1

FIGURE 23.3 Acquisition geometry for the wide-offset reflection (WOR) profiles. The transmitter antenna is held stationary and the receiver antenna is moved away at 0.1 m increments until the optimum offset is obtained. This stage is the walkaway stage. The antennas are then moved together in 0.25 m increments across the profile. FIGURE 23.4 An east-west wide-offset reflection (WOR) profile along the prototype surface barrier. The walkaway start to the survey is at the east end of the profile....

Field Operations

In practice, GPR measurements can be made by towing the antennas continuously over the ground, or at discreet points along the surface. These two modes of operation are illustrated in Figure 7.5. The fixed-mode antenna arrangement consists of moving antennas independently to different points and making discrete measurements. The moving-mode arrangement keeps the transmit and receive antennas at a fixed distance with the antenna pair moved along the surface by pulling them by hand or with a...

Info

When live and dead root mass were combined, a strong positive relationship was observed with the GPR data (r 0.80). The high proportion of buried organic debris at Sanderson limits the utility of the technique to detect live roots. At KSC the correlation between GPR and live roots was much better (r 0.84). The Sanderson findings highlight the fact that presently, it is not possible to separate live and dead buried biomass. At KSC, dead biomass represented only 13 percent of the total buried...

References

Alstetter, Subsurface moisture determination with the ground wave of GPR, Proceedings from GPR '98, 7th International Conference, May 27-30, 675-680, 1998. Chanzy, A., A. Tarussov, A. Judge, and F. Bonn, Soil water content determination using a digital ground-penetrating radar, Soil Science Society of America Journal, 60, 1318-1326, 1996. Charlton, M., Small scale soil-moisture variability estimated using ground penetrating radar, SPIE Proceedings Series,...

Acknowledgments

The authors gratefully acknowledge the support of The Trustees of the Hobart Ames Foundation, and the staff of Ames Plantation, Grand Junction, Tennessee. Freeland, R. S., R. E. Yoder, J. T. Ammons, and L. L. Leonard. 2002b. Integration of real-time global positioning with ground-penetrating radar surveys. Appl. Eng. in Agric 18(5) 647-650. Hardeman, W. D. 1966. Geologic Map of Tennessee (West Sheet). State of Tennessee Department of Conservation, Division of Geology, Nashville, TN. Odhiambo,...

Positioning With

FIGURE 9.10 Range from satellite s to ground receiver r. FIGURE 9.10 Range from satellite s to ground receiver r. As already mentioned, the fundamental GPS observable is the signal travel time between the satellite and the receiver. However, the receiver clock that measures the time is not perfect and may introduce an error to the measured pseudorange (even though we limit our discussion here to pseudoranges, the same applies to the carrier phase measurement that is indirectly related to the...

Introduction

Due in large measure to the research that has been conducted at the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) United States Salinity Laboratory over the past 50 years, the measurement of electrical conductivity (EC) has become a standard soil physicochem-ical measurement both in the laboratory and in the field to address agricultural and environmental concerns. In particular, the geospatial measurement of EC with geophysical techniques, including electrical...

Johnson Sariowan

Annan, A.P., Davis, J.L. and Vaughn C.J. 1984. Radar mapping of buried pipes and cables. Technical note 1. A-Cubed Inc., Mississauga, Ontario, Canada. Asmussen, L.E., Perkins, H.F. and Allison, H.D. 1986. Subsurface descriptions by ground-penetrating radar for watershed delineations. Research Bulletin 340. Georgia Agricultural Experiment Stations, University of Georgia, Athens. Bengeyfield, W.H. 1976. Drainage So easy it's difficult. USGA Green Section, January, 1976. Boniak, R., Chong, S.-K.,...

Display and interpretation

Processing and display are an integral part of being able to effectively interpret GPR data. GPR data can rarely be interpreted without some type of processing to improve the resolution of coherent signals that represent the targets that are the objective of the survey, and a display that enables the interpreter to easily identify the anomalies that identify the time-space location of the targets. Processing and display can be conducted in the field, but in many cases, it is more convenient to...

P1

FIGURE 5.4 Arrangement and spacing of current electrodes (C1 and C2) and potential electrodes (P1 and P2) for the three resistivity electrode arrays most commonly employed. noise caused by naturally occurring electric currents (Dobrin, 1976 Milsom, 2003 Parasnis, 1986). When using any of the three electrode arrays shown in Figure 5.4 for the purpose of areal resistivity mapping, the measured apparent resistivity value, pa, is referenced to the midpoint location between the two outer electrodes,...

Case History

This case study highlights mapping subsurface lateral preferential flow in Major Land Resource Area 134 (MLRA 134 Southern Mississippi Valley Silty Uplands), which extends along the Mississippi River from southern Illinois to northern Louisiana. These highly productive agricultural lands are primarily in row-crop production and represent thousands of hectares that formed in the loess-covered Tertiary-aged Claiborne and Wilcox geologic formations (Hardeman, 1966). At one research site, an...

Methodology

The GPR, consisting of a transmitter and receiver, is elevated above the surface at a typical height of 1 m as shown in Figure 24.1. A vehicle-mounted implementation of a surface reflectivity system (Figure 24.2) shows the GPR mounted to the left of the vehicle, with GPS providing positioning information. The transmitter emits a short EM pulse. Part of the energy is transmitted into the soil and part is reflected back into the air. The reflected pulse amplitude is measured in the receiver....

Table

Outline of Steps for an eCa-Directed Soil Sampling Survey 1. Site description and ECa survey design (c) Select Global Positioning System (GPS) coordinate system (d) Establish ECa measurement intensity 2. ECa data collection with mobile GPS-based equipment (a) Geo-reference site boundaries and significant physical geographic features with GPS (b) Measure geo-referenced ECa data at the predetermined spatial intensity and record associated metadata 3. Soil sample design based on geo-referenced ECa...

The Main Components Of

The main components of the GPS system are Space, Control, and User segments. The GPS operational constellation is made up of twenty-four satellites that orbit Earth at the altitude of 20,000 km (Figure 9.2). The satellites are placed in six nearly circular orbital planes, inclined at 55 degrees with respect to the equatorial plane, with nominally four satellites in each plane. This configuration assures the simultaneous visibility of five to eight satellites at any point on Earth. The...

Materials And MethoDS

27.2.1 Description of the Selected Golf Greens The GPR was used to locate drainage tile on two different greens. These two golf greens were constructed by different styles. Figure 27.1 shows golf green No. 3, with an area of about 500 m2, at the Stone Creek golf course (SCGC), Makanda, IL. This green was constructed following the U.S. Golf Association (USGA) recommendations. The USGA green consisted of a 30 cm thick layer of sand mix overlying a 10 cm layer of gravel. The drainage tile,...

Discussion

There were significant correlations between apparent electrical conductivity (ECa) and all the texture fractions except for clay content. This exception is not typical, because ECa is normally strongly correlated with clay content on nonsaline soils (Sudduth et al., 2001). Moreover, other findings on morainic soil in the region have shown strong correlations between ECa and clay content (Kor-saeth, 2005a, 2005b). Such high correlations may be partly explained by the exchangeable cations...

Im vwwwv

(a) Frequency Domain Input-output Signals FIGURE 6.6 The time and frequency domains transmit and receive signals (a) time domain transmits (input) and receives (output) signals, and (b) frequency domain transmits and receives signals. Frequency domain systems utilize an input signal that is a sinusoidal wave with a fixed frequency (a square wave time domain signal is composed of many frequencies), as shown in Figure 6.6b. The signal recorded at the receive coil is delayed (called a phase shift)...

Geophysical Methods Applicable To Agriculture

Geophysical methods can be classified as passive or active. There is no artificial application of energy with passive geophysical methods. On the other hand, active geophysical methods do require the artificial application of some form of energy. The three geophysical methods predominantly used for agricultural purposes are resistivity, electromagnetic induction, and ground-penetrating radar. All three of these predominantly employed methods are active, and each is summarized within this book...

P

Where k is the bulk modulus, is the rigidity modulus (or shear modulus), and p is density. As indicated by the equation directly above, the P-wave velocity in soil or rock depends only on elastic moduli and density of these Earth materials. Rayleigh Wave A type of seismic wave that travels along the surface. Rayleigh wave particle motion is elliptical retrograde in a vertical plane oriented coincident with the direction of wave propagation. The amplitude of a Rayleigh wave decreases...

Geophysics

Daniels M. Reza Ehsani BOOKS IN SOILS, PLANTS, AND THE ENVIRONMENT Robert M. Peart, University of Florida, Gainesville Mohammad Pessarakli, University of Arizona, Tucson Kenneth G. Cassman, University of Nebraska, Lincoln Donald R. Nielsen, University of California, Davis Jan Dirk van Elsas, Research Institute for Plant Protection, Wageningen, The Netherlands L. David Kuykendall, U.S. Department of Agriculture, Beltsville, Maryland Kenneth B. Marcum, Arizona State...

Basic Principles

GPR uses the principle of scattering electromagnetic energy in the form of an electromagnetic wave to locate buried objects. The basic principles and theory of operation for GPR have evolved through the disciplines of electrical engineering and seismic exploration, and GPR specialists tend to have backgrounds either in geophysical exploration or electrical engineering. The fundamental principle of operation is the same as that used to detect aircraft overhead, but with GPR, antennas are moved...

Acquisition of nongeophysical spatial data

Geophysical measurements are commonly integrated with additional geospatial infromation in order to make appropriate agricultural management decisions. This additional geospatial information can be collected using field surveying methods, aerial photogrammetry, satellite imagery, and GPS (Global Positioning System). Field surveying is used to determine the positions or coordinates of features observed in the field. Field mapping is typically conducted when detailed surveys are required....

Gps signal characteristics

GPS satellites transmit low-power radio signals on two carrier frequencies designated as L1 and L2. The L1 carrier is 1575.42 MHz, and the L2 carrier is 1227.60 MHz in the ultrahigh frequency (UHF) band. GPS is a line-of-sight (LOS) system, and thus the signals can penetrate clouds, glass, and plastic but will not go through most solid objects, such as buildings and dense foliage. A GPS signal contains three different types of information a Pseudo-Random Noise (PRN) code, ephem-eris data...

Mathematical models of pseudorange and carrier phase observables

Pseudorange is a geometric range between the transmitter and the receiver, distorted by the propagation media and the lack of synchronization between the satellite and the receiver clocks. It is recovered from the measured time difference between the epoch of the signal transmission and the epoch of its reception by the receiver. The actual time measurement is performed with the use of the PRN code. In principle, the receiver and the satellite generate the same PRN sequence. The arriving signal...

Indirect Gpr Applications To Agricultural Investigations

Agricultural utilization of remote sensing to detect, identify, locate, map, predict, or estimate a buried feature or object that may affect production or management is an increasing application for GPR. This section will discuss the various ways that radar has been used for these indirect purposes. Let us begin by looking at studies involving GPR to detect and monitor groundwater. GPR investigations to detect and monitor groundwater have several components. It has been used to estimate soil...

Wkv

See Alternating electric current (AC) Accuracy of Global Positioning System, 191-192 AEM. See Airborne electromagnetic (AEM) systems Aerial photogrammetry, 207 AGCF. See Automatic Gain Control Function (AGCF) AgGPS Parallel Swathing Option, 63 Agricultural applications contamination transport and GPR, 346 cover crop, 276, 277-278 directed soil sampling, 32-34 electrical conductivity, 273 electromagnetic induction, 19 environmental and hydrological disciplines, 107 and GPR, 47 loop-loop...

S

See Selective Availability (SA) Saline-sodic soil, 33 Salinity mapping and assessment, 59, 106 Sampling-site scale properties, 268, 269 SAR. See Sodium adsorption ratio (SAR) SAREC. See Sustainable Agriculture Research and Extension Center (SAREC) Satellite and receiver clock errors, 172 Satellite imagery, 207 Satellite magnetometry, 148 Satellites and their geometry, 174-175 Satellite signal, intentional degradation of, 175-176 Satellite systems, modernization other, 194 Saturated soil...

Gps Instrumentation

During the past two decades, the civilian as well as military GPS instrumentation evolved through several stages of design and implementation, focusing primarily on achieving an enhanced reliability of positioning and timing, modularization, and miniaturization. In addition, one of the most important aspects, especially for the civilian market, has been the decreased cost of the receivers, as the explosion of GPS applications calls for a variety of low-cost, application-oriented, and reliable...

Factors influencing resistivity or electrical conductivity in soil materials

This section provides a brief overview of the factors influencing soil resistivity (or electrical conductivity). Additional discussion regarding this subject is given in Chapter 2 and Chapter 4. The ability of a soil material to transfer electric current, as indicated by the resistivity (or electrical conductivity) of the soil, is determined by the components that make up the soil. Soil typically consists of solid, gas, and liquid phases (Figure 5.2). The solid phase of the soil includes both...

Closing Remarks

The need for a means of measuring within-field variation in soil salinity within the root zone in a quick, reliable, and cost-effective manner resulted in the development of GPS-based mobile ER and EMI techniques to measure and map ECa. However, the measurement of ECa is complicated by the influence of several soil properties aside from soil salinity, including soil texture, temperature, and water content. This has enabled geospatial measurements of ECa to become a tool for directing soil...

Magnetometry Methods

8.1.1 Magnetometry Method Introduction Magnetometry is a passive remote sensing method that records the magnitude of Earth's local magnetic field at a sensor location. The Earth's overall magnetic field is a dipole field with the North Magnetic Pole and the South Magnetic Pole acting much like the ends of a bar magnet. There are secondary regional and local variations to the primary dipole field caused by soils and objects with different magnetic properties located above, on, or beneath the...

Contributors

Water Management Research Laboratory U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) Parlier, California Department of Plant, Soil and Agricultural Systems Southern Illinois University Carbondale, Illinois U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) Water Management Unit Fort Collins, Colorado U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) Water Management Unit Fort Collins, Colorado U.S. Department of Agriculture...

General Considerations for Geophysical Methods Applied to Agriculture

Reza Ehsani, and Jeffrey J. Daniels 1.1 Introduction Geophysics Definitions, Development Chronology, Investigation Scale 3 1.2 Geophysical Methods Applicable to 1.2.1 Resistivity 1.2.2 Electromagnetic Induction 1.2.3 Ground-Penetrating Radar 1.2.4 Magnetometry 1.2.5 Self-Potential 1.3 Aspects of Agricultural Geophysics Data Collection and 1.3.1 Selecting the Proper Geophysical 1.3.2 Investigation Depth and Feature Resolution 1.3.3 Field Operations Station Interval, Stacking,...

Results

Comparison of the ERM borehole instrument with the inverted GeoTom data is shown in Figure 22.2. The correlations for each single test site were 0.559 at Bornim, 0.709 at Golzow, and 0.896 at Kassow. No measurements with the ERM were made at Beckum. The t correlation over all fields was 0.703 (Pearson's r is 0.871 for log-l g transformed values). This comparison FIGURE 22.2 Log-log scatterplot of inverted sur-confirms the reliability of the GeoTom surface face measurements by the GeoTom versus...

Common Coordinate Systems

A GIS is used to study various phenomena based on the spatial relationships among features. The location information of every entity in a GIS must be in the same coordinate system. The data layer needs to be registered to the same reference coordinate system. Otherwise, errors will result that will lead to problems in interpretation and analysis during the later stages of GIS operations. Converting the coordinate system of individual data layers to a unified coordinate system is the first...

Continuous Measurement Systems

Conventional resistivity surveys, whether for areal pa mapping or assessing soil resistivity changes with depth, proceed at a relatively slow pace, because electrodes need to be pulled from the ground, moved, and then reinserted before the next pa measurement is obtained. Computer-controlled multielectrode systems are certainly an improvement over conventional equipment with respect to resistivity survey efficiency however, there is still a considerable amount of initial setup time needed,...

Gps modernization and other satellite systems

The current plan of GPS modernization is focused on improving the quality of civilian uses of GPS, primarily through the implementation of a new L2C code on L2 frequency and a new civilian signal on L5 frequency of 1227.6 MHz (Spilker and Van Dierendonck, 2001). In addition, a new M-code (encrypted) has been implemented exclusively for military use, ensuring that military and civilian users will have entirely separate signals and codes. Consequently, AS policy will be abandoned. (SA has already...

Selfpotential methods

8.2.1 Self-Potential Method Introduction Self-potential is a passive geophysical method that is, it does not rely on the application of energy from an artificial source. Self-potential, from an operational standpoint, is probably the simplest geophysical method, essentially requiring only the measurement of a naturally occurring electric potential difference between two locations on the ground surface. The electric potential difference measured is associated with nonartificial electric current...

Gps mapping project and connection to agricultural geophysics

Modern geophysics uses a variety of sensors and techniques for exploration, probing, and mapping, in applications such as mining petroleum exploration, environmental studies, engineering investigations, and agricultural field assessments. The geophysical techniques presently used most often for agricultural purposes include resistivity, electromagnetic induction, and ground-penetrating radar. These three geophysical methods are being employed for soil mapping of salinity, water content, and...