorporates an extended transmitter, coupled with an array of four receive coils. The
system incorporates a pilot guidance survey navigation aid, a dual GPS sensor system to provide
positioning and attitude information, and the Data Acquisition (DAQ) and Data Analysis Systems
(DAS) adapted from the Airborne Multi-sensor Towed Array Detection System (MTADS), which
incorporate 3-dimensional sensor position information into a 3-dimensional, physics-based target fitting
GUI. Additional marine components include an autopilot system to control the depth and attitude of the
sensor platform, digital magnetic compasses, a high-frequency digital imaging sonar, an inertial attitude
measurement sensor, depth sensors, and echo sounders. The tow vessel is a pontoon boat. The first full
scale demonstration at a former UXO target range will take place in 2005.
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Detection of Uxo In Marine Environments With Towed Array Ip Measurements
Authors D.D. “Skip” Snyder, Scott C. MacInnes, Douglas LaBrecque and Roger SharpeDuring World War II, scientists at the Naval Ordnance Laboratory (NOL) based the development
of the RX-1 Beach Mine Locator on “Induced Electrical Potential” (IEP), the phenomenon we now call
IP. Although deployed briefly in Okinawa just before the end of the war, there is no record of any
further development of the IP method for locating metal objects in the marine environment.
In this paper, we describe a research project undertaken jointly by Zonge Engineering and Multi-
Phase Technologies, LLC with the objective of demonstrating that IP is a practical method for detecting
metallic objects such as sea mines and UXO. The Strategic Environmental Research and Development
Program (SERDP) funded the project. During the project, we performed IP measurements in the
laboratory using a small metal target immersed in both fresh water and in salt water (30,000ppm NaCl).
These experiments provided us with an indication of the amplitude of the IP response that we can expect
from a target and the dependence of response amplitude on salinity of host medium. We used the
laboratory measurements to calibrate numerical models used to study electrode arrays for deployment in
full-scale experiments. Using results from our modeling, we assembled an electrode array and we
conducted experiments at the Mare Island Naval Shipyard in San Francisco Bay.
Our results confirm the presence of measurable IP responses associated with metallic targets.
The responses are 3-5 times larger in salt water than they are in fresh water. We estimate the intrinsic
response of metallic object in salt water is 100-200 ms (Newmont IP units). Detection range is
intimately tied both to the characteristic size of an object and to the size of the electric dipole used to
measure it. We conclude that measurement dipoles should have a length that is on the order of a
characteristic dimension of the object to be detected. Detection range is on the order of 3-5 dipole
lengths. Detection range is still an issue that can only be resolved with further research. Practical
exploitation of IP for UXO detection will require a submerged electrode platform with measurement
dipoles scaled to detect both small and large targets.
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Design and Testing An Airborne Squid Magnetometer for Uxo Detection
Authors T.J. Gamey, W.E. Doll, L.P. Beard and J.R. SheehanOak Ridge National Laboratory is conducting a project under SERDP to design, test and
field an airborne full-tensor magnetic gradiometer using a Superconducting Quantum Interference
Device (SQUID). This is the second year of a multi-year project. In this paper we discuss the
basic electronic design, the shielded operations, unshielded operations and orientation noise.
UXO signatures and results of ground-based walk over surveys are covered in the associated
paper by Doll et al. (this volume).
The electronics were designed to optimize the resolution of the digital data given
the limitations of 24-bit analog-digital converters (A/DC). This will be achieved to a
certain extent through variable gain settings and by halting operations during aircraft
turns. The greatest gains in resolution result from forcing the instrument to reset back to
zero each time it reaches a saturation threshold. This function requires reconstruction of
the original signal from a “saw-tooth” output.
Measurements during shielded operations were conducted to determine the
absolute minimum noise level in near-ideal laboratory conditions. In the bandwidth of
interest, these were found to be quite variable depending on the test facilities. Noise
levels at Tristan’s facilities were measured as 14.1pT/√Hz at 1Hz as compared to the
manufacturer’s measurements of 0.10pT/√Hz at 1Hz. The difference was attributed to
the high noise environment and potentially poorer shielding facilities. While in the
shield, a vertical dipole (85 μAm2) was synthesized and mapped using a calibrated loop
of wire dragged through the access port in the shield. The results were comparable in
character to synthetic models, indicating that the system was performing properly.
Unshielded static tests demonstrated an average background noise level of 46.5pT
(rms). They also revealed a requirement for additional RF-shielding to remove periodic
and random steps in the data. Three levels of shields have been designed and built.
Orientation tests measured a maximum instrument slew rate of approximately
42,000nT/s. This corresponds to motion equivalent to ±5° at 1Hz, which is within the
normal operating parameters of the helicopter while on line.
These tests also revealed several areas that require additional investigation. More
detailed measurements are required to calibrate the instrument for gain, orthogonality and
linearity. These additional tests are being planned for 2005 in cooperation with the
USGS-Denver, using their shielded facilities and calibration algorithms developed with
SERDP funding for their fluxgate tensor system.
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Combining Em and Lidar To Map Coastal Wetlands: An Example From Mustang Island, Texas
More LessWe combined airborne lidar and ground-based EM induction measurements with vegetation surveys along
two transects across Mustang Island, a barrier island on the Texas coast, to examine whether these methods can
be used to map coastal wetlands and associated geomorphic environments.
Conductivity varied inversely with elevation along both transects. Elevation and conductivity profiles correlated
reasonably well with habitat mapped in the largely imagery-based 1992 National Wetland Inventory (NWI),
but they possessed greater detail and identified misclassified habitat. Detail achievable with elevation and conductivity
data was similar to that achieved in on-the-ground vegetation surveys. Lowest elevations and highest conductivities
were measured in saline environments (marine and estuarine units, forebeach, salt marsh, and wind-tidal
flats). Highest elevations and lowest conductivities were measured in nonsaline environments (upland and palustrine
units, dunes, vegetated-barrier flats, and fresh marsh).
Elevation and conductivity data allow better discrimination among coastal wetland and geomorphic environments
than can be achieved from image interpretation alone. Future work should include evaluating the effect of
vegetation density on lidar-beam penetration, quantifying seasonal change in ground conductivity in fresh and saline
coastal environments, examining the geographic variability of elevation and conductivity statistics, and evaluating
the use of airborne EM sensors to measure ground conductivity at multiple exploration depths.
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Unconventional Deep-Water GPR Investigation of Drilling Obstructions
Authors Jutta Hager, Mario Carnevale and Brian R. JonesGPR was used at a dam rehabilitation drill site to assess the extent of a metal
obstruction within limestone bedrock beneath almost 100 feet of water. The obstruction,
thought to be pipe casing, was encountered during the emplacement of a concrete pile
cutoff wall. The metal had been removed by excavation to a depth of 20 feet and the
excavation filled with concrete, but further drilling encountered additional metal. The
problem was to determine if the metal persisted at depth. The lake bottom survey was
made more challenging by the constraints that the survey location was situated 5 feet
behind the dam and 5 to 15 feet from metal sheet piles of unknown depth. Other
constraints included spill-way releases during high water levels and power generating
schedules.
The survey was designed for an underwater investigation on the lake bottom using
the Tubewave-100 borehole radar antenna. Work was performed from a mini-tug, with
the antenna dragged along the lake bottom. Additional investigations were conducted in
the same manner to locate rebar in concrete structures.
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Uncommon Applications of Computer Assisted Radar Tomography
Authors Kate McKinley and E. Jorgen BergstromComputer Assisted Radar Tomography (CART) is typically best fit for projects where the
density of subsurface targets is high. It has proved to be invaluable in subsurface utility engineering
(SUE) projects and for cemetery mapping projects. In addition to such projects, we have found that
CART is very useful when high positioning accuracy is required, when a large amount of unimportant
targets exist in the subsurface, and when the project requirements include determining accurate target
sizes and shapes. Due to the ease of data acquisition and breakthroughs in data processing, these
surveys can still be performed cost-effectively. Over the past few years, we have encountered many
interesting applications for this technology. This paper will highlight some of these applications:
archaeology, depth profiling projects, and biological preservation.
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Senegal –Irrigation and Water Quality Project
More LessThe Colorado School of Mines has initiated a minor program in Humanitarian Engineering made
possible through a grant from the Paul and Flora Hewlett Foundation. A “Humanitarian Engineer” tries
to balance technical excellence, economic feasibility, ethical maturity, and cultural sensitivity to
significantly improve the lives of others. Clean groundwater is an important commodity needed
throughout the world. Through “Engineers Without Borders”, CSM has partnered with a community in
Senegal. In the village of Rao, Senegal, irrigation of onion fields is primitive and often is plagued by
problems of saltwater encroachment. Resistivity surveying will help to map both the depth to the water
table as well the salt/fresh water interface. The survey results will aid in the location of wells for
irrigation. At present, bucket watering of crops is the primary method for irrigation. We will replace
this slow and inefficient process with a drip irrigation system. A simple resistivity monitoring system
will be designed that can be used by the villagers and will provide a signal when the fresh well water has
been drawn down so much that saltwater has invaded.
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Archaeological Reconnaissance at Tel Yavne, Israel: 2-D Electrical Imaging and Low Altitude Aerial Photography
Authors Paul C. Bauman, Dan Parker, Avner Goren, Richard Freund and Phillip ReederTel Yavne in Israel is the site of the ancient city of Yavne. Located about 20 kilometers south of Tel Aviv, and about 8 km inland from the ancient seaport of Yavne Yam (meaning Yavne by the Sea), it is believed that underneath the tel (an archaeological mound) are the remains of more than 3,000 years of continuous occupation. The tel, at 4 hectares in area and approximately 30 m in elevation, is relatively large in comparison to other ancient sites in Israel. To date, no excavations have been carried out at the site. In preparation for excavation work at a later date, electrical resistivity tomography (ERT) surveys, ground penetrating radar surveys, and low altitude photography from kites and balloons were carried out at the site. This paper will discuss the ERT and photographic surveys. The objectives of these two surveys were to delineate the plan view and vertical extent of accumulated cultural debris, and to identify particular areas for initial test pitting by archaeologists. Eight ERT cross-sections were imaged, ranging in length from 80 to 140 m. Approximately 500 low altitude photographs were shot. Specific features possibly identified include a 9th century B.C.E. (before the common era) water system, the Philistine city wall dating from 790 B.C.E., the ruins of a 12th century C.E. Crusader castle, and numerous architectural features from the Mameluke, Ottoman, and Palestinian periods of habitation. This is the first time that non-destructive techniques have been used in the first phase of an
archaeological exploration program in Israel at such an important, well recognised ancient site.
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