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Sample records for resistance tomography ert

  1. Electrical Resistivity Tomography (ERT) Applied to Karst Carbonate Aquifers: Case Study from Amdoun, Northwestern Tunisia

    NASA Astrophysics Data System (ADS)

    Redhaounia, Belgacem; Ilondo, Batobo Ountsche; Gabtni, Hakim; Sami, Khomsi; Bédir, Mourad

    2016-04-01

    The Amdoun region is characterized by a high degree of karstification due to the climate impact (±1500 mm year-1) and the development of fracture network. Survey using electrical resistivity tomography (ERT) is deployed to provide a cost-effective characterization of the subsurface karst environments. A total of seven ERT profiles with lengths of 315 m were evaluated at the Béja governorate (NW Tunisia). The area represents a small syncline of Boudabbous limestone rocks (Lower Eocene), which is covered by a thin layer of clay. In this study, an ERT survey was conducted to examine the spatial distribution and shape of underground cavities in the karst area in Jebel Sabah anticline and Aïn Sallem-Zahret Medien syncline. In this study, geological, hydro-geological and electrical resistivity tomography (ERT) methods were applied to determine the geometry of the perched aquifer in the Amdoun region (NW Tunisia). The area is characterized by fractured and karstic limestone aquifer of Late Cretaceous (Abiod Fm.) and Lower Eocene (Boudabbous Fm.). The aquifers have a karstic functioning and drain aquifers of economical interest, despite some wells exploiting them. Seven resistivity profiles were conducted along the survey area at three sites. The orientation, extension and the degree of inclination of those profiles are shown in the location map. The correct resistivity data were interpreted using Earth Imager 2D software. The results of the interpreted geo-electrical sections showed that the resistivity of the carbonate aquifer varied between 2.5 to over 5794 Ωm. The thickness of the perched aquifer ranged from 15 to 50 m, while its depth from the surface lies between 10 and 60 m. The ERT not only provided precise near surface information, but was also very useful for establishing the 3D geometry and the position of several potential cavities and karts. The results show the presence of small to large isolated cavities at various depths. The low resistivity of cavities

  2. The `L' Array, a method to model 3D Electrical Resistivity Tomography (ERT) data

    NASA Astrophysics Data System (ADS)

    Chavez Segura, R. E.; Chavez-Hernandez, G.; Delgado, C.; Tejero-Andrade, A.

    2010-12-01

    The electrical resistivity tomography (ERT) is a method designed to calculate the distribution of apparent electrical resistivities in the subsoil by means of a great number of observations with the aim of determining an electrical image displaying the distribution of true resistivities in the subsoil. Such process can be carried out to define 2D or 3D models of the subsurface. For a 3D ERT, usually, the electrodes are placed in a squared grid keeping the distance between adjacent electrodes constant in the x and y directions. Another design employed, consists of a series of parallel lines whose space inter-lines must be smaller or equal to four times the electrode separation. The most common electrode arrays frequently employed for this type of studies are the pole-pole, pole-dipole and dipole-dipole. Unfortunately, ERT surface sampling schemes are limited by physical conditions or obstacles, like buildings, highly populated urban zones, and geologic/topographic features, where the lines of electrodes cannot be set. However, it is always necessary to characterize the subsoil beneath such anthropogenic or natural features. The ‘L’ shaped array has the main purpose to overcome such difficulties by surrounding the study area with a square of electrode lines. The measurements are obtained by switching automatically current and potential electrodes from one line to the other. Each observation adds a level of information, from one profile to the other. Once the total levels of data are completed, the opposite ‘L’ array can be measured following the same process. The complete square is computed after the parallel profiles are observed as well. At the end, the computed resistivities are combined to form a 3D matrix of observations. Such set of data can be inverted to obtain the true resistivity distribution at depth in the form of a working cube, which can be interpreted. The method was tested with theoretical models, which included a set of two resistive cubes

  3. Characterization of water content dynamics and tracer breakthrough by 3-D electrical resistivity tomography (ERT) under transient unsaturated conditions

    NASA Astrophysics Data System (ADS)

    Wehrer, Markus; Slater, Lee D.

    2015-01-01

    Characterization of preferential flow and transport is still a major challenge but may be improved employing noninvasive, tomographic methods. In this study, 3-D time lapse electrical resistivity tomography (ERT) was employed during infiltration on an undisturbed, unsaturated soil core in a laboratory lysimeter. A tracer breakthrough was conducted during transient conditions by applying a series of short-term infiltrations, simulating natural precipitation events. The electrical response was quantitatively validated using data from a multicompartment suction sampler. Water content probes were also installed for ground-truthing of ERT responses. Water content variations associated with an infiltration front dominated the electrical response observed during individual short-term infiltration events, permitting analysis of water content dynamics from ERT data. We found that, instead of the application of an uncertain petrophysical function, shape measures of the electrical conductivity response might be used for constraining hydrological models. Considering tracer breakthroughs, the ERT observed voxel responses from time lapse tomograms at constant water contents in between infiltration events were used to quantitatively characterize the breakthrough curve. Shape parameters of the breakthrough derived from ERT, such as average velocity, were highly correlated with the shape parameters derived from local tracer breakthrough curves observed in the compartments of the suction plate. The study demonstrates that ERT can provide reliable quantitative information on both, tracer breakthroughs and water content variations under the challenging conditions of variable background electrical conductivity of the pore solution and non steady-state infiltration.

  4. Core-scale electrical resistivity tomography (ERT) monitoring of CO2-brine mixture in Fontainebleau sandstone

    NASA Astrophysics Data System (ADS)

    Bosch, David; Ledo, Juanjo; Queralt, Pilar; Bellmunt, Fabian; Luquot, Linda; Gouze, Philippe

    2016-07-01

    The main goal of the monitoring stage of Carbon Capture and Storage (CCS) is to obtain an accurate estimation of the subsurface CO2 accumulation and to detect any possible leakage. Laboratory experiments are necessary to investigate the small scale processes governing the CO2-brine-rock interaction. They also provide a means to calibrate the results coming from field scale geophysical methods. In this work we set up an experimental system which is able to perform Electrical Resistivity Tomography (ERT) measurements on centimeter-scale rock samples at various P-T conditions. We present the results of two new experiments related to CO2 monitoring, performed on a cylindrical (4 × 8 cm) Fontainebleau rock sample. In the first one, we have quantified the CO2 saturation at different volume fractions, representing zones from a deep saline aquifer with varying degrees of saturation. In the second one, we have monitored and quantified the effect of CO2 dissolution in the brine at a pressure of 40 bar during eight days, emulating the invasion of CO2 into a shallow aquifer. Results highlight the importance of accounting for the contribution of surface conductivity in highly CO2-saturated regions, even in clay-free rocks, and also for brine conductivity variation due to CO2 dissolution. Ignoring any of these effects will end up in a CO2 saturation underestimation. We present a modified CO2 saturation equation to account for these two influences.

  5. Identifying the changes of geo-engineering properties of dunites due to weathering utilizing electrical resistivity tomography (ERT)

    NASA Astrophysics Data System (ADS)

    Ündül, Ömer; Tuğrul, Atiye; Özyalın, Şenol; Halil Zarif, İ.

    2015-04-01

    Weathering phenomena have an important role in many construction facilities with varying depths and grades. Due to the anisotropic and heterogeneous nature of weathering profiles of some rocks, uncertainities exist in determining the geo-engineering properties. Geo-electrical studies have been utilized to overcome such uncertainities for various subsurface conditions including the determination of boundaries between weathered and unweathered parts of different rock types. In this study, the electrical resistivity tomography (ERT) results were correlated with conventional methods in determining the effects of weathering on the geo-engineering properties of dunites. During the research, weathering grades were determined by field studies including discontinuity spacings, aperture and properties of fill materials. The detailed petrographical studies, determination of petrophysical properties (e.g. water absorption and effective porosity) and mechanical properties (e.g. unconfined compressive strength (UCS)) constitute the laboratory studies. ERT studies were carried out in a row of sixty electrodes with electrode spacings of 0.5 m utilizing a Wenner-Schlumberger configuration. According to the comparison of the inversion model sections with the weathering profiles obtained by field and laboratory studies it is concluded that the use of ERT with a Wenner-Schlumberger configuration supplies comparable data for wider subsurface areas from the view of weathering and its effect on geo-engineering properties of dunites. In addition, ERT techniques are very useful where conventional techniques are inadequate in determining the full weathering profile.

  6. Tri-Dimensional Electric Resistivity Tomography (ERT-3D) Technique, an Efficient Tool to Unveil the Subsoil of Archaeological Structures

    NASA Astrophysics Data System (ADS)

    Chavez, R. E.; Vargas, D.; Cifuentes-Nava, G.; HernaNdez-Quintero, J. E.; Tejero, A.

    2014-12-01

    Three-Dimensional Electrical Resistivity Tomography techniques (ERT-3D) have demonstrated to be an efficient tool to study the subsurface of areas of archaeological interest by special arrays designed to 'illuminate' the subsoil beneath the structure under study. 'L'- and 'Corner'-arrays are applied to design alternative electrode geometries, which attempt to cover the subsurface with enough resistivity observations underneath the studied target. Two examples are presented where novel geometries can be applied to investigate the subsoil of two important pyramids in Mexico. First, the archaeological site of Cuicuilco is studied. The area is found towards the southern portion of the Mexican Basin. This pyramid presents a circular structure of 110 m in diameter and a total height of 25 m. The region is partially covered by the lava flows that came from an eruptive event form the Xitle Volcano 1500 years ago. The geophysical study was carried out at the base of the pyramid. 48 electrodes were deployed along a circular transect, with an electrode separation of 5.4 m. A total of 1716 apparent resistivity observations were measured. The inverted model computed is obtained with an investigation depth of 30 m, approximately (Figure 1, in color). A resistive anomaly can be observed towards the central portion of the model. This anomaly can be associated to a burial chamber, excavated by the archaeologists. The second example corresponds to the pyiramid El Castillo, located in the archaeological site of Chichen Itza, in the southern lowlands of Mexico, within the Yucatan Peninsula. Previous GPR studies carried out within the pyramid's Plaza provided evidences of a buried tunnel excavated within the limestone rocks. Such feature seemed to run beneath the eastern flank of the pyramide. The geophysical study was carried out by employing 96 flat-surface electrodes, which surrounded the edifice forming a square geometry. A total of 5,350 apparent resistivity observations were

  7. Revealing plot scale heterogeneity in soil moisture dynamics under contrasting vegetation assemblages using 3D electrical resistivity tomography (ERT) surveys

    NASA Astrophysics Data System (ADS)

    Dick, Jonathan; Tetzlaff, Doerthe; Bradford, John; Soulsby, Chris

    2016-04-01

    Soil moisture is a fundamental component of the water cycle that influences many hydrological processes, such as flooding, solute transport, biogeochemical processes, and land-atmosphere interactions. The relationship between vegetation and soil moisture is complex and reciprocal. Soil moisture may affect vegetation distribution due to its function as the primary source of water, in turn the structure of vegetation canopies regulate water partitioning into interception, throughfall and steam flow. Such spatial differences in inputs, together with complex patterns of water uptake from distributed root networks can create marked heterogeneity in soil moisture dynamics at small scales. Traditional methods of monitoring soil moisture have revolved around limited point measurements, but improved geophysical techniques have facilitated a trend towards more spatially distributed measurements to help understand this heterogeneity. Here, we present a study using 3D ERT surveys in a 3.2km upland catchment in the Scottish Highlands where increasing afforestation (for climate change adaptation, biofuels and conservation) has the potential to increase interception losses and reduce soil moisture storage. The study combined 3D surveys, traditional point measurements and laboratory analysis of soil cores to assess the plot scale soil moisture dynamics in podzolic soils under forest stands of 15m high Scots pine (Pinus sylvestris) and adjacent non-forest plots dominated by heather (Calluna vulgaris) shrubs (<0.5m high). These dominant species are typical of forest and non-forest vegetation communities the Scottish Highlands. Results showed differences in the soil moisture dynamics under the different vegetation types, with heterogeneous patterns in the forested site mainly correlated with canopy cover and mirroring interception losses. Temporal variability in the forested site was greater, probably due to the interception, and increased evapotranspiration losses relative to the

  8. Mapping Contaminant Remediation with Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Gerhard, J.; Power, C.; Tsourlos, P.; Karaoulis, M.; Giannopoulos, A.; Soupios, P. M.; Simyrdanis, K.

    2014-12-01

    The remediation of sites contaminated with industrial chemicals - specifically dense non-aqueous phase liquids (DNAPLs) like coal tar and chlorinated solvents - represents a major geoenvironmental challenge. Remediation activities would benefit from a non-destructive technique to map the evolution of DNAPL mass in space and time. Electrical resistivity tomography (ERT) has long-standing potential in this context but has not yet become a common tool at DNAPL sites. This work evaluated the potential of time-lapse ERT for mapping DNAPL mass reduction in real time during remediation. Initially, a coupled DNAPL-ERT numerical model was developed for exploring this potential at the field scale, generating realistic DNAPL scenarios and predicting the response of an ERT survey. Also, new four-dimensional (4D) inversion algorithms were integrated for tracking DNAPL removal over time. 4D ERT applied at the surface for mapping an evolving DNAPL distribution was first demonstrated in a laboratory experiment. Independent simulation of the experiment demonstrated the reliability of the DNAPL-ERT model for simulating real systems. The model was then used to explore the 4D ERT approach at the field scale for a range of realistic DNAPL remediation scenarios. The approach showed excellent potential for mapping shallow DNAPL changes. However, remediation at depth was not as well resolved. To overcome this limitation, a new surface-to-horizontal borehole (S2HB) ERT configuration is proposed. A second laboratory experiment was conducted that demonstrated that S2HB ERT does better resolve changes in DNAPL distribution relative to surface ERT, particularly at depth. The DNAPL-ERT model was also used to demonstrate the improved mapping of S2HB ERT for field scale DNAPL scenarios. Overall, this work demonstrates that, with these innovations, ERT exhibits significant potential as a real time, non-destructive geoenvironmental remediation site monitoring tool.

  9. Electrical resistivity tomography investigations on a paleoseismological trenching study

    NASA Astrophysics Data System (ADS)

    Berge, Meriç Aziz

    2014-10-01

    Two-dimensional electrical resistivity tomography (ERT) investigation was performed in a paleoseismological trenching study. Data acquisition strategies such as the selection of electrode configuration and electrode intervals of ERT application were investigated in this paper. The ERT results showed that the Wenner and Wenner-Schlumberger arrays yielded similar results for subsurface characteristics whereas the DD array provided slightly different results. The combined usage of these arrays produced satisfactory images of the subsurface resistivity distribution. In addition, the electrode spacing tests revealed that a suitable interpretation of subsurface geology can be obtained from a 5 m electrode interval. However, a suitable trenching location defined by successful 2D resistivity models was obtained for 1 m electrode spacing. Therefore, the comparison of the trench and ERT results was also possible. The results of trenching and ERT studies substantially support each other.

  10. Electrical resistance tomography of concrete structures

    SciTech Connect

    Daily, W.; Ramirez, A.; Binley, A.; Henry-Poulter, S.

    1993-10-01

    The purpose of this work is to determine the feasibility of using Electrical resistance tomography (ERT) to nondestructively examine the interior of concrete structures such as bridge pillars and roadways. We report the results of experiments wherein ERT is used to image the two concrete specimens in the laboratory. Each specimen is 5 inches square and 12 inches long and contained steel reinforcing rods along its length. Twenty electrodes were placed on each sample and an-image of electrical resistivity distribution was generated from current and voltage measurements. We found that the images show the general location of the reinforcing steel and, what`s more important, delineate the absence of the steel. The method may therefore be useful for determining if such steel has been destroyed by corrosion, however to make it useful, the technique must have better resolution so that individual reinforcing steel units are resolved.

  11. Electrical resistance tomography for imaging concrete structures

    SciTech Connect

    Buettner, M.; Ramirez, A.; Daily, W.

    1995-11-08

    Electrical Resistance Tomography (ERT) has been used to non-destructively examine the interior of reinforced concrete pillars in the laboratory during a water infiltration experiment. ERT is a technique for determining the electrical resistivity distribution within a volume from measurement of injected currents and the resulting electrical potential distribution on the surface. The transfer resistance (ratio of potential to injected current) data are inverted using an algorithm based on a finite element forward solution which is iteratively adjusted in a least squares sense until the measured and calculated transfer resistances agree to within some predetermined value. Laboratory specimens of concrete pillars, 61.0 cm (24 in) in length and 20.3 cm (8 in) on a side, were prepared with various combinations of steel reinforcing bars and voids (1.27 cm diameter) which ran along the length of the pillars. An array of electrodes was placed around the pillar to allow for injecting current and measuring the resulting potentials. After the baseline resistivity distribution was determined, water was added to a void near one comer of the pillar. ERT was used to determine the resistivity distribution of the pillar at regular time intervals as water was added. The ERT images show very clearly that the water was gradually imbibed into the concrete pillar during the course of the experiment. The resistivity decreased by nearly an order of magnitude near the point of water addition in the first hour, and by nearly two orders of magnitude by the end of the experiment. Other applications for this technology include monitoring of curing in concrete structures, detecting cracks in concrete structures, detecting rebar location and corrosion state, monitoring slope stability and the stability of footings, detecting and monitoring leaks from storage tanks, monitoring thermal processes during environmental remediation, and for detecting and monitoring contaminants in soil and groundwater.

  12. Electrical resistivity tomography at the DOE Hanford site

    SciTech Connect

    Narbutovskih, S.M.; Halter, T.D.; Sweeney, M.D.; Daily, W.; Ramirez, A.L.

    1996-01-01

    Recent work at the DOE Hanford site has established the potential of applying Electrical Resistivity Tomography (ERT) for early leak detection under hazardous waste storage facilities. Several studies have been concluded to test the capabilities and limitations of ERT for two different applications. First, field experiments have been conducted to determine the utility of ERT to detect and map leaks from underground storage tanks during waste removal processes. Second, the use of ERT for long term vadose zone monitoring has been tested under different field conditions of depth, installation design, acquisition mode/equipment and infiltration chemistry. This work involves transferring the technology from Lawrence Livermore National Laboratory (LLNL) to the Resource Conservation and Recovery Act (RCRA) program at the DOE Hanford Site. This paper covers field training studies relevant to the second application for long term vadose zone monitoring.

  13. Resistivity structure of the Furnas hydrothermal system (Azores archipelago, Portugal) from AMT and ERT imaging.

    NASA Astrophysics Data System (ADS)

    Byrdina, Svetlana; Vandemeulebrouck, Jean; Rath, Volker; Silva, Catarina; Hogg, Colin; Kiyan, Duygu; Viveiros, Fatima; Eleuterio, Joana; Gresse, Marceau

    2016-04-01

    The Furnas volcanic complex is located in the eastern part of the São Miguel Island and comprises a 5 km × 8 km summit depression filled by two nested calderas with several craters and a lake. Present-day volcanic activity of Furnas volcano is mostly located in the northern part of the caldera, within the Furnas village and north to Furnas Lake, where hydrothermal manifestations are mainly fumarolic fields, steam vents, thermal springs, and intense soil diffuse degassing. Considering the Furnas volcano as a whole, the total integrated CO2 efflux is extremely high, with a total amount of CO2 close to 1000 ton per day (Viveiros et al., 2009). We present the first results of an electrical resistivity tomography (ERT), combined with audio-magneto-telluric (AMT) measurements aligned along two profiles inside the caldera. The purpose of this survey is to delimit the extent, the geometry, and the depth of the hydrothermal system and to correlate the deep resistivity structure with high resolution cartography of diffuse CO2 flux (Viveiros et al, 2015). The ERT and AMT methods are complementary in terms of resolution and penetration depth: ERT can image the structural details of shallow hydrothermal system (down to 100 m in our study) while AMT can image at lower resolution deeper structures at the roots of a volcano (down to 4 km in our study). Our first independent 2D inversions of the ERT-AMT data show a good agreement between the surficial and deeper features. Below the main fumarole area we observe a low resistivity body (less than 1 Ohmm) which corresponds well to the high CO2 flux at the surface and is associated with an extended conductive body at larger depth. These results strongly suggest the presence of hydrothermal waters at depth or/and the presence of altered clay-rich material. On a larger scale however, the geometry of the conducting zones differs slightly from what was expected from earlier surface studies, and may not be directly related to fault zones

  14. Measuring turbulence in a flotation cell using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Meng, Jun; Xie, Weiguo; Runge, Kym; Bradshaw, Dee

    2015-11-01

    Measuring turbulence in an industrial flotation environment has long been problematic due to the opaque, aggressive, and abrasive three-phase environment in a flotation cell. One of the promising measurement techniques is electrical resistance tomography (ERT). By measuring the conductivity distribution across a measurement area, ERT has been adopted by many researchers to monitor and investigate many processes involving multiphase flows. In the research outlined in this paper, a compact ERT probe was built and then used to measure the conductivity distribution within a 60 l flotation cell operated with water and air. Two approaches were then developed to process the ERT data and estimate turbulence-related parameters. One is a conductivity variance method and the other is based on the Green-Kubo relations. Both rely on and use the fluctuation in the ERT measurement caused by bubbles moving through the measurement area changing the density of the fluid. The results from both approaches were validated by comparing the results produced by the ERT probe in a 60l flotation cell operated at different air rates and impeller speeds to that measured using an alternative turbulence measurement device. The second approach is considered superior to the first as the first requires the development of auxiliary information which would not usually be known for a new system.

  15. Electrical resistance tomography from measurements inside a steel cased borehole

    DOEpatents

    Daily, William D.; Schenkel, Clifford; Ramirez, Abelardo L.

    2000-01-01

    Electrical resistance tomography (ERT) produced from measurements taken inside a steel cased borehole. A tomographic inversion of electrical resistance measurements made within a steel casing was then made for the purpose of imaging the electrical resistivity distribution in the formation remotely from the borehole. The ERT method involves combining electrical resistance measurements made inside a steel casing of a borehole to determine the electrical resistivity in the formation adjacent to the borehole; and the inversion of electrical resistance measurements made from a borehole not cased with an electrically conducting casing to determine the electrical resistivity distribution remotely from a borehole. It has been demonstrated that by using these combined techniques, highly accurate current injection and voltage measurements, made at appropriate points within the casing, can be tomographically inverted to yield useful information outside the borehole casing.

  16. Estimating groundwater velocity using apparent resistivity tomography: A sandbox experiment

    NASA Astrophysics Data System (ADS)

    Chen, J. L.; Chen, C. H.; Kuo, C. L.; Fen, C. S.; Wu, C. C.

    2016-08-01

    The electrical resistivity tomography (ERT) technique can estimate groundwater velocity to within 5% of the pre-set groundwater velocity. The apparent conductivity obtained by the ERT technique is linearly related to the groundwater conductivity, as described by Archie's law. Gaussian-like profiles of the tracer concentration were demonstrated with the ERT technique, and the estimated dispersion coefficient was between 0.0015 and 0.0051 cm2/sec. In terms of monitoring changes in groundwater conductivity, the ERT technique has two major advantages over monitoring wells: (1) it measures a larger area and provides more representative results; and, (2) it does not withdraw groundwater samples, and therefore does not affect the groundwater flow. The objective of this research is to measure groundwater velocity with the ERT technique using only one well. The experiments in this research were divided into two parts. The first part evaluated the accuracy and repeatability of the ERT technique using a dipole-dipole array, and the second part estimated the groundwater velocity in a sandbox using the ERT technique. The length, width, and height of the sandbox, which was made of acrylic, were 1.5, 5, and 1.0 m, respectively. The ERT sandbox was sequentially filled with 5-cm layers of the silica sand to a total height of 70 cm. A total of 32 electrodes spaced every 5-cm were installed in the center of the sandbox. Three monitoring wells were installed along the line of the electrodes. Both no-flow and constant flow (NaCl solution with electrical conductivity and concentration of 5,000 μs/cm and 2.456 g/L, respectively) tracer experiments were conducted.

  17. Micro 3D ERT tomography for data assimilation modelling of active root zone

    NASA Astrophysics Data System (ADS)

    Vanella, Daniela; Busato, Laura; Boaga, Jacopo; Cassiani, Giorgio; Binley, Andrew; Putti, Mario; Consoli, Simona

    2016-04-01

    Within the soil-plant-atmosphere system, root activity plays a fundamental role, as it connects different domains and allows a large part of the water and nutrient exchanges necessary for plant sustenance. The understanding of these processes is not only useful from an environmental point of view, making a fundamental contribution to the understanding of the critical zone dynamics, but also plays a pivotal role in precision agriculture, where the optimisation of water resources exploitation is mandatory and often carried out through deficit irrigation techniques. In this work, we present the results of non-invasive monitoring of the active root zone of two orange trees (Citrus sinensis, cv Tarocco Ippolito) located in an orange orchard in eastern Sicily (Italy) and drip irrigated with two different techniques: partial root drying and 100% crop evapotranspiration. The main goal of the monitoring activity is to assess possible differences between the developed root systems and the root water uptake between the two irrigation strategies. The monitoring is conducted using 3D micro-electrical resistivity tomography (ERT) based on an apparatus composed of a number of micro-boreholes (about 1.2 m deep) housing 12 electrodes each, plus a number of surface electrodes. Time-lapse measurements conducted both with long-term periodicity and short-term repetition before and after irrigation clearly highlight the presence and distribution of root water uptake zone both at shallow and larger depth, likely to correspond to zones utilized during the irrigation period (shallow) and during the time when the crop is not irrigated (deep). Subsidiary information is available in terms of precipitation, sap flow measurements and micrometeorological evapotranspiration estimates. This data ensemble lends itself to the assimilation into a variably saturated flow model, where both soil hydraulic parameters and root distribution shall be identified. Preliminary results in this directions show

  18. Micro 3D ERT tomography for data assimilation modelling of active root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Busato, L.; Vanella, D.; Consoli, S.; Binley, A. M.

    2015-12-01

    Within the soil-plant-atmosphere system, root activity plays a fundamental role, as it connects different domains and allows a large part of the water and nutrient exchanges necessary for plant sustenance. The understanding of these processes is not only useful from an environmental point of view, making a fundamental contribution to the understanding of the critical zone dynamics, but also plays a pivotal role in precision agriculture, where the optimisation of water resources exploitation is mandatory and often carried out through deficit irrigation techniques. In this work, we present the results of non-invasive monitoring of the active root zone of two orange trees (Citrus sinensis, cv Tarocco Ippolito) located in an orange orchard in eastern Sicily (Italy) and drip irrigated with two different techniques: partial root drying and 100% crop evapotranspiration. The main goal of the monitoring activity is to assess possible differences between the developed root systems and the root water uptake between the two irrigation strategies. The monitoring is conducted using 3D micro-electrical resistivity tomography (ERT) based on an apparatus composed of a number of micro-boreholes (about 1.2 m deep) housing 12 electrodes each, plus a number of surface electrodes. Time-lapse measurements conducted both with long-term periodicity and short-term repetition before and after irrigation clearly highlight the presence and distribution of root water uptake zone both at shallow and larger depth, likely to correspond to zones utilized during the irrigation period (shallow) and during the time when the crop is not irrigated (deep). Subsidiary information is available in terms of precipitation, sap flow measurements and micrometeorological evapotranspiration estimates. This data ensemble lends itself to the assimilation into a variably saturated flow model, where both soil hydraulic parameters and root distribution shall be identified. Preliminary results in this directions show

  19. Contact resistance problems applying ERT on low bulk density forested stony soils. Is there a solution?

    NASA Astrophysics Data System (ADS)

    Deraedt, Deborah; Touzé, Camille; Robert, Tanguy; Colinet, Gilles; Degré, Aurore; Garré, Sarah

    2015-04-01

    Electrical resistivity tomography (ERT) has often been put forward as a promising tool to quantify soil water and solute fluxes in a non-invasive way. In our experiment, we wanted to determine preferential flow processes along a forested hillslope using a saline tracer with ERT. The experiment was conducted in the Houille watershed, subcatchment of the Meuse located in the North of Belgian Ardennes (50° 1'52.6'N, 4° 53'22.5'E). The climate is continental but the soil under spruce (Picea abies (L.) Karst.) and Douglas fire stand (Pseudotsuga menziesii (Mirb.) Franco) remains quite dry (19% WVC in average) during the whole year. The soil is Cambisol and the parent rock is Devonian schist covered with variable thickness of silty loam soil. The soil density ranges from 1.13 to 1.87 g/cm3 on average. The stone content varies from 20 to 89% and the soil depth fluctuates between 70 and 130 cm. The ERT tests took place on June 1st 2012, April 1st, 2nd and 3rd 2014 and May 12th 2014. We used the Terrameter LS 12 channels (ABEM, Sweden) in 2012 test and the DAS-1 (Multi-Phase Technologies, United States) in 2014. Different electrode configurations and arrays were adopted for different dates (transect and grid arrays and Wenner - Schlumberger, Wenner alpha and dipole-dipole configurations). During all tests, we systematically faced technical problems, mainly related to bad electrode contact. The recorded data show values of contact resistance above 14873 Ω (our target value would be below 3000 Ω). Subsequently, we tried to improve the contact by predrilling the soil and pouring water in the electrode holes. The contact resistance improved to 14040 Ω as minimum. The same procedure with liquid mud was then tested to prevent quick percolation of the water from the electrode location. As a result, the lower contact resistance dropped to 11745 Ω. Finally, we applied about 25 litre of saline solution (CaCl2, 0.75g/L) homogeneously on the electrode grid. The minimum value of

  20. Electrical resistance tomography to monitor unsaturated moisture flow in cementitious materials

    SciTech Connect

    Hallaji, Milad; Seppänen, Aku; Pour-Ghaz, Mohammad

    2015-03-15

    Traditionally the electrically-based assessment of the moisture flow in cement-based materials relies on two- or four-point measurements. In this paper, imaging of moisture distribution with electrical resistance tomography (ERT) is considered. Especially, the aim is to study whether ERT could give information on unsaturated moisture flows in cases where the flow is non-uniform. In the experiment, the specimens are monitored with ERT during the water ingress. The ERT reconstructions are compared with neutron radiographs, which provide high resolution information on the 2D distribution of the moisture. The results indicate that ERT is able to detect the moisture movement and to show approximately the shape and position of the water front even if the flow is nonuniform.

  1. Geophysical Exploration of Castle Remains in Barwałd Górny (Near Kalwaria Zebrzydowska, Poland) Using Electrical Resistivity Tomography (ERT) with Assistance of Depth of Investigation Index (DOI) Method.

    NASA Astrophysics Data System (ADS)

    Glazer, Michał; Kula, Damian; Saternus, Robert; Lewicki, Paweł

    2014-09-01

    In March of 2014 at ruins of the 14th century castle, situated at the top of Mount Żar in Małopolska region, Poland, geophysical surveys were performed. Surveys were planned to investigate remains of the castle that could remain in the ground. Electrical Resistivity Tomography method was used there. In the paper 4 sections have been presented. During interpretation, as the supporting method, maps of Depth-of-Investigation (DOI) index have been used. Results of the surveys can point out potential remains of the castle walls and ruins of buildings that were situated in the stronghold

  2. Infiltration front monitoring using 3D Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Oxarango, Laurent; Audebert, Marine; Guyard, Helene; Clement, Remi

    2016-04-01

    The electrical resistivity tomography (ERT) geophysical method is commonly used to identify the spatial distribution of electrical resisitivity in the soil at the field scale. Recent progress in commercial acquisition systems allows repeating fast acquisitions (10 min) in order to monitor a 3D dynamic phenomenon. Since the ERT method is sensitive to moisture content variations, it can thus be used to delineate the infiltration shape during water infiltration. In heterogeneous conditions, the 3D infiltration shape is a crucial information because it could differ significantly from the homogeneous behavior. In a first step, the ERT method is validated at small scale (<1m) studying a suction infiltrometer test. The experiment is carried out in a pit filled with a homogenous silty-sandy soil. It is instrumented by 17 resistivity probes and 3 commercial capacitive moisture content probes to provide local measurements of the moisture content variation. The Multiple Inversion and Clustering Strategy (MICS) (Audebert et al 2014) is used to delineate the infiltration patern. A satisfying agreement between infiltration delineation and sensor measurements is obtained with a few centimeter accuracy on the moisture front location. In a second step, the same methodology is applied at a larger scale (> 10m). Two examples of leachate injection monitoring in municipal solid waste landfills are used to put forward benefits and limitations of the ERT-MICS method. Effective infiltration porosities in a range between 3% and 8% support the assumption of a flow in heterogeneous media. Audebert, M., R. Clément, N. Touze-Foltz, T. Günther, S. Moreau, and C. Duquennoi (2014), Time-lapse ERT interpretation methodology for leachate injection monitoring based on multiple inversions and a clustering strategy (MICS), Journal of Applied Geophysics, 111, 320-333. Keywords: ERT, infiltration front, field survey

  3. Investigations of discontinuous permafrost using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Lewkowicz, Antoni

    2016-04-01

    We have used electrical resistivity tomography (ERT) extensively over the past five years to examine frozen ground characteristics at natural and disturbed sites within the discontinuous permafrost zones of northern Canada. Examples of pure research include investigations to delimit permafrost patch size, to examine changes in permafrost conditions at altitudinal treeline, and to assess permafrost thickness in palsa bogs. Applied research has included hazard mapping where ERT, in association with boreholes, has been used to characterize permafrost conditions in different terrain units at Yukon communities as part of planning for climate change adaptation. ERT has also been used to examine temporal change through repeated surveys at sites equipped with permanent arrays. Rapid change is occurring at sites which were subject to recent forest fire in the Northwest Territories. Gradual reductions in average resistivity at sites along the Alaska Highway in Yukon and northern British Columbia indicate progressive increases in unfrozen moisture while ground temperatures at the same sites have increased only very slightly. We conclude that ERT should become a standard technique for the investigation of discontinuous permafrost sites and should be incorporated as a monitoring technique within international programs such as the Global Terrestrial Network for Permafrost.

  4. Using electrical resistance tomography to map subsurface temperatures

    DOEpatents

    Ramirez, Abelardo L.; Chesnut, Dwayne A.; Daily, William D.

    1994-01-01

    A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations.

  5. Using electrical resistance tomography to map subsurface temperatures

    DOEpatents

    Ramirez, A.L.; Chesnut, D.A.; Daily, W.D.

    1994-09-13

    A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations. 1 fig.

  6. Applications of electrical resistance tomography to subsurface environmental restoration

    SciTech Connect

    Ramirez, A.L.; Daily, W.D.

    1994-11-15

    We are developing a new imaging technique, Electrical Resistance Tomography (ERT), to map subsurface liquids as flow occurs during natural or clean-up processes and to map geologic structure. Natural processes (such as surface water infiltrating the vadose zone) and man-induced processes (such as tank leaks and clean-up processes such as steam injection), can create changes in a soil`s electrical properties that are readily measured. We have conducted laboratory and a variety of field experiments to investigate the capabilities and limitations of ERT for imaging underground structures and processes. In the last four years we have used ERT to successfully monitor several field processes including: a subsurface steam injection process (for VOC removal), an air injection process (below the water table) for VOC removal, water infiltration through the vadose zone, radio-frequency heating, ohmic heating, and tank and pond leaks. The information derived from ERT can be used by remediation projects to: detect and locate leaks, determine the effectiveness of clean-up processes, select appropriate clean-up alternatives, and to verify the installation and performance of subsurface barriers.

  7. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, A.L.; Cooper, J.F.; Daily, W.D.

    1996-02-27

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination. 1 fig.

  8. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, Abelardo L.; Cooper, John F.; Daily, William D.

    1996-01-01

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination.

  9. A unique data acquisition system for electrical resistance tomography

    SciTech Connect

    Daily, W.; Ramirez, A.; Zonge, K.

    1996-01-04

    Unique capabilities are needed in instrumentation used for acquiring data to do electrical resistance tomography (ERT). A data acquisition system is described which has a good combination of the required capabilities and yet is field rugged and user friendly. The system is a multichannel detector for high data rates, can operate over a wide range of load conditions, will measure both in phase and quadrature resistance at frequencies between 0.0007 Hz and 8 kHz. The system has been used in both the field and laboratory to collect data with a typical accuracy between 1 and 10%.

  10. Soil characterization using electrical resistivity tomography and geotechnical investigations

    NASA Astrophysics Data System (ADS)

    Sudha, Kumari; Israil, M.; Mittal, S.; Rai, J.

    2009-01-01

    Electrical Resistivity Tomography (ERT) has been used in association with Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) for Geotechnical investigations at two sites, proposed for thermal power plants, in Uttar Pradesh (UP), India. SPT and DCPT tests were conducted at 28 points and two ERT profiles, each measuring 355 m long, were recorded using 72 electrodes deployed at 5 m spacing. Electrical characterization of subsurface soil was done using borehole data and grain size analysis of the soil samples collected from boreholes. The concept of electrical resistivity variation with soil strength related to the grain size distribution, cementation, porosity and saturation has been used to correlate the transverse resistance of soil with the number of blow counts ( N-values) obtained from SPT and DCPT data. It was thus observed that the transverse resistance of soil column is linearly related with the number of blow counts ( N-values) at these sites. The linear relationships are site-specific and the coefficients of linear relation are sensitive to the lithology of subsurface formation, which was verified by borehole data. The study demonstrates the usefulness of the ERT method in geotechnical investigations, which is economic, efficient and less time consuming in comparison to the other geotechnical methods, such as SPT and DCPT, used for the purpose.

  11. Influence of salinity and moisture content in electrical resistivity tomography readings in geomaterials used in construction

    NASA Astrophysics Data System (ADS)

    Gomez-Heras, Miguel; Fort, Rafael; Garcia Morales, Soledad

    2014-05-01

    Wetness and salts are among the main agents hindering the performance of any porous building material. There are a number of techniques based on electrical properties for the detection of these agents in buildings, such as portable moisture meters and electric resistivity tomography (ERT). These methods are used to locate wet areas based on the lower electrical resistivity wet materials have in relation to dry ones. However, as both moisture and salts contribute to low resistivity readings, the ERT readings may have a degree of uncertainty. This research aims to study the contribution of salinity and moisture content on the readings of ERT by testing laminated gypsum boards in the laboratory with solutions with different compositions (i.e. sodium chloride, magnesium sulphate and a mixture of both) and concentrations of salts. An industrial product, such as the laminated gypsum board, was chosen to minimize the effects that heterogeneities in composition and physical properties could have in the ERT readings and facilitate the interpretation of the wetness/salt content difference. Gypsum board was soaked with a fixed amount of the chosen solutions and several ERT transects were performed with a GeoTom device (Geolog2000) while drying. Results show the influence salinity of solutions have in drying process, and how the salt content remaining within the pores of geomaterials impact on ERT results. Research funded by Geomateriales (S2009/MAT-16) and CEI Moncloa (UPM, UCM, CSIC) through a PICATA contract and the equipment from RedLAbPAt Network

  12. Imaging pathways in fractured rock using three-dimensional electrical resistivity tomography

    USGS Publications Warehouse

    Robinson, Judith; Slater, Lee; Johnson, Timothy B.; Shapiro, Allen M.; Tiedeman, Claire; Ntlargiannis, Dimitrios; Johnson, Carole D.; Day-Lewis, Frederick D.; Lacombe, Pierre; Imbrigiotta, Thomas; Lane, Jr., John W.

    2016-01-01

    Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used three-dimensional cross borehole electrical resistivity tomography (ERT) in a 9 m (diameter) × 15 m well field to capture high-resolution flow and transport processes in a fractured mudstone contaminated by chlorinated solvents, primarily trichloroethylene. Conductive (sodium bromide) and resistive (deionized water) injections were monitored in seven boreholes. Electrode arrays with isolation packers and fluid sampling ports were designed to enable acquisition of ERT measurements during pulsed tracer injections. Fracture zone locations and hydraulic pathways inferred from hydraulic head drawdown data were compared with electrical conductivity distributions from ERT measurements. Static ERT imaging has limited resolution to decipher individual fractures; however, these images showed alternating conductive and resistive zones, consistent with alternating laminated and massive mudstone units at the site. Tracer evolution and migration was clearly revealed in time-lapse ERT images and supported by in situ borehole vertical apparent conductivity profiles collected during the pulsed tracer test. While water samples provided important local information at the extraction borehole, ERT delineated tracer migration over spatial scales capturing the primary hydrogeological heterogeneity controlling flow and transport. The fate of these tracer injections at this scale could not have been quantified using borehole logging and/or borehole sampling methods alone.

  13. Imaging Pathways in Fractured Rock Using Three-Dimensional Electrical Resistivity Tomography.

    PubMed

    Robinson, Judith; Slater, Lee; Johnson, Timothy; Shapiro, Allen; Tiedeman, Claire; Ntarlagiannis, Dimitrios; Johnson, Carole; Day-Lewis, Frederick; Lacombe, Pierre; Imbrigiotta, Thomas; Lane, John

    2016-03-01

    Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used three-dimensional cross borehole electrical resistivity tomography (ERT) in a 9 m (diameter) × 15 m well field to capture high-resolution flow and transport processes in a fractured mudstone contaminated by chlorinated solvents, primarily trichloroethylene. Conductive (sodium bromide) and resistive (deionized water) injections were monitored in seven boreholes. Electrode arrays with isolation packers and fluid sampling ports were designed to enable acquisition of ERT measurements during pulsed tracer injections. Fracture zone locations and hydraulic pathways inferred from hydraulic head drawdown data were compared with electrical conductivity distributions from ERT measurements. Static ERT imaging has limited resolution to decipher individual fractures; however, these images showed alternating conductive and resistive zones, consistent with alternating laminated and massive mudstone units at the site. Tracer evolution and migration was clearly revealed in time-lapse ERT images and supported by in situ borehole vertical apparent conductivity profiles collected during the pulsed tracer test. While water samples provided important local information at the extraction borehole, ERT delineated tracer migration over spatial scales capturing the primary hydrogeological heterogeneity controlling flow and transport. The fate of these tracer injections at this scale could not have been quantified using borehole logging and/or borehole sampling methods alone.

  14. Monitoring High Velocity Salt Tracer via 4D Electrical Resistivity Tomography - Possibility for Salt Tracer Tomography

    NASA Astrophysics Data System (ADS)

    Doro, K. O.; Cirpka, O. A.; Patzelt, A.; Leven, C.

    2014-12-01

    Hydrogeological testing in a tomographic sequence as shown by the use of hydraulic tomography, allows an improvement of the spatial resolution of subsurface parameters. In this regard, recent studies show increasing interest in tracer tomography which involves sequential and spatially separated tracer injections and the measurement of their corresponding tracer breakthrough at different locations and depths. Such concentration measurements however require large experimental efforts and can be simplified by geophysical tracer monitoring techniques such as electrical resistivity. In this study, we present the use of 4-D, cross-hole electrical resistivity tomography (ERT) for monitoring salt tracer experiments in high velocity flow fields. For our study, we utilized a set up that enables the conduction of salt tracer experiments with complete recovery within 84 hours over a transport distance of 16 m. This allows the repetition of the experiments with different injection depths for a tomographic salt tracer testing. For ERT monitoring, we designed modular borehole electrodes for repeated usage in a flexible manner. We also assess the use of a high speed resistivity data acquisition mode for field scale tracer monitoring ensuring high spatial and temporal resolution without sacrificing data accuracy. We applied our approach at the Lauswiesen test site, Tübingen, Germany. In our 10 m × 10 m tracer monitoring domain with 16 borehole electrodes, we acquired 4650 data points in less than 18 minutes for each monitoring cycle. Inversion results show that the tracer could be successfully imaged using this approach. The results show that repeated salt tracer tests can be efficiently monitored at a high resolution with ERT which gives the possibility for salt tracer tomography at field scale. Our results also provide a data base for extending current hydrogeophysical inversion approaches to field scale data.

  15. Delineation of graves using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Nero, Callistus; Aning, Akwasi Acheampong; Danuor, Sylvester K.; Noye, Reginald M.

    2016-03-01

    A suspected old royal cemetery has been surveyed at the Kwame Nkrumah University of Science and Technology (KNUST) campus, Kumasi, Ghana using Electrical Resistivity Tomography (ERT) with the objective of detecting graves in order to make informed decisions with regard to the future use of the area. The survey was conducted on a 10,000 m2 area. Continuous Vertical Electrical Sounding (CVES) was combined with the roll along technique for 51 profiles with 1 m probe separation separated by 2 m. Inverted data results indicated wide resistivity variations ranging between 9.34 Ωm and 600 Ωm in the near surface. Such heterogeneity suggests a disturbance of the soil at this level. Both high (≥ 600 Ωm) and low resistivity (≤ 74.7 Ωm) anomalies, relative to background levels, were identified within the first 4 m of the subsurface. These were suspected to be burial tombs because of their rectangular geometries and resistivity contrasts. The results were validated with forward numerical modeling results. The study area is therefore an old cemetery and should be preserved as a cultural heritage site.

  16. Monitoring of olive oil mills' wastes using electrical resistivity tomography techniques

    NASA Astrophysics Data System (ADS)

    Simyrdanis, Kleanthis; Papadopoulos, Nikos; Kirkou, Stella; Sarris, Apostolos; Tsourlos, Panagiotis

    2014-08-01

    Olive oil mills' wastes (OOMW) are one of the byproducts of the oil production that can lead to serious environmental pollution when they are deposited in ponds dug on the ground surface. Electrical Resistivity Tomography (ERT) method can provide a valuable tool in order to monitor through time the physical flow of the wastes into the subsurface. ERT could potentially locate the electrical signature due to lower resistivity values resulting from the leakage of OOMW to the subsurface. For this purpose, two vertical boreholes were installed (12m depth, 9 m apart) in the vicinity of an existing pond which is filled with OOMW during the oil production period. The test site is situated in Saint Andreas village about 15km south of the city of Rethymno (Crete, Greece). Surface ERT measurements were collected along multiple lines in order to reconstruct the subsurface resistivity models. Data acquisition was performed with standard and optimized electrode configuration protocols. The monitoring survey includes the ERT data collection for a period of time. The study was initiated before the OOMW were deposited in the pond, so resistivity fluctuations are expected due to the flow of OOMW in the porous subsurface media through time. Preliminary results show the good correlation of the ERT images with the drilled geological formations and the identification of low resistivity subsurface zone that could be attributed to the flow of the wastes within the porous layers.

  17. Electrical resistance tomography for imaging the spatial distribution of moisture in pavement sections

    SciTech Connect

    Buettner, M.; Ramirez, A.; Daily, W.

    1995-11-08

    Electrical Resistance Tomography (ERT) was used to image spatial moisture distribution and movement in pavement sections during an infiltration test. ERT is a technique for determining the electrical resistivity distribution within a volume from measurement of injected currents and the resulting electrical potential distribution on the surface. The transfer resistance (ratio of potential to injected current) data are inverted using an algorithm based on a finite element forward solution which is iteratively adjusted in a least squares sense until the measured and calculated transfer resistances agree to within some predetermined value. Four arrays of ERT electrodes were installed in vertical drill holes 1.22 m (4 ft) placed at the comers of a square 61 cm (2 ft) on a side into a pavement section which is used for a truck scale ramp on U.S. Highway 99 just north of Sacramento, CA. Water was introduced slowly into the pavement through a shallow hole in the center of this pattern and ERT data were collected in various planes as the water infiltrated into the pavement and subgrade materials over a period of several hours. The ERT data were inverted, and the resulting images show (1) the basic structure of the pavement section and (2) the movement of water through the image planes as a function of time during infiltration. An interesting result is that the water does not appear to drain from the section toward the shoulder as had been expected based on the design.

  18. Anisotropic resistivity tomography

    NASA Astrophysics Data System (ADS)

    Herwanger, J. V.; Pain, C. C.; Binley, A.; de Oliveira, C. R. E.; Worthington, M. H.

    2004-08-01

    Geophysical tomographic techniques have the potential to remotely detect and characterize geological features, such as fractures and spatially varying lithologies, by their response to signals passed through these features. Anisotropic behaviour in many geological materials necessitates the generalization of tomographic methods to include anisotropic material properties in order to attain high-quality images of the subsurface. In this paper, we present a finite element (FE) based direct-current electrical inversion method to reconstruct the conductivity tensor at each node point of a FE mesh from electrical resistance measurements. The inverse problem is formulated as a functional optimization and the non-uniqueness of the electrical inverse problem is overcome by adding penalty terms for structure and anisotropy. We use a modified Levenberg-Marquardt method for the functional optimization and the resulting set of linear equation is solved using pre-conditioned conjugate gradients. The method is tested using both synthetic and field experiments in cross-well geometry. The acquisition geometry for both experiments uses a cross-well experiment at a hard-rock test site in Cornwall, southwest England. Two wells, spaced at 25.7 m, were equipped with electrodes at a 1 m spacing at depths from 21-108 m and data were gathered in pole-pole geometry. The test synthetic model consists of a strongly anisotropic and conductive body underlain by an isotropic resistive formation. Beneath the resistive formation, the model comprises a moderately anisotropic and moderately conductive half-space, intersected by an isotropic conductive layer. This model geometry was derived from the interpretation of a seismic tomogram and available geological logs and the conductivity values are based on observed conductivities. We use the test model to confirm the ability of the inversion scheme to recover the (known) true model. We find that all key features of the model are recovered. However

  19. Evaluating four-dimensional time-lapse electrical resistivity tomography for monitoring DNAPL source zone remediation.

    PubMed

    Power, Christopher; Gerhard, Jason I; Karaoulis, Marios; Tsourlos, Panagiotis; Giannopoulos, Antonios

    2014-07-01

    Practical, non-invasive tools do not currently exist for mapping the remediation of dense non-aqueous phase liquids (DNAPLs). Electrical resistivity tomography (ERT) exhibits significant potential but has not yet become a practitioner's tool due to challenges in interpreting the survey results at real sites. This study explores the effectiveness of recently developed four-dimensional (4D, i.e., 3D space plus time) time-lapse surface ERT to monitor DNAPL source zone remediation. A laboratory experiment demonstrated the approach for mapping a changing NAPL distribution over time. A recently developed DNAPL-ERT numerical model was then employed to independently simulate the experiment, providing confidence that the DNAPL-ERT model is a reliable tool for simulating real systems. The numerical model was then used to evaluate the potential for this approach at the field scale. Four DNAPL source zones, exhibiting a range of complexity, were initially simulated, followed by modeled time-lapse ERT monitoring of complete DNAPL remediation by enhanced dissolution. 4D ERT inversion provided estimates of the regions of the source zone experiencing mass reduction with time. Results show that 4D time-lapse ERT has significant potential to map both the outline and the center of mass of the evolving treated portion of the source zone to within a few meters in each direction. In addition, the technique can provide a reasonable, albeit conservative, estimate of the DNAPL volume remediated with time: 25% underestimation in the upper 2m and up to 50% underestimation at late time between 2 and 4m depth. The technique is less reliable for identifying cleanup of DNAPL stringers outside the main DNAPL body. Overall, this study demonstrates that 4D time-lapse ERT has potential for mapping where and how quickly DNAPL mass changes in real time during site remediation.

  20. Electrical Resistivity Tomography in the characterisation of wetting patterns of historical masonry

    NASA Astrophysics Data System (ADS)

    López-González, Laura; Gomez-Heras, Miguel; Ortiz de Cosca, Raquel Otero; García-Morales, Soledad

    2016-04-01

    Electrical Resistivity Tomography (ERT) is a geophysical technique widely used to identify subsurface structures based on electrical resistivity measurements made at the surface. In recent years this technique has been used for surveying historic buildings and characterise the subsurface of walls by using non-invasive EKG electrodes. This methods is used to locate wet areas based on the lower electrical resistivity wet materials have in relation to dry ones. A good knowledge of the wetting patterns of historic buildings during, for example, rainfalls is crucial to understand the decay processes that take place in the building and plan interventions. This paper presents results of transects of Electric Resistivity Tomography of walls of the Monastery of Santa Maria de Mave (Palencia, Spain), a 9th century Romanesque building, during rainfall. ERT transects were performed with a GeoTom device (Geolog2000) in areas with and without buttresses to understand how this architectural detail affected the wetting dynamics of the building. The ERT results were integrated with other resistivity-based techniques and Thermohygrometric survey in a GIS and showed how lower resistivity surface measurements ERT correspond with areas of higher humidity. Resistivity-based techniques measured and evaporation focal points take in the interior of the building mark the outer ground level. The highest moisture content measurements do not always correspond to the visibly most damaged areas of the wall. The consecutive ERT transects show the wall getting wetter as rainfall progresses. The comparison of the measurements obtained of a wall affected by water obtained with GIS mapping, allowed to quickly studying the development of moisture in the wall over time, which is essential for a correct diagnosis of the building. Research funded by Madrid's Regional Government project Geomateriales 2 S2013/MIT-2914

  1. Tracking tracer motion in a 4-D electrical resistivity tomography experiment

    NASA Astrophysics Data System (ADS)

    Ward, W. O. C.; Wilkinson, P. B.; Chambers, J. E.; Nilsson, H.; Kuras, O.; Bai, L.

    2016-05-01

    A new framework for automatically tracking subsurface tracers in electrical resistivity tomography (ERT) monitoring images is presented. Using computer vision and Bayesian inference techniques, in the form of a Kalman filter, the trajectory of a subsurface tracer is monitored by predicting and updating a state model representing its movements. Observations for the Kalman filter are gathered using the maximally stable volumes algorithm, which is used to dynamically threshold local regions of an ERT image sequence to detect the tracer at each time step. The application of the framework to the results of 2-D and 3-D tracer monitoring experiments show that the proposed method is effective for detecting and tracking tracer plumes in ERT images in the presence of noise, without intermediate manual intervention.

  2. Predicting and tracking spatiotemporal moments in electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Ward, W. O. C.; Wilkinson, P. B.; Chambers, J.; Bai, L.

    2015-12-01

    Visualisation is an invaluable tool in the study of near sub-surface processes, whether by mathematical modelling or by geophysical imaging. Quantitative analysis can further assist interpretation of the ongoing physical processes, and it is clear that any reliable model should take direct observations into account. Using electrical resistivity tomography (ERT), localised areas can be surveyed to produce 2-D and 3-D time-lapse images. This study investigates combining quantitative results obtained via ERT with spatio-temporal motion models in tracer experiments to interpret and predict fluid flow. As with any indirect imaging technique, ERT suffers specific issues with resolution and smoothness as a result of its inversion process. In addition, artefacts are typical in the resulting volumes. Mathematical models are also a source of uncertainty - and in combining these with ERT images, a trade-off must be made between the theoretical and the observed. Using computational imaging, distinct regions of stable resistivity can be directly extracted from a time-slice of an ERT volume. The automated nature, as well the potential for more than one region-of-interest, means that multiple regions can be detected. Using Kalman filters, it is possible to convert the detections into a process state, taking into account pre-defined models and predicting progression. In consecutive time-steps, newly detected features are assigned, where possible, to existing predictions to create tracks that match the tracer model. Preliminary studies looked at a simple motion model, tracking the centre of mass of a tracer plume with assumed constant velocity and mean resistivity. Extending the model to factor in spatial distribution of the plume, an oriented semi-axis is used to represent the centralised second-order moment, with an increasing factor of magnitude to represent the plume dispersion. Initial results demonstrate the efficacy of the approach, significantly improving reliability as the

  3. Tank Leak Experiment at the Monk Tank Site, 200 East Area: Electrical Resistance Tomography-Preliminary Results

    SciTech Connect

    Ramirez, A.; Daily, W.D.; Binley, A.

    2001-09-20

    This report covers the electrical resistance tomography (ERT) work performed at the Mock Tank site, 200 East Area, Hanford Reservation, during the months of July and August, 2001. The work reported herein is to be considered preliminary because it is work in progress. Some of the analyses and interpretation of results are incomplete at this time.

  4. Electrical Resistivity Tomography Monitoring of Soil Remediation for a Garbage Dump

    NASA Astrophysics Data System (ADS)

    shi, X.; Luo, Z.; Zhang, Y.; Fu, Q.; Xu, Z.

    2011-12-01

    Electrical resistivity tomography (ERT) survey was firstly used to investigate the distribution of contaminated soil in a garbage dump area, Wuhan city, China. The result shows that sulfated soil resistivity is about 4 to 7 ohm-m, which is relatively lower than normal soil resistivity of about 15 to 25 ohm-m. The distribution of contaminated soil was delineated using ERT images. Then, ERT survey was carried out in this area for monitoring of remediation of contaminated soil and groundwater. Werner measurements with 60 electrodes of 1 m spacing were taken during the 9-well oxygen injection and nutrition liquid injection period. The difference of apparent resistivity between before gas injection and after gas injection was used to delineate the channel of gas and the trace of gas migration in the porous garbage dump. The electrical resitivity changes between before and after nutrition liquid injection were used to analyze the liquid migration and distribution. The dynamic procedures of gas and water migration are outlined. The results suggest that ERT is a powerful technique for monitoring of soil remediation.

  5. Electrical resistivity tomography study of Taal volcano hydrothermal system, Philippines

    NASA Astrophysics Data System (ADS)

    Fikos, I.; Vargemezis, G.; Zlotnicki, J.; Puertollano, J. R.; Alanis, P. B.; Pigtain, R. C.; Villacorte, E. U.; Malipot, G. A.; Sasai, Y.

    2012-10-01

    Taal volcano (311 m in altitude) is located in The Philippines (14°N, 121°E) and since 1572 has erupted 33 times, causing more than 2,000 casualties during the most violent eruptions. In March 2010, the shallow structures in areas where present-day surface activity takes place were investigated by DC resistivity surveys. Electrical resistivity tomography (ERT) lines were performed above the two identified hydrothermal areas located on the northern flank of the volcano and in the Main Crater, respectively. Due to rough topography, deep valleys, and dense vegetation, most measurements were collected using a remote method based on a laboratory-made equipment. This allowed retrieval of information down to a depth of 250 m. ERTs results detail the outlines of the two geothermal fields defined by previous self-potential, CO2 soil degassing, ground temperature, and magnetic mapping (Harada et al. Japan Acad Sci 81:261-266, 2005; Zlotnicki et al. Bull Volcanol 71:29-49, 2009a, Phys Chem Earth 34:294-408, 2009b). Hydrothermal fluids originate mainly from inside the northern part of the Main Crater at a depth greater than the bottom of the Crater Lake, and flow upward to the ground surface. Furthermore, water from the Main Crater Lake infiltrates inside the surrounding geological formations. The hydrothermal fluids, outlined by gas releases and high temperatures, cross the crater rim and interact with the northern geothermal field located outside the Main Crater.

  6. Small scale monitoring of a bioremediation barrier using miniature electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Sentenac, Philippe; Hogson, Tom; Keenan, Helen; Kulessa, Bernd

    2015-04-01

    The aim of this study was to assess, in the laboratory, the efficiency of a barrier of oxygen release compound (ORC) to block and divert a diesel plume migration in a scaled aquifer model using miniature electrical resistivity tomography (ERT) as the monitoring system. Two plumes of contaminant (diesel) were injected in a soil model made of local sand and clay. The diesel plumes migration was imaged and monitored using a miniature resistivity array system that has proved to be accurate in soil resistivity variations in small-scaled models of soil. ERT results reflected the lateral spreading and diversion of the diesel plumes in the unsaturated zone. One of the contaminant plumes was partially blocked by the ORC barrier and a diversion and reorganisation of the diesel in the soil matrix was observed. The technique of time-lapse ERT imaging showed that a dense non-aqueous phase liquid (DNAPL) contaminant like diesel can be monitored through a bioremediation barrier and the technique is well suited to monitor the efficiency of the barrier. Therefore, miniature ERT as a small-scale modelling tool could complement conventional techniques, which require more expensive and intrusive site investigation prior to remediation.

  7. Preliminary analysis of the use of electrical resistance tomography for injectate tracking at the Geysers geothermal field

    SciTech Connect

    Creed, Bob; Daily, Bill

    1996-01-24

    Current geochemical and geophysical injectate tracking methods are useful reservoir management techniques but do not track injectate movement quick enough to maximize injection efficiency or avoid negative impacts on nearby steam production wells. A preliminary analysis indicates that two dimensional electrical resistance tomography (ERT) may be useful for imaging plume movement resulting from Geysers/Lake County Effluent Pipeline injectate in near real time. ERT models comparing an injection plume resistivity of 50 Ohm-m with background resistivities of 10, 100 (typical Geysers greywacke), and 500 Ohm-m (typical Geysers felsite) indicate that liquid plumes can be imaged at depths of 6,000 feet to 8,000 feet or greater for resistivity contrasts of 2 to 1 or greater. Further refinement of the ERT model could be accomplished with more data on porosity in the vicinity of the borehole, resistivity measurements, and reservoir engineering estimates of plume temperature and saturation. Based on the results of this analysis and previous successes in using ERT to map shallow subsurface steam and water movement in porous media it is likely, but not certain, that ERT will prove to be an additional reservoir management tool to be used in conjunction with additional geochemical, geophysical, and reservoir engineering techniques. A field scale test at The Geysers is required to verify the utility of ERT for injectate tracking. The goal of this paper is to stimulate discussion among geothermal researchers regarding use of the ERT technique for injectate tracking at The Geysers and get some input on the appropriateness and utility of the assumptions used.

  8. The data preprocessing in apparent resistivity pesudo-section construction of two-dimensional electrical resistivity tomography survey

    NASA Astrophysics Data System (ADS)

    Zhou, Q.

    2015-12-01

    Although three-dimensional (3-D) electrical resistivity tomography (ERT) survey has become a popular practice in the site characterization and process monitoring, the two-dimensional (2-D) ERT survey is still often used in the field. This is because that the 2-D ERT survey is relatively easy to do and the focus of site characterization is on the information of 2-D cross section, not necessarily of the 3-D subsurface structure. Examples of such practice include tunnel line and crossing fault survey. In these cases, depending on the property of surface soil to be surveyed, the 2-D ERT survey with pole-pole array may occasionally make us obtain quality good data, however it often gives us a suit of data set both with real and erroneous ones that incorporated the effects of electrode contact and not far enough far electrodes. Without preprocessing, the apparent resistivity pseudo-section constructed from this kind of data set may quite deviate from the real one and the information obtained from it may be misleading and even completely incorrect. In this study, we developed a method of far electrode dynamic correction that is appropriate for raw data preprocessing from 2-D pole-pole array ERT survey. Based on this method, we not only can find and delete the abnormal data points easily, but also can position the coordinates of far electrodes actually working in the field, thus delete the far electrode effects and make best use of the looked strange data points. The method also makes us to be able to judge the effects of electrode contact and avoid using such data points in the following apparent resistivity pseudo-section construction. With this preprocessing to the data set, the constructed apparent resistivity pseudo-section is demonstrated to be more approximate to the real one. This makes the following reversion calculation more robust. We'll introduce this far electrode dynamic correction method and show application examples in the meeting.

  9. Uncertainty quantification of CO₂ saturation estimated from electrical resistance tomography data at the Cranfield site

    DOE PAGESBeta

    Yang, Xianjin; Chen, Xiao; Carrigan, Charles R.; Ramirez, Abelardo L.

    2014-06-03

    A parametric bootstrap approach is presented for uncertainty quantification (UQ) of CO₂ saturation derived from electrical resistance tomography (ERT) data collected at the Cranfield, Mississippi (USA) carbon sequestration site. There are many sources of uncertainty in ERT-derived CO₂ saturation, but we focus on how the ERT observation errors propagate to the estimated CO₂ saturation in a nonlinear inversion process. Our UQ approach consists of three steps. We first estimated the observational errors from a large number of reciprocal ERT measurements. The second step was to invert the pre-injection baseline data and the resulting resistivity tomograph was used as the priormore » information for nonlinear inversion of time-lapse data. We assigned a 3% random noise to the baseline model. Finally, we used a parametric bootstrap method to obtain bootstrap CO₂ saturation samples by deterministically solving a nonlinear inverse problem many times with resampled data and resampled baseline models. Then the mean and standard deviation of CO₂ saturation were calculated from the bootstrap samples. We found that the maximum standard deviation of CO₂ saturation was around 6% with a corresponding maximum saturation of 30% for a data set collected 100 days after injection began. There was no apparent spatial correlation between the mean and standard deviation of CO₂ saturation but the standard deviation values increased with time as the saturation increased. The uncertainty in CO₂ saturation also depends on the ERT reciprocal error threshold used to identify and remove noisy data and inversion constraints such as temporal roughness. Five hundred realizations requiring 3.5 h on a single 12-core node were needed for the nonlinear Monte Carlo inversion to arrive at stationary variances while the Markov Chain Monte Carlo (MCMC) stochastic inverse approach may expend days for a global search. This indicates that UQ of 2D or 3D ERT inverse problems can be performed

  10. Uncertainty quantification of CO₂ saturation estimated from electrical resistance tomography data at the Cranfield site

    SciTech Connect

    Yang, Xianjin; Chen, Xiao; Carrigan, Charles R.; Ramirez, Abelardo L.

    2014-06-03

    A parametric bootstrap approach is presented for uncertainty quantification (UQ) of CO₂ saturation derived from electrical resistance tomography (ERT) data collected at the Cranfield, Mississippi (USA) carbon sequestration site. There are many sources of uncertainty in ERT-derived CO₂ saturation, but we focus on how the ERT observation errors propagate to the estimated CO₂ saturation in a nonlinear inversion process. Our UQ approach consists of three steps. We first estimated the observational errors from a large number of reciprocal ERT measurements. The second step was to invert the pre-injection baseline data and the resulting resistivity tomograph was used as the prior information for nonlinear inversion of time-lapse data. We assigned a 3% random noise to the baseline model. Finally, we used a parametric bootstrap method to obtain bootstrap CO₂ saturation samples by deterministically solving a nonlinear inverse problem many times with resampled data and resampled baseline models. Then the mean and standard deviation of CO₂ saturation were calculated from the bootstrap samples. We found that the maximum standard deviation of CO₂ saturation was around 6% with a corresponding maximum saturation of 30% for a data set collected 100 days after injection began. There was no apparent spatial correlation between the mean and standard deviation of CO₂ saturation but the standard deviation values increased with time as the saturation increased. The uncertainty in CO₂ saturation also depends on the ERT reciprocal error threshold used to identify and remove noisy data and inversion constraints such as temporal roughness. Five hundred realizations requiring 3.5 h on a single 12-core node were needed for the nonlinear Monte Carlo inversion to arrive at stationary variances while the Markov Chain Monte Carlo (MCMC) stochastic inverse approach may expend days for a global search. This indicates that UQ of 2D or 3D ERT inverse problems can be performed on a

  11. Monitoring a pilot CO2 injection experiment in a shallow aquifer using 3D cross-well electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Yang, X.; Lassen, R. N.; Looms, M. C.; Jensen, K. H.

    2014-12-01

    Three dimensional electrical resistance tomography (ERT) was used to monitor a pilot CO2 injection experiment at Vrøgum, Denmark. The purpose was to evaluate the effectiveness of the ERT method for monitoring the two opposing effects from gas-phase and dissolved CO2 in a shallow unconfined siliciclastic aquifer. Dissolved CO2 increases water electrical conductivity (EC) while gas phase CO2 reduce EC. We injected 45kg of CO2 into a shallow aquifer for 48 hours. ERT data were collected for 50 hours following CO2 injection. Four ERT monitoring boreholes were installed on a 5m by 5m square grid and each borehole had 24 electrodes at 0.5 m electrode spacing at depths from 1.5 m to 13 m. ERT data were inverted using a difference inversion algorithm for bulk EC. 3D ERT successfully detected the CO2 plume distribution and growth in the shallow aquifer. We found that the changes of bulk EC were dominantly positive following CO2 injection, indicating that the effect of dissolved CO2 overwhelmed that of gas phase CO2. The pre-injection baseline resistivity model clearly showed a three-layer structure of the site. The electrically more conductive glacial sand layer in the northeast region are likely more permeable than the overburden and underburden and CO2 plumes were actually confined in this layer. Temporal bulk EC increase from ERT agreed well with water EC and cross-borehole ground penetrating radar data. ERT monitoring offers a competitive advantage over water sampling and GPR methods because it provides 3D high-resolution temporal tomographic images of CO2 distribution and it can also be automated for unattended operation. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC. LLNL IM release#: LLNL-PROC-657944.

  12. 2D Time-lapse Resistivity Monitoring of an Organic Produced Gas Plume in a Landfill using ERT.

    NASA Astrophysics Data System (ADS)

    Amaral, N. D.; Mendonça, C. A.; Doherty, R.

    2014-12-01

    This project has the objective to study a landfill located on the margins of Tietê River, in São Paulo, Brazil, using the electroresistivity tomography method (ERT). Due to huge organic matter concentrations in the São Paulo Basin quaternary sediments, there is subsurface depth related biogas accumulation (CH4 and CO2), induced by anaerobic degradation of the organic matter. 2D resistivity sections were obtained from a test area since March 2012, a total of 7 databases, being the last one dated from October 2013. The studied line has the length of 56m, the electrode interval is of 2m. In addition, there are two boreholes along the line (one with 3 electrodes and the other one with 2) in order to improve data quality and precision. The boreholes also have a multi-level sampling system that indicates the fluid (gas or water) presence in relation to depth. With our results it was possible to map the gas plume position and its area of extension in the sections as it is a positive resistivity anomaly, with the gas level having approximately 5m depth. With the time-lapse analysis (Matlab script) between the obtained 2D resistivity sections from the site, it was possible to map how the biogas volume and position change in the landfill in relation to time. Our preliminary results show a preferential gas pathway through the subsurface studied area. A consistent relation between the gas depth and obtained microbiological data from archea and bacteria population was also observed.

  13. Electrical resistance tomography for real-time mapping of the solid-liquid interface in tanks containing optically opaque fluids

    NASA Astrophysics Data System (ADS)

    Madupu, Amar; Mazumdar, Anindra; Zhang, Jinsong; Roelant, David; Srivastava, Rajiv

    2005-03-01

    The visualization of settled solid layers in vessels have many applications, of interest here is for facilitating the efficient retrieval of high-level radioactive waste (HLW) from underground storage tanks at Department of Energy sites. Visualization of the solids interface with opaque liquid above can"t be accomplished by regular optical imaging methods and hence our interest in using Electrical Resistance Tomography (ERT). The ideal arrangement for 3-D ERT imaging inside tanks is to use a multiple ring electrode system, which is complex and expensive. This research describes ERT imaging done with a single linear array as a benchmark study to ascertain the viability of its imaging of the interface. Experiments focused upon systematic analysis of many ERT tomograms of two simple settled solids layers (horizontal, 30o) using pulverized kaolin clay (10μdia) and water. Visualization was done using commercial ERT software. Injection current and electrode orientation were the two system parameters varied and analyzed. Reproducibility, accuracy and reliability of this ERT system will be presented.

  14. Electrical Resistivity, Seismic Refraction Tomography and Drilling Logs to Identify the Heterogeneity and the Preferential Flow in a Shallow Aquifer

    NASA Astrophysics Data System (ADS)

    Lachhab, A.

    2015-12-01

    The study site is located at the Center for Environmental Education and Research (CEER) at Susquehanna University. Electrical Resistivity and Seismic Refraction Tomography (ERT and SRT), as well as several pumping tests were performed to identify zones of heterogeneities and hydrogeophysical characteristics of a shallow unconfined aquifer. The combination of these methods was selected to study the local geology and the subsurface preferential pathways of groundwater flow. 22 Dipole-Dipole ERT transects with 56 electrodes each and 11 SRT transects with 24 geophones each were performed. Drilling logs of 5 observation wells located within the site were also used. All drilling logs showed clearly the heterogeneity of the aquifer when compared to each other. The combination of ERT and SRT indicated that a potential zone of preferential flow is present within the aquifer and can be accurately identified based on the approach adopted in this study. The drilling logs served to specifically identify the soil and the geological formations making the heterogeneity of the aquifer. 3D ERT and SRT block diagrams were generated to connect all formations shown in the 2D tomography profiles to visualize the pathways of preferential flow and non-conductive formations. While ERT has proven to show saturated areas of the subsurface, SRT was more effective in identifying the bedrock-soil discontinuity and other near surface formations contributing to the local heterogeneity.

  15. Development of a Landslide Monitoring System using Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Hen-Jones, R. M.; Hughes, P. N.; Glendinning, S.; Gunn, D.; Chambers, J.; Stirling, R.

    2015-12-01

    Current assessments of slope stability rely on the use of point sensors, the results of which are often difficult to interpret, have relatively high associated installation and maintenance costs, and do not provide large-area coverage. A new system is currently under development, based on the use of integrated geophysical - geotechnical sensors to monitor ground water conditions via electrical resistivity tomography. This study presents the results of an in-situ electrical resistivity tomography survey, gathered over a two year investigation period at a full-scale clay test embankment in Northumberland, UK. The 3D resistivity array comprised 288 electrodes, at 0.7m grid spacing, covering an area of approximately 90 m2. The first year of investigation involved baseline data collection, followed by a second year which saw a series of deliberate interventions targeted at weakening the slope, to determine whether corresponding geotechnical property changes would be reflected in resistivity images derived from ERT. These interventions included the manual extension of four tension cracks already present in the slope, and the installation of a sprinkler system, eight months later. Laboratory methods were employed to derive a system of equations for relating resistivity to geotechnical parameters more directly relevant to slope stability, including moisture content, suction and shear strength. These equations were then applied to resistivity data gathered over the baseline and intervention periods, yielding geotechnical images of the subsurface which compared well with in-situ geotechnical point sensors. During the intervention period, no slope movement was recorded, however, tensiometers at 0.5 m and 1.0 m depths showed elevated pore pressures, with positive pressures being recorded at depths less than 0.5 m. Resistivity images were successful in capturing the extension of the tension cracks, and in identifying the development of a potential shear failure plane as water

  16. TOMOGRAPHIC SITE CHARACTERIZATION USING CPT, ERT, AND GPR

    SciTech Connect

    Rexford M. Morey; Susanne M. Conklin; Stephen P. Farrington, P.E.; James D. Shinn II, P.E.

    1999-07-01

    The US Department of Energy (DOE) is responsible for the cleanup of inactive DOE sites and for bringing DOE sites and facilities into compliance with federal, state, and local laws and regulations. The DOE's Office of Environmental Management (EM) needs advanced technologies that can make environmental restoration and waste management operations more efficient and less costly. These techniques are required to better characterize the physical, hydrogeological, and chemical properties of the subsurface while minimizing and optimizing the use of boreholes and monitoring wells. Today the cone penetrometer technique (CPT) is demonstrating the value of a minimally invasive deployment system for site characterization. Applied Research Associates, Inc. is developing two new sensor packages for site characterization and monitoring. The two new methods are: (1) Electrical Resistivity Tomography (ERT); and (2) Ground Penetrating Radar (GPR) Tomography. These sensor systems are now integrated with the CPT. The results of this program now make it possible to install ERT and GPR units by CPT methods and thereby reduce installation costs and total costs for ERT and GPR surveys. These two techniques can complement each other in regions of low resistivity where ERT is more effective and regions of high resistivity where GPR is more effective. The results show that CPT-installed GeoWells can be used for both ERT and GPR borehole tomographic subsurface imaging. These two imaging techniques can be used for environmental site characterization and monitoring have numerous and diverse applications within site cleanup and waste management operations.

  17. Estimation of tree root distribution using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Schmaltz, Elmar; Uhlemann, Sebastian

    2016-04-01

    Trees influence soil-mantled slopes mechanically by anchoring in the soil with coarse roots. Forest-stands play an important role in mechanical reinforcement to reduce the susceptibility to slope failures. However, the effect of stabilisation of roots is connected with the distribution of roots in the ground. The architecture and distribution of tree roots is diverse and strongly dependent on species, plant age, stand density, relief, nutrient supply as well as climatic and pedologic conditions. Particularly trees growing on inclined slopes show shape-shifting root systems. Geophysical techniques are commonly used to non-invasively study hydrological and geomorphological subsurface properties, by imaging contrasting physical properties of the ground. This also poses the challenge for geophysical imaging of root systems, as properties, such as electrical resistivity, of dry and wet roots fall within the range of soils. The objective of this study is whether electrical resistivity tomography (ERT) allows a reliable reproduction of root systems of alone-standing trees on diverse inclined slopes. In this regard, we set the focus on the branching of secondary roots of two common walnut trees (Juglans regia L.) that were not disturbed in the adjacencies and thus expected to develop their root systems unhindered. Walnuts show a taproot-cordate root system with a strong tap-root in juvenile age and a rising cordate rooting with increasing age. Hence, mature walnuts can exhibit a root system that appears to be deformed or shifted respectively when growing at hillslope locations. We employed 3D ERT centred on the tree stem, comprising dipole-dipole measurements on a 12-by-41 electrode grid with 0.5 m and 1.0m electrode spacing in x- and y-direction respectively. Data were inverted using a 3D smoothness constrained non-linear least-squares algorithm. First results show that the general root distribution can be estimated from the resistivity models and that shape

  18. Electrical resistance tomography for monitoring the infiltration of water into a pavement section

    SciTech Connect

    Buettner, M.; Daily, B.; Ramirez, A.

    1997-07-03

    Electrical resistance tomography (ERT) was used to follow the infiltration of water into pavement section at the UC Berkeley Richmond Field Station. A volume of pavement 1m square and 1.29 m deep was sampled by an ERT array consisting of electrodes in 9 drilled holes plus 8 surface electrodes. The data were collected using a computer controlled data acquisition system capable of collecting a full data set in under 1 hour, allowing for nearly real time sampling of the infiltration. The infiltration was conducted in two phases. During the first phase, water was introduced into the asphalt-concrete (AC) layers at a slow rate of about 8 ml per hour for a period of about 6 days. In the second phase, water was introduced into the asphalt-treated-permeable base (ATPB) layer at a more rapid rate of about 100 ml/h for about 2 days. The ERT images show that water introduced into the upper AC layers shows up as a decrease in resistivity which grows with time. The images also appear to show that when water moves into the layers below the ATPB, the resistivity increases; an unexpected result. There are some indications that the water moved laterally as well as down into the deeper ATPB and the aggregate base. The images also show that when water is introduced directly into the ATPB and aggregate layer, the water moves into the the underlying materials much more quickly.

  19. Characterization of a contaminated wellfield using 3D electrical resistivity tomography implemented with geostatistical, discontinuous boundary, and known conductivity constraints

    SciTech Connect

    Johnson, Timothy C.; Versteeg, Roelof J.; Rockhold, Mark L.; Slater, Lee D.; Ntarlagiannis, Dimitrios; Greenwood, William J.; Zachara, John M.

    2012-09-17

    Continuing advancements in subsurface electrical resistivity tomography (ERT) are giving the method increasing capability for understanding shallow subsurface properties and processes. The inability of ERT imaging data to uniquely resolve subsurface structure and the corresponding need include constraining information remains one of the greatest limitations, and provides one of the greatest opportunities, for further advancing the utility of the method. In this work we describe and demonstrate a method of incorporating constraining information into an ERT imaging algorithm in the form on discontinuous boundaries, known values, and spatial covariance information. We demonstrate the approach by imaging a uranium-contaminated wellfield at the Hanford Site in southwestern Washington State, USA. We incorporate into the algorithm known boundary information and spatial covariance structure derived from the highly resolved near-borehole regions of a regularized ERT inversion. The resulting inversion provides a solution which fits the ERT data (given the estimated noise level), honors the spatial covariance structure throughout the model, and is consistent with known bulk-conductivity discontinuities. The results are validated with core-scale measurements, and display a significant improvement in accuracy over the standard regularized inversion, revealing important subsurface structure known influence flow and transport at the site.

  20. Can we use Electrical Resistivity Tomography to measure root zone moisture dynamics in fields with multiple crops?

    NASA Astrophysics Data System (ADS)

    Garre, S.; Coteur, I.; Wongleecharoen, C.; Diels, J.; Vanderborght, J.

    2012-12-01

    Agriculture on shallow or steep soils in the humid tropics often leads to low resource use efficiency. Contour hedgerow intercropping systems have been proposed to reduce run-off and control soil erosion. However, competition for water and nutrients between crops and associated hedgerows may reduce the overall performance of contour hedgerow systems. Electrical resistivity tomography (ERT) is a valuable technique to assess the distribution and dynamics of soil moisture non-invasively. Root water uptake is a spatially variable and small-scale process, which requires at least decimeter resolution and a high sensitivity in order to be able to monitor changes in time and space. Careful experimental design is of uttermost importance in order to maximize the information content of the ERT survey and to gain insights in the possibilities and limitations of the survey. Virtual experiments in combination with absolute and spatial performance measures provide a way to optimize the information that can be retrieved from an ERT experiment. We used this approach to identify a suitable measurement methodology to monitor water fluxes in a contour hedgerow intercropping system in Ratchaburi province, Thailand. The virtual experiment showed that there are important differences between the tested measurement configurations. We saw that the optimal ERT array was capable of recognizing distinct water depletion zones under the different crops. However, sharp contrasts in the 1-D water depletion profile are smoothened. ERT measurements conducted in Thailand showed that the soils of our experimental plots were very heterogeneous both along the slope as with depth. This observation highlighted some constraints of the ERT method for soil moisture monitoring in the field, such as the difficulty to define a relationship between electrical conductivity and soil moisture in very heterogeneous soils. Nevertheless, the data indeed revealed contrasting water depletion patterns under monocropping

  1. Constraining 3-D electrical resistance tomography with GPR reflection data for improved aquifer characterization

    NASA Astrophysics Data System (ADS)

    Doetsch, Joseph; Linde, Niklas; Pessognelli, Mirco; Green, Alan G.; Günther, Thomas

    2012-03-01

    Surface-based ground penetrating radar (GPR) and electrical resistance tomography (ERT) are common tools for aquifer characterization, because both methods provide data that are sensitive to hydrogeologically relevant quantities. To retrieve bulk subsurface properties at high resolution, we suggest incorporating structural information derived from GPR reflection data when inverting surface ERT data. This reduces resolution limitations, which might hinder quantitative interpretations. Surface-based GPR reflection and ERT data have been recorded on an exposed gravel bar within a restored section of a previously channelized river in northeastern Switzerland to characterize an underlying gravel aquifer. The GPR reflection data acquired over an area of 240 × 40 m map the aquifer's thickness and two internal sub-horizontal regions with different depositional patterns. The interface between these two regions and the boundary of the aquifer with the underlying clay are incorporated in an unstructured ERT mesh. Subsequent inversions are performed without applying smoothness constraints across these boundaries. Inversion models obtained by using these structural constraints contain subtle resistivity variations within the aquifer that are hardly visible in standard inversion models as a result of strong vertical smearing in the latter. In the upper aquifer region, with high GPR coherency and horizontal layering, the resistivity is moderately high (> 300 Ωm). We suggest that this region consists of sediments that were rearranged during more than a century of channelized flow. In the lower low coherency region, the GPR image reveals fluvial features (e.g., foresets) and generally more heterogeneous deposits. In this region, the resistivity is lower (~ 200 Ωm), which we attribute to increased amounts of fines in some of the well-sorted fluvial deposits. We also find elongated conductive anomalies that correspond to the location of river embankments that were removed in 2002.

  2. Calibration of seawater intrusion models: Inverse parameter estimation using surface electrical resistivity tomography and borehole data

    NASA Astrophysics Data System (ADS)

    Beaujean, J.; Nguyen, F.; Kemna, A.; Antonsson, A.; Engesgaard, P.

    2014-08-01

    Electrical resistivity tomography (ERT) can be used to constrain seawater intrusion models because of its high sensitivity to total dissolved solid contents (TDS) in groundwater and its relatively high lateral coverage. However, the spatial variability of resolution in electrical imaging may prevent the correct recovery of the desired hydrochemical properties such as salt mass fraction. This paper presents a sequential approach to evaluate the feasibility of identifying hydraulic conductivity and dispersivity in density-dependent flow and transport models from surface ERT-derived mass fraction. In the course of this study, geophysical inversion was performed by using a smoothness constraint Tikhonov approach, whereas the hydrological inversion was performed using a gradient-based Levenberg-Marquardt algorithm. Two synthetic benchmarks were tested. They represent a pumping experiment in a homogeneous and heterogeneous coastal aquifer, respectively. These simulations demonstrated that only the lower salt mass fraction of the seawater-freshwater transition zone can be recovered for different times. This ability has here been quantified in terms of cumulative sensitivity and our study has further demonstrated that the mismatch between the targeted and the recovered salt mass fraction occurs from a certain threshold. We were additionally able to explore the capability of sensitivity-filtered ERT images using ground surface data only to recover (in both synthetic cases) the hydraulic conductivity while the dispersivity is more difficult to estimate. We attribute the latter mainly to the lack of ERT-derived data at depth (where resolution is poorer) as well as to the smoothing effect of the ERT inversion.

  3. PILOT-SCALE FIELD VALIDATION OF THE LONG ELECTRODE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD

    SciTech Connect

    GLASER DR; RUCKER DF; CROOK N; LOKE MH

    2011-07-14

    Field validation for the long electrode electrical resistivity tomography (LE-ERT) method was attempted in order to demonstrate the performance of the technique in imaging a simple buried target. The experiment was an approximately 1/17 scale mock-up of a region encompassing a buried nuclear waste tank on the Hanford site. The target of focus was constructed by manually forming a simulated plume within the vadose zone using a tank waste simulant. The LE-ERT results were compared to ERT using conventional point electrodes on the surface and buried within the survey domain. Using a pole-pole array, both point and long electrode imaging techniques identified the lateral extents of the pre-formed plume with reasonable fidelity, but the LE-ERT was handicapped in reconstructing the vertical boundaries. The pole-dipole and dipole-dipole arrays were also tested with the LE-ERT method and were shown to have the least favorable target properties, including the position of the reconstructed plume relative to the known plume and the intensity of false positive targets. The poor performance of the pole-dipole and dipole-dipole arrays was attributed to an inexhaustive and non-optimal coverage of data at key electrodes, as well as an increased noise for electrode combinations with high geometric factors. However, when comparing the model resolution matrix among the different acquisition strategies, the pole-dipole and dipole-dipole arrays using long electrodes were shown to have significantly higher average and maximum values than any pole-pole array. The model resolution describes how well the inversion model resolves the subsurface. Given the model resolution performance of the pole-dipole and dipole-dipole arrays, it may be worth investing in tools to understand the optimum subset of randomly distributed electrode pairs to produce maximum performance from the inversion model.

  4. Hydrogeological application of electrical resistivity tomography: Implementing a fixed-electrode strategy

    NASA Astrophysics Data System (ADS)

    Pezeshkpour, Parsa

    The requirements of environmental assessments and of understanding and monitoring in-situ mass and heat processes in porous media have led to the development of geophysical methods for remote mapping and monitoring of contaminant plumes and fluid migration. With the possible exception of seismic approaches, electrical methods known as Electrical Resistivity Tomography (ERT) have become the most widely studied and used for these purposes. Wherever a sufficient contrast in ground resistivity is generated by human or natural processes, monitoring the resistivity structure over time may give insight into these processes. ERT has monitoring applications in processes such as Enhanced Oil Recovery (EOR), Slurry Fracture Injection (SFI), and monitoring transport processes in hydrogeology. A permanent electrode arrangement for long term monitoring removes the effects of Earth's heterogeneity and anisotropy when a process is analyzed as a function of time. As a starting point on the work described in this thesis, ERT data were collected from a Cambridge, Ontario, sand pit before, immediately after and one week following a 11000 liters slurry injection. These measurements verified that ERT could detect changes caused by the injection and later movement of this conductive mixture in the ground. The commercial equipment used for these measurements was not well suited to the tasks, mainly because it was extremely slow. Further, there was a lack of robust and user-friendly three-dimensional modeling software to use as a means of predicting response and---eventually---as the engine of an inversion routine. Finally, it was difficult to analyze the injection situation in terms of how best to place a limited number of surface and borehole electrodes to most effectively monitor the injection fluids. The remainder of the thesis addresses these problems. The first objective was to design and construct a more suitable ERT measurement system. The second objective was to adapt SALTFLOW as

  5. Monitoring snowmelt induced unsaturated flow and transport using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    French, Helen K.; Hardbattle, Carol; Binley, Andrew; Winship, Peter; Jakobsen, Leif

    2002-10-01

    The flow and transport of a non-reactive tracer and melt water was monitored in a heterogeneous coarse sandy unsaturated zone in southeastern Norway, during the snowmelt of 2001. Electrical resistivity tomography (ERT) as well as conventional suction cup techniques was employed. A frozen solution of NaBr in water was supplied as a line source on the ground surface above two parallel vertical profiles monitored by the two measurement systems prior to the onset of snowmelt. The two monitored vertical profiles were separated by approximately 1 m. The results were analysed by visual comparison of images and by the use of spatial moments analysis. The two measurement approaches showed that the system was affected by the presence of preferential flow paths during the early stages of the snowmelt, perhaps due to ice near the surface, but the major part of the plume moves uniformly later in the snow-melting period. After most of the tracer plume has reached the depth monitored by both systems (i.e. below 0.4 m depth) there is a good consistency between the two datasets. Spatial moment calculations on the basis of ERT cannot be used to describe the movement of tracer alone, as the resistivity is affected by changes in both saturation levels and tracer concentration. Nevertheless, ERT appears to be an appropriate method to characterise regions of localised high infiltration in this type of soil. The method therefore constitutes a possible alternative and supplement to suction cups in a monitoring system.

  6. Time-lapse electrical resistivity tomography of a water infiltration test on Johannishus Esker, Sweden

    NASA Astrophysics Data System (ADS)

    Ulusoy, İnan; Dahlin, Torleif; Bergman, Bo

    2015-05-01

    Managed aquifer recharge (MAR) is an efficient way to remove organic matter from raw water and, at the same time, reduce temperature variation. Two MAR sites were constructed by Karlskrona municipality on Johannishus Esker in Sweden. One of these sites, Vång, was monitored for electrical conductivity and electrical resistivity (using electrical resistivity tomography - ERT) during a 9-week tracer infiltration test. The aim of the monitoring was to map the pathways of the infiltrated water, with the overall goal to increase the efficiency of the MAR. ERT proved useful in determining both the nature of the esker formation and the water migration pathways. In Vång, the esker ridge follows a tectonically controlled paleo-valley. The fault/fracture zone in the bedrock along this paleo-valley was mapped. During the tracer test, the infiltrated water was detected in the area close to the infiltration ponds, whereas far-situated observation wells were less affected. For sequential infiltration and recharge periods in MAR, the timing of the well pumping is another important factor. Natural groundwater flow direction was a determinant in the infiltration process, as expected. ERT measurements provide supplementary data for site selection, for monitoring the functionality of the MAR sites, and for revealing the geological, hydrogeological and structural characteristics of the site.

  7. Final Report, FY 2001 200 East Vadose Test Site Hanford Washington Electrical Resistance Tomography

    SciTech Connect

    Ramirez, A.; Daily, W.; Binley, A.

    2001-06-30

    This report covers the electrical resistance tomography (ERT) work performed at the Hanford Reservation, 200 East Area Vadose test (Sisson and Lu) site during the period March 23 through May 5,2001. The purposes of the ERT work were to: (1) Compare and contrast the development of the highly concentrated sodium thiosulfate plume (FY 01 work) with the fresh river water plume observed during FY 00. (2) Use the resistance images to infer the dynamics of the plume during two or three of the sodium thio-sulfate releases and during the water ''chaser'' release. (3) Determine the influence of the site's steel casings on the ability to construct reliable ERT images. (4) Determine if the steel casings at the site can be used as long electrodes to provide useful images of at least one release. (5) Develop quantitative estimates of the noise in the data and its effect on reconstructed images. Eleven electrode arrays (nine electrodes arrays available for the FY00 work), each with 15 electrodes, were installed at the site. These were used to perform 3D surveys before, during, and after 3 different spills.

  8. Sensing uniaxial tensile damage in fiber-reinforced polymer composites using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Lestari, Wahyu; Pinto, Brian; La Saponara, Valeria; Yasui, Jennifer; Loh, Kenneth J.

    2016-08-01

    This work describes the application of electrical resistance tomography (ERT) in sensing damage in fiber-reinforced polymer composites under uniaxial quasi-static tension. Damage is manifested as numerous matrix cracks which are distributed across the composite volume and which eventually coalesce into intralayer cracks. Hence, tensile damage is distributed throughout the volume, and could be more significant outside the sensor area. In this work, tensile damage of unidirectional glass fiber-reinforced polymer composites (GFRP) and plain weave carbon fiber-reinforced polymer composites (CFRP) is sensed by utilizing a spray-on nanocomposite sensor, which is then instrumented by boundary electrodes. The resistance change distribution within the sensor area is reconstructed from a series of boundary voltage measurements, and ERT is implemented using a maximum a posteriori approach and assumptions on the type of noise in the reconstruction. Results show that this technique has promise in tracking uniaxial damage in composites. The different fiber architectures (unidirectional GFRP, plain weave CFRP) give distinct features in the ERT, which are consistent with the physical behavior of the tested samples.

  9. Fracture network characterisation of a landslide by electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Szalai, S.; Szokoli, K.; Novák, A.; Tóth, Á.; Metwaly, M.; Prácser, E.

    2014-06-01

    In contrary to most of the landslide studies which concentrate to the sliding surface in this paper the fracture system of a loess landslide is investigated. The continuity and geometry, orientation and dip of the major fractures are crucial parameters for assessing rock stability and landslide evolution. Rain infiltrating moreover easily into the rock mass through fractures providing lubrication for the material to slide, and increases the self-mass of the material increasing the slumping rate. Fracture maps enable beside of the characterisation of the fractured area the delineation of the endangered area of slow-moving landslides in due time and getting information about its inner structure. For constructing such maps Electrical Resistivity Tomography (ERT) measurements have been carried out using different geoelectric configurations. In spite of the high density of the fractures and their changing physical parameters in function of their water content - which make the interpretation rather difficult - a number of fractures have been detected and more or less well localised. On the basis of the present research the application of the Schlumberger and the Pole-Dipole arrays is recommended to fulfil the aim of the study. The optimised Stummer array is at the same time the only array which presents conductive anomalies (supposedly water filled fractures), as well, and indicates that fractures elongate deep downwards. Because these features seem to be realistic based on field observations or theoretical considerations the Stummer array may be a very good tool for completing e.g. P-Dp measurements. The study area could have been divided by all arrays into differently fractured zones, which assists a lot in understanding the landslide structure and evolution. It was shown, moreover, that in the still passive area there are thick fractures, too, verifying its dangerousness, as well. The ERT results enabled localising the rupture surfaces of future slumps which proved to

  10. Re-Inversion of Surface Electrical Resistivity Tomography Data from the Hanford Site B-Complex

    SciTech Connect

    Johnson, Timothy C.; Wellman, Dawn M.

    2013-05-01

    This report documents the three-dimensional (3D) inversion results of surface electrical resistivity tomography (ERT) data collected over the Hanford Site B-Complex. The data were collected in order to image the subsurface distribution of electrically conductive vadose zone contamination resulting from both planned releases of contamination into subsurface infiltration galleries (cribs, trenches, and tile fields), as well as unplanned releases from the B, BX, and BY tank farms and/or associated facilities. Electrically conductive contaminants are those which increase the ionic strength of pore fluids compared to native conditions, which comprise most types of solutes released into the subsurface B-Complex. The ERT data were collected and originally inverted as described in detail in report RPP-34690 Rev 0., 2007, which readers should refer to for a detailed description of data collection and waste disposal history. Although the ERT imaging results presented in that report successfully delineated the footprint of vadose zone contamination in areas outside of the tank farms, imaging resolution was not optimized due to the inability of available inversion codes to optimally process the massive ERT data set collected at the site. Recognizing these limitations and the potential for enhanced ERT characterization and time-lapse imaging at contaminated sites, a joint effort was initiated in 2007 by the U.S. Department of Energy – Office of Science (DOE-SC), with later support by the Office of Environmental Management (DOE-EM), and the U.S. Department of Defense (DOD), to develop a high-performance distributed memory parallel 3D ERT inversion code capable of optimally processing large ERT data sets. The culmination of this effort was the development of E4D (Johnson et al., 2010,2012) In 2012, under the Deep Vadose Zone Applied Field Research Initiative (DVZ-AFRI), the U.S. Department of Energy – Richland Operations Office (DOE-RL) and CH2M Hill Plateau Remediation

  11. Visualizing Hyporheic Flow Paths in Three Dimensions Using Time-Lapse Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Kohler, B.; Hall, R. O., Jr.; Carr, B.

    2015-12-01

    The hyporheic zone, the region underneath/surrounding a stream where surface and subsurface waters - and subsequently solutes - are exchanged and interact, is important for many biogeochemical, hydrological, and ecological processes. However, it has remained difficult for researchers to sufficiently describe solute transport within the hyporheic zone, due, in part, to the great degree of heterogeneity of the subsurface. Thus, more direct and invasive sampling techniques are limited in their usefulness. We used an indirect approach for measuring the hyporheic zone, employing 3D time-lapse electrical resistivity tomography (ERT), with a pole-dipole configuration, downstream of a constant-rate addition of an electrically conductive salt tracer (Cl-) as a solution via a high-precision peristaltic pump. This method allowed us to measure the extent of subsurface dynamics of streams in Wyoming's Laramie and Snowy Range mountains, as it yields a three-dimensional view of solute transport and exchange within the hyporheic zone. We found that the physical size of the hyporheic zone and the rate of exchange between the hyporheic and surface waters, as estimated from 3D ERT, are largely related to sediment properties (i.e. grain size distribution) and the extent of tailing of the solute's breakthrough curve (length of time for the solute to flush from the subsurface post cessation of the pump upstream). Coarser sediments with a relatively large porosity, such as gravels and sands, allowed for more subsurface exchange, and larger flow paths, than finer sediments with tighter packing structures, such as clays. Stream reaches that showed a higher degree of tailing in the breakthrough curve, traditionally implying a large transient storage zone, had larger and more active hyporheic zones as measured by 3D ERT. We therefore believe further investigations with 3D ERT will better our understanding of hyporheic exchange and stream solute transport.

  12. Contribution of 3-D electrical resistivity tomography for landmines detection

    NASA Astrophysics Data System (ADS)

    Metwaly, M.; El-Qady, G.; Matsushima, J.; Szalai, S.; Al-Arifi, N. S. N.; Taha, A.

    2008-12-01

    Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and non-metallic (mostly plastic) landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR), and metal detector (MD) techniques. These geophysical techniques however have significant limitations in resolving the non-metallic landmines and wherever the host materials are conductive. In this work, the 3-D electric resistivity tomography (ERT) technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths. This can be achieved using the capacitive resistivity imaging system, which does not need direct contact with the ground surface. Synthetic models for each case have been introduced using metallic and non-metallic bodies buried in wet and dry environments. The inversion results using the L1 norm least-squares optimization method tend to produce robust blocky models of the landmine body. The dipole axial and the dipole equatorial arrays tend to have the most favorable geometry by applying dynamic capacitive electrode and they show significant signal strength for data sets with up to 5% noise. Increasing the burial depth relative to the electrode spacing as well as the noise percentage in the resistivity data is crucial in resolving the landmines at different environments. The landmine with dimension and burial depth of one electrode separation unit is over estimated while the spatial resolutions decrease as the burial depth and noise percentage increase.

  13. Evaluating time-lapse ERT for monitoring DNAPL remediation via numerical simulation

    NASA Astrophysics Data System (ADS)

    Power, C.; Karaoulis, M.; Gerhard, J.; Tsourlos, P.; Giannopoulos, A.

    2012-12-01

    Dense non-aqueous phase liquids (DNAPLs) remain a challenging geoenvironmental problem in the near subsurface. Numerous thermal, chemical, and biological treatment methods are being applied at sites but without a non-destructive, rapid technique to map the evolution of DNAPL mass in space and time, the degree of remedial success is difficult to quantify. Electrical resistivity tomography (ERT) has long been presented as highly promising in this context but has not yet become a practitioner's tool due to challenges in interpreting the survey results at real sites where the initial condition (DNAPL mass, DNAPL distribution, subsurface heterogeneity) is typically unknown. Recently, a new numerical model was presented that couples DNAPL and ERT simulation at the field scale, providing a tool for optimizing ERT application and interpretation at DNAPL sites (Power et al., 2011, Fall AGU, H31D-1191). The objective of this study is to employ this tool to evaluate the effectiveness of time-lapse ERT to monitor DNAPL source zone remediation, taking advantage of new inversion methodologies that exploit the differences in the target over time. Several three-dimensional releases of chlorinated solvent DNAPLs into heterogeneous clayey sand at the field scale were generated, varying in the depth and complexity of the source zone (target). Over time, dissolution of the DNAPL in groundwater was simulated with simultaneous mapping via periodic ERT surveys. Both surface and borehole ERT surveys were conducted for comparison purposes. The latest four-dimensional ERT inversion algorithms were employed to generate time-lapse isosurfaces of the DNAPL source zone for all cases. This methodology provided a qualitative assessment of the ability of ERT to track DNAPL mass removal for complex source zones in realistically heterogeneous environments. In addition, it provided a quantitative comparison between the actual DNAPL mass removed and that interpreted by ERT as a function of depth below

  14. An Ultra-Precise System for Electrical Resistivity Tomography Measurements

    SciTech Connect

    LaBrecque, Douglas J; Adkins, Paula L

    2008-12-09

    The objective of this research was to determine the feasibility of building and operating an ERT system that will allow measurement precision that is an order of magnitude better than existing systems on the market today and in particular if this can be done without significantly greater manufacturing or operating costs than existing commercial systems. Under this proposal, we performed an estimation of measurement errors in galvanic resistivity data that arise as a consequence of the type of electrode material used to make the measurements. In our laboratory, measurement errors for both magnitude and induced polarization (IP) were estimated using the reciprocity of data from an array of electrodes as might be used for electrical resistance tomography using 14 different metals as well as one non-metal - carbon. In a second phase of this study, using archival data from two long-term ERT surveys, we examined long-term survivability of electrodes over periods of several years. The survey sites were: the Drift Scale Test at Yucca Mountain, Nevada (which was sponsored by the U. S. Department of Energy as part of the civilian radioactive waste management program), and a water infiltration test at a site adjacent to the New Mexico Institute of Mines and Technology in Socorro, New Mexico (sponsored by the Sandia/Tech vadose program). This enabled us to compare recent values with historical values and determine electrode performance over the long-term as well as the percentage of electrodes that have failed entirely. We have constructed a prototype receiver system, made modifications and revised the receiver design. The revised prototype uses a new 24 bit analog to digital converter from Linear Technologies with amplifier chips from Texas Instruments. The input impedance of the system will be increased from 107 Ohms to approximately 1010 Ohms. The input noise level of the system has been decreased to approximately 10 Nanovolts and system resolution to about 1 Nanovolt at

  15. Heterogeneous reactive transport under unsaturated transient conditions characterized by 3D electrical resistivity tomography and advanced lysimeter methods

    NASA Astrophysics Data System (ADS)

    Wehrer, Markus; Slater, Lee

    2015-04-01

    Our ability to predict flow and transport processes in the unsaturated critical zone is considerably limited by two characteristics: heterogeneity of flow and transience of boundary conditions. The causes of heterogeneous flow and transport are fairly well understood, yet the characterization and quantification of such processes in natural profiles remains challenging. This is due to current methods of observation, such as staining and isotope tracers, being unable to observe multiple events on the same profile and offering limited spatial information. In our study we demonstrate an approach to characterize preferential flow and transport processes applying a combination of geoelectrical methods and advanced lysimeter techniques. On an agricultural soil profile, which was transferred undisturbed into a lysimeter container, we systematically applied a variety of input flow boundary conditions, resembling natural precipitation events. We measured breakthroughs of a conservative tracer and of nitrate, originating from the application of a slow release fertilizer and serving as a reactive tracer. Flow and transport in the soil column were observed using electrical resistivity tomography (ERT), tensiometers, water content probes and a multicompartment suction plate (MSP). These techniques allowed a direct validation of water content dynamics and tracer breakthrough under transient boundary conditions characterized noninvasively by ERT. We were able to image the advancing infiltration front and the advancing front of tracer and nitrate using time lapse ERT. Water content changes associated with the advancing infiltration front dominated over pore fluid conductivity changes during short term precipitation events. Conversely, long-term displacement of the solute fronts was monitored during periods of constant water content in between infiltration events. We observed preferential flow phenomena through ERT and through the MSP, which agreed in general terms. The preferential

  16. ERTS & EROS

    ERIC Educational Resources Information Center

    Geotimes, 1972

    1972-01-01

    Describes the proposed investigations to be conducted with ERTS (Earth Resources Technology Satellite), the first experimental satellite for systematically surveying earth resources by remote sensing. Launching set for June, 1972. (PR)

  17. Hydrological Interpretation of ERT Monitoring Data on active landslides by implementation of numerical modelling at sites of the LAMOND Long-Term Landslide Monitoring Network

    NASA Astrophysics Data System (ADS)

    Hoyer, Stefan; Ottowitz, David; Supper, Robert; Jochum, Birgit; Riegler, Monika; Scolobig, Anna; Pfeiler, Stefan

    2016-04-01

    Five landslides are monitored in the framework of the LAMOND Network using Electrical Resistivity Tomography (ERT), three of these are located in Austria, one in Italy and one in France. Hydrological interpretation of the collected ERT data is typically carried out qualitatively on a visual basis. In this study, numerical modelling in combination with parameter estimation is implemented to build a basis for an enhanced interpretation. Parameter estimation is carried out by Comsol Multiphysics using Richard's equation and the Optimization module. The result of the forward model (water saturation) is compared to the ERT section (resistivity) using Archies law. The study LAMOND is funded by the Austrian Academy of sciences.

  18. Pedotransfer functions in soil electrical resistivity estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface electrical resistivity tomography (ERT) is recognized as a powerful non-invasive soil survey and monitoring method. Relationships between ER and soil water contents that are needed to infer the spatial distribution of soil moisture from the ERT results, are known to reflect soil properties. ...

  19. Imaging subsurface migration of dissolved CO2 in a shallow aquifer using 3-D time-lapse electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Auken, Esben; Doetsch, Joseph; Fiandaca, Gianluca; Christiansen, Anders Vest; Gazoty, Aurélie; Cahill, Aaron Graham; Jakobsen, Rasmus

    2014-02-01

    Contamination of groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment in western Denmark, we investigate to what extent surface electrical resistivity tomography (ERT) can detect and image dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5 and 10 m and monitored its migration using 320 electrodes on a 126 m × 25 m surface grid. A fully automated acquisition system continuously collected data and uploaded it into an online database. The large amount of data allows for time-series analysis using geostatistical techniques for noise estimation and data interpolation to compensate for intermittent instrument failure. We estimate a time-dependent noise level for each ERT configuration, taking data variation and measurement frequency into account.

  20. Uncertainty Quantification of CO2 Saturation Estimated from Electrical Resistivity Tomography Data at the SECARB Cranfield Site

    NASA Astrophysics Data System (ADS)

    Yang, X.; Carrigan, C. R.; Chen, X.

    2012-12-01

    Estimation of CO2 saturation with its associated uncertainty in an underground CO2 reservoir during a CO2 injection process can aid the risk assessment of potential CO2 leakage. Time lapse electrical resistivity tomography (ERT) was used effectively for tracking CO2 plume migration in a saline environment at the SECARB Cranfield site. It is clear that displacement of saline fluids by supercritical CO2 increases formation resistivity significantly. We inverted time lapse resistivity data by using a deterministic least squares type inverse method for subsurface resistivity models. CO2 saturation can be derived from resistivity data by substituting saline fluids with insulating CO2 in the Archie's equation. Our inversion results clearly revealed the development of a CO2 plume in the reservoir. The degree of uncertainty in the estimates of CO2 saturation is unknown but needed in the verification and accounting of CO2 in the storage. We are developing an uncertainty quantification (UQ) method to assess the uncertainty of CO2 saturation derived from ERT data. This UQ approach consists of three steps. We first estimated the observation errors based on repeat and reciprocal ERT measurements. This step produced mean and standard deviation of observations. The second step is driven by the LLNL PSUADE UQ tool that repeatedly samples data noises and launches deterministic ERT inversion. Finally, a posteriori covariance matrix of CO2 saturation can then be obtained from a large number of samples of CO2 saturation estimates. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC. LLNL-ABS-569132.

  1. Monitoring CO 2 sequestration into deep saline aquifer and associated salt intrusion using coupled multiphase flow modeling and time lapse electrical resistivity tomography

    SciTech Connect

    Chuan Lu; CHI Zhang; Hai Hanag; Timothy C. Johnson

    2014-04-01

    Successful geological storage and sequestration of carbon dioxide (CO2) require efficient monitoring of the migration of CO2 plume during and after large-scale injection in order to verify the containment of the injected CO2 within the target formation and to evaluate potential leakage risk. Field studies have shown that surface and cross-borehole electrical resistivity tomography (ERT) can be a useful tool in imaging and characterizing solute transport in heterogeneous subsurface. In this synthetic study, we have coupled a 3-D multiphase flow model with a parallel 3-D time-lapse ERT inversion code to explore the feasibility of using time-lapse ERT for simultaneously monitoring the migration of CO2 plume in deep saline formation and potential brine intrusion into shallow fresh water aquifer. Direct comparisons of the inverted CO2 plumes resulting from ERT with multiphase flow simulation results indicate the ERT could be used to delineate the migration of CO2 plume. Detailed comparisons on the locations, sizes and shapes of CO2 plume and intruded brine plumes suggest that ERT inversion tends to underestimate the area review of the CO2 plume, but overestimate the thickness and total volume of the CO2 plume. The total volume of intruded brine plumes is overestimated as well. However, all discrepancies remain within reasonable ranges. Our study suggests that time-lapse ERT is a useful monitoring tool in characterizing the movement of injected CO2 into deep saline aquifer and detecting potential brine intrusion under large-scale field injection conditions.

  2. Tomographic Site Characterization Using CPT, ERT, and GPR

    SciTech Connect

    Rexford M. Morey

    1997-05-23

    The U.S. Department of Energy (DOE) is responsible for the cleanup of inactive DOE sites and for bringing DOE sites and facilities into compliance with federal, state and local laws and regulations. The DOE's Office of Environmental Management (EM) needs advanced technologies that can make environmental restoration and waste management operations more efficient and less costly. These techniques are required to better characterize the physical, hydrogeological, and chemical properties of the subsurface while minimizing and optimizing the use of boreholes and monitoring wells. Today the cone penetrometer technique (CPT) is demonstrating the value of a minimally invasive deployment system fix site characterization. Applied Research Associates is developing two new sensor packages for site characterization and monitoring. The two new methods are: . Electrical Resistivity Tomography (ERT) and . Ground Penetrating Radar (GPR) Tomography. These sensor systems are now integrated with the Cone Penetrometer Technique (CPT). The results of this program now make it possible to install ERT and GPR units by CPT methods and thereby reduce installation costs and total costs for ERT and GPR surveys. These two techniques can complement each other in regions of low resistivity where ERT is more effective and regions of high resistivity where GPR is more effective. The results show that CPT-installed GeoWells can be used in both ERT and GPR borehole tomographic subsurface imaging. These two imaging techniques can be used for environmental site characterization and environmental remediation monitoring. Technologies used for site characterization and monitoring have numerous and diverse applications within site clean-up and waste management operations.

  3. ERT monitoring of environmental remediation processes

    NASA Astrophysics Data System (ADS)

    La Brecque, D. J.; Ramirez, A. L.; Daily, W. D.; Binley, A. M.; Schima, S. A.

    1996-03-01

    The use of electrical resistance tomography (ERT) to monitor new environmental remediation processes is addressed. An overview of the ERT method, including design of surveys and interpretation, is given. Proper design and lay-out of boreholes and electrodes are important for successful results. Data are collected using an automated collection system and interpreted using a nonlinear least squares inversion algorithm. Case histories are given for three remediation technologies: Joule (ohmic) heating, in which clay layers are heated electrically; air sparging, the injection of air below the water table; and electrokinetic treatment, which moves ions by applying an electric current. For Joule heating, a case history is given for an experiment near Savannah River, Georgia, USA. The target for Joule heating was a clay layer of variable thickness. During the early stages of heating, ERT images show increases in conductivity due to the increased temperatures. Later, the conductivities decreased as the system became dehydrated. For air sparging, a case history from Florence, Oregon, USA is described. Air was injected into a sandy aquifer at the site of a former service station. Successive images clearly show the changes in shape of the region of air saturation with time. The monitoring of an electrokinetic laboratory test on core samples is shown. The electrokinetic treatment creates a large change in the core resistivity, decreasing near the anode and increasing near the cathode. Although remediation efforts were successful both at Savannah River and at Florence, in neither case did experiments progress entirely as predicted. At Savannah River, the effects of heating and venting were not uniform and at Florence the radius of air flow was smaller than expected. Most sites are not as well characterized as these two sites. Improving remediation methods requires an understanding of the movements of heat, air, fluids and ions in the sub-surface which ERT can provide. The

  4. Inspection of earthen embankment dams using time lapse electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Case, Jared S.

    According to the National Inventory of Dams (NID), the number of dams across the United States is approximately 85,000. Many of these dams are more than 50 years old and need vast attention to ensure their safety. It is difficult to obtain a full assessment of the dam just by visual inspections alone. This is because many problems associated with dam failure occur internally, which makes it difficult to be observed by the dam inspectors. Examples of these flaws are piping and seepage (flow of water through or around dam walls). It is in this area where geophysical methods can aid in obtaining a more confident evaluation of a dam's integrity. Electrical resistivity is one geophysical technique that would be useful in detecting internal flaws associated with seepage and piping because it is sensitive to moisture changes. A study is being conducted to examine the feasibility of electrical resistivity tomography (ERT) to map and monitor internal compromised zones within earthen embankment dams. Two quarter-scaled earthen embankment dams were built at the United States Department of Agriculture (USDA) Agriculture Research Service (ARS) Hydraulics and Engineering Research Unit (HERU) in Stillwater, Oklahoma. These two dams were constructed with known internal compromised zones that are susceptible to seepage and piping. Electrical resistivity surveys were conducted on the completed dams using a 56 electrode dipole-dipole array. The collected data was then processed using electrical resistivity tomography (ERT) imaging software and evidence of these two compromised zones was easily visible. Also, additional surveys were conducted in order to monitor the changes in electrical signatures associated with changes in these zones due to filling of the reservoir and environmental/climate changes.

  5. Characterization and calibration of seawater intrusion models using electrical resistivity tomography (Invited)

    NASA Astrophysics Data System (ADS)

    Nguyen, F. H.; Kemna, A.; Antonsson, A.; Engesgaard, P. K.; Beaujean, J.

    2009-12-01

    The urban development of coastal regions create seawater intrusion (SWI) problems which threatens groundwater quality and coastal ecosystems. To study SWI, one needs both robust measuring technologies, and reliable predictions. A key aspect in the calibration of SWI models involves reproducing measured groundwater chloride concentrations. Drilling such multi-screen wells to obtain a whole concentration profile is a risky task if reliable information about the position of the salt wedge is not available. Electrical resistivity tomography (ERT) is increasingly being used to characterize seawater intrusion and constrain corresponding models, given its high sensitivity to ion concentration in groundwater and its relatively high spatial resolution. We have investigated the potential of ERT using field data from a site in Almeria, SE Spain and synthetic data. Simulations have been run for several scenarios, with a simple hydrogeological model reflecting the local site conditions. The simulations showed that only the lower salt concentrations of the seawater-freshwater transition zone could be recovered, due to the loss of resolution with depth. We quantified this capability in terms of image appraisal indicators (cumulative sensitivity) associated with the measurement setup and showed that the mismatch between the targeted and imaged parameter values occurs from a certain threshold. Similarly, heterogeneity may only be determined accurately if located in an adequately sensitive area. Inversion of the synthetic data was performed by coupling an inversion code (PEST) with a finite-difference density-dependent flow and transport modeling code (HTS). The numerical results demonstrate the capacity of sensitivity-filtered ERT images to constrain transverse hydraulic dispersivity and longitudinal hydraulic conductivity of homogeneous seawater intrusion models. At the field site, we identified SWI at the scale of a few kilometers down to a hundred meters. Borehole logs show a

  6. Influence of shallow infiltration on time-lapse ERT: Experience of advanced interpretation

    NASA Astrophysics Data System (ADS)

    Clément, Rémi; Descloitres, Marc; Günther, Thomas; Ribolzi, Olivier; Legchenko, Anatoli

    2009-10-01

    Previous time-lapse Electrical Resistivity Tomography (ERT) studies have experienced difficulties in reconstructing reliable calculated resistivity changes in the subsurface. Increases or decreases of resistivity appear in the calculated ERT image where no changes were noted in the subsurface, leading to erroneous hydrological interpretations of the geophysical results. In this article, we investigate how a variation of actual resistivity with time and at shallow depth can influence time-lapse ERT results and produce resistivity artefacts at depth. We use 1 and 2-D numerical modelling to simulate infiltration scenarios. Using a standard time-lapse inversion, we demonstrate the resistivity artefact production according to the electrode spacing parameter. We used an advanced inversion methodology with a decoupling line at shallow depth to attenuate or remove resistivity artefacts. We also applied this methodology to a field data set obtained in a semi-arid environment in Burkina Faso, West Africa. Here, time-lapse ERT shows several resistivity artefacts of calculated resistivity if a standard inversion is used. We demonstrate the importance of a dense sampling of shallow resistivity variations at shallow depth. Advanced interpretation allows us to significantly attenuate or remove the resistivity artefact production at intermediate depth and produce reliable interpretation of hydrological processes.

  7. Time-lapse ERT for the monitoring of soil-plant interactions in the root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Rossi, M.; D'Alpaos, A.; Fadda, G.; Putti, M.; Marani, M.

    2011-12-01

    The application of time-lapse non invasive 3D micro-scale electrical resistivity tomography (ERT) has been proven to be an efficient tool to monitor the soil-plant interactions and particularly the root zone activity. This information can support water balance modeling in the upper subsoil critical zone. Here we present the results of two field experiments in very different environments: the case of a single apple tree in an orchard located in the Trentino region (Northern Italy), and the case of salt-marshes plants in the Venice Lagoon. The micro-scale ERT apparatus consists of buried electrodes installed on micro boreholes, plus mini-electrodes on the ground surface. We collected repeated ERT, TDR and tensiometer data. For the apple orchard site test we adopted controlled irrigation tests in different seasons, while in the lagoon salt-marshes we monitored the root-plant activity during tidal flooding. The results demonstrate that micro-scale ERT is a very effective tool to characterize subsoil conditions and monitor root zone activities, especially in terms of root zone suction regions. Micro-scale ERT can detect the main suction zones caused by the tree root activity, as demonstrated in the case of the apple orchard, while ERT and moisture measurements in the lagoon environment show a high resistivity suction layer located at root depth even during marsh flooding. Both observations will be important pieces of information for the comprehension of relevant eco- hydrological dynamics.

  8. Time-lapse ERT for the monitoring of soil-plant interactions in the root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Rossi, M.; D'Alpaos, A.; Fadda, G.; Putti, M.; Marani, M.

    2013-12-01

    The application of time-lapse non invasive 3D micro-scale electrical resistivity tomography (ERT) has been proven to be an efficient tool to monitor the soil-plant interactions and particularly the root zone activity. This information can support water balance modeling in the upper subsoil critical zone. Here we present the results of two field experiments in very different environments: the case of a single apple tree in an orchard located in the Trentino region (Northern Italy), and the case of salt-marshes plants in the Venice Lagoon. The micro-scale ERT apparatus consists of buried electrodes installed on micro boreholes, plus mini-electrodes on the ground surface. We collected repeated ERT, TDR and tensiometer data. For the apple orchard site test we adopted controlled irrigation tests in different seasons, while in the lagoon salt-marshes we monitored the root-plant activity during tidal flooding. The results demonstrate that micro-scale ERT is a very effective tool to characterize subsoil conditions and monitor root zone activities, especially in terms of root zone suction regions. Micro-scale ERT can detect the main suction zones caused by the tree root activity, as demonstrated in the case of the apple orchard, while ERT and moisture measurements in the lagoon environment show a high resistivity suction layer located at root depth even during marsh flooding. Both observations will be important pieces of information for the comprehension of relevant eco- hydrological dynamics.

  9. Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals.

    PubMed

    Wehrer, Markus; Lissner, Heidi; Bloem, Esther; French, Helen; Totsche, Kai Uwe

    2014-01-01

    Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques. PMID:24194415

  10. Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals.

    PubMed

    Wehrer, Markus; Lissner, Heidi; Bloem, Esther; French, Helen; Totsche, Kai Uwe

    2014-01-01

    Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques.

  11. River terrace sand and gravel deposit reserve estimation using three-dimensional electrical resistivity tomography for bedrock surface detection

    NASA Astrophysics Data System (ADS)

    Chambers, J. E.; Wilkinson, P. B.; Penn, S.; Meldrum, P. I.; Kuras, O.; Loke, M. H.; Gunn, D. A.

    2013-06-01

    We describe the application of 3D electrical resistivity tomography (ERT) to the characterisation and reserve estimation of an economic fluvial sand and gravel deposit. Due to the smoothness constraints used to regularise the inversion, it can be difficult to accurately determine the geometry of sharp interfaces. We have therefore considered two approaches to interface detection that we have applied to the 3D ERT results in an attempt to provide an accurate and objective assessment of the bedrock surface elevation. The first is a gradient-based approach, in which the steepest gradient of the vertical resistivity profile is assumed to correspond to the elevation of the mineral/bedrock interface. The second method uses an intrusive sample point to identify the interface resistivity at a location within the model, from which an iso-resistivity surface is identified that is assumed to define the interface. Validation of these methods has been achieved through direct comparison with observed bedrock surface elevations that were measured using real-time-kinematic GPS subsequent to the 3D ERT survey when quarrying exposed the bedrock surface. The gradient-based edge detector severely underestimated the depth to bedrock in this case, whereas the interface resistivity method produced bedrock surface elevations that were in close agreement with the GPS-derived surface. The failure of the gradient-based method is attributed to insufficient model sensitivity in the region of the bedrock surface, whereas the success of the interface resistivity method is a consequence of the homogeneity of the mineral and bedrock, resulting in a consistent interface resistivity. These results highlight the need for some intrusive data for model validation and for edge detection approaches to be chosen on the basis of local geological conditions.

  12. Surface and subsurface damage detection in cement-based materials using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Ruan, T.; Poursaee, A.

    2016-04-01

    Cement-based materials are widely used in infrastructure facilities. However, often the degradation of structures leads to the failures earlier than designed service life. Thus, non-destructive testing techniques are urgently needed to evaluate the health information of the structures. In this paper, the implementation of Electrical Resistance Tomography (ERT) was investigated. This low cost, radiation free and easy to perform modality is based on measuring the electrical properties of the material under test and using that to evaluate the existence of defects in that material. It uses a set of boundary potentials and injected current to reconstruct the conductivity distribution. An automatic measurement system was developed and surface damages as well as subsurface damages on mortar specimens were investigated. The reconstructed images were capable to show the presence and the location of the damages.

  13. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale.

    PubMed

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600ppm) in 3months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique.

  14. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale.

    PubMed

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600ppm) in 3months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique. PMID:26697744

  15. Electrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale

    NASA Astrophysics Data System (ADS)

    Masy, Thibaut; Caterina, David; Tromme, Olivier; Lavigne, Benoît; Thonart, Philippe; Hiligsmann, Serge; Nguyen, Frédéric

    2016-01-01

    Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clay loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique.

  16. Electrical resistivity tomography at the search of groundwater near Anapa town in the south of Russia.

    NASA Astrophysics Data System (ADS)

    Kvon, Dina; Vladimir, Shevnin; Boris, Nikulin; Albert, Ryjov; Alexey, Skobelev

    2013-04-01

    Electrical resistivity tomography at the search of groundwater near Anapa town in the south of Russia. Kvon D. A.(1)*, Shevnin V.A.(1), Nikulin B. A.(1), Ryjov A. A.(2), Skobelev A. O.(1) (1)Geophysical dept., Faculty of Geology, Moscow state university; (2)VSEGINGEO Due to acute shortage of fresh drinking water near Anapa town (not far from the Black Sea), geophysical investigations were performed for searching and mapping aquifers in the area, where, according to rare wells exist probability to find fresh underground water. Geophysical explorations were carried out by Electrical resistivity tomography (ERT) method and water resistivity measurements. The resistivity of fresh groundwater is 15 Ohm.m, its salinity is 0.4 g/l. The structure of the area has been obtained by previous geological and hydrogeological studies and boreholes drilling. Geological structure of the area consists of two parts: the upper part of cross-section presented by loose lacustrine-alluvial sediments of Upper Pleistocene - Holocene, the lower part presented by hard rocs of carbonate-flysch formation of Upper Cretaceous age consisted of marl and limestone. Prospective areas to find underground water are: water-bearing horizon of upper Pleistocene-Holocene sediments, which is presented by gravel layer (base layer of modern lacustrine-alluvial sediments), and fractured zones in hard rocks of the carbonate-flysch formation of Maastricht age (Supseh formation). Analysis of rocks' resistivity obtained from Electrical resistivity tomography followed by calculation of rock resistivity on known petrophysical parameters (in Petrowin program created by A. A. Ryjov) [Shevnin et al., 2007]. The calculation showed that there is low clay content in carbonate rocks of the studied area, and the rock is limestone, not marl. Measurement of rock samples with X-ray radiometric method showed high calcium content (30-35%) or 75-87.5% limestone. This fact shows that flysch formation of the area is mainly

  17. Adjoint-state inversion of electric resistivity tomography data of seawater intrusion at the Argentona coastal aquifer (Spain)

    NASA Astrophysics Data System (ADS)

    Fernández-López, Sheila; Carrera, Jesús; Ledo, Juanjo; Queralt, Pilar; Luquot, Linda; Martínez, Laura; Bellmunt, Fabián

    2016-04-01

    Seawater intrusion in aquifers is a complex phenomenon that can be characterized with the help of electric resistivity tomography (ERT) because of the low resistivity of seawater, which underlies the freshwater floating on top. The problem is complex because of the need for joint inversion of electrical and hydraulic (density dependent flow) data. Here we present an adjoint-state algorithm to treat electrical data. This method is a common technique to obtain derivatives of an objective function, depending on potentials with respect to model parameters. The main advantages of it are its simplicity in stationary problems and the reduction of computational cost respect others methodologies. The relationship between the concentration of chlorides and the resistivity values of the field is well known. Also, these resistivities are related to the values of potentials measured using ERT. Taking this into account, it will be possible to define the different resistivities zones from the field data of potential distribution using the basis of inverse problem. In this case, the studied zone is situated in Argentona (Baix Maresme, Catalonia), where the values of chlorides obtained in some wells of the zone are too high. The adjoint-state method will be used to invert the measured data using a new finite element code in C ++ language developed in an open-source framework called Kratos. Finally, the information obtained numerically with our code will be checked with the information obtained with other codes.

  18. Time-Lapse Seismic Tomography and Electrical Resistivity Mapping of a Small Embankment Dam with Possible Zones of Weakness

    NASA Astrophysics Data System (ADS)

    Wodajo, L. T.; Hickey, C. J.; Song, C. R.

    2013-12-01

    Earthen dam or levee failure can occur with little to no warning. Internal problems such as seepage and piping are among the major causes of failure in earthen embankment dams and levees. Identifying and mitigating these problems requires a cost effective and non-invasive method of investigating these critical structures. This study focuses on the early detection of internal problems such as seepage and piping using time lapse seismic refraction tomography (SRT) and electrical resistivity tomography (ERT). For this study, two quarter scale model dams were built at the USDA-ARS Hydraulic Engineering Research Unit in Stillwater, OK. These dams were constructed with two internal compromised zones that would be susceptible to seepage and piping. The zones consist of a sandy region and a region compacted at lower moisture content. Time lapse seismic refraction and electrical resistivity measurements were conducted over a course of two years to monitor changes in the internal structure of the model dams due to seasonal changes, cyclic loadings and internal erosion failure. The results will provide an insight on how compromised zones due to seepage and piping can be identified at an early stage using both SRT and ERT time-lapse measurements and how joint interpretation of these two methods helps in closely identifying what attributed to the compromised zone. [This research was funded by the department of Homeland Security- sponsored Southeast Region Research Initiative (SERRI) at the Department of Energy's Oak Ridge National Laboratory.

  19. Rainfall infiltration process in mountain headwater region using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Ono, M.; Yamamiya, K.; Shimada, J.

    2008-12-01

    Many researchers have studied about the hydrological process, especially rainfall-runoff process, in the headwater region using multi hydrometric methods. Since the possibility has been recognized that bedrock groundwater has important role to play in the rainfall-runoff process, it is important to comprehend the rainfall infiltration process within fluctuations of bedrock groundwater. However, we would need many hydrological instruments to understand this process precisely. So we have applied electrical resistivity tomography (ERT) method to understand rainfall infiltration process in the area that is estimated the contribution of bedrock groundwater for rainfall-runoff processes. Resistivity changes with the saturation rate of the pore fluid in the subsurface material. So it is possible to estimate spatial and temporal distribution of subsurface water by using ERT. In this study, we will estimate rainfall infiltration process in mountain headwater region using resistivity method. The study area is the Mamushi-dani watershed in Shiranui, Kumamoto, Japan. We described the bedrock groundwater storage systems using resistivity method in this watershed previously. Resistivity has been observed at 2 measurement lines in slope areas of this watershed. Both measurement lines have 47m in length, 1m electrode spacing and 48 electrodes. We used the multi-electrode system, NEXT-400(Kowa Co. Ltd., Japan) for measuring apparent resistivity and the application software, E-tomo (Diaconsultant Co. Ltd., Japan) for inversion of apparent resistivity data. The observed resistivity data were compared with water head observed at borehole and specific discharge observed at foot of the watershed. Inverted resistivity profiles and observed hydrological data showed the interface between saturated and unsaturated zone. During rainfall occurs, resistivity in surface area gets lower than that before the rainfall and resistivity in some part of unsaturated area shows increasing tendency. Both

  20. Contribution of 3D inversion of Electrical Resistivity Tomography data applied to volcanic structures

    NASA Astrophysics Data System (ADS)

    Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe

    2016-04-01

    The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for geological structures imaging. Such structures can present complex characteristics that conventional 2D inversion processes cannot perfectly integrate. Here we present a new 3D inversion algorithm named EResI, firstly developed for levee investigation, and presently applied to the study of a complex lava dome (the Puy de Dôme volcano, France). EResI algorithm is based on a conventional regularized Gauss-Newton inversion scheme and a 3D non-structured discretization of the model (double grid method based on tetrahedrons). This discretization allows to accurately model the topography of investigated structure (without a mesh deformation procedure) and also permits a precise location of the electrodes. Moreover, we demonstrate that a complete 3D unstructured discretization limits the number of inversion cells and is better adapted to the resolution capacity of tomography than a structured discretization. This study shows that a 3D inversion with a non-structured parametrization has some advantages compared to classical 2D inversions. The first advantage comes from the fact that a 2D inversion leads to artefacts due to 3D effects (3D topography, 3D internal resistivity). The second advantage comes from the fact that the capacity to experimentally align electrodes along an axis (for 2D surveys) depends on the constrains on the field (topography...). In this case, a 2D assumption induced by 2.5D inversion software prevents its capacity to model electrodes outside this axis leading to artefacts in the inversion result. The last limitation comes from the use of mesh deformation techniques used to accurately model the topography in 2D softwares. This technique used for structured discretization (Res2dinv) is prohibed for strong topography (>60 %) and leads to a small computational errors. A wide geophysical survey was carried out

  1. Olive-oil mill wastewater transport under unsaturated and saturated laboratory conditions using the geoelectrical resistivity tomography method and the FEFLOW model

    NASA Astrophysics Data System (ADS)

    Seferou, P.; Soupios, P.; Kourgialas, N. N.; Dokou, Z.; Karatzas, G. P.; Candasayar, E.; Papadopoulos, N.; Dimitriou, V.; Sarris, A.; Sauter, M.

    2013-09-01

    An integrated approach for monitoring the vertical transport of a solute into the subsurface by using a geophysical method and a simulation model is proposed and evaluated. A medium-scale (1 m3) laboratory tank experiment was constructed to represent a real subsurface system, where an olive-oil mill wastewater (OOMW) spill might occur. High-resolution cross-hole electrical resistivity tomography (ERT) was performed to monitor the OOMW transport. Time-lapse ERT images defined the spatial geometry of the interface between the contaminated and uncontaminated soil into the unsaturated and saturated zones. Knowing the subsurface characteristics, the finite element flow and transport model FEFLOW was used for simulating the contaminant movement, utilizing the ERT results as a surrogate for concentration measurements for the calibration process. A statistical analysis of the ERT measurements and the corresponding transport model results for various time steps showed a good agreement between them. In addition, a sensitivity analysis of the most important parameters of the simulation model (unsaturated flow, saturated flow and transport) was performed. This laboratory-scale study emphasizes that the combined use of geophysical and transport-modeling approaches can be useful for small-scale field applications where contaminant concentration measurements are scarce, provided that its transferability from laboratory to field conditions is investigated thoroughly.

  2. Seawater intrusion mapping using electrical resistivity tomography and hydrochemical data. An application in the coastal area of eastern Thermaikos Gulf, Greece.

    PubMed

    Kazakis, N; Pavlou, A; Vargemezis, G; Voudouris, K S; Soulios, G; Pliakas, F; Tsokas, G

    2016-02-01

    The aim of this study was to determine the extent and geometrical characteristics of seawater intrusion in the coastal aquifer of the eastern Thermaikos Gulf, Greece. Hydrochemical data and geoelectrical measurements were combined and supplemented to determine the hydrochemical regime of the study site in regard to seawater phenomena. Chemical analysis of groundwater was performed in 126 boreholes and fifteen electrical resistivity tomographies (ERT) were measured, whereas in two sites the ERT measurements were repeated following the wet season. The Cl(-) concentrations recorded reached 2240 mg/L indicating seawater intrusion which was also verified by ionic ratios. The ionic ratios were overlapped and a seawater intrusion map (SWIM) was produced. A significant part of the coastal aquifer (up to 150 km(2)) is influenced by seawater intrusion. The areas with the most intensive salinization are located between Nea Kallikratia-Epanomi and Aggelochori-Peraia. According to the ERTs, in the influenced areas the salinization of the aquifer exceeds 1 km toward the mainland and its depth reaches 200 m. In the area surrounding Thessaloniki airport, the ERTs revealed salinization of the upper aquifer to depths of up to 40 m, whereas the lower aquifer is uninfluenced. This abnormal distribution of seawater intrusion demonstrates the value of geoelectrical methods in the study of seawater intrusion especially in areas with limited available hydrochemical data.

  3. Cone-based electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Pidlisecky, Adam

    Determining the 3-D spatial distribution of subsurface properties is a critical part of managing the clean-up of contaminated sites. Most standard hydrologic methods sample small regions immediately adjacent to wells or testing devices. This provides data which are not representative of the entire region of interest. Furthermore, at many contaminated sites invasive methods are not acceptable, due to the risks associated with contacting and spreading the contaminants. To address these issues, I have developed a minimally invasive technology that provides information about the 3-D distribution of electrical conductivity. This new technique, cone-based electrical resistivity tomography (C-bert), integrates the existing technologies of resistivity cone penetration testing (RCPT) with electrical resistivity tomography. Development of this tool included the creation of new software and modeling algorithms, the design of field equipment, field testing, and processing and interpretation of the resulting data. I present a 2.5-D forward modeling algorithm that incorporates an effective correction for the errors caused by boundary effects and source singularities. The algorithm includes an optimization technique for acquiring the Fourier coefficients required for the solution. A 3-D inversion algorithm is presented that has two major improvements over existing algorithms. First, it includes a 3-D version of the boundary correction/source singularity correction developed for the 2.5-D problem. Second, the algorithm can handle any type of acquisition geometry; this was a requirement for the development of C-bert. C-bert involves placing several permanent current electrodes in the subsurface and using electrodes mounted on a cone penetrometer and at the surface to measure the resultant potential field. In addition to these measurements, we obtain the standard suite of RCPT data, including high resolution resistivity logs. The RCPT data can be used to generate a realistic

  4. The effect of irrigation frequency on water depletion by bell pepper: the added value of electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Garre, S.; Assouline, S.; Furman, A.

    2013-12-01

    The dynamics of root uptake, and its relation to soil water content, are still insufficiently understood. Nevertheless, it is a very important component in the terrestrial water balance and may determine water resources management, ecology and agriculture. In this research we explore the spatial and temporal distribution of soil water under different irrigation schemes in high resolution using electrical resistivity tomography (ERT). Bell peppers were planted in a chamber and irrigated in two different schemes, differing only in irrigation frequency. The daily dose remains the same for both treatments. This irrigation difference results in different spatio-temporal distribution of the soil water in the root zone, which in turn implies spatio-temporal differences in root uptake. The experiment was conducted under very high evapotranspiration (ET) conditions. The resistivity surveys, using 96 electrodes placed around the growth chamber were taken over 10 times daily. Plants subjected to high frequency irrigation generally were faster in growth and matured about a week earlier. This is primarily attributed to the higher water content that exists in the root zone, and primarily during the high ET periods at noon. The 3-D resistivity distributions provide an interesting insight into the water depletion by the crop in space and time. However, the ERT survey also encountered some challenges related to time-varying error levels and electrode contact changes during wetting and drying cycles.

  5. The effect of irrigation frequency on water depletion by bell pepper: the added value of electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Garré, Sarah; Assouline, Shmuel; Furman, Alex

    2014-05-01

    The dynamics of root uptake, and its relation to soil moisture, is a very important component in the terrestrial water balance and may determine water resources management, ecology and agriculture. In this research we explore the spatial and temporal distribution of soil water under different irrigation schemes in high resolution using electrical resistivity tomography (ERT). Bell pepper was planted in containers and irrigated in two different schemes, differing only in irrigation frequency. The daily dose remains the same for both treatments. This irrigation difference results in different spatio-temporal distribution of the soil water in the root zone, which in turn implies spatio-temporal differences in root uptake. The experiment was conducted under very high evapotranspiration (ET) conditions. The resistivity surveys, using 96 electrodes placed around the growth chamber were taken over 10 times daily. Plants subjected to high frequency irrigation generally were faster in growth and matured about a week earlier. This is primarily attributed to the higher water content that exists in the root zone, and primarily during the high ET periods at noon. The 3-D resistivity distributions provide an interesting insight into the water depletion by the crop in space and time. However, the ERT survey also encountered some challenges related to time-varying error levels and electrode contact changes during wetting and drying cycles.

  6. The use of the Electrical Resistivity Tomography to image deep volcanic structures: a methodological study applied to Mt. Vesuvius (Italy).

    NASA Astrophysics Data System (ADS)

    Troiano, Antonio; Giulia Di Giuseppe, Maria; Somma, Renato; Brandi, Giuseppe; Troise, Claudia; De Natale, Giuseppe

    2016-04-01

    Geophysics is considered a powerful tool both for modeling the structure and controlling the dynamics of active volcanoes. In particular, the application of the electrical and electromagnetic (EM) methods is a topic of great interest, given the strong dependence of the electrical resistivity on the shallow and deep physical characteristics of a volcanic apparatus. Among the EM methods, the magnetotellurics (MT), reaching investigation depth ranging from a few hundred meters to tens of km, is the optimal tool to characterize the volcanic environments leading often to remarkable imaging of the buried structures. However, its dependence from a natural source make its application often difficult due to the presence of high noise levels. Moreover, MT curves are subjected to the so-called static shift effect, an anomalous displacement of the curves that cannot be modeled without some external constrain. Electrical Resistivity Tomography (ERT), on other hands, using an artificial source, ends in a more controlled imaging that is, however, often limited to the very shallow parts of the structures. The realization of a deeper ERT imaging is complicated by both physical and logistic reasons. The resolved depths depend from the intensity of the source, an electrical current injected into the ground, whereas the displacement of the measurements array often implies hard problems due to the nature of the volcanic environments. The actual progresses of the technologies offer some way to bypass the main limitation of the ERT technique. The use of new kind of measurement stations permits the realization of a sort of wireless electrodic arrays. The easiness of use of the actual power generators represents a further notable element. In conclusion, the ERT imaging could now represents an optimal tool also in the imaging of structures buried at intermediate depths (up to a few km). In such a way, also its interaction with the MT methods could results notably enhanced, due to the

  7. Electrical resistivity tomography applied to a complex lava dome: 2D and 3D models comparison

    NASA Astrophysics Data System (ADS)

    Portal, Angélie; Fargier, Yannick; Lénat, Jean-François; Labazuy, Philippe

    2015-04-01

    The study of volcanic domes growth (e.g. St. Helens, Unzen, Montserrat) shows that it is often characterized by a succession of extrusion phases, dome explosions and collapse events. Lava dome eruptive activity may last from days to decades. Therefore, their internal structure, at the end of the eruption, is complex and includes massive extrusions and lava lobes, talus and pyroclastic deposits as well as hydrothermal alteration. The electrical resistivity tomography (ERT) method, initially developed for environmental and engineering exploration, is now commonly used for volcano structure imaging. Because a large range of resistivity values is often observed in volcanic environments, the method is well suited to study the internal structure of volcanic edifices. We performed an ERT survey on an 11ka years old trachytic lava dome, the Puy de Dôme volcano (French Massif Central). The analysis of a recent high resolution DEM (LiDAR 0.5 m), as well as other geophysical data, strongly suggest that the Puy de Dôme is a composite dome. 11 ERT profiles have been carried out, both at the scale of the entire dome (base diameter of ~2 km and height of 400 m) on the one hand, and at a smaller scale on the summit part on the other hand. Each profile is composed of 64 electrodes. Three different electrode spacing have been used depending on the study area (35 m for the entire dome, 10 m and 5 m for its summit part). Some profiles were performed with half-length roll-along acquisitions, in order to keep a good trade-off between depth of investigation and resolution. Both Wenner-alpha and Wenner-Schlumberger protocols were used. 2-D models of the electrical resistivity distribution were computed using RES2DINV software. In order to constrain inversion models interpretation, the depth of investigation (DOI) method was applied to those results. It aims to compute a sensitivity index on inversion results, illustrating how the data influence the model and constraining models

  8. Monitoring radio-frequency heating of contaminated soils using electrical resistance tomography

    SciTech Connect

    Ramirez, A.L.; Daily, W.D.

    1993-09-01

    Electrical resistance tomography (ERT) was used to monitor a radio-frequency heating process for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. A dipole antenna located in a horizontal well in the unsaturated zone was used to heat a contaminated clay layer. The heat-induced changes were tomographically imaged by their effects on the formation electrical resistivity. The resistivity changes observed appear to be related to heating and vaporization of the pore water, formation of steam condensate, and infiltration of rainwater through the heated zones and adjacent areas. There is a clear asymmetry downward in the resistivity decreases associated with the heating process. The resistivity decreases observed in the vicinity of the heating well are believed to be caused by the heating and downward migration of warm water originally located within a radius of a few feet around the heating well; the magnitude of the change is between 10--20%. The decreasing resistivity implies an increasing rate of radio wave attenuation as heating progressed; therefore, the rate of energy deposition around the heating well increased while the penetration distance of the radio waves decreased. Saturation changes in the clay near the antenna during heating were estimated to be 50--55% based on the observed resistivity decreases. Resistivity changes observed at distances greater than 3 meters to one side of the antenna appear to be related to rainwater infiltration. We propose that gaps in near surface clay layers allow rainwater to migrate downward and reach the top of clay rich zone penetrated by the antenna borehole. The water may then accumulate along the top of the clay.

  9. Assessment of local hydraulic properties from electrical resistivity tomography monitoring of a three-dimensional synthetic tracer test experiment

    NASA Astrophysics Data System (ADS)

    Camporese, M.; Cassiani, G.; Deiana, R.; Salandin, P.

    2011-12-01

    In recent years geophysical methods have become increasingly popular for hydrological applications. Time-lapse electrical resistivity tomography (ERT) represents a potentially powerful tool for subsurface solute transport characterization since a full picture of the spatiotemporal evolution of the process can be obtained. However, the quantitative interpretation of tracer tests is difficult because of the uncertainty related to the geoelectrical inversion, the constitutive models linking geophysical and hydrological quantities, and the a priori unknown heterogeneous properties of natural formations. Here an approach based on the Lagrangian formulation of transport and the ensemble Kalman filter (EnKF) data assimilation technique is applied to assess the spatial distribution of hydraulic conductivity K by incorporating time-lapse cross-hole ERT data. Electrical data consist of three-dimensional cross-hole ERT images generated for a synthetic tracer test in a heterogeneous aquifer. Under the assumption that the solute spreads as a passive tracer, for high Peclet numbers the spatial moments of the evolving plume are dominated by the spatial distribution of the hydraulic conductivity. The assimilation of the electrical conductivity 4D images allows updating of the hydrological state as well as the spatial distribution of K. Thus, delineation of the tracer plume and estimation of the local aquifer heterogeneity can be achieved at the same time by means of this interpretation of time-lapse electrical images from tracer tests. We assess the impact on the performance of the hydrological inversion of (i) the uncertainty inherently affecting ERT inversions in terms of tracer concentration and (ii) the choice of the prior statistics of K. Our findings show that realistic ERT images can be integrated into a hydrological model even within an uncoupled inverse modeling framework. The reconstruction of the hydraulic conductivity spatial distribution is satisfactory in the portion

  10. Digital photogrammetric analysis and electrical resistivity tomography for investigating the Picerno landslide (Basilicata region, southern Italy)

    NASA Astrophysics Data System (ADS)

    de Bari, Claudia; Lapenna, Vincenzo; Perrone, Angela; Puglisi, Claudio; Sdao, Francesco

    2011-10-01

    Digital photogrammetric analysis and Electrical Resistivity Tomography (ERT) techniques were applied to evaluate the volume of material involved in a complex roto-translational slide occurred in the territory of Picerno (Basilicata region, southern Italy). Analytical and digital photogrammetric techniques facilitated a multi-temporal analysis of aerial photos for the years 1997, 2004 and 2006. In order to identify different geomorphologic features (scarps, terraces and trenches) of the landslide and their development, the analytical and digital photo interpretation was performed at the maximum scale of 1:5000. Geological and geomorphological surveys were carried out to verify photo-interpretation results. Digital Elevation Models (DEMs) for 1997, 2004 and 2006 were produced by applying the Grid Adaptive method. The differential DEMs (2006-1997; 2006-2004; 2004-1997) for the most dangerous part of the landslide allowed us to recognize the areas affected either by deposition or erosion and also estimate any altitudinal changes in each geomorphologic unit. To detect the sliding surface and estimate the thickness of the sliding material, several transversal and longitudinal ERT profiles were obtained. The electrical images of subsurface supported by stratigraphical data from boreholes were integrated with the information from the DEMs. The altitudinal changes and the sizes of the source and accumulation areas allowed us to estimate the volume of material involved in the mass movement. The fusion of data from different sensors allows us to gather indications on the surface and subsurface characteristics of the landslide providing useful information for landslide mitigation activities. Such an approach can help both to improve our knowledge and overcome the drawbacks of each methodology.

  11. Resistive plate chambers in positron emission tomography

    NASA Astrophysics Data System (ADS)

    Crespo, Paulo; Blanco, Alberto; Couceiro, Miguel; Ferreira, Nuno C.; Lopes, Luís; Martins, Paulo; Ferreira Marques, Rui; Fonte, Paulo

    2013-07-01

    Resistive plate chambers (RPC) were originally deployed for high energy physics. Realizing how their properties match the needs of nuclear medicine, a LIP team proposed applying RPCs to both preclinical and clinical positron emission tomography (RPC-PET). We show a large-area RPC-PET simulated scanner covering an axial length of 2.4m —slightly superior to the height of the human body— allowing for whole-body, single-bed RPC-PET acquisitions. Simulations following NEMA (National Electrical Manufacturers Association, USA) protocols yield a system sensitivity at least one order of magnitude larger than present-day, commercial PET systems. Reconstruction of whole-body simulated data is feasible by using a dedicated, direct time-of-flight-based algorithm implemented onto an ordered subsets estimation maximization parallelized strategy. Whole-body RPC-PET patient images following the injection of only 2mCi of 18-fluorodesoxyglucose (FDG) are expected to be ready 7 minutes after the 6 minutes necessary for data acquisition. This compares to the 10-20mCi FDG presently injected for a PET scan, and to the uncomfortable 20-30minutes necessary for its data acquisition. In the preclinical field, two fully instrumented detector heads have been assembled aiming at a four-head-based, small-animal RPC-PET system. Images of a disk-shaped and a needle-like 22Na source show unprecedented sub-millimeter spatial resolution.

  12. The integration of 3D electrical resistivity tomography and ET flux measurements to characterize water mass balance in the soil-plant-atmosphere continuum

    NASA Astrophysics Data System (ADS)

    Vanella, Daniela; Boaga, Jacopo; Perri, Maria Teresa; Consoli, Simona; Cassiani, Giorgio

    2014-05-01

    The system of soil, vegetation, and the adjacent atmosphere is characterized by complex patterns, structures, and processes that act on a wide range of time and space scales. While the exchange of energy and water is continuous between compartments, the pertinent fluxes are strongly heterogeneous and variable in space and time. Therefore, quantitatively predicting the systems' behaviour constitutes a major challenge. Traditionally, soil moisture beneath irrigated crops has been determined using point measurement methods such as neutron probes or capacitance systems. These approaches cannot measure soil moisture at depths beyond the root-zone of plants and have limited lateral coverage. Literature results show that electrical resistivity tomography (ERT) can be used to reliable map the spatial heterogeneity in soil moisture. Here we present the application of the time-lapse non-invasive 3D micro - electrical tomography (ERT) to monitor soil-plant interactions in the root zone of an orange tree located in the Mediterranean semi-arid Sicilian (South Italy) context. The subsoil dynamics, particularly influenced by irrigation and root uptake, has been characterized a 3D ERT apparatus consisting of 48 buried electrodes on 4 instrumented micro boreholes plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. During the monitoring, repeated ERT soil moisture measurements were collected, as well as laboratory characterization of the soil electrical properties as a function of moisture content and pore water electrical conductivity. Plant transpiration was continuously monitored during the ERT experiment by the sap flow heat pulse (HP) method for a quantitative analysis of the mass balance in the soil-plant-atmosphere system under observation. In addition, evapo-transpiration has been continuously monitored at the same site using an eddy-correlation tower. The integration of measurements regarding soil,plant and atmosphere allows a better understanding of

  13. Comparison of transport in lysimeters with undisturbed loamy sand and silty soil using non invasive imaging with electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Garre, S.; Köstel, J.; Vanderborght, J.; Javaux, M.

    2009-04-01

    The transport of chemicals through soil is subject to the 3-D structure of the soil hydraulic properties (e.g. unsaturated hydraulic conductivity function) and state variables (e.g. water content). Although this is known for decades, it is still difficult to quantitatively predict solute transport especially when preferential flow or fingering occurs. One reason for this is the shortcoming of 3-D data on both the solute transport process itself and its determining parameters. Lysimeters provide excellent means to control the boundary conditions and are accessible from all sides. Filled with undisturbed soil and equipped with geophysical imaging devices they provide a valuable tool to visualize and better understand solute transport in natural soils. In our study we conducted solute tracer step experiments on two distinct undisturbed unsaturated field soils (gleyic Cambisol and orthic Luvisol). The boundary conditions were set to constant irrigation (1.5 cm/day) at the top and a constant suction at the bottom. Tracer breakthrough was monitored using 3-D Electrical Resistivity Tomography (ERT) and Time-Domain Reflectometry (TDR). We used the effluent tracer breakthrough and TDR measured breakthrough as a ground truth for the ERT data. From these data, apparent convection-dispersion transport parameters were derived. We found considerably different transport velocities and dispersivities for the two soils. In the orthic Luvisol, distinct preferential transport paths were visualized and followed in time. In the gleyic Cambisol we observed minor heterogeneities in the transport front which were aligned to the plowing direction. The study demonstrates the usefulness of ERT to characterize and compare the 3-D spatio-temporal evolution of solute fronts. The results are beneficial to investigate relationships between soil structure and the transport process and to explain the scale dependency of the transport processes from the spatial structure of the process at a smaller

  14. Quantifying potential recharge in mantled sinkholes using ERT.

    PubMed

    Schwartz, Benjamin F; Schreiber, Madeline E

    2009-01-01

    Potential recharge through thick soils in mantled sinkholes was quantified using differential electrical resistivity tomography (ERT). Conversion of time series two-dimensional (2D) ERT profiles into 2D volumetric water content profiles using a numerically optimized form of Archie's law allowed us to monitor temporal changes in water content in soil profiles up to 9 m in depth. Combining Penman-Monteith daily potential evapotranspiration (PET) and daily precipitation data with potential recharge calculations for three sinkhole transects indicates that potential recharge occurred only during brief intervals over the study period and ranged from 19% to 31% of cumulative precipitation. Spatial analysis of ERT-derived water content showed that infiltration occurred both on sinkhole flanks and in sinkhole bottoms. Results also demonstrate that mantled sinkholes can act as regions of both rapid and slow recharge. Rapid recharge is likely the result of flow through macropores (such as root casts and thin gravel layers), while slow recharge is the result of unsaturated flow through fine-grained sediments. In addition to developing a new method for quantifying potential recharge at the field scale in unsaturated conditions, we show that mantled sinkholes are an important component of storage in a karst system.

  15. Electrical Resistivity Tomography of the Karstic Aquifer of Bittit spring (Middle Atlas, Morocco)

    NASA Astrophysics Data System (ADS)

    Qarqori, Kh.; Rouai, M.; Moreau, F.; Saracco, G.; Hermitte, D.; Boualoul, M.; Dauteuil, O.; Biessy, G.; Sahbi, H.

    2009-04-01

    The Tabular Middle Atlas reservoir is one of the most important aquifers in northern Morocco. It is mainly a water table fractured reservoir consisting of Lias limestone and dolomite. The matrix permeability is very low and water flows essentially along open fractures and karsts. The Bittit Spring belongs to this karstic system and constitutes an important aquifer lying at the junction between the tabular reservoir and the Sais basin. Bittit spring, with an average annual discharge of about 1600 l/s, contributes largely to water supply of the big city of Meknes. Groundwater circulation is complex due to tectonics and to presence of karstic Quaternary travertine overlying Lias carbonate. In Bittit area, travertine is mostly covered by Quaternary basalt. Up to now water flow paths and the underground karst organization remain misknown, and turbidity affects the water quality after rain events. To highlight these issues, an integrated geophysical survey was performed in this area in the framework of a French-Moroccan scientific project. The geophysical imaging was carried out mainly by Electrical Resistivity Tomography (ERT). Resistivity data were acquired by an ABEM Terrameter SAS1000 and a multi-electrode Lund system imaging using a Wenner array configuration of 64 electrodes and 5m spacing, reaching a depth of about 50m. Topographic corrections and 2D inversion models were performed using Res2Dinv software package. Seven 2D resistivity high resolution images have been obtained allowing to detect, delineate important fractures and also to hydrogeological characterization of the underground karst. A borehole of 100m depth was drilled in order to correlate and calibrate geophysical data and proposed models. Two sub-vertical fracture families have been identified with NE-SW and NW-SE directions respectively. These results correlate well with fracture data analysis gathered from remote sensing Spot images at large scale, and from local field fracture scanline surveys. A

  16. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  17. State Waste Discharge Permit Application: Electric resistance tomography testing

    SciTech Connect

    Not Available

    1994-04-01

    This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the areal extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks.

  18. An ensemble Kalman filter approach to identify the hydraulic conductivity spatial distribution from electrical resistivity tomography time-lapse monitoring of three-dimensional tracer test experiments

    NASA Astrophysics Data System (ADS)

    Camporese, M.; Cassiani, G.; Deiana, R.; Perri, M. T.; Salandin, P.

    2012-04-01

    An approach based on the Lagrangian formulation of transport and the ensemble Kalman filter (EnKF) is applied to assess the spatial distribution of hydraulic conductivity K by assimilating time-lapse cross-hole electrical resistivity tomography (ERT) images generated for a synthetic tracer test in a heterogeneous aquifer. Assuming that the solute spreads as a passive tracer, for high Peclet numbers the spatial moments of the evolving plume are dominated by the spatial distribution of the hydraulic conductivity. The assimilation of the electrical conductivity 4D images allows updating both the hydrological state in terms of solute concentration and the spatial distribution of K. Thus, delineation of the tracer plume and estimation of the aquifer heterogeneity at the local scale can be achieved at the same time by means of this interpretation of time-lapse electrical images from tracer tests. We assess the impact on the performance of the hydrological inversion of the uncertainty inherently affecting ERT inversions in terms of tracer concentration and the choice of the prior statistics of K. The results show that realistic ERT images can be integrated into a hydrological model even within an uncoupled inverse modeling framework, the reconstruction of the hydraulic conductivity spatial distribution being satisfactory in the portion of the domain directly covered by the passage of the tracer. Aside from the issues commonly affecting inverse models, the proposed approach is subject to the problem of the filter inbreeding and the retrieval performance is sensitive to the choice of K prior geostatistical parameters.

  19. Application Of ERT For Tracking CO2 Plume Growth And Movement At The SECARB Cranfield Site

    SciTech Connect

    Carrigan, C R; Ramirez, A L; Newmark, R L; Aines, R; Friedmann, S J

    2009-04-27

    Electrical Resistance Tomography (ERT) installed to track the development of an injected subsurface CO{sub 2} plume at the SECARB Cranfield, MS. sequestration site will be the deepest subsurface application of this method to date. ERT utilizes vertical arrays of electrodes, usually in a cross-well arrangement, to perform four-electrode measurements of changes in the spatial distribution of electrical resistance within a subsurface formation. Because a formation containing super-critical CO{sub 2} is approximately five times as resistive as its surroundings, significant resistance changes are anticipated during plume growth and movement within a brine-filled formation. ERT has also been shown to be quite sensitive to CO{sub 2} saturation changes. The Cranfield ERT electrode arrays will be emplaced at a depth exceeding 10,000 ft. (3280 m); the system design and installation must address significant challenges associated with both the depth and borehole conditions including temperatures of 258 F (126 C), pressures exceeding 5000 psi and a groundwater pH of 3. In addition, the system must allow co-located emplacement and concurrent operation with other monitoring techniques that utilize the same boreholes. ERT electrode and cabling will be attached to the outside of the well casing, allowing free access to the interior of the well, which is required by some of the other monitoring techniques being fielded. We will highlight these design challenges along with preliminary simulations indicating the anticipated level of imaging and the advantages of applying the technique in conjunction with other methods (such as cross-well seismics) to more accurately track the properties, location and movement of CO{sub 2} plumes.

  20. Dynamic Inversion for Hydrological Process Monitoring with Electrical Resistance Tomography Under Model Uncertainty

    SciTech Connect

    Lehikoinen, A.; Huttunen, J.M.J.; Finsterle, S.; Kowalsky, M.B.; Kaipio, J.P.

    2009-08-01

    We propose an approach for imaging the dynamics of complex hydrological processes. The evolution of electrically conductive fluids in porous media is imaged using time-lapse electrical resistance tomography. The related dynamic inversion problem is solved using Bayesian filtering techniques, that is, it is formulated as a sequential state estimation problem in which the target is an evolving posterior probability density of the system state. The dynamical inversion framework is based on the state space representation of the system, which involves the construction of a stochastic evolution model and an observation model. The observation model used in this paper consists of the complete electrode model for ERT, with Archie's law relating saturations to electrical conductivity. The evolution model is an approximate model for simulating flow through partially saturated porous media. Unavoidable modeling and approximation errors in both the observation and evolution models are considered by computing approximate statistics for these errors. These models are then included in the construction of the posterior probability density of the estimated system state. This approximation error method allows the use of approximate - and therefore computationally efficient - observation and evolution models in the Bayesian filtering. We consider a synthetic example and show that the incorporation of an explicit model for the model uncertainties in the state space representation can yield better estimates than a frame-by-frame imaging approach.

  1. Sandbox experiments on Uraninite Ore: ERT and SP measurments.

    NASA Astrophysics Data System (ADS)

    Singh, R. K.

    2015-12-01

    Nuclear energy, considering its own intrinsic merits, would be a leading source for meeting the energy requirement in present and future scenario. Concealed Uranium deposits under sedimentary cover, with poor surface indications calls for reorientation of survey with large inputs involving integrated geophysical approach. Sand Box experiments have been carried out over Uraninite ore. The tank is a glass fish tank (height 39 cm, length 75 cm, width 30 cm). It was filled with sand up to 35 cm high. The sand was saturated from below to minimize the entrapment of the gas bubbles. The average size for sand grains is ~ 0.295mm. The formation factor of the sand is 3.5, with a negligible surface conductivity because of the coarse nature of the sand grains. The dimension of considered Uraninite ore sample is 4cm x 4cm x 4cm. The depth of top of the ore sample is kept at 3cm. In this paper both resistivity and self-potential measurements were carried out for possible detection of Uraninite. The resistivity measurements were made with 64 non-polarizable electrodes using Electrical Resistivity Tomography (ERT) equipment of FlashRes Universal developed by ZZ Resistivity Imaging Pty. Ltd. We have used screws of length 3cm as electrodes. The separation between these electrodes are ~ 1cm. The resistivity tomography results clearly outlines the target Uraninite body. The resistivity tomography results also detects small heterogeneities associated with air bubbles possibly due to unsaturated pore spaces. SP measurements were made using two non-polarizing Pb/PbCl2 electrodes and a Fluke 289 voltmeter (sensitivity 0.001 mV, internal impedance 100 MOhm). The reference electrode was located on the corner of the sandbox. The other electrode was used to scan the electrical potential at the surface of the sand. SP measurements were made with a spacing of 3 cm over the same ERT profile. The SP results also shows a dip (or a low SP anomaly) over the target ore body sample. Thus, both SP and

  2. Application of electrical resistivity tomography for investigating the internal structure of a translational landslide and characterizing its groundwater circulation (Kualiangzi landslide, Southwest China)

    NASA Astrophysics Data System (ADS)

    Ling, Chengpeng; Xu, Qiang; Zhang, Qiang; Ran, Jiaxin; Lv, Hongbin

    2016-08-01

    Electrical resistivity tomography (ERT) is a widely used tool in near surface geophysical surveys for the investigation of various geological and engineering problems, including landslides. In this study, the internal structure of the southern region of the Kualiangzi landslide, which is located in Sichuan province, China, was investigated using four ERT profiles, drill cores, and inclinometer data. The characteristics of the groundwater circulation were evaluated from variations in electrical resistivity and groundwater level. The results showed that the sliding surface corresponds to a deep zone with low resistivity and that the sliding material consists of clay, gravelly soil, and weathered sandstone and mudstone. The thickness of the sliding material is 50 m in the main tension trough and decreases to several meters in the direction of sliding. The dip angle of the sliding surface that has low resistivity is generally consistent with that of the bedrock. The groundwater level in the tension trough and in the middle transitional part from hill-country to flat terrain was highest in the landslide. The groundwater level close to the toe front of the landslide was the lowest. The groundwater is recharged by the precipitation and generally drains to the toe front by seasonal springs along the sliding surface. The rapid increment of the groundwater level in the tension trough kept pace with that of the displacement rate after intense rainfall. The improved understanding of internal structure and groundwater recirculation is beneficial for the analysis of the mechanisms of translational landslides and their hazard prevention.

  3. Characterization of a dismissed landfill via electrical resistivity tomography and mise-à-la-masse method

    NASA Astrophysics Data System (ADS)

    De Carlo, Lorenzo; Perri, Maria Teresa; Caputo, Maria Clementina; Deiana, Rita; Vurro, Michele; Cassiani, Giorgio

    2013-11-01

    Electrical resistivity methods are widely used for environmental applications, and they are particularly useful for the characterization and monitoring of sites where the presence of contamination requires a thorough understanding of the location and movement of water, that can act as a carrier of solutes. One such application is landfill studies, where the strong electrical contrasts between waste, leachate and surrounding formations make electrical methods a nearly ideal tool for investigation. In spite of the advantages, however, electrical investigation of landfills poses also challenges, both logistical and interpretational. This paper presents the results of a study conducted on a dismissed landfill, close to the city of Corigliano d'Otranto, in the Apulia region (Southern Italy). The landfill is located in an abandoned quarry, that was subsequently re-utilized about thirty years ago as a site for urban waste disposal. The waste was thought to be more than 20 m thick, and the landfill bottom was expected to be confined with an HDPE (high-density poli-ethylene) liner. During the digging operations performed to build a nearby new landfill, leachate was found, triggering an in-depth investigation including also non-invasive methods. The principal goal was to verify whether the leachate is indeed confined, and to what extent, by the HDPE liner. We performed both surface electrical resistivity tomography (ERT) and mise-à-la-masse (MALM) surveys, facing the severe challenges posed by the rugged terrain of the abandoned quarry complex. A conductive body, probably associated with leachate, was found as deep as 40 m below the current landfill surface i.e. at a depth much larger than the expected 20 m thickness of waste. Given the logistical difficulties that limit the geometry of acquisition, we utilized synthetic forward modeling in order to confirm/dismiss interpretational hypotheses emerging from the ERT and MALM results. This integration between measurements and

  4. An extended L-curve method for choosing a regularization parameter in electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Xu, Yanbin; Pei, Yang; Dong, Feng

    2016-11-01

    The L-curve method is a popular regularization parameter choice method for the ill-posed inverse problem of electrical resistance tomography (ERT). However the method cannot always determine a proper parameter for all situations. An investigation into those situations where the L-curve method failed show that a new corner point appears on the L-curve and the parameter corresponding to the new corner point can obtain a satisfactory reconstructed solution. Thus an extended L-curve method, which determines the regularization parameter associated with either global corner or the new corner, is proposed. Furthermore, two strategies are provided to determine the new corner-one is based on the second-order differential of L-curve, and the other is based on the curvature of L-curve. The proposed method is examined by both numerical simulations and experimental tests. And the results indicate that the extended method can handle the parameter choice problem even in the case where the typical L-curve method fails. Finally, in order to reduce the running time of the method, the extended method is combined with a projection method based on the Krylov subspace, which was able to boost the extended L-curve method. The results verify that the speed of the extended L-curve method is distinctly improved. The proposed method extends the application of the L-curve in the field of choosing regularization parameter with an acceptable running time and can also be used in other kinds of tomography.

  5. Bench-Scale Experiments to Evaluate ERT as a Monitoring Tool for Geologic CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Breen, S. J.; Detwiler, R. L.; Carrigan, C. R.

    2010-12-01

    Field-scale studies have shown Electrical Resistivity Tomography (ERT) to be an effective tool for imaging resistivity anomalies and monitoring changing saturations in the near subsurface. Despite the challenges of implementing ERT in the deep subsurface, it has potential as a surveying technology for visualizing sequestered CO2, in part because it can be localized within the target reservoir. Currently, the technology is being evaluated as part of a geologic sequestration project in Cranfield, MS, where supercritical CO2 is injected to ten thousand feet below the surface. In support of this field-scale activity, we have designed an analog bench-scale experimental system to further evaluate the ability of ERT to quantify both the volume and spatial distribution of gas injected into a saline aquifer. Our translucent sand chambers measure 58cm x 30cm x 1cm and are lined with twenty-one stainless steel electrodes on each long side, inserted into a nonconductive plastic gasket. We fill the chamber with quartz sand with different grain sizes with a filling procedure that generates small-scale layering within the injection zone, which is overlain by a fine-grained layer that serves as a capillary barrier. Prior to gas injection, the porous medium is saturated with a low resistivity salt solution. We then inject gas into the bottom of the injection zone. Buoyant forces drive gas migration into the chamber, resulting in a combination of small-scale trapping in horizontal layers, fingering between the horizontal layers, and large-scale trapping of the gas plume along the upper capillary barrier. During pauses in gas injection, a CCD camera captures high-resolution images, and an ERT data acquisition system scans the chamber. Quantitative visualization techniques are used to process the CCD images resulting in high-resolution measurements of the spatial distribution of the injected gas. These results are directly compared to resistivity fields that result from the inversion

  6. Ecohydrologic Investigations of Shallow Lateral Subsurface Flow in Tropical Soils using Time-Lapse Surface Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Ogden, F. L.; Mojica, A.; Abebe, N. A.; Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project

    2010-12-01

    The hydrologic effects of deforestation and aforestation in the tropics remain an area of active research. Hydrologic predictions of land-use change effects remain elusive. One of the unique features of catchment hydrology in the tropics is the effect of intense, continuous biological activity by insects, shrubs, trees, and small mammals. Sapprolitic soils derived from weathered bedrock cover widespread areas. These soils have low matrix permeabilities on the order of 1 mm/h, are 10 to 20 m in thickness and have relatively low activity because they have been depleted of light cations by annual rainfall over 2000 mm. As part of the Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, we have observed shallow subsurface flow in tropical soils in central Panama using an introduced salinity contrast and surface electrical resistivity tomography (ERT). In 2009 and 2010, experiments were conducted in a 30 year-old secondary succession forest, and in two former pasture sites that were planted with native timber species and teak, respectively, in 2008. At each site, saline water (NaCl tagged with LiBr) was introduced to the soil using two different methods: soil pits and ponded surface applications. Results showed the strongest response in the case of ponded surface applications with observed changes in resistivity between -50% and 50%. In soil pit applications, the change in electrical resistivity varied from -10% to 10%. Results suggest that in the case of surface application, a transient perched water table is created near the bottom of the bioturbation layer that activates the downslope macropore network and results in bulk flow velocities that are significantly higher than observed soil matrix permeabilities. When heavy rainfall occurred during tests, increased mobility of the salinity contrast more clearly showed the active layer where most flow occurred. Time-series ERT observations enabled measurements of downslope bulk

  7. Application of 2-D geoelectrical resistivity tomography for mountain permafrost detection in sporadic permafrost environments: Experiences from Eastern Austria

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas

    2015-04-01

    Mountain permafrost covers some 2000 km² of the Austrian Alps which is less than 2.5% of the national territory. Delineating the altitudinal lower limit of permafrost in the mountains of Austria is difficult due the complex topography, the rather sparseness of field verification data and the lack of long-term permafrost monitoring data. Such monitoring data should cover different slope aspects, different elevations, different substrates and different mountain regions of Austria. In this study it was attempted to delineate the lower limit of permafrost at two study sites in the Tauern Range, Austria, applying two-dimensional geoelectrical resistivity tomography (ERT). In addition, multi-annual ground temperature data collected by miniature temperature datalogger (MDT) were used to validate the results. At the study site Hochreichart (maximum elevation 2416 m asl), located in the Seckauer Tauern Range, 14 ERT profiles (lengths 48-196 m; electrode spacing 2, 2.5 or 4 m) were measured at elevations between 1805 and 2416 m asl. Measurements were carried out at two cirques (Reichart, Schöneben) and at the summit plateau of Hochreichart. Results at this site indicate that permafrost lenses are detectable at elevations down to c.1900 m asl at radiation-sheltered sites. Furthermore, at the summit plateau permafrost only occurs as rather small lenses. The ERT-based permafrost pattern is generally confirmed by the MTD data with negative mean annual ground temperature values at only a few monitoring sites. However, the possibility of air-filled cavities causing higher resistive zones faking permafrost existence cannot be excluded because coarse-grained sediments (i.e. relict rock glaciers and autochthonous block fields) are widespread at this study site. At the second study site Kögele Cirque (maximum elevation 3030 m asl) located in the Schober Mountains 12 ERT profiles (lengths 48 m; electrode spacing 2 m) were measured at elevations between 2631 and 2740 m asl. Spatially

  8. Electrical Resistivity Tomography and Ground Penetrating Radar for locating buried petrified wood sites: a case study in the natural monument of the Petrified Forest of Evros, Greece

    NASA Astrophysics Data System (ADS)

    Vargemezis, George; Diamanti, Nectaria; Tsourlos, Panagiotis; Fikos, Ilias

    2014-05-01

    A geophysical survey was carried out in the Petrified Forest of Evros, the northernmost regional unit of Greece. This collection of petrified wood has an age of approximately 35 million years and it is the oldest in Greece (i.e., older than the well-known Petrified Forest of Lesvos island located in the North Aegean Sea and which is possibly the largest of the petrified forests worldwide). Protection, development and maintenance projects still need to be carried out at the area despite all fears regarding the forest's fate since many petrified logs remain exposed both in weather conditions - leading to erosion - and to the public. This survey was conducted as part of a more extensive framework regarding the development and protection of this natural monument. Geophysical surveying has been chosen as a non-destructive investigation method since the area of application is both a natural ecosystem and part of cultural heritage. Along with electrical resistivity tomography (ERT), ground penetrating radar (GPR) surveys have been carried out for investigating possible locations of buried fossilized tree trunks. The geoelectrical sections derived from ERT data in combination with the GPR profiles provided a broad view of the subsurface. Two and three dimensional subsurface geophysical images of the surveyed area have been constructed, pointing out probable locations of petrified logs. Regarding ERT, petrified trunks have been detected as high resistive bodies, while lower resistivity values were more related to the surrounding geological materials. GPR surveying has also indicated buried petrified log locations. As these two geophysical methods are affected in different ways by the subsurface conditions, the combined use of both techniques enhanced our ability to produce more reliable interpretations of the subsurface. After the completion of the geophysical investigations of this first stage, petrified trunks were revealed after a subsequent excavation at indicated

  9. Monitoring hillslope moisture dynamics with surface ERT for enhancing spatial significance of hydrometric point measurements

    NASA Astrophysics Data System (ADS)

    Hübner, R.; Heller, K.; Günther, T.; Kleber, A.

    2015-01-01

    Besides floodplains, hillslopes are basic units that mainly control water movement and flow pathways within catchments of subdued mountain ranges. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap in the knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. This study presents a robust multi-method framework of electrical resistivity tomography (ERT) in addition to hydrometric point measurements, transferring hydrometric data into higher spatial scales to obtain additional patterns of distribution and dynamics of soil moisture on a hillslope. A geoelectrical monitoring in a small catchment in the eastern Ore Mountains was carried out at weekly intervals from May to December 2008 to image seasonal moisture dynamics on the hillslope scale. To link water content and electrical resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data. The results from ERT measurements show a strong correlation with the hydrometric data. The response is congruent to the soil tension data. Water content calculated from the ERT profile shows similar variations as that of water content from soil moisture sensors. Consequently, soil moisture dynamics on the hillslope scale may be determined not only by expensive invasive punctual hydrometric measurements, but also by minimally invasive time-lapse ERT, provided that pedo-/petrophysical relationships are known. Since ERT integrates larger spatial scales, a combination with hydrometric point measurements improves the understanding of the ongoing hydrological processes and better suits identification of heterogeneities.

  10. Cross-borehole ERT monitoring of a tracer injection into chlorinated-solvent contaminated fractured mudstone

    NASA Astrophysics Data System (ADS)

    Robinson, J.; Slater, L. D.; Johnson, T. C.; Day-Lewis, F. D.; Imbrigiotta, T. E.; Johnson, C. D.; Lacombe, P.; Lane, J. W., Jr.; Ntarlagiannis, D.; Shapiro, A. M.; Tiedeman, C. R.

    2014-12-01

    There is a need to monitor remedial injections in contaminated fractured rock to determine if targeted areas have been reached and to monitor treatment effectiveness. While detailed information can be obtained at boreholes, these locations are limited; determining connectivity in fracture networks is difficult and borehole monitoring locations may miss the injection entirely. The primary and secondary domains in fractured rock have hydraulic conductivities that differ by orders of magnitude such that tracer injections commonly have rapid breakthrough followed by extended tailings. Often, it is presumed that the tracer is transported into dead-end pore spaces or unknown inter-connected networks and/or sorbed into the primary porosity. Cross-borehole electrical resistivity tomography (ERT), guided by information from borehole geophysical logging and hydraulic testing, has the potential to monitor the fate of tracer injections between borehole locations. ERT has been under-exploited in fractured rock due to: (1) a lack of available 3D codes, (2) a lack of computing resources to accommodate a large number of model parameters, and (3) limitations of regularization constraints used in ERT modeling for representing fractured rock settings along with a full understanding of these constraints. Recognizing numerous advances in ERT imaging and building on our previous studies, we present results from a field-scale ERT experiment in fractured rock. We use ERT to monitor a conductive tracer injection in a fractured mudstone at the Naval Air Warfare Center (NAWC) in New Jersey. A custom-built electrode array included inflatable bladders to isolate fractures within each borehole and allowed for discrete water sampling and injection. By injecting the tracer in pulses and collecting 3D ERT measurements following each pulse, we were able to (1) avoid rapid breakthrough and large dilution rates and thus maintain a high conductivity contrast, and (2) characterize ambient flow by

  11. Application of electrical resistivity tomography to map lithological differences and subsurface structures (Eastern Sudetes, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Stan, Dominika; Stan-Kłeczek, Iwona

    2014-09-01

    The aim of this study is to determine the subsurface lithological variability and thickness of each metamorphic rocks unit by means of geophysical methods, which were presented within the framework of SEDIBUD. Research was performed on the ridge and the steep eastern slope of the Orlik massif (1204 m) in the Hrubý Jesenik range of the Eastern Sudetes, the Czech Republic. To obtain a spatial image of a geological rock mass, the non-invasive and relatively rapid method of electrical resistivity tomography (ERT) was used, which resulted in the creation of six profiles using the Dipole-Dipole and Wenner-Schlumberger arrays. As complementary methods, vertical electrical sounding (VES) and seismic refraction tomography were chosen. Fifteen measuring points along two profiles obtained by vertical electrical sounding allowed the determination of the following in the vertical section layers of different resistivity and thickness at direct points in contact primarily with Devonian quartzite rocks and weathered covers. In a series of field studies, a four-layered rock mass was examined in which the first layer is of fine-grained materials with medium- and large-size clasts, the second layer is quartzite, the third is gneiss and the fourth is phyllite. The five profiles measured by seismic refraction tomography made it possible to draw the boundary between the studied phyllites, gneisses and quartzites. In addition, geophysical surveys and the results of mineralogical composition analysis allowed us to determine the nature and thickness of the weathered layers present on the massif area, which, in the upper sections, are predominantly a clayey loam partially covered with blocks. The inclination of the slope is associated with an increase in the fraction of coarse material. The majority of the thickness of these layers is related to the local flattened surfaces and the presence of numerous streams, which contributed to the accumulation of the sediments that were also

  12. Estimation of the Unsaturated Hydraulic Soil Properties From Joint Inversion of Tension Infiltrometer and ERT Measurements: Numerical Experiments

    NASA Astrophysics Data System (ADS)

    Schneider, S.; Vanderborght, J.; Kemna, A.; Pessel, M.; Coquet, Y.

    2007-12-01

    An accurate and time-efficient estimation of unsaturated hydraulic soil properties in the field remains a challenge. Tension-infiltrometry is often used to determine unsaturated hydraulic soil properties and their spatial variability in the field. Due to capillary flow, a 3-D wetting bulb, which depends on the unsaturated hydraulic soil properties, the radius of the infiltrometer disk, and the applied water tension, develops under a tension infiltrometer. Electrical resistivity tomography (ERT) offers the possibility to image the spatial distribution of bulk soil electrical conductivity, which is related through a petrophysical model to the soil water content. Therefore, ERT data contain information about the 3-D structure of the wetting bulb, which may be exploited to infer hydraulic soil properties. A combination of tension-infiltrometer and ERT data for an inverse estimation of the soil hydraulic parameters was tested in a numerical experiment. Both 3-D water flow and electrical potential fields were simulated with the SWMS_3-D model using the van Genuchten hydraulic functions and the Rhoades petrophysical model. Simulated infiltration and simulated apparent electrical resistivities were subsequently inverted using the PEST software. Inversion of the combined infiltration and ERT datasets showed that the hydraulic parameters could be inverted from a single infiltration experiment, which is not possible when only infiltration data are used in the inversion. Also petrophysical parameters could be inverted simultaneously with hydraulic parameters from the combined ERT-infiltrometer data. These results demonstrate the potential of the method by considering additional information about the structure of the wetting bulb which is contained in ERT data.

  13. Monitoring six-phase ohmic heating of contaminated soils using electrical resistance tomography

    SciTech Connect

    Ramirez, A.L.; Daily, W.D.

    1994-09-01

    Electrical resistance tomography (ERT) was used to monitor six-phase ohmic heating used for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. The changes in electrical conductivity caused by six-phase ohmic-heating in a clay layer located in the vadose zone were monitored during a period of approximately 2 months, before, during and after heating. From an array of electrodes located in 4 boreholes, we collected electrical resistivity data between five pairs of adjacent holes pairs. This data was used to calculate tomographs which showed the electrical conductivity changes along five vertical planes. The difference tomographs show the combined effects of moisture redistribution and heating caused by six-phase heating and vapor extraction. The tomographs show that most of the clay layer increased in electrical conductivity during the first 3 weeks of the 4 week long heating phase. At this time, the electrical conductivities near the center of the heating array were twice as large as the pre-heat conductivities. Then the electrical conductivity started to decrease for portions of the clay layer closest to the vapor extraction well. We propose that the conductivity decreases are due to the removal of moisture by the heating and vacuum extraction. Parts of the clay layer near the extraction well reached electrical conductivities as low as 40% of the pre-heating values. We propose that these regions of lower than ambient electrical conductivities are indicators of regions where the vapor removal by vacuum extraction was most effective. At the end of the heating phase, our estimates suggest that the clay saturation may have dropped to as low as 10% based on the observed conductivity changes.

  14. Comparing spatial series of soil bulk electrical conductivity as obtained by Time Domain Reflectometry and Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Saeed, Ali; Dragonetti, Giovanna; Comegna, Allessandro; Garre, Sarah; Lamaddalena, Nicola; Coppola, Antonio

    2016-04-01

    Conventional ground survey of soil root zone salinity by direct soil sampling are time consuming, costly and destructive. Alternatively, soil salinity can be evaluated by measuring the bulk electrical conductivity, σb, in the field. This approach is faster and cheaper, and allows a more intensive surveying. Measurements of σb can be made either in situ or with remote devices. Time domain reflectometry (TDR) sensors allow simultaneous measurements of water content, θ, and σb. They may be calibrated for estimating the electrical conductivity of the soil solution (σw). However, they have a relatively small observation window and thus they are thought to only provide local-scale measurements. The spatial range of the sensors is limited to tens of centimeters and extension of the information to a large area can be problematic. Also, information on the vertical distribution of the σb soil profile may only be obtained by installing sensors at different depths. In this sense, the TDR may be considered as an invasive technique. Compared to the TDR, other geophysical methods based for example on the Electrical Resistivity Tomography (ERT) techniques represent an alternative in respect to those traditional for soil salinity characterization. In order to deduce the actual distribution of the bulk electrical conductivity, σb, in the soil profile, one needs to invert the signal coming from ERT sensors. The latter, in turn, depends on the specific depth distribution of the σb, as well as on the electrical configuration of the sensor used. With these premises, the main aim of this study is to estimate the vertical σb distribution starting from resistivity data series measured using the ERT method under different salinity conditions and using TDR data as ground-truth data for calibration and validation of the ERT sensor. This way, limited measured TDR data may be used for translating extensive ERT apparent electrical conductivity, σa, measurements to estimate depth

  15. Time-lapse 3D electrical resistivity tomography to monitor soil-plant interactions

    NASA Astrophysics Data System (ADS)

    Boaga, Jacopo; Rossi, Matteo; Cassiani, Giorgio; Putti, Mario

    2013-04-01

    In this work we present the application of time-lapse non-invasive 3D micro- electrical tomography (ERT) to monitor soil-plant interactions in the root zone in the framework of the FP7 Project CLIMB (Climate Induced Changes on the Hydrology of Mediterranean Basins). The goal of the study is to gain a better understanding of the soil-vegetation interactions by the use of non-invasive techniques. We designed, built and installed a 3D electrical tomography apparatus for the monitoring of the root zone of a single apple tree in an orchard located in the Trentino region, Northern Italy. The micro-ERT apparatus consists of 48 buried electrodes on 4 instrumented micro boreholes plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. We collected repeated ERT and TDR soil moisture measurements for one year and performed two different controlled irrigation tests: one during a very dry Summer and one during a very wet and highly dynamic plant growing Spring period. We also ran laboratory analyses on soil specimens, in order to evaluate the electrical response at different saturation steps. The results demonstrate that 3D micro-ERT is capable of characterizing subsoil conditions and monitoring root zone activities, especially in terms of root zone suction regions. In particular, we note that in very dry conditions, 3D micro ERT can image water plumes in the shallow subsoil produced by a drip irrigation system. In the very dynamic growing season, under abundant irrigation, micro 3D ERT can detect the main suction zones caused by the tree root activity. Even though the quantitative use of this technique for moisture content balance suffers from well-known inversion difficulties, even the pure imaging of the active root zone is a valuable contribution. However the integration of the measurements in a fully coupled hydrogeophysical inversion is the way forward for a better understanding of subsoil interactions between biomass, hydrosphere and atmosphere.

  16. Floodplain architecture of an actively meandering river (the Ploučnice River, the Czech Republic) as revealed by the distribution of pollution and electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Matys Grygar, T.; Elznicová, J.; Tůmová, Š.; Faměra, M.; Balogh, M.; Kiss, T.

    2016-02-01

    The aim of this study was to describe the floodplain architecture of the Ploučnice River, a naturally meandering river in the Czech Republic, using manual drill coring, the element analysis of sediments, and electrical resistivity tomography (ERT). The Ploučnice River has received diffuse pollution since the early twentieth century (mainly Pb) followed by a prominent, temporally well-defined pollution pulse from uranium mining in the 1970s and 1980s (mainly U and 226Ra). The pollution created a chemostratigraphic (temporal) framework for overbank fines. We used geographical information systems (GIS) to describe the channel's dynamics and visualise fluvial landforms. We sampled and analysed the finest floodplain sediments in the top 1 to 2 m of the floodplain fill (silty and sandy deposits), and we used ERT to visualise bodies of coarser and deeper strata at depths down to ~ 3 m. Several limits of ERT imaging have been found by a comparison of the resistivity domains with lithological descriptions of the cores: several decimetre-thick strata were not revealed (they are below the spatial resolution of that method), and humidity affected the results that were obtained in the topmost strata. The space for deposition of fluvial sediments in the Ploučnice River is being created by (1) natural lateral shifts in the channel (up to 0.5 m/year); (2) meander loop development and cutoffs at the timescale of decades to centuries and spatial scale of up to ~ 1/4 of the floodplain width; and (3) more substantial reorganisation of the channel structure by avulsions, probably at the timescale of centuries. These processes continuously create space for the deposition of overbank fines on the top of former point bars and in swales and abandoned channels. As a consequence of the speed of the channel shifts, at least 80% of the fine-grained top of the floodplain fill (overbank fines) was reworked over approximately three centuries.

  17. Spatial focusing of electrical resistivity surveys considering geologic and hydrologic layering

    SciTech Connect

    Gail L. Heath; Alex Fuman; Ty P.A. Ferre'

    2007-03-01

    Electrical resistivity tomography (ERT) has shown great promise for monitoring transient hydrologic processes. One advantage of ERT under those conditions is the ability of a user to tailor the spatial sensitivity of an ERT survey through selection of electrode locations and electrode combinations. Recent research has shown that quadripoles can be selected in a manner that improves the independent inversion of ERT data. Our ultimate interest lies in using ERT data along with measurements from other sensors, which typically can provide high-quality data from shallow regions of the subsurface, in a joint inversion. As a result, we do not consider the selection of quadripoles specifically for inde-pendent ERT inversion. Rather, we present an approach to focusthe spatial sensitivity of ERT surveys in specificsubsurface regions with the assumption that those data, when interpreted along with other measurements that are sensitive to those regions, will lead to more complete hydrologic characterization. Because we are interested in monitoring rapid processes, our approach is designed to efficiently identify optimal quadripoles. This is achieved by separating the optimization from the inversion grid, significantly reducing computational effort. We extend our previous work to consider the use of both surface and borehole ERT electrodes and to consider the impacts of horizontally layered electrical conductivity conditions. Results confirm the ability of the method to focus survey sensitivity while showing the importance of incorporation of prior knowledge of the subsurface electric conductivity structure in designing optimal ERT surveys.

  18. Tank Leak Experiment at the Mock Tank Site, 200 East Area: Electrical Resistance Tomography-Preliminary Results

    SciTech Connect

    Ramirez, A; Daily, W; Binley, A

    2002-01-18

    Electrical resistance measurements were used to monitor several releases of brine from the Mock Tank Test site at the 200 East Area. Three different methods were used to analyze the data: (1) a simple average of the raw data was used as an indicator of the presence/absence of a leak, (2) tomography of the region beneath the tank using data from steel-cased borehole, and (3) tomography of the region beneath the tank using data from vertical electrode arrays. Each of these methods was able to detect the presence of what appeared to be conductive plumes forming beneath the tank. The results suggest the following: (1) The minimum detectable leak volume is of the Order of a few hundred gallons. (2) procedure involving the use of reciprocal data can be used to evaluate the reliability of the results and minimize the potential for false-positive and false-negative conclusions; (3) The dry wells may be used as long electrodes to obtain 2D images of the plume under the tank. (4) 3D electrical resistance tomography (ERT) images provide information that can be used to determine the released volume, the speed and direction of plume movement, the regions of the soil that are being contaminated, and the approximate location of the hole in the tank. (5) It may be possible to map pre-existing plumes when no pre-spill data exists. (6) A ''quick look'' calculation can be used in the field can reliably detect the occurrence of a leak.

  19. 3D Electrical resistivity tomography monitoring of an artificial tracer injected within the hyporheic zone

    NASA Astrophysics Data System (ADS)

    Houzé, Clémence; Pessel, Marc; Durand, Veronique

    2016-04-01

    Due to the high complexity level of hyporheic flow paths, hydrological and biogeochemical processes which occur in this mixing place are not fully understood yet. Some previous studies made in flumes show that hyporheic flow is strongly connected to the streambed morphology and sediment heterogeneity . There is still a lack of practical field experiment considering a natural environment and representation of natural streambed heterogeneities will be always limited in laboratories. The purpose of this project is to propose an innovative method using 3D Electrical Resistivity Tomography (ERT) monitoring of an artificial tracer injection directly within the streambed sediments in order to visualize the water pathways within the hyporheic zone. Field experiment on a small stream was conducted using a plastic tube as an injection piezometer and home-made electrodes strips arranged in a rectangular form made of 180 electrodes (15 strips of 12 electrodes each). The injection of tracer (NaCl) lasted approximatively 90 minutes, and 24h monitoring with increasing step times was performed. The physical properties of the water are controlled by CTD probes installed upstream and downstream within the river. Inverse time-lapse tomographs show development and persistence of a conductive water plume around the injection point. Due to the low hydraulic conductivity of streambed sediments (clay and overlying loess), the tracer movement is barely visible, as it dilutes gradually in the pore water. Impact of boundary conditions on inversion results can lead to significant differences on images, especially in the shallow part of the profiles. Preferential paths of transport are not highlighted here, but this experiment allows to follow spatially and temporarily the evolution of the tracer in a complex natural environment .

  20. Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben, Mozambique

    NASA Astrophysics Data System (ADS)

    Chirindja, F. J.; Dahlin, T.; Perttu, N.; Steinbruch, F.; Owen, R.

    2016-09-01

    This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30-40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.

  1. Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben, Mozambique

    NASA Astrophysics Data System (ADS)

    Chirindja, F. J.; Dahlin, T.; Perttu, N.; Steinbruch, F.; Owen, R.

    2016-05-01

    This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30-40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.

  2. Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2D time-lapse surface electrical resistivity tomography

    SciTech Connect

    Wallin, Erin L.; Johnson, Timothy C.; Greenwood, William J.; Zachara, John M.

    2013-03-29

    The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper we use time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river during high stage conditions. We demonstrate a modified time-lapse inversion approach, whereby the transient water table elevation is explicitly modeled by removing regularization constraints across the water table boundary. This implementation was critical for producing meaningful imaging results. We inverted approximately 1200 data sets (400 per line over 3 lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal non-uniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity ‘break through’ curves and longer river water residence times. The time-lapse ERT inversion approach removes the deleterious effects of changing water table elevation and enables remote and spatial continuous groundwater-river water exchange monitoring using surface based ERT arrays under conditions where groundwater and river water conductivity are in contrast.

  3. Implementation of ground penetrating radar and electrical resistivity tomography for inspecting the Greco-Roman Necropolis at Kilo 6 of the Golden Mummies Valley, Bahariya Oasis, Egypt

    NASA Astrophysics Data System (ADS)

    Abbas, Abbas M.; Ghazala, Hosni H.; Mesbah, Hany S.; Atya, Magdy A.; Radwan, Ali; Hamed, Diaa E.

    2016-06-01

    Bahariya Oasis is one of the lately inspected spots in Egypt and has a long historical record extending from the old kingdom till the emergence of Islam. Since June 1999, the Valley of the Golden Mummies near Bawiti (at kilometer 6 on the road leads to Farafra Oasis) became significant due to the discoveries of amazing mummies of gelded faces. The archeologists believe that the Valley has more valuable tombs that still unrevealed. Also, the possibility that the Greco-Roman Necropolis extends to areas other than Kilo-6 is sustainable. The ground penetrating radar and electrical resistivity tomography are two geophysical tools that have successful applications in archeological assessment. The two techniques were used in integration plan to assert the archeological potentiality of the studied site and to map the feasible tombs. Sum of 798 GPR profiles and 19 ERT cross sections was carried out over the study area. The results of them were analyzed to envisage these results in archeological terms.

  4. Fourier-based magnetic induction tomography for mapping resistivity

    SciTech Connect

    Puwal, Steffan; Roth, Bradley J.

    2011-01-01

    Magnetic induction tomography is used as an experimental tool for mapping the passive electromagnetic properties of conductors, with the potential for imaging biological tissues. Our numerical approach to solving the inverse problem is to obtain a Fourier expansion of the resistivity and the stream functions of the magnetic fields and eddy current density. Thus, we are able to solve the inverse problem of determining the resistivity from the applied and measured magnetic fields for a two-dimensional conducting plane. When we add noise to the measured magnetic field, we find the fidelity of the measured to the true resistivity is quite robust for increasing levels of noise and increasing distances of the applied and measured field coils from the conducting plane, when properly filtered. We conclude that Fourier methods provide a reliable alternative for solving the inverse problem.

  5. Calibration of EMI derived apparent electrical conductivity based on ERT measurements

    NASA Astrophysics Data System (ADS)

    Rudolph, S.; Mester, A.; van der Kruk, J.; Weihermüller, L.; Zimmermann, E.; Vereecken, H.

    2012-04-01

    Soil electrical conductivity (ECa) is an indirect measure for various soil physical and chemical parameters. Among non-invasive geophysical methods, electromagnetic induction (EMI) appears to be the most efficient one that is able to measure ECa over large areas in short time. However, this method currently does not provide quantitative values of ECa due to calibration problems. In the calibration approach of Lavoué et al. (2010) inverted electrical conductivity data from a 120 m long ERT (electrical resistivity tomography) calibration transect were used as input parameter for an electromagnetic forward model to predict ECa measured with EMI. To further improve this calibration method we conducted a field survey within an agricultural field for crop breeding studies. The entire field (60x100 m) was mapped with the EM38-MK2 (Geonics, Ontario, Canada), an EMI system with multiple coil spacing which measures the weighted average of ECa over four depth ranges, immediately after the harvest of sugar beet. On the basis of high-resolution ECa distribution maps, an area with high contrast in ECa was selected for calibrating the EMI sensor with ERT. Along a 30 m long transect EMI measurements with two different internal calibration settings were carried out. A Syscal Pro System (IRIS Instruments, Orleans France) and 120 electrodes with an electrode spacing of 0.25 m were used to measure the apparent resistivity of soil. Post processed ERT measurements were inverted using the robust inversion method of the RES2DINV software. Quantitative EM inductions measurements were derived by linear regression between measured and predicted ECa measurements. The observed offset between the repeated EMI measurements could be removed successfully. Furthermore, shortening and focusing the ERT measurements to a specific area of interest could reduce the measurement time for calibration significantly. Prospectively, the application of a quantitative multi-layer inversion of multi

  6. Electrical resistance tomography using steel cased boreholes as electrodes

    DOEpatents

    Daily, William D.; Ramirez, Abelardo L.

    1999-01-01

    An electrical resistance tomography method using steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constain the models.

  7. Electrical resistance tomography using steel cased boreholes as electrodes

    DOEpatents

    Daily, W.D.; Ramirez, A.L.

    1999-06-22

    An electrical resistance tomography method is described which uses steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constrain the models. 2 figs.

  8. The detection of cavities and funnels over closed mines of Albania with the use of SP and Electrical Resistance Tomography

    NASA Astrophysics Data System (ADS)

    Reci, H.; Balliu, E.

    2006-05-01

    This study consists in the detection of cavities that could be present over closed mines of Albania with the use of SP and Electrical Resistance Tomography. In general, natural and artificial cavities represent an important investigation target in geotechnical, environmental and scientific studies. These studies could be engineering, archaeological or spelaeologal. For the detection and localization of such cavities during the latter 20 years, several geophysical studies have been used worldwide. In this field study several geophysical methods could be used such electrical, electromagnetic, gravimetric and seismic ones. Now days, the Ground Penetrating Radar Technique and Electrical Resistance Tomography (ERT) are widely used. Depending on geological formation conditions every used method is more or less effective. As a result of actual conditions of works on ore mines, the dynamic regime of the surroundings areas has undergone changes creating superficial cavities and funnels and as consequence the geological risk to the community is present. The detection of cavities is a challenge for geophysicists and in these cases the ambiguity on interpretation of geophysical data has to be solved properly. The simultaneous application of different geophysical methods and monitoring in time are necessary in order that the field data interpretation could be significant.On the frame of a collaboration with Institute of Mines of Albania, a staff from Geophysical Center of Tirana during the period 2004-2005 has undertaken one project for the detection of superficial cavities and funnels on surrounding areas over work mines which are planned to be closed. In order to make clear the presence of geological risk to community, geophysical investigation were carried out as tests over galleries of tow ore mines of Albania in Dhrovjan and Perrenjas regions. The effectiveness of the used geophysical methods was present.

  9. Electrical resistance tomography experiments at the Oregon Graduate Institute

    NASA Astrophysics Data System (ADS)

    Daily, W.; Ramirez, A.; LaBrecque, D.; Barber, W.

    1995-04-01

    Three controlled experiments were conducted at the Oregon Graduate Institute (OGI) with the purpose of evaluating electrical resistance tomography for imaging underground processes associated with in-situ site assessment and remediation. The OGI facilities are unique: a double-wall tank 10 m square and 5 m deep, filled with river bottom sediments and instrumented for geophysical and hydrological studies. At this facility, liquid contaminants could be released into the confined soil at a scale sufficiently large to represent real-world physical phenomena. In the first test, images of electrical resistivity were made before and during a controlled spill of gasoline into a sandy soil. The primary purpose was to determine if electrical resistivity images could detect the hydrocarbon in either the vadose or saturated zone. Definite changes in electrical resistivity were observed in both the vadose and saturated soils. The effects were an increase in resistivity of as much as 10% above pre-release values. A single resistive anomaly was imaged, directly below the release point, principally within the vadose zone but extending below the phreatic surface. The anomaly remained identifiable in tomograms taken two days after the release ended with clear indications of lateral spreading along the water table. The second test involved electrical resistance measurements before, during, and after air sparging in a saturated soil. The primary purpose was to determine if the electrical images could be used to detect and delineate the extent of the zone influenced by sparging. The images showed an increase of about 20% in resistivity over background values within the sparged zone and the extent of the imaged zone agreed with that inferred from other information. Electrical resistivity tomography measurements were made under a simulated oil storage tank in the third test. Comparison of images taken before and during separate releases of brine and water showed effects of changes

  10. ERTS and EROS

    USGS Publications Warehouse

    Staff, EROS Program

    1972-01-01

    In June the National Aeronautics & Space Administration is to launch its first experimental satellite designed to view the Earth systematically with remote-sensing instruments that will provide new information about our resources and environment. The launching will culminate more than 8 years of planning and research by resource agencies of the Federal Government in cooperation with NASA, state and local governments, universities, and industry. The first Earth Resources Technology Satellite, ERTS-A, will be followed a year later by ERTS-B. Analyses of data from them, it is hoped, will lead to design of operational satellites for Earth resources investigations in the future. In the belief that satellite systems will be of significant assistance in meeting its responsibilities to map, monitor, and manage the vast resources and the public lands of the United States, the Department of the Interior assumed a major role in the ERTS-A Experiment.

  11. Time-lapse ERT interpretation methodology for leachate injection monitoring based on multiple inversions and a clustering strategy (MICS)

    NASA Astrophysics Data System (ADS)

    Audebert, M.; Clément, R.; Touze-Foltz, N.; Günther, T.; Moreau, S.; Duquennoi, C.

    2014-12-01

    Leachate recirculation is a key process in municipal waste landfills functioning as bioreactors. To quantify the water content and to assess the leachate injection system, in-situ methods are required to obtain spatially distributed information, usually electrical resistivity tomography (ERT). This geophysical method is based on the inversion process, which presents two major problems in terms of delimiting the infiltration area. First, it is difficult for ERT users to choose an appropriate inversion parameter set. Indeed, it might not be sufficient to interpret only the optimum model (i.e. the model with the chosen regularisation strength) because it is not necessarily the model which best represents the physical process studied. Second, it is difficult to delineate the infiltration front based on resistivity models because of the smoothness of the inversion results. This paper proposes a new methodology called MICS (multiple inversions and clustering strategy), which allows ERT users to improve the delimitation of the infiltration area in leachate injection monitoring. The MICS methodology is based on (i) a multiple inversion step by varying the inversion parameter values to take a wide range of resistivity models into account and (ii) a clustering strategy to improve the delineation of the infiltration front. In this paper, MICS was assessed on two types of data. First, a numerical assessment allows us to optimise and test MICS for different infiltration area sizes, contrasts and shapes. Second, MICS was applied to a field data set gathered during leachate recirculation on a bioreactor.

  12. 2D and 3D Electrical Resistivity Tomography imaging of earthquake related ground deformations at the Ancient Roman Forum and Isis Temple of Baelo Claudia (Cádiz, South Spain).

    NASA Astrophysics Data System (ADS)

    Silva, Pablo G.

    2010-05-01

    The ancient roman city of Baelo Claudia has been subject of several papers on earthquake environmental effects (EEE) and well as earthquake archaeological effects (EAE). During the field training course on archaeoseismology and palaeoseismology conducted in September 2009 (INQUA-IGCP567 Workshop) held at Baelo Claudia, four Electric Resistivity Tomography (ERT) profiles were carried out, by the teams of the Salamanca University (Spain), RWTH Aachen University (Germany) and the Geological Survey of Spain (IGME). ERT surveys were developed in the eastern side of the ancient roman Forum across the unexcavated sector of the archaeological site heading on the 1st Century AD Isis Temple. Each ERT profile was constituted by a 48 multielectrode array with spacing of 2 m resulting in a total length of investigation of around 384 m. ERT lines were separated 10 m each other resulting in a total research area of 3840 m2 to a mean investigation depth of 16 m. The selected survey configurations were Pole-Dipole and Wenner in order to get detailed information about lateral resistivity contrasts, but with a reasonable depth of investigation. The resulting 2D resistivity pseudosections clearly display deformations of the buried roman pavements which propagated in depth within the pre-roman clayey substratum of the Bolonia Bay area.. 3D modelling of the 2D pseudosections indicates that the observed deformations are related to near-surface landsliding, being possible to calculate the minimum volume of mobilized material. ERT 3D imaging allow to refine previous GPR surveys conducted at this same area and to get a subsurface picture of ground deformations caused by repeated earthquakes during the 1st and 3rd Centuries AD. Preliminary calculated volume for the mobilized materials affecting the foundations of the Isis Temple and Forum clearly points to a minimum ESI-07 VIII Intensity validating previous research in the zone. This study has been supported by the Spanish Research Projects

  13. ERT studies on tailings ponds of the Sierra Minera Cartagena-La Union, SE Spain (Invited)

    NASA Astrophysics Data System (ADS)

    Martinez-Pagan, P.; Faz-Cano, A.; Rosales-Aranda, M. R.

    2009-12-01

    The Sierra Minera Cartagena - La Union (SE Spain) is a huge area that has been mined for centuries. That mining extraction activity was particularly enormous in the second half of the twentieth century. By the early 1980’s almost all mineral deposits of this area had been depleted and the mineral processing plants had left 80 tailings ponds of different shape and height as a result of their activity. At the present, these former mining areas are close to important urban and industrial centers, where the tailings ponds are potential points of environmental and geotechnical concerns among others. In the 1972, there was also an important collapse of a tailings pond after a strong stormy event. Because of that, nowadays, there are several researcher groups working on the area with the goal of improving the environmental, geotechnical, safety, and use conditions of the tailings ponds. In this framework, the electrical resistivity tomography (ERT) method was used to obtain complementary information from the inner of the tailings ponds itself. Due to the high electrical resistivity contrast between the tailings and the hard-rock the geo-electrical methods became very useful in getting information about the bedrock geometry. In addition, where the tailing ponds have not been built up with a more complex interne structure (Figure 1) then it has been possible to obtain their construction history based on the grain distribution which is related in some extent to the electrical resistivity. In some cases, based on the fact of the presence of big cracks into the pond as pathways (Figure 2) where the mine acid waters are infiltrated easily, the use of ERT technique has proved its usefulness in highlighting them. Moreover, the ERT method can be an interesting tool in tailings ponds remediation works by delimiting the acid areas on the surface characterized by low electrical resistivity values.

  14. Complex electrical resistance tomography of a subsurface PCE plume

    SciTech Connect

    Ramirez, A.; Daily, W,; LeBrecque, D.

    1996-01-01

    A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly.

  15. Monitoring water flows with time-lapse Electrical Resistivity Tomography on the Super-Sauze landslide

    NASA Astrophysics Data System (ADS)

    Gance, J.; Sailhac, P.; Malet, J.-P.; Grandjean, G.; Supper, R.; Jochum, B.; Ottowitz, D.

    2012-04-01

    in sub-surface soil temperature. Two high-resolution optical cameras are installed on stable crests on the side of the cross-sections and time-lapse stereoscopy is used to reconstruct the displacement field to locate the electrodes in space and time (in order to take into account changes in the dipole geometry). The apparent electrical resistivity values were inverted with a time-lapse approach using an initial model constructed from statistical analysis of resistivity data and a priori knowledge on the landslide structure from a previous geotechnical model. The near surface apparent resistivity can vary of ten percent without any input of water. This shows the importance of temperature effect on the measurement. The temperature correction is handled from a complete study of the soil temperature propagation solving the heat equation with several temperature probes placed at different depths in soil and in the water table. The results are interpreted in combination to hydrological data (rain, water table level). The acquisition of 8 ERT all over the studied area, in different directions permits to create by interpolation a 3D electrical resistivity model of the area. This model shows the importance of the bedrock topography because high water content areas are visible at the theoretical hydrological network computed from the 3D geotechnical model of Travelletti and Malet (2011). Transversal waterflow circulation not predicted are also visible and permit to interpret the results taking into account the 3D structure of the landslide. A 250 m long P-wave tomography acquired on the studied profile and inversed with a quasi-Newton algorithm that uses Fresnel wavepaths and the finite bandwidth of the source signal, specially developed for the study of very heterogeneous soils, shows a very good correlation with electrical resistivity and permits to propose a geotechnical model of the profile. Spatially heterogeneous water flow patterns are identified and the presence of a

  16. Comparative Investigation of Guided Fuzzy Clustering and Mean Shift Clustering for Edge Detection in Electrical Resistivity Tomography Images of Mineral Deposits

    NASA Astrophysics Data System (ADS)

    Ward, Wil; Wilkinson, Paul; Chambers, Jon; Bai, Li

    2014-05-01

    Geophysical surveying using electrical resistivity tomography (ERT) can be used as a rapid non-intrusive method to investigate mineral deposits [1]. One of the key challenges with this approach is to find a robust automated method to assess and characterise deposits on the basis of an ERT image. Recent research applying edge detection techniques has yielded a framework that can successfully locate geological interfaces in ERT images using a minimal assumption data clustering technique, the guided fuzzy clustering method (gfcm) [2]. Non-parametric clustering techniques are statistically grounded methods of image segmentation that do not require any assumptions about the distribution of data under investigation. This study is a comparison of two such methods to assess geological structure based on the resistivity images. In addition to gfcm, a method called mean-shift clustering [3] is investigated with comparisons directed at accuracy, computational expense, and degree of user interaction. Neither approach requires the number of clusters as input (a common parameter and often impractical), rather they are based on a similar theory that data can be clustered based on peaks in the probability density function (pdf) of the data. Each local maximum in these functions represents the modal value of a particular population corresponding to a cluster and as such the data are assigned based on their relationships to these model values. The two methods differ in that gfcm approximates the pdf using kernel density estimation and identifies population means, assigning cluster membership probabilities to each resistivity value in the model based on its distance from the distribution averages. Whereas, in mean-shift clustering, the density function is not calculated, but a gradient ascent method creates a vector that leads each datum towards high density distributions iteratively using weighted kernels to calculate locally dense regions. The only parameter needed in both methods

  17. Modelling Sediment Thickness for Site-Effect Characterisation using H/V Spectral Ratio Analysis and Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Van Noten, Koen; Lecocq, Thomas; Watlet, Arnaud; Camelbeeck, Thierry

    2014-05-01

    The H/V Spectral Ratio (HVSR) analysis of ambient seismic noise has been widely used to estimate the fundamental site resonance frequency in the context of site-effect characterisation. In regions of unknown subsurface structure, in which there is a significant acoustic impedance contrast between sediments and the underlying bedrock, HVSR can be a very powerful tool to map bedrock morphology and sediment thickness. Calibrating the power-law relationship between the variation in fundamental frequency and sediment thickness around these unknown sites is crucial for sediment thickness mapping. This empirical relationship can be easily calculated by conducting HVSR analysis of ambient noise measurements above boreholes with known bedrock depth. Additional local H/V measurements above near-surface geophysical profiles, for instance created by Electrical Resistivity Tomography (ERT), allow training and improving the power-law relationship for sites with a shallow bedrock depth. As the compaction of sediments influences the Vs, one has however to take into account that this empirical relationship can only be applied in relative small areas with a similar local geology. Between 2008 and 2010, a seismic swarm (MLmax = 3.2) occurred in a hilly area, 20 km SE of Brussels (Belgium). 60 of the 300 recorded events were felt/heard by the local residents and were reported in the corresponding 'Did You Feel It' internet inquiries held by Royal Observatory of Belgium. Several low-magnitude events show a distinct macroseismic intensity variation that can be explained by the geological site effect, i.e. the local sediment thickness, affecting the human perception of these earthquake-induced ground motions. In this presentation, we apply the above described methodology and discuss the results of a geophysical survey including ERT-profiling, ambient noise recording, HVSR analysis in Geopsy and DEM-modelling to characterise the local site effects. The resulting sediment thickness model

  18. Three-dimensional structure of a highly heterogeneous horizon described by Electrical Resistivity Tomography: consequences on the determination of effective hydraulic properties

    NASA Astrophysics Data System (ADS)

    Cousin, I.; Frison, A.; Samouëlian, A.; Bourennane, H.; Guérin, R.; Richard, G.

    2009-04-01

    Despite the increasing demand of soil hydraulic properties as input data for soil-plant-atmosphere models, the estimation of hydraulic properties in heterogeneous horizons remains a challenge. One reason is the lack of knowledge of the structure of such horizons, which limits the estimation of effective hydraulic properties at small scale. The aim of this paper is to demonstrate the interest of 3-D Electrical Resistivity Tomography (ERT) to describe the soil structure and to identify the Representative Elementary Volume of a heterogeneous horizon. The studied soil is an Albeluvisol that exhibits some horizons composed by the juxtaposition of two Elementary Pedological Volumes (EPVs); they can be visually distinguished by their colours (ochre and white) and they have differential hydraulic functioning: the clayey ochre ones conduct less water than the loamy white ones. Local electrical resistivity measurements showed that the ochre and white EPVs could be identified by ERT. Several 3D ERTs with an interelectrode spacing equal to 3 cm were then conducted on a 1 m² surface : i) seven Wenner arrays (16 electrodes) spaced of 9 cm and four Wenner arrays (32 electrodes) spaced of 9 cm, perpendicular to the seven previous ones; ii) a square array of 32 electrodes spaced of 3 cm. After these measurements, a 6 cm slice of the studied horizon was removed and the electrical resistivity measurements were recorded again at this second depth, and the whole protocol was recorded a third time. Thanks to all these measurements, the decrease of resolution with depth could be corrected. The data were then interpreted by using the Res2DInv and the Res3DInv softwares by using different strategies: -a- each 2D ERT was interpreted independently and all the interpreted resistivity data were gathered to create a 3-D block by regular kriging, -b- the 3D square array was interpreted and the resulting interpreted data were added to the 2D previous ones, -c- all the apparent resistivity data

  19. Hidden gully erosion - detection and characterization of piping systems using geomorphological and geophysical methods (GPR, ERT)

    NASA Astrophysics Data System (ADS)

    Bernatek-Jakiel, Anita; Kondracka, Marta

    2016-04-01

    The significance of piping in gully formation and hillslope hydrology has been discussed for many years. However, piping as a subsurface erosion caused by water flowing through the soil is still considered as one of the most difficult erosion processes to study, because it occurs below the soil surface and traces of piping become visible on the surface only when a pipe roof collapses, or a pipe inlet or a pipe outlet has been located. Detection of pipes and their complex characterization is still a methodological challenge. Therefore, this study aims at a better detection and characterization of piping systems in a mountainous area under a temperate climate using geomorphological mapping and geophysical methods (ground penetrating radar and electrical resistivity tomography). The survey was carried out in the Bereźnica Wyżna catchment, in the Bieszczady Mts. (Eastern Carpathians, Poland), where pipes develop in Cambisols at a depth ranging from ca 0.70 to 1.00 m. The geomorphological mapping was carried out in the in the whole catchment (2.96 km2), whereas the geophysical survey was limited to two zones (zone A - ca 32 x 82 m, zone B - ca 58 x 115 m). In this study a standard RAMAC GPR system (Malå GeoScience) with shielded 500 MHz antenna was used. The electrical resistivity tomography (ERT) was performed using electrical imaging system LUND with Terrameter SAS 4000 produced by company ABEM. The ERT and GPR data were interpreted in the RES2DINV (Geotomo Software) and RadExplorer software (DECO Geophysical Ltd) respectively. In total, 3 longitudinal and 26 transverse GPR profiles and five ERTs were performed. The used geophysical techniques are shown to be successful in identifying pipes tested in the pilot catchment. Pipes identified by GPR and ERT were verified by the surface indicators (i.e. lowering of surface above pipes). The GPR and ERT applications suggest that piping systems density is much greater than could be detected from surface observation alone

  20. Cooperative Cross-Hole Ert and 2-D Full-Waveform Gpr Inversion

    NASA Astrophysics Data System (ADS)

    Bouchedda, A.; Chouteau, M.

    2012-12-01

    Recent advances in high-performance computing make full-waveform inversion (FWI) of cross-hole ground penetrating data feasible. FWI, where high-resolution imaging at half the propagated wavelength is expected, allows a better resolution in comparison to ray-based tomography. The inverse problem is generally solved using local optimization algorithms that can converge to local minimum depending on the selection of starting model, nonlinearity of the problem, lack of low frequencies, presence of noise, and approximate modeling of the wave-physics complexity. In this work, multiscale FWI strategy is combined cooperatively with electrical resistivity tomography (ERT) to mitigate the nonlinearity and ill-posedness of FWI and improve the ERT resolution. In the FWI, the gradient of the misft function is generally dominated by the high frequencies. This behaviour can potentially be the cause of convergence into local minima, as the determination of the high frequencies depends in turn on the accuracy of the low frequencies. Different from taking advantage of low frequencies in the data, the proposed multiscale FWI reduces the number of model parameters and yields low frequencies in the model space using a regularization method that consists of imposing an L1-norm penalty in the wavelet domain. The minimization of the L1-norm penalty is carried out using an accelerated iterative soft-thresholding algorithm. As wavelet transforms provide estimates of the local frequency content of the conductivity or permittivity images, the thresholds are used to control the frequency content in the model space. Generally, a high threshold value is chosen for the 20th first iterations in order to enhance the update of the low frequencies. After that the soft thresholding step tries to find the best thresholds to maximize the structural similarities between conductivity and permittivity images. The initial velocity model for FWI is built from first-arrival traveltime tomography, whereas the

  1. Applying electrical resistivity tomography and biological methods to assess the surface-groundwater interaction in two Mediterranean rivers (central Spain)

    NASA Astrophysics Data System (ADS)

    Iepure, Sanda; Gómez Ortiz, David; Lillo Ramos, Javier; Rasines Ladero, Ruben; Persoiu, Aurel

    2014-05-01

    Delineation of the extent of hyporheic zone (HZ) in river ecosystems is problematic due to the scarcity of spatial information about the structure of riverbed sediments and the magnitude and extent of stream interactions with the parafluvial and riparian zones. The several existing methods vary in both quality and quantity of information and imply the use of hydrogeological and biological methods. In the last decades, various non-invasive geophysical techniques were developed to characterise the streambed architecture and also to provide detailed spatial information on its vertical and horizontal continuity. All classes of techniques have their strengths and limitations; therefore, in order to assess their potential in delineating the lateral and vertical spatial extents of alluvial sediments, we have combined the near-surface images obtained by electrical resistivity tomography (ERT) with biological assessment of invertebrates in two Mediterranean lowland rivers from central Spain. We performed in situ imaging of the thickness and continuity of alluvial sediments under the riverbed and parafluvial zone during base-flow conditions (summer 2013 and winter 2014) at two different sites with distinct lithology along the Tajuña and Henares Rivers. ERT was performed by installing the electrodes (1 m spacing) on a 47 m long transect normal to the river channel using a Wener-Schlumberger array, across both the riparian zones and the river bed. Invertebrates were collected in the streambed from a depth of 20-40 cm, using the Bou-Rouch method, and from boreholes drilled to a depth of 1.5 m in the riparian zone. The ERT images obtained at site 1 (medium and coarse sand dominated lithology) shows resistivity values ranging from ~20 to 80 ohm•m for the in-stream sediments, indicating a permeable zone up to ~ 0.5 m thick and extending laterally for ca. 5 m from the channel. These sediments contribute to active surface/hyporheic water exchanges and to low water retention in

  2. The summit part of Mount Etna revealed by High Resolution DC Electrical Resistivity Tomography coupled with complementary geophysical and soil gas techniques

    NASA Astrophysics Data System (ADS)

    Finizola, Anthony; Ricci, Tullio; Antoine, Raphael; Delcher, Eric; Peltier, Aline; Bernard, Julien; Brothelande, Elodie; Fargier, Yannick; Fauchard, Cyrille; Foucart, Brice; Gailler, Lydie; Gusset, Rachel; Lazarte, Ivonne; Martin, Erwan; Mézon, Cécile; Portal, Angélie; Poret, Matthieu; Rossi, Matteo

    2016-04-01

    In the framework of the EC FP7 project "MEDiterranean SUpersite Volcanoes", one profile coupling DC electrical resistivity tomography (Pole-Dipole configuration with a remote electrode located between 8-10 km from the middle of the different acquisitions, 64 electrodes and 40 m spacing between the electrodes), self-potential, soil CO2 degassing, Radon measurements and sub-surface (30cm depth) temperature have been performed between June 25th and July 13th 2015. This profile, NE-SW direction, crossed the summit part of Mount Etna. A total 5720m of profile was performed, with a roll along protocol of 1/4 of the dispositive, for each new acquisitions. A total of 6 acquisitions was made to complete the entire profile. For the first time in the world, a multi-electrodes DC ERT profile, of high resolution (40 m of spacing between the electrodes) reached, thanks to a pole-dipole configuration, 900m for the depth of investigation. The ERT profile clearly evidences the hydrothermal system of Mount Etna: the lowest resistivity values are associated with a large scale positive self-potential anomaly, and smaller wavelength anomalies for temperature, CO2 concentration and Radon, in the area where the electrical conductor reach the surface. Structural discontinuities such as the Elliptic crater, was clearly evidenced by a sharp decrease of the self-potential values in the inner part of this crater. The striking result of this profile is the presence of a resistive body located just below the NE crater. This structure displays the highest degassing values of the entire profile. We interpret this resistive body as a consequence of the thermic over-heated plume rising from the top of the shallow feeding system. Indeed, above several hundred of degrees Celsuis, it is impossible to consider rain water infiltration and the presence of a wet hydrothermal system. The consequence would be therefore to obtain this resistive body, centred on the area of main heat transfer. Above this

  3. Canadian ERTS program progress report

    NASA Technical Reports Server (NTRS)

    Morley, L. W.; Mcquillan, A. K.

    1974-01-01

    Progress of the Canadian ERTS program is provided along with statistics on the production and role of ERTS images both from the CCRS in Ottawa and from the Prince Albert Saskatchewan satellite station. The types of products, difficulties of production and some of the main applications in Canada are discussed.

  4. Application of 2D surface ERT to on-site wastewater treatment survey

    NASA Astrophysics Data System (ADS)

    Forquet, N.; French, H. K.

    2012-05-01

    Interest in the functioning of on-site wastewater treatment in rural areas has grown both among authorities and private companies in France and elsewhere in Europe. This is partly due to the enforcement of a new law that obliges communities to control on-site wastewater treatment systems. For extensive systems—mostly Vertical Flow Sand Filters (VFSF)—the introduction of this law revealed the absence of reliable methods to assess if a system was built according to recommendations and is operating well. The aim of this paper is to examine whether surface Electrical Resistivity Tomography (ERT) is a reliable method for mapping outline of filter dimensions and reveal clogging effects. Using forward modeling of synthetic models, we created sensitivity maps of ideal resistivity maps revealing that the method is well-suited to outline the horizontal extent of the filter but not necessarily its constitutive layers because the coarse gravel layer near the surface reduces the sensitivity to features below this layer. Hence whatever the geophysical signal is produced by clogging, this will be difficult to detect. The most appropriate inversion procedure, i.e. the L1-norm inversion, reveals the filter extent with an error less than the electrode spacing independent of noise levels. Finally, the procedure is illustrated for a real case ERT survey on a full scale VFSF. This study reveals that simple surface ERT measurements provide a good estimate of the filter area, but additional methods are required for more detailed vertical analysis including potential detection of clogging effects.

  5. Cross-hole ERT monitoring of freshwater injection in a hyper-saline aquifer

    NASA Astrophysics Data System (ADS)

    Haaken, K.; Deidda, G. P.; Cassiani, G.; Kemna, A.; Deiana, R.; Putti, M.; Paniconi, C.; Schirru, F.; Mura, M.

    2012-04-01

    In November 2011 we performed a freshwater injection experiment in the hyper-saline aquifer underlying the Molentargius-Saline Regional Park located near Cagliari in southern Sardinia, very close to the coastline. The subsurface water reaches salinity levels as high as three times the NaCl content of seawater, most likely as a consequence of salt release from the nearby salt works, active from Roman times to the mid-twentieth century. Five ERT boreholes were drilled with 4 inches inner diameter to a depth of 20 m and positioned in the shape of a square with an 8-m long side, with one borehole at the centre. All boreholes are equipped with a fully screened PVC pipe bearing externally twenty-four stainless steel cylindrical electrodes from 0.6 m to 19 m depth with 0.8 m separation. The water table is stable around -5.2 m from the ground surface. The sediments are mostly composed of sands with thin layers of silty sand, clayey sand and silty clay. Electric fluid logs recorded in the boreholes allowed to discriminate two zones, with a transitional layer in between: (a) from the water table to 7.5 m the water electrical conductivity is about 2 S/m; (b) below 12 m depth the water electrical conductivity reaches 18.5 S/m. In November 2011 we injected 19.4 m3 of freshwater in about 4 hours using a double packer system positioned in the central borehole, with an injection chamber located between 13.5 and 14.5 m below ground surface. Time-lapse ERT monitoring was achieved by measuring along two 2D ERT planes corresponding to the two square diagonals, thus involving three boreholes at a time for a total of 72 electrodes. A mixture of skip 0 dipole-dipole and bipole-bipole configurations was used in each acquisition, that required about 1 hour using an IRIS Syscal Pro resistivity meter. The resulting ERT time-lapse images show clearly the development and motion of the injected freshwater bulb, that undergoes a fast vertical migration and a quick disappearance probably caused

  6. Quantifying Permafrost Characteristics with DCR-ERT

    NASA Astrophysics Data System (ADS)

    Schnabel, W.; Trochim, E.; Munk, J.; Kanevskiy, M. Z.; Shur, Y.; Fortier, R.

    2012-12-01

    Geophysical methods are an efficient method for quantifying permafrost characteristics for Arctic road design and engineering. In the Alaskan Arctic construction and maintenance of roads requires integration of permafrost; ground that is below 0 degrees C for two or more years. Features such as ice content and temperature are critical for understanding current and future ground conditions for planning, design and evaluation of engineering applications. This study focused on the proposed Foothills West Transportation Access project corridor where the purpose is to construct a new all-season road connecting the Dalton Highway to Umiat. Four major areas were chosen that represented a range of conditions including gravel bars, alluvial plains, tussock tundra (both unburned and burned conditions), high and low centered ice-wedge polygons and an active thermokarst feature. Direct-current resistivity using galvanic contact (DCR-ERT) was applied over transects. In conjunction complimentary site data including boreholes, active layer depths, vegetation descriptions and site photographs was obtained. The boreholes provided information on soil morphology, ice texture and gravimetric moisture content. Horizontal and vertical resolutions in the DCR-ERT were varied to determine the presence or absence of ground ice; subsurface heterogeneity; and the depth to groundwater (if present). The four main DCR-ERT methods used were: 84 electrodes with 2 m spacing; 42 electrodes with 0.5 m spacing; 42 electrodes with 2 m spacing; and 84 electrodes with 1 m spacing. In terms of identifying the ground ice characteristics the higher horizontal resolution DCR-ERT transects with either 42 or 84 electrodes and 0.5 or 1 m spacing were best able to differentiate wedge-ice. This evaluation is based on a combination of both borehole stratigraphy and surface characteristics. Simulated apparent resistivity values for permafrost areas varied from a low of 4582 Ω m to a high of 10034 Ω m. Previous

  7. The lost church of Montemurro (Basilicata, Italy): Ground Penetrating Radar and Electrical Resistivity Tomography for detecting its buried remains in S. Maria Square.

    NASA Astrophysics Data System (ADS)

    Bavusi, Massimo; Giocoli, Alessandro; de Martino, Gregory; Loperte, Antonio; Lapenna, Vincenzo

    2010-05-01

    Montemurro is a little centre town located in the Agri Valley (Basilicata Region, Italy) which was affected by two catastrophic events: in the 1842 a very large landslide has damaged great part of the centre and in the 1857 the town was destroyed completely by the "Great Neapolitan Earthquake" (Mallet, 1862), a seismic event having epicenter in the Agri Valley (Cello et al., 2003; Bavusi et al., 2004). Signs of those tragic events can be still found in the fabric of the city. One of these is certainly S. Maria square, a place suspected to house a church before the disastrous events of 1842. This suspicion is supported by a series of evidences: a historical drawing, dating back to before 1842, shows a church in position compatible with the location of the square; in aerial view S. Maria square appears as tear in the fabric of the city; the tales of the erderlies of Montemurro speak about an ancient missing church in the town. Then, in the attempt to resolve the doubt about the presence of the church, a geophysical survey was planned in S. Maria Square with the aim to detect some buried masonry structures related to the church. In this work we selected two active techniques such as the Ground Penetrating Radar (GPR) and the Electrical Resistivity Tomography (ERT). Sixty parallel GPR profiles 0.5 m spaced were gathered in S. Maria Square and in a contiguous street by using a GSSI SIR3000 system with a central frequency antenna of 200 MHz. Processed radargrams showed numerous reflectors and heterogeneities in the subsoil related to manmade objects. Then, a laborious data processing (Nuzzo et al., 2002) allowed to obtain several time-slices showing noticeable reflections compatible with masonry structures. Moreover, two ERT profiles were carried out by using an IRIS Syscal R2 system equipped with a multielectrode cable. The first ERT profile 86 m long and having 44 electrodes 2 m spaced allowed to investigate up to 9 m of depth. The second, overlapped on the previous

  8. Modelling orange tree root water uptake active area by minimally invasive ERT data and transpiration measurements

    NASA Astrophysics Data System (ADS)

    Vanella, Daniela; Boaga, Jacopo; Perri, Maria Teresa; Consoli, Simona; Cassiani, Giorgio

    2015-04-01

    The comprehension of the hydrological processes involving plant root dynamics is crucial for implementing water saving measures in agriculture. This is particular urgent in areas, like those Mediterranean, characterized by scarce water availability. The study of root water dynamics should not be separated from a more general analysis of the mass and energy fluxes transferred in the soil-plant-atmosphere continuum. In our study, in order to carry this inclusive approach, minimal invasive 3D time-lapse electrical resistivity tomography (ERT) for soil moisture estimation was combined with plant transpiration fluxes directly measured with Sap Flow (SF) techniques and Eddy Covariance methods, and volumetric soil moisture measurements by TDR probes. The main objective of this inclusive approach was to accurately define root-zone water dynamics and individuate the root-area effectively active for water and nutrient uptake process. The monitoring was carried out in Eastern Sicily (south Italy) in summers 2013 and 2014, within an experimental orange orchard farm. During the first year of experiment (October 2013), ERT measurements were carried out around the pertinent volume of one fully irrigated tree, characterized by a vegetation ground cover of 70%; in the second year (June 2014), ERT monitoring was conducted considering a cutting plant, thus to evaluate soil water dynamics without the significant plant transpiration contribution. In order to explore the hydrological dynamics of the root zone volume surrounded by the monitored tree, the resistivity data acquired during the ERT monitoring were converted into soil moisture content distribution by a laboratory calibration based on the soil electrical properties as a function of moisture content and pore water electrical conductivity. By using ERT data in conjunction with the agro-meteorological information (i.e. irrigation rates, rainfall, evapotranspiration by Eddy Covariance, transpiration by Sap Flow and soil moisture

  9. Normal-reciprocal error models for quantitative ERT in permafrost environments: bin analysis versus histogram analysis

    NASA Astrophysics Data System (ADS)

    Verleysdonk, Sarah; Flores-Orozco, Adrian; Krautblatter, Michael; Kemna, Andreas

    2010-05-01

    Electrical resistivity tomography (ERT) has been used for the monitoring of permafrost-affected rock walls for some years now. To further enhance the interpretation of ERT measurements a deeper insight into error sources and the influence of error model parameters on the imaging results is necessary. Here, we present the effect of different statistical schemes for the determination of error parameters from the discrepancies between normal and reciprocal measurements - bin analysis and histogram analysis - using a smoothness-constrained inversion code (CRTomo) with an incorporated appropriate error model. The study site is located in galleries adjacent to the Zugspitze North Face (2800 m a.s.l.) at the border between Austria and Germany. A 20 m * 40 m rock permafrost body and its surroundings have been monitored along permanently installed transects - with electrode spacings of 1.5 m and 4.6 m - from 2007 to 2009. For data acquisition, a conventional Wenner survey was conducted as this array has proven to be the most robust array in frozen rock walls. Normal and reciprocal data were collected directly one after another to ensure identical conditions. The ERT inversion results depend strongly on the chosen parameters of the employed error model, i.e., the absolute resistance error and the relative resistance error. These parameters were derived (1) for large normal/reciprocal data sets by means of bin analyses and (2) for small normal/reciprocal data sets by means of histogram analyses. Error parameters were calculated independently for each data set of a monthly monitoring sequence to avoid the creation of artefacts (over-fitting of the data) or unnecessary loss of contrast (under-fitting of the data) in the images. The inversion results are assessed with respect to (1) raw data quality as described by the error model parameters, (2) validation via available (rock) temperature data and (3) the interpretation of the images from a geophysical as well as a

  10. Observation of flow processes in the vadose zone using ERT on different space and time scales: results, obstacles, and suggestions

    NASA Astrophysics Data System (ADS)

    Noell, Ursula; Ganz, Christina; Lamparter, Axel; Duijnisveld, Wilhelmus; Bachmann, Jörg

    2013-04-01

    Electrical resistivity tomography (ERT) observes the flow processes in the vadose zone indirectly. ERT has been used to estimate water flow in different soil types and under different flow conditions using active experiments or monitoring the natural process in many cases. Our experiments in sand and loess soil connected ERT with local soil probing using TDR devices and tensiometers in order to proof the reliability of the ERT inversion results in terms of infiltration velocity. Additionally, a colour tracer was used and sections through the infiltration zones were excavated in order to compare the shape of the dye -stained infiltration zone with the results of the ERT inversion. The data revealed the complicated infiltration pattern with a higher transport velocity in sand and a different shape than expected by classical soil hydraulic models. These results indicate the need for independent observations in order to correctly assess the water storage in the vadose zone with its hydrological consequences, the groundwater recharge and the contamination risk caused by rapid movement of water. ERT can be used for this purpose on different spatial- and time scales but for reliable results various obstacles need to be dealt with. Firstly, the ambiguity of the resistivity because soil resistivity depends on both, soil water content and electrical soil/water conductivity. This obstacle is less severe when the infiltration velocity is investigated, because then only the first onset of resistivity change is interpreted as the water arrival time. Our results show that the arrival of the water front as well as the final infiltration depth can be reliably detected. In contrast, this obstacle is very severe when the amount of water stored is observed using conductive tracer. The problem is not critical during a passive experiment when the natural rain fall and the waters fate through the vadose zone is monitored. The second obstacle is the limited resolution of ERT which

  11. Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

    PubMed

    Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

    2016-09-01

    The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects. PMID:26926783

  12. Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

    PubMed

    Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

    2016-09-01

    The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects.

  13. Time-lapse ERT and DTS for seasonal and short-term monitoring of an alpine river hyporheic zone

    NASA Astrophysics Data System (ADS)

    Boaga, Jacopo; Laura, Busato; Mariateresa, Perri; Giorgio, Cassiani

    2016-04-01

    The hyporheic zone (HZ) is the area located beneath and adjacent to rivers and streams, where the interactions between surface water and groundwater take place. This complex physical domain allows the transport of several substances from a stream to the unconfined aquifer below, and vice versa, thus playing a fundamental role in the river ecosystem. The importance of the hyporheic zone makes its characterization a goal shared by several disciplines, which range from applied geophysics to biogeochemistry, from hydraulics to ecology. The frontier field of HZ characterization stays in applied non-invasive methodologies as Electrical Resistivity Tomography - ERT - and Distributed Temperature Sensing - DTS. ERT is commonly applied in cross-well configuration or with a superficial electrodes deployment while DTS is used in hydro-geophysics in the last decade, revealing a wide applicability to the typical issues of this field of study. DTS for hydro-geophysics studies is based on Raman scattering and employs heat as tracer and uses a fiber-optic cable to acquire temperature values. We applied both techniques for an alpine river case studies located in Val di Sole, TN, Italy. The collected measurements allow high-resolution characterization of the hyporheic zone, overcoming the critical problem of invasive measurements under riverbeds. In this work, we present the preliminary results regarding the characterization of the hyporheic zone of the alpine river obtained combining ERT and DTS time-lapse measurements. The data collection benefits from an innovative instrumentation deployment, which consists of both an ERT multicore cable and a DTS fiber-optic located in two separated boreholes drilled 5m under the watercourse and perpendicular to it. In particular we present the first year monitoring results and a short time-lapse monitoring experiment conducted during summer 2015. The site and the results here described are part of the EU FP7 CLIMB (Climate Induced Changes on the

  14. Integrated GPR and ERT as Enhanced Detection for Subsurface Historical Structures Inside Babylonian Houses Site, Uruk City, Southern Iraq

    NASA Astrophysics Data System (ADS)

    Al-Khersan, Emad H.; Al-Ani, Jassim M. T.; Abrahem, Salah N.

    2016-03-01

    Uruk archaeological site, which located in Al-Muthanna Governorate southern Iraq, was investigated by integrated geophysical methods, ground penetration radar (GPR) and electric resistivity tomography (ERT) to image the historical buried structures. The GPR images show large radar attributes characterized by its continuous reflections having different widths. GPR attributes at shallower depth are mainly representing the upper part of Babylonian Houses that can often be found throughout the study area. In addition, radargrams characterized objects such as buried items, buried trenches and pits which were mainly concentrated near the surface. The ERT results show the presence of several anomalies at different depths generally having low resistivities. It is clear that the first upper zone can be found throughout the whole area and it may represent the top zone of the Babylonian houses. This zone is characterized by its dry clay and sandy soil containing surface broken bricks and slag mixed with core boulders. The second one underneath the top shows a prominent lower resistivity zone. It is probably caused by the moisture content that reduces the resistivity. The thickness of this zone is not equal at all parts of the site. The third deeper zone typically represents the archaeological walls. Most of the main anomalies perhaps referred to the buried clay brick walls. The map of the archaeological anomalies distribution and 3D view of the foundations at the study area using GPR and ERT techniques clearly show the characteristics of the Babylonian remains. A contour map and 3D view of Uruk show that the archaeological anomalies are concentrated mainly at the NE part of the district with higher values of wall height that range between 6 and 8 m and reach to more than 10 m. At the other directions, there are fewer walls with lower heights of 4-6 m and reach in some places the wall foot.

  15. Influence of the geomembrane on time-lapse ERT measurements for leachate injection monitoring.

    PubMed

    Audebert, M; Clément, R; Grossin-Debattista, J; Günther, T; Touze-Foltz, N; Moreau, S

    2014-04-01

    Leachate recirculation is a key process in the operation of municipal waste landfills as bioreactors. To quantify the water content and to evaluate the leachate injection system, in situ methods are required to obtain spatially distributed information, usually electrical resistivity tomography (ERT). However, this method can present false variations in the observations due to several parameters. This study investigates the impact of the geomembrane on ERT measurements. Indeed, the geomembrane tends to be ignored in the inversion process in most previously conducted studies. The presence of the geomembrane can change the boundary conditions of the inversion models, which have classically infinite boundary conditions. Using a numerical modelling approach, the authors demonstrate that a minimum distance is required between the electrode line and the geomembrane to satisfy the good conditions of use of the classical inversion tools. This distance is a function of the electrode line length (i.e. of the unit electrode spacing) used, the array type and the orientation of the electrode line. Moreover, this study shows that if this criterion on the minimum distance is not satisfied, it is possible to significantly improve the inversion process by introducing the complex geometry and the geomembrane location into the inversion tools. These results are finally validated on a field data set gathered on a small municipal solid waste landfill cell where this minimum distance criterion cannot be satisfied.

  16. Monitoring and Modelling of Soil-Plant Interactions: the Joint Use of ERT, Sap Flow and Eddy Covariance to Define the Volume of Orange Tree Active Root Zones.

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Vanella, D.; Perri, M. T.; Consoli, S.

    2014-12-01

    Mass and energy exchanges between soil, plants and atmosphere are key factors controlling a number of environmental processes involving hydrology, biota and climate. The understanding of these exchanges also play a critical role for practical purposes such as precision agriculture. In this contribution we present a methodology based on coupling innovative data collection and models. In particular we propose the use of hydro-geophysical monitoring via 4D Electrical Resistivity Tomography (ERT) in conjunction with measurements of plant transpiration via sap flow and evapotranspiration from Eddy Correlation (EC). This abundance of data are to be fed in spatially distributed soil models in order to comprehend the distribution of active roots. We conducted experiments in an orange orchard in Eastern Sicily (Italy). We installed a 3D electrical tomography apparatus consisting of 4 instrumented micro boreholes placed at the corners of a square (about 1.3 m in side) surrounding an orange tree. During the monitoring, we collected repeated ERT and TDR soil moisture measurements, soil water sampling, sap flow measurements from the orange tree and EC data. Irrigation, precipitation, sap flow and ET data are available for a long period of time allowing knowledge of the long term forcing conditions on the system. This wealth of information was used to calibrate a 1D Richards' equation model representing the dynamics of the volume monitored via 3D ERT. Information on the soil hydraulic properties was collected from laboratory experiments as well as by time-lapse ERT monitoring of irrigation a few months after the main experiment, when the orange tree had been cut. The results of the calibrated modeling exercise allow the quantification of the soil volume interested by root water uptake. This volume is much smaller (an area less than 2 square meters, 40 cm thick) than generally believed and assumed in the design of classical drip irrigation schemes.

  17. Electrical resistivity of coal-bearing rocks under high temperature and the detection of coal fires using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Shao, Zhenlu; Wang, Deming; Wang, Yanming; Zhong, Xiaoxing; Tang, Xiaofei; Xi, Dongdong

    2016-02-01

    Coal fires are severe hazards to environment, health and safety throughout the world. Efficient and economical extinguishing of these fires requires that the extent of the subsurface coal fires should be delineated. Electrical and electromagnetic methods have been used to detect coal fires in recent years. However, the resistivity change of coal-bearing rocks at high temperature is rarely investigated. The resistivity characteristics of coal fires at different temperatures and depths are seldomly researched as well. In this paper, we present the results of measurements of several coal-bearing rocks' resistivity and permeability under high temperature. Two major causes for the change in resistivity with increasing temperature are recognized, there are the increase of charge carriers and thermal fracturing, of which the first one is probably the dominant cause. A set of 2-D simulations is carried out to compare the relation of resolution and efficiency of coal fires detection to temperature and depth when adopting the electrical resistance tomography. The simulation results show that the resolution and efficiency decrease with the decrease of temperature and the increase of depth. Finally, the electrical resistance tomography is used to delineate coal fires in the Anjialing Open Pit Mine. Most low-resistivity regions are verified as coal-fire areas according to the long-term monitoring of borehole temperature. The results indicate that the electrical resistance tomography can be used as a tool for the detection of coal fires.

  18. Deep electrical resistivity tomography along the tectonically active Middle Aterno Valley (2009 L'Aquila earthquake area, central Italy)

    NASA Astrophysics Data System (ADS)

    Pucci, Stefano; Civico, Riccardo; Villani, Fabio; Ricci, Tullio; Delcher, Eric; Finizola, Anthony; Sapia, Vincenzo; De Martini, Paolo Marco; Pantosti, Daniela; Barde-Cabusson, Stéphanie; Brothelande, Elodie; Gusset, Rachel; Mezon, Cécile; Orefice, Simone; Peltier, Aline; Poret, Matthieu; Torres, Liliana; Suski, Barbara

    2016-11-01

    Three 2-D Deep Electrical Resistivity Tomography (ERT) transects, up to 6.36 km long, were obtained across the Paganica-San Demetrio Basin, bounded by the 2009 L'Aquila Mw 6.1 normal-faulting earthquake causative fault (central Italy). The investigations allowed defining for the first time the shallow subsurface basin structure. The resistivity images, and their geological interpretation, show a dissected Mesozoic-Tertiary substratum buried under continental infill of mainly Quaternary age due to the long-term activity of the Paganica-San Demetrio normal faults system (PSDFS), ruling the most recent deformational phase. Our results indicate that the basin bottom deepens up to 600 m moving to the south, with the continental infill largely exceeding the known thickness of the Quaternary sequence. The causes of this increasing thickness can be: (1) the onset of the continental deposition in the southern sector took place before the Quaternary, (2) there was an early stage of the basin development driven by different fault systems that produced a depocentre in the southern sector not related to the present-day basin shape, or (3) the fault system slip rate in the southern sector was faster than in the northern sector. We were able to gain sights into the long-term PSDFS behaviour and evolution, by comparing throw rates at different timescales and discriminating the splays that lead deformation. Some fault splays exhibit large cumulative throws (>300 m) in coincidence with large displacement of the continental deposits sequence (>100 m), thus testifying a general persistence in time of their activity as leading splays of the fault system. We evaluate the long-term (3-2.5 Myr) cumulative and Quaternary throw rates of most of the leading splays to be 0.08-0.17 mm yr-1, indicating a substantial stability of the faults activity. Among them, an individual leading fault splay extends from Paganica to San Demetrio ne' Vestini as a result of a post-Early Pleistocene linkage of

  19. Using electric resistivity tomography in a small scale catchment to evaluate the effectiveness of surfactans in water repellent soils of Western Australia

    NASA Astrophysics Data System (ADS)

    Lowe, Mary-Anne; Leopold, Matthias; McGrath, Gavan; Mattes, Falko; Murphy, Daniel

    2015-04-01

    Water repellent soils (WRS) are a major limitation on crop production in the southwest of Western Australia, with losses estimated at 250 million per annum. The amelioration of WRS through surfactant application shows variable success in field trials. This study aims to determine the effectiveness of surfactants on surface runoff and infiltration on WRS in a new laboratory based approach. The experiment used a physical, bench-scale catchment model (0.7 m x 0.7 m), where soils were arranged with a ridge and furrow shape similar to agricultural practices. It quantified irrigation, surface runoff, interflow and basal flow volumes. Electrical Resistivity Tomography (ERT) was used to measure the sub-surface electrical resistivity which is influenced by the amount of water in the soil. Three WRS from Western Australia were tested: very severely repellent (MED score 4.2 from South Stirling), moderate-severely repellent (MED score 2.4 from Badgingarra), and low repellence (MED score 1 from Dandaragan). Two different surfactants were compared to an untreated control, with application in furrow according to common agricultural practice at two replications and multiple wetting and drying cycles. Using ERT data, 2D-volumetric water contents for each WRS and test run were calculated. Surfactant application increased water infiltration in moderate-severely repellent soils by up to 73%, concentrated within the furrows. Water content also increased below 20 mm depth, where seeds would be located, suggesting a successful amelioration strategy for water repellency in agriculture. Very severely WRS revealed a more concentrated flow where surfactant was applied and only a 33% increase in infiltration. This physical catchment model in conjunction with hydrological and geophysical methods provides a useful tool to assess the effectiveness of surfactants to increase water infiltration into non-wetting soils. It is an inexpensive tool and could be used in future research before the most

  20. The use of soil electrical resistivity to monitor plant and soil water relationships in vineyards

    NASA Astrophysics Data System (ADS)

    Brillante, L.; Mathieu, O.; Bois, B.; van Leeuwen, C.; Lévêque, J.

    2015-03-01

    Soil water availability deeply affects plant physiology. In viticulture it is considered a major contributor to the "terroir" effect. The assessment of soil water in field conditions is a difficult task, especially over large surfaces. New techniques are therefore required in order to better explore variations of soil water content in space and time with low disturbance and with great precision. Electrical resistivity tomography (ERT) meets these requirements for applications in plant sciences, agriculture and ecology. In this paper, possible techniques to develop models that allow the use of ERT to spatialise soil water available to plants are reviewed. An application of soil water monitoring using ERT in a grapevine plot in Burgundy (north-east France) during the vintage 2013 is presented. We observed the lateral heterogeneity of ERT-derived fraction of transpirable soil water (FTSW) variations, and differences in water uptake depend on grapevine water status (leaf water potentials measured both at predawn and at solar noon and contemporary to ERT monitoring). Active zones in soils for water movements were identified. The use of ERT in ecophysiological studies, with parallel monitoring of plant water status, is still rare. These methods are promising because they have the potential to reveal a hidden part of a major function of plant development: the capacity to extract water from the soil.

  1. Detection of Old Mine Tunnels in Mexico City Highlands by Electric Resistivity Image Methods

    NASA Astrophysics Data System (ADS)

    Chavez, R. E.; Tejero, A.; Cifuentes-Nava, G.; HernaNdez-Quintero, J.

    2013-12-01

    Electrical Resistivity Tomography (ERT) methods have been applied to study cavities or subsurface subsidence threatening urbanized areas. Unfortunately, ERT-3D techniques carried out on heavily urbanized areas become a difficult task, since parallel ERT arrays cannot be deployed. Then, a conventional regular grid cannot be carried out. We present a subsidence problem located in a densely populated portion of Mexico City highlands. Since the damaged houses are in the middle of a highly populated low-class neighborhood, an unconventional ERT array had to be applied. At first, a ';T'-array formed by two perpendicular transects was applied, deployed within a small alley, that stretched from the house entrance. This study determined a tubular structure beneath the houses following an irregular path at depth. Finally, houses were demolished due to the extensive damaged in their foundations. This made possible to carry out a second ERT-3D study, which included a dipolar array called ';L' and ';Corner' arrays. Such a new work defined a similar tubular structure. The cavity entrance was discovered, when excavations were made, although its precise shape could not be defined. The ERT-3D interpretation contributed to locate and accurately determine the geometrical characteristics of the geological feature that caused the collapse of dwellings.

  2. Multidisciplinary investigation (ERT, CO2, SP and T) reveals fluid circulation at Somma-Vesuvius

    NASA Astrophysics Data System (ADS)

    Poret, Matthieu; Ricci, Tullio; Finizola, Anthony; Delcher, Eric; Peltier, Aline

    2016-04-01

    Somma-Vesuvius volcano, located near the city of Naples, threatens about 800,000 peoples producing one of the highest volcanic risk in the world. In the framework of the EC FP7 project "MEDiterranean SUpersite Volcanoes" a multidisciplinary investigation was performed in March 2014. This survey aimed (1) at locating the present-day hydrothermal system of Somma-Vesuvius and (2) at identifying the preferential paths and fluid flows inside the volcano.
 The prospecting methods used were Electrical Resistivity Tomography (ABEM SAS 4000) with 64 electrodes at 40 m spacing (in Wenner alpha configuration), self-potential (SP), temperature (30 cm depth) and CO2 concentration in the soil at 20 m spacing. All the measurements were performed along a 7 km long profile completed with roll-along (North- West to South-East). The depth of investigation for ERT reached about 500 m. This method revealed an electrical conductive body (20-100 ohm.m) centered beneath the summit of the Vesuvius cone. This conductive body was interpreted as the present-day hydrothermal system of the volcanic complex. Regarding the shape of this structure we noticed a deeply different shape respect to the one observed on both Stromboli and Vulcano volcanoes. Indeed, the Vesuvius hydrothermal system appears to act as a body which is constrained up to 200-250 m below the surface and, moreover, also emphasized by the W-like shape of the SP signal. From ERT and SP results a diameter of around 1.7 km at the maximum depth of investigation is estimated for the hydrothermal system of Somma-Vesuvius.
 In addition, four weak thermal anomalies (6-13°C) are identified on the summit area. They can be explained as preferential paths of up-flowing fluids. It follows that the largest structure seen on both temperature signal and ERT tomography is related to the crater rim of the 1906 eruption. Furthermore, on both lower sides of Vesuvius cone a conductive body (300-600 ohm.m) is identified within a resistive

  3. Isolation of the combined water content and salinity effects on ERT measurement to locate the preferential flow pathways in water repellent soils

    NASA Astrophysics Data System (ADS)

    Brindt, Naaran; Rahav, Matan; Furman, Alex; Wallach, Rony

    2016-04-01

    Electrical resistivity tomography (ERT) has been used for measuring the dynamics of water flow in soils without disturbing the soil, and recently for identifying the preferential flow pathways that are reported to develop in water repellent soils. Since electrical resistivity is affected mainly by soil saturation and salinity, and given that in many cases salinity in the root zone reaches high values, the isolation of spatial and temporal distribution of water content or salinity in the root zone from ERT scans is a challenge. A model for transient variation of soil water content and salinity within a well-mixed soil unit was developed in the frame of this challenge. The model aims to isolate the temporal changes in water content from subsequent ERT scans. The model assumes that four stages of water dynamics occur in the root zone during an irrigation cycle: 1) Soil water content decreases by evapotranspiration - no irrigation, 2) Irrigation with saline water begins, water content increases but remains below field capacity - negligible drainage, 3) Irrigation continues and drainage starts as the water content becomes higher than field capacity, and 4) Irrigation stops, water content is higher than field capacity, and water content decreases by drainage and evapotranspiration. These four stages restart when drainage stops and water content decreases solely by evapotranspiration. The model was solved analytically and successfully applied to a series of sequential ERT scans accomplished during and between subsequent irrigation events for a soil that was rendered hydrophobic by olive trees irrigated with saline water, and a soil in a citrus orchard that was rendered hydrophobic by prolonged effluent irrigation. The suggested model helps in distinguishing between the temporal changes in water content and salinity within a given soil volume, locating the preferential plow pathways, and tracking the spatial and temporal salinity variation within the root zone during and

  4. Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling - Part II: Constraint methodology of hydrodynamic models.

    PubMed

    Audebert, M; Oxarango, L; Duquennoi, C; Touze-Foltz, N; Forquet, N; Clément, R

    2016-09-01

    Leachate recirculation is a key process in the operation of municipal solid waste landfills as bioreactors. To ensure optimal water content distribution, bioreactor operators need tools to design leachate injection systems. Prediction of leachate flow by subsurface flow modelling could provide useful information for the design of such systems. However, hydrodynamic models require additional data to constrain them and to assess hydrodynamic parameters. Electrical resistivity tomography (ERT) is a suitable method to study leachate infiltration at the landfill scale. It can provide spatially distributed information which is useful for constraining hydrodynamic models. However, this geophysical method does not allow ERT users to directly measure water content in waste. The MICS (multiple inversions and clustering strategy) methodology was proposed to delineate the infiltration area precisely during time-lapse ERT survey in order to avoid the use of empirical petrophysical relationships, which are not adapted to a heterogeneous medium such as waste. The infiltration shapes and hydrodynamic information extracted with MICS were used to constrain hydrodynamic models in assessing parameters. The constraint methodology developed in this paper was tested on two hydrodynamic models: an equilibrium model where, flow within the waste medium is estimated using a single continuum approach and a non-equilibrium model where flow is estimated using a dual continuum approach. The latter represents leachate flows into fractures. Finally, this methodology provides insight to identify the advantages and limitations of hydrodynamic models. Furthermore, we suggest an explanation for the large volume detected by MICS when a small volume of leachate is injected. PMID:27095292

  5. Application of time-lapse ERT to Characterize Soil-Water-Disease Interactions of Citrus Orchard - Case Study

    NASA Astrophysics Data System (ADS)

    Peddinti, S. R.; Kbvn, D. P.; Ranjan, S.; Suradhaniwar, S.; J, P. A.; R M, G.

    2015-12-01

    Vidarbha region in Maharashtra, India (home for mandarin Orange) experience severe climatic uncertainties resulting in crop failure. Phytopthora are the soil-borne fungal species that accumulate in the presence of moisture, and attack the root / trunk system of Orange trees at any stage. A scientific understanding of soil-moisture-disease relations within the active root zone under different climatic, irrigation, and crop cycle conditions can help in practicing management activities for improved crop yield. In this study, we developed a protocol for performing 3-D time-lapse electrical resistivity tomography (ERT) at micro scale resolution to monitor the changes in resistivity distribution within the root zone of Orange trees. A total of 40 electrodes, forming a grid of 3.5 m x 2 m around each Orange tree were used in ERT survey with gradient and Wenner configurations. A laboratory test on un-disturbed soil samples of the region was performed to plot the variation of electrical conductivity with saturation. Curve fitting techniques were applied to get the modified Archie's model parameters. The calibrated model was further applied to generate the 3-D soil moisture profiles of the study area. The point estimates of soil moisture were validated using TDR probe measurements at 3 different depths (10, 20, and 40 cm) near to the root zone. In order to understand the effect of soil-water relations on plant-disease relations, we performed ERT analysis at two locations, one at healthy and other at Phytopthora affected Orange tree during the crop cycle, under dry and irrigated conditions. The degree to which an Orange tree is affected by Phytopthora under each condition is evaluated using 'grading scale' approach following visual inspection of the canopy features. Spatial-temporal distribution of moisture profiles is co-related with grading scales to comment on the effect of climatic and irrigation scenarios on the degree and intensity of crop disease caused by Phytopthora.

  6. Earth Resources Technology Satellite (ERTS)

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The Earth Resources Technology Satellite (ERTS) mock-up in a space chamber test at General Electric's Space Division. The ERTS program represented a concentrated effort to observe and monitor the limited resources of the Earth, in order to best conserve and utilize the resources in support of a burgeoning world population. The first ERTS was launched in 1972 and was later named Land Remote-Sensing Satellite (Landsat), to better represent the civil satellite program's prime emphasis on remote sensing of land resources. Multiple sensors survey and relay back masses of data in various ways from the Landsat. NASA has built 7 Land Remote Sensing Satellites, which have helped agricultural experts pick up underutilized land areas and new prospects for land use through irrigation. It has also assisted in pinpointing the spread of crop disease and in charting new uses of the sea for oceanographers.

  7. Monitoring a shallow geothermal experiment in a sandy aquifer using electrical resistivity tomography: a feasibility study

    NASA Astrophysics Data System (ADS)

    Hermans, Thomas; Vandenbohede, Alexander; Nguyen, Frederic; Lebbe, Luc

    2010-05-01

    The use of low-enthalpy geothermal ressources is increasingly growing in Europe and around the world. This domain constitutes an essential field of research and development in the diversification of energy ressources to hinder global warming. The advantages of very low temperature systems are, first, that they are much more available than the geothermal high temperature, since the underground often contains important shallow aquifers (e.g. alluvial plains), and second, that their exploitation involve relatively low costs of implementation. Very low energy systems exhibit underground fluid with a temperature ranging from 5 to 30 ° C, which may be used for cooling or heating. The two main modes of exploitation of geothermal energy rely on the extraction of the hydrothermal fluid in the aquifer from wells and on the circulation of a heat transfer fluid in a closed and buried geothermal circuit. Underground heat exchange and overall exploitation system design may be undertaken in an optimized and sustainable fashion if the parameters governing the coupled heat transport and flow equations are know to a certain degree. As for many underground reservoir problems, sufficient knowledge on the distribution of the parameters of interests (e.g. thermal conductivity, thermal diffusivity, thermomechanic dispersitivity, effective porosity) must be obtained to perform reliable predictions. Designing novel experiments to estimate those parameters in-situ is therefore essential. In this framework, we examine the feasibility of a thermal tracer experiment similar to the ones performed in hydrogeology or hydrogeophysics. The test consists in following the evolution of a heat plume through the underground as it is injected in one well and pumped to another one. The thermal tracer evolution is followed by gathering electrical resistivity (ERT) images in a time-lapse framework over 10 days. In this contribution, we examine the potential of ERT to image such thermal plume and its

  8. Application of ensemble-based methods for assimilating 4D ERT data at the groundwater-river water interaction zone based on a coupled hydrogeophysical model

    NASA Astrophysics Data System (ADS)

    Chen, X.; Johnson, T.; Hammond, G. E.; Zachara, J. M.

    2013-12-01

    Dynamic groundwater-river water exchange between the Columbia River and the Hanford 300 Area has substantial influence on flow and transport processes and biogeochemical cycles at the site. Existing research efforts have shown that the groundwater-river water interaction zone is a heterogeneous and highly dynamic region exhibiting variability over a range of space and time scales. Since it is insufficient to rely on well-based information to characterize the spatially variable subsurface properties within this interaction zone, we have installed a large-scale (300 m by 300 m) 3-dimensional electrical resistivity tomography (ERT) array to monitor river water intrusion and retreat at a temporal resolution of four images per day, using a novel time lapse ERT imaging methodology that explicitly accommodates the sharp, transient bulk conductivity contrast at the water table. The 4-dimensional electrical geophysical data is incorporated into ensemble-based data assimilation algorithms (e.g., ensemble Kalman filter and ensemble smoother) to statistically estimate the heterogeneous permeability field at the groundwater-river water interaction zone, which is critical for modeling flow and biogeochemical transport processes at the site. A new high performance computing capability has been developed to couple the ERT imaging code E4D (Johnson et al., 2010) with the site-scale flow and transport code, PFLOTRAN (Hammond et al., 2012), which serves as the forward simulator of the hydrogeophysical data assimilation. The joint, parallel, multi-physics code is able to simulate well-based pressure and pore-fluid conductivity measurements, as well as spatially continuous ERT measurements collected throughout the experiment. The data assimilation framework integrates both the well-based point measurements and spatially continuous ERT measurements in a sequential Bayesian manner. Our study demonstrates the effectiveness of ERT data for large-scale characterization of subsurface

  9. A new combined wavelet methodology applied to GPR and ERT data in the Montagnole experiment (French Alps)

    NASA Astrophysics Data System (ADS)

    Alperovich, L.; Eppelbaum, L.; Zheludev, V.; Dumoulin, J.; Soldovieri, F.; Proto, M.; Bavusi, M.; Loperte, A.

    2012-04-01

    Ground Penetrating Radar (GPR) and Electric Resistivity Tomography (ERT) methods are well assessed and accurate geophysical methods for studying subsurface geological sections. These methods were jointly applied at the Montagnole (French Alps) experimental site with the aim to study effects of possible catastrophic rockslides in transport infrastructures. The main goal of the experiment was a careful geophysical imaging of subsurface structure before and after of iron ball on the ground impact series. It is known that factors as ambiguity of geophysical field examination, complex geological media, and unfavourable "useful signal"-to-noise ratio in some situations do not permit to construct reliable physical-geological models of the studied subsurface structure. Here, we applied for the GPR and ERT methods at the Montagnole site, the recent advances in the wavelet theory and data mining. Wavelet approach was specifically applied to achieve enhanced (e.g., coherence portraits) images due to the integration of different geophysical fields; in fact, the methodology based on the matching pursuit with wavelet packet dictionaries enabled us to extract desired signals even from strongly noised data. Such tools as complex wavelets were employed to the coherence portraits, combined GPR-ERT coherency orientation angle, to name a few, enable performing non-conventional operations of integration and correlation in subsurface geophysics. These parameters can be used not only for location of buried inhomogeneties, but also for a rough estimation of their electromagnetic and related properties. The combination of the above approaches has allowed to set-up a novel methodology, which enhances reliability and confidence of each individually geophysical method and their integration. Acknowledgement This investigation is funding from the European Community's FP7 Program under grant agreement No. 225663, Joint Call FP7-ICT-SEC-2007-1

  10. Mapping of near surface fold structures with GPR and ERT near Steinbrunn (Northern Burgenland, Austria)

    NASA Astrophysics Data System (ADS)

    Kreutzer, Ingrid; Chwatal, Werner; Häusler, Hermann; Scheibz, Jürgen; Steirer, Fritz

    2014-05-01

    In the transition zone between the southern Vienna Basin and the Eisenstadt basin, close to Wr. Neustadt, spectacular fold structures are exposed in the former sand pit of Steinbrunn. The succession of Upper Pannonian age consists of decimetre to meter thick sandy, silty and clayey beds, which are overlain by sandstone beds (Grundtner et al., 2009). The anticline and syncline structures were interpreted as of gravitational origin by Exner et al. (2009), and reinterpreted as of tectonic origin by Häusler (2012a). In order to gain a more detailed insight to the three dimensional distribution and orientation of the folds high resolution geophysics such as electrical resistivity tomography (ERT), ground penetrating radar (GPR) and electromagnetics (EM) were applied to map the surroundings of the sandpit. The ERT- and EM-profiles show that the uppermost layer is more clayey northwest and sandier southeast of the sandpit. This is important for the GPR because clay attenuates the radar signals and therefore no clear layering of the subsurface could be mapped in these areas. In order to directly compare ERT and GPR results with the lithology of the fold structures observed in the sandpit, a reference profile on top of the 140 m long wall of the sandpit was performed. Both methods clearly reveal fold structures paralleling the folded Pannonian strata of the outcrop. While the GPR data displays boundaries and their geometry in the succession, the resistivities in the ERT portrays a more smoothened image of the observed fold structure. In almost all GPR profiles wavelike structures are visible with axes in northern direction and dome-shaped structures with axes in eastern direction, deepening towards the west. In conclusion this pattern is comparable to sections of rounded buckle folds. Although there are clayey areas wave-like and dome-like reflections can be followed in the GPR profiles over a distance of several hundred meters. This is confirmed by the ERT profiles

  11. Imaging high stage river-water intrusion into a contaminated aquifer along a major river corridor using 2-D time-lapse surface electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Wallin, E. L.; Johnson, T. C.; Greenwood, W. J.; Zachara, J. M.

    2013-03-01

    The Hanford 300 Area is located adjacent to the Columbia River in south-central Washington State, USA, and was a former site for nuclear fuel processing operations. Waste disposal practices resulted in persistent unsaturated zone and groundwater contamination, the primary contaminant of concern being uranium. Uranium behavior at the site is intimately linked with river stage driven groundwater-river water exchange such that understanding the nature of river water intrusion into the 300 Area is critical for predicting uranium desorption and transport. In this paper, we use 2-D surface-based time-lapse electrical resistivity tomography (ERT) to image the inland intrusion of river water during high stage conditions. We inverted approximately 1200 data sets (400 per line over three lines) using high performance computing resources to produce a time-lapse sequence of changes in bulk conductivity caused by river water intrusion during the 2011 spring runoff cycle over approximately 125 days. To invert the data, we use an image differencing approach that does not require regularization in the time dimension, enabling the inversion to accommodate the sharp, time varying contrasts in conductivity imposed by the moving water table. The resulting time series for each mesh element was then analyzed using common time series analysis to reveal the timing and location of river water intrusion beneath each line. The results reveal nonuniform flows characterized by preferred flow zones where river water enters and exits quickly with stage increase and decrease, and low permeability zones with broader bulk conductivity "break through" curves and longer river water residence times.

  12. Dissolution rates of subsoil limestone in a doline on the Akiyoshi-dai Plateau, Japan: An approach from a weathering experiment, hydrological observations, and electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Akiyama, Sanae; Hattanji, Tsuyoshi; Matsushi, Yuki; Matsukura, Yukinori

    2015-10-01

    This study aims at estimating the controlling factors for the denudation rates of limestone, which often forms solution dolines on karst tablelands. Our approaches include (1) electrical resistivity tomography (ERT) to reveal shallow subsurface structures and hydrological settings, (2) automated monitoring of volumetric water content in soil profiles and manual measurements of subsurface CO2 concentrations and soil water chemistry, and (3) a field weathering experiment using limestone tablets with the micro-weight loss technique for determining current denudation rates. The field experiment and monitoring were carried out over 768 days from 2009-2011 at four sites with varying topographic and hydrological conditions along the sideslope of a doline on the Akiyoshi-dai karst plateau in SW-Japan. The installation depths of the limestone tablets were 15 cm or 50 cm below the slope surface. The soil moisture conditions varied site by site. Water-saturated conditions continued for 40-50% of the whole experimental period at 50-cm depth of upper and middle sites, while only 0-10% of the experimental period was water-saturated at the other sites. Chemical analysis revealed that the soil water was chemically unsaturated with calcite for all the sites. Spatial differences in concentrations of CO2 in soil pore air were statistically less significant. The denudation rates of the buried limestone tablets were 17.7-21.9 mg cm- 2 a- 1 at the upper and middle slopes, where the soil was water-saturated for a long time after precipitation. The lowest denudation of 3.9 mg cm- 2 a- 1 was observed on lower slopes where soil was not capable of maintaining water at a near saturation level even after precipitation. Statistical analysis revealed that the denudation rates of the tablets were strongly controlled by the duration for which soil pores were saturated by water (the conditions defined here are degrees of water saturation greater than 97%). Electrical resistivity tomography

  13. Pseudocolor transformation of ERTS imagery

    NASA Technical Reports Server (NTRS)

    Lamar, J. V.; Merifield, P. M.

    1973-01-01

    One of the photographic techniques which shows great promise as an aid in interpreting ERTS imagery is pseudocolor transformation. It is a process where each shade of gray in an original black-and-white image is seen as a different color in the transformation. The well known ERTS-1 MSS image of the Monterey Bay-San Francisco area was transformed using a technique which requires only two intermediate separations. Possible faults were delineated on an overlay of the transformation before referring to geologic maps. The results were quite remarkable in that all large active or recently active faults shown on the latest geologic map of California were interpreted from the image for all, or much, of their length. Perhaps the most interesting result was the Reliz fault. The fault is shown as covered; however, a lineation corresponding to the position of the fault is visible on the image. The usefulness of ERTS image in identifying recently active faults is demonstrable. Although the faults are also visible in the unenhanced image, they are clearly accentuated and more easily mapped on the pseudocolor transformation.

  14. A sprinkling experiment using multiple tracers and ERT to conceptualize subsurface storm flow

    NASA Astrophysics Data System (ADS)

    Rothuizen, R. D.; Bogaard, T. A.; Westhoff, M. C.; Savenije, H. H. G.

    2010-05-01

    Rapid subsurface flow is one of the most important water flow processes in hillslopes. This process shows significant threshold behaviour as a certain amount of rainfall has to be added to the hillslope before the rapid subsurface flow process becomes active. Moreover, many tracer studies have shown a large fraction of ‘old' water in the rapid subsurface flow. The magnitude of the threshold and the fraction of ‘old' and ‘new' water still get significant research attention. However, this behaviour and magnitude can be explained by different hydrological concepts. In this study, we aim to identify and quantify the hydrological processes responsible for the threshold behaviour of the rapid subsurface flow and the extent of new water contribution during 5 sprinkling experiments on a 150 m2 plot, just uphill of a previously identified groundwater source. Five consecutive days we added approximately 9 mm of artificial rain on an experimental plot during one hour with salt and deuterium as artificial tracers. The analysis is based on a combination of hydrometric, hydrochemical and Electrical Resistivity Tomography (ERT) observations. The time lapse ERT observations gave most information on the saturation of and the salt content within the unsaturated soil, while the hydrometric observations quantified the storage in the saturated soil. The hydrochemical information was useful to differentiate between old and new water. We developed a conceptual model of the hydrological processes in the subsurface. The main hydrological processes that were identified and modeled are the unsaturated zone storage, the rapid subsurface flow and the slow matrix flow. By constraining the model only on the observed source outflow and not using the water quality information, we obtained a good fit between measured and modeled outflow. However, the simulated salt concentrations did not resemble the observations. This was caused by an overestimated exchange between the unsaturated zone and

  15. ERTS-1 applications to California resource inventory

    NASA Technical Reports Server (NTRS)

    Colwell, R. N. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. ERTS-1 information will be utilized by resource management groups working in the fields of forestry, hydrology, range management, and agriculture to develop resource inventories of the state of California. Five examples are given of the use of ERTS-1 imagery and aerial photography in identifying different crops and field conditions.

  16. Critical land resources inventory using ERTS data

    NASA Technical Reports Server (NTRS)

    Kiefer, R. W.; Niemann, B. J., Jr.; Keyes, D. L.; Kuhlmey , E. L.; Miller, A. H.

    1973-01-01

    The State of Wisconsin has embarked on a Critical Resources Information Program aimed at defining, establishing the units of measurement, inventorying, and monitoring natural and cultural spatial resource elements which are of statewide or regional significance. This paper presents the results of using ERTS data to inventory certain significant natural resources, such as agricultural land, forests, surface water and wetlands. Computer-generated spatial and statistical comparisons of resource data derived from conventional sources, RB-57 photographs, and ERTS images of Wisconsin suggest that certain resources can be inventoried and monitored on a statewide basis using ERTS images. Preliminary results of data extraction using ERTS digital tapes are also presented. The interpretation of certain natural and cultural resource information from ERTS images is anticipated to be an operational part of Wisconsin's Critical Resources Information Program.

  17. A high resolution resistive plate chamber tracking system developed for cosmic ray muon tomography

    NASA Astrophysics Data System (ADS)

    Baesso, P.; Cussans, D.; Thomay, C.; Velthuis, J. J.; Burns, J.; Steer, C.; Quillin, S.

    2013-08-01

    This work describes the performance of a muon tracker built with high resolution glass resistive plate chambers. The tracker is the result of a collaboration between University of Bristol and the Atomic Weapon Establishment to develop a reliable and cost effective system to scan shipping containers in search of special nuclear materials. The current setup consists of 12 detection layers, each comprised of a resistive plate chamber read out by 1.5 mm pitch strips. For most of the layers we achieved an efficiency better than 95%, a purity above 95% and a signal-to-noise ratio better than 300. A spatial resolution better than 500μm was obtained for most layers, thus satisfying the main requirements to apply resistive plate chambers to cosmic ray tomography.

  18. Determination of the Low Permeability of the Rocks from Fracture Zones in Beishan by Incorporating ERT into Infiltration Test

    NASA Astrophysics Data System (ADS)

    Song, Y.; Song, Z.

    2015-12-01

    The hydraulic study of low permeability rocks has a great significance for the low permeable oilfield and nature gas field development, as well as the nuclear waste disposal. The traditional test method for hydraulic parameters usually determines an average value of certain region, and this is always insufficient in the study of fractured porous media. This research developed a method with high performance and accuracy to show the heterogeneity and anisotropy of sample rocks. While permeability measurement was conducted, electrical resistivity tomography (ERT) method was incorporated simultaneously to obtain the rock saturation information, which could be used to determine the permeability. Besides, the infiltration process of water infiltrating through the fractured porous media was simulated by TOUGH2 to corroborate the results calculated from the experimental data. The preliminary results showed that the permeability of rock samples was as low as 10-16 m2 and showed high sample variance. By incorporating electrical resistivity tomography into the experiment, the test could specify more details of the infiltration process as well as identify the heterogeneity and anisotropy of sample rocks.

  19. Afar and ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Mohr, P. A. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. The excellent ERTS-1 imagery of the Afar region of Ethiopia permits a preliminary revision to the analysis of the structures of this triple-rift junction, and also revisions to the outcrops of some lithological formations. The fault-belts of the Afar floor can now be mapped in fine detail. The Danakil horst is identified to be limited on its western side against Afar by a major fault-line, and it seems unlikely that the horst is the exposed, easterly portion of a west-dipping sialic block underlying all northern Afar. The Salt Plain appears to be a true graben. The Ethiopian plateau-Afar margin consists of a series of right-offset sectors, the offsets being marked by silicic volcanic centers. The nature of these offsets is related to the vexed question of cross-rift faulting. Such faulting is identifiable on the ERTS-1 imagery, both on the Afar floor, and in the monoclinally warped western margin. The significance of this faulting, though subordinate to the tensional faults of the fault-belts, awaits elucidation.

  20. In situ spectroradiometric quantification of ERTS data

    NASA Technical Reports Server (NTRS)

    Yost, E.

    1973-01-01

    The task of correlating in situ spectral reflectance measurements with ERTS imagery has commenced. A method of additive color analysis of a single multispectral band taken on different dates indicates that ERTS-1 bulk images have sufficient spatial and spectral fidelity to show indications of the presence of soil moisture in desert playas and changes in soil moisture with time. The chain of causality between soil moisture, in situ spectral reflectance, and ERTS multispectral scanner image density remains to be established during the subsequent phases of this study.

  1. Anisotropic resistivity tomography: A model study for characterization of fractured rocks

    SciTech Connect

    Sasaki, Yutaka

    1994-12-31

    Since fractured rocks often exhibit anisotropy with respect to hydraulic conductivity, it is expected that anisotropy may play an important factor in describing their electrical properties. Based upon this observation, numerical experiments have been carried out to determine whether anisotropic resistivity tomography can be used for characterization of fractured rocks. In fractured rock masses, the conventional 2-D inversion in which anisotropy is ignored produces peculiar distortions of the resistivity distribution. In contrast, the inversion accounting for anisotropy reconstructs anisotropic background media, as well as conductive anomalies associated with the zones of concentrated fracturing. It is also found that the fracture planes inclined with respect to the strike direction may have no significant effects on 2-D inversion if the angle is within about 20{degree}.

  2. High resolution 3D ERT to help GPR data interpretation for researching archaeological items in a geologically complex subsurface

    NASA Astrophysics Data System (ADS)

    Negri, S.; Leucci, G.; Mazzone, F.

    2008-09-01

    Muro Leccese (Lecce) contains one the most important Messapian archaeological sites in southern Italy. The archaeological interest of the site arises from the discovery of the remains of Messapian walls, tombs, roads, etc. (4th-2nd centuries BC) in the neighbourhood. The archaeological remains were found at about 0.3 m depth. At present the site belongs to the municipality, which intends to build a new sewer network through it. The risk of destroying potentially interesting ancient archaeological structures during the works prompted an archaeological survey of the area. The relatively large dimensions of the area (almost 10,000 m 2), together with time and cost constraints, made it necessary to use geophysical investigations as a faster means to ascertain the presence of archaeological items. Since the most important targets were expected to be located at a soil depth of about 0.3 m, a ground-penetrating radar (GPR) survey was carried out in an area located near the archaeological excavations. Unfortunately the geological complexity did not allow an easy interpretation of the GPR data. Therefore a 3D electrical resistivity tomography (ERT) scan was conducted in order to resolve these interpretation problems. A three-way comparison of the results of the dense ERT measurements parallel to the x axis, the results of the measurements parallel to the y axis and the combined results was performed. Subsequently the synthetic model approach was used to provide a better characterization of the resistivity anomalies visible on the ERT field data. The 3D inversion results clearly illustrate the capability to resolve in view of quality 3D structures of archaeological interest. According to the presented data the inversion models along one direction ( x or y) seems to be adequate in reconstructing the subsurface structures. Naturally field data produce good quality reconstructions of the archaeological features only if the x-line and y-line measurements are considered together

  3. Sinkhole risk assessment by ERT: The case study of Sirino Lake (Basilicata, Italy)

    NASA Astrophysics Data System (ADS)

    Giampaolo, V.; Capozzoli, L.; Grimaldi, S.; Rizzo, E.

    2016-01-01

    The presence of natural or artificial lakes and reservoirs that can drain because of natural phenomena can generate catastrophic events affecting urban and agricultural areas next to the source area. Therefore, geophysical prospecting techniques have been applied in the study of Sirino Lake, which, during the last century, was affected by the sudden opening of small sinkholes, resulting in the almost total draining of the lake and in the sudden increase of water flow rates of distal springs. Two electrical resistivity tomographies (ERTs) were carried out across the lake, using electrode arrays located on land and across the water body. Self-potential (SP) data were acquired around the lake shore and the surrounding area. The geophysical prospecting contributed significant data toward explaining the unique hydrogeological characteristics of the lake. Integration of geophysical, geological, hydrogeological, and geomorphological data allowed us to estimate the thickness of the lacustrine deposits beneath the lake, to describe the main patterns of the subsurface fluid flows in the area, and to identify possible water escape routes causing the piping phenomena.

  4. Parallel inversion of a massive ERT data set to characterize deep vadose zone contamination beneath former nuclear waste infiltration galleries at the Hanford Site B-Complex (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, T.; Rucker, D. F.; Wellman, D.

    2013-12-01

    The Hanford Site, located in south-central Washington, USA, originated in the early 1940's as part of the Manhattan Project and produced plutonium used to build the United States nuclear weapons stockpile. In accordance with accepted industrial practice of that time, a substantial portion of relatively low-activity liquid radioactive waste was disposed of by direct discharge to either surface soil or into near-surface infiltration galleries such as cribs and trenches. This practice was supported by early investigations beginning in the 1940s, including studies by Geological Survey (USGS) experts, whose investigations found vadose zone soils at the site suitable for retaining radionuclides to the extent necessary to protect workers and members of the general public based on the standards of that time. That general disposal practice has long since been discontinued, and the US Department of Energy (USDOE) is now investigating residual contamination at former infiltration galleries as part of its overall environmental management and remediation program. Most of the liquid wastes released into the subsurface were highly ionic and electrically conductive, and therefore present an excellent target for imaging by Electrical Resistivity Tomography (ERT) within the low-conductivity sands and gravels comprising Hanford's vadose zone. In 2006, USDOE commissioned a large scale surface ERT survey to characterize vadose zone contamination beneath the Hanford Site B-Complex, which contained 8 infiltration trenches, 12 cribs, and one tile field. The ERT data were collected in a pole-pole configuration with 18 north-south trending lines, and 18 east-west trending lines ranging from 417m to 816m in length. The final data set consisted of 208,411 measurements collected on 4859 electrodes, covering an area of 600m x 600m. Given the computational demands of inverting this massive data set as a whole, the data were initially inverted in parts with a shared memory inversion code, which

  5. DC resistivity tomography applied to monitoring active layer environments below patterned ground in Svalbard

    NASA Astrophysics Data System (ADS)

    Watanabe, Tatsuya; Juliussen, Hâvard; Matsuoka, Norikazu; Christiansen, Hanne H.

    2010-05-01

    Patterned ground is one of the most characteristic features in arctic periglacial landscapes that originated from various periglacial processes. On flat tundra surfaces composed of fine-grained soils, ice-wedge polygons are dominant, but mud boils and hummocks are also developed. Their distribution is constrained by local ground material, hydrology, snow cover, vegetation and freeze/thaw regimes. Whereas there have been a large number of studies on patterned ground phenomena, environmental factors distinguishing the types of patterned ground are not well understood. We applied DC resistivity tomography to understanding hydrological characteristics and freeze/thaw dynamics at adjoining ice-wedge and mud-boil sites in Adventdalen, Svalbard, where comprehensive periglacial process monitoring has been undertaken. Electrode arrays consisting of 81 nails spaced at 20 cm intervals were fixed at each site early in June 2009 immediately after the snow cover disappeared. The nails were stuck within the top 5 cm to resolve the top layer of the ground. Measurements were carried out repeatedly at approximately two week intervals. Spring results from both sites are characterized by an increase in resistivity near surface due to drying up. This tendency is prominent in the ice-wedge polygon centre where standing water remains until late spring. Time-lapse analyses indicate a distinct decrease in resistivity in seasonal frozen layer at both sites probably due to an increase in unfrozen water content by downward heat transfer. Summer profiles from both sites display a distinct resistivity boundary propagating downward with time, corresponding well with the thaw depth measured by mechanical probing. These data also show near-surface high resistivity spots indicating the location of desiccation cracks. Profiles from the mud-boil site show higher resistivity in the thaw layer than those of ice-wedge site, implying different drainage condition between them. After seasonal freezing

  6. Using electrical impedance tomography to map subsurface hydraulic conductivity

    DOEpatents

    Berryman, James G.; Daily, William D.; Ramirez, Abelardo L.; Roberts, Jeffery J.

    2000-01-01

    The use of Electrical Impedance Tomography (EIT) to map subsurface hydraulic conductivity. EIT can be used to map hydraulic conductivity in the subsurface where measurements of both amplitude and phase are made. Hydraulic conductivity depends on at least two parameters: porosity and a length scale parameter. Electrical Resistance Tomography (ERT) measures and maps electrical conductivity (which can be related to porosity) in three dimensions. By introducing phase measurements along with amplitude, the desired additional measurement of a pertinent length scale can be achieved. Hydraulic conductivity controls the ability to flush unwanted fluid contaminants from the surface. Thus inexpensive maps of hydraulic conductivity would improve planning strategies for subsequent remediation efforts. Fluid permeability is also of importance for oil field exploitation and thus detailed knowledge of fluid permeability distribution in three-dimension (3-D) would be a great boon to petroleum reservoir analysts.

  7. High resolution electrical resistivity tomography of golf course greens irrigated with reclaimed wastewater: Hydrological approach

    NASA Astrophysics Data System (ADS)

    Tapias, Josefina C.; Lovera, Raúl; Himi, Mahjoub; Gallardo, Helena; Sendrós, Alexandre; Marguí, Eva; Queralt, Ignasi; Casas, Albert

    2014-05-01

    Actually, there are over 300 golf courses and more than three thousand licensed players in Spain. For this reason golf cannot be considered simply a hobby or a sport, but a very significant economic activity. Considered as one of the most rapidly expanding land-use and water demanding business in the Mediterranean, golf course development generates controversy. In the recent years there has been a considerable demand for golf courses to adopt environmentally sustainable strategies and particularly water authorities are forcing by law golf managers to irrigate with alternative water resources, mainly reclaimed wastewater. Watering practices must be based on soil properties that are characterized by samples removed from the different zones of the golf course and submitted to an accredited physical soil testing laboratory. Watering schedules are critical on greens with poor drainage or on greens with excessively high infiltration rates. The geophysical survey was conducted over the greens of the Girona Golf Club. Eighteen electrical resistivity tomographies were acquired using a mixed Wenner-Schlumberger configuration with electrodes placed 0.5 meter apart. Small stainless-steel nails were used as electrodes to avoid any damage in the fine turfgrass of greens The resistivity meter was set for systematically and automatically selects current electrodes and measurement electrodes to sample apparent resistivity values. Particle size analysis (PSA) has been performed on soil materials of any putting green. The PSA analysis has been composed of two distinct phases. The first has been the textural analysis of the soils for determining the content of sand, silt, and clay fraction via the use of a stack of sieves with decreasing sized openings from the top sieve to the bottom. Subsequently, the hydraulic conductivity of the substrates has been evaluated by means of Bredding and Hazen empirical relationships. The results of this research show that the electrical resistivity

  8. Electromagnetic Induction and Electrical Resistivity Tomography Applied to evaluate contamination at a site of disposal of animal wastes from a feedlot

    NASA Astrophysics Data System (ADS)

    Sainato, C. M.; Marquez Molina, J.; Losinno, B.; Urricariet, A. S.

    2012-12-01

    In Argentina, the systems of animal feeding in pens (feedlots) are expanding the production, generating a great quantity of solids and liquid residuals, being a highly risky source of soil and groundwater contamination. The aim of this work was to evaluate the relation between soil bulk conductivity and the distribution of concentrations of nitrates and other potential contaminants of groundwater from animal manure. Shallow electromagnetic induction (EMI) and electrical resistivity tomography (ERT) surveys were carried out at a pen of a feedlot at San Pedro , Bs. As. Province , Argentina, where large quantities of manure (3.5 m height) had been placed at the center of them, for a few months of activity. Soil sampling up to 2 m depth was performed for physical and chemical analysis. Wells were drilled for monitoring groundwater level (12 m depth) and water quality. Soil texture was defined as loamy clayey silty. Distribution of electrical conductivity obtained from the two exploration methods was similar, being higher the values at the pen than at the background site, coinciding with laboratory measurements of electrical conductivity of the saturation paste extract. At the center of the pen, bellow the manure accumulation, the highest values of conductivity were found (greater than 120mS/m), decreasing to the surroundings. However, values of N-NO3 in soil were lower at the center of the pen than at the surroundings. Concentration decreases with depth at sites of the pen with high soil compaction. Water content showed a strong influence on values of conductivity. Groundwater values of NO3 concentration do not exceed the level for human consumption although SO4 concentration increases respect to background deeper well.Values of conductivity and N-NO3 were still lower compared with the ones found at another pen with 10 years of use. An EMI survey carried out two years later showed an increase of twice the values of electrical conductivity. We conclude that higher

  9. Electrical resistivity characterization and defect detection on a geosynthetic clay liner (GCL) on an experimental site

    NASA Astrophysics Data System (ADS)

    Sirieix, C.; Fernández Martínez, J. L.; Riss, J.; Genelle, F.

    2013-03-01

    In this paper we analyze the onsite characterization of a geosynthetic clay liner (GCL) that serves to ensure the impermeability of a landfill cap by DC electrical methods. The imaging of the GCL geoelectrical properties is a challenging problem because it is a very thin (between 4 and 7 mm thick) and resistive layer (from 100,000 to 2,000,000 Ω·m) depending on meteorological conditions and aging. We compare results obtained using electrical resistivity tomography (ERT) using two different kinds of arrays (dipole-dipole DD and Wenner-Schlumberger) on an experimental site with engineered defects. To confirm these results and to find the real onsite GCL resistivity we have performed sampling of the posterior distribution of this parameter using vertical electrical sounding (VES) inversions. Different VES methods were extracted from ERT with DD array and converted into a Schlumberger array. As a main conclusion the dipole-dipole array provides a better resistivity resolution of the defects than the Wenner-Schlumberger array. On ERT images, the defect detection seems to be impossible if the GCL has very high resistivity, as it happened when it was put in place. Taking into account the equivalence rules, the inversions are in both cases (ERT and VES) compatible. The GCL resistivity estimated from PSO (particle swarm optimization) varies from 3.0 105 to 1.106 Ω·m depending on saturation conditions during the twenty first months of its placing. Then, the resistivity dropped to 4.104-9.104 Ω·m, indicating a probable chemical damage of the GCL due to aging. Finally the fact that the VES inversions are solved via PSO sampling allows for the detection of a very thin and resistive layer and opens the possibility of performing micro VES surveys along the landfill to detect possible GCL defects.

  10. Characterization and monitoring of subsurface processes using parallel computing and electrical resistivity imaging

    SciTech Connect

    Johnson, Timothy C.; Truex, Michael J.; Wellman, Dawn M.; Marble, Justin

    2011-12-01

    This newsletter discusses recent advancement in subsurface resistivity characterization and monitoring capabilities. The BC Cribs field desiccation treatability test resistivity monitoring data is use an example to demonstrate near-real time 3D subsurface imaging capabilities. Electrical resistivity tomography (ERT) is a method of imaging the electrical resistivity distribution of the subsurface. An ERT data collection system consists of an array of electrodes, deployed on the ground surface or within boreholes, that are connected to a control unit which can access each electrode independently (Figure 1). A single measurement is collected by injecting current across a pair of current injection electrodes (source and sink), and measuring the resulting potential generated across a pair of potential measurement electrodes (positive and negative). An ERT data set is generated by collecting many such measurements using strategically selected current and potential electrode pairs. This data set is then processed using an inversion algorithm, which reconstructs an estimate (or image) of the electrical conductivity (i.e. the inverse of resistivity) distribution that gave rise to the measured data.

  11. 3-D Time-lapse Electrical Resistivity Monitoring of Injected CO2 in a Shallow Aquifer

    NASA Astrophysics Data System (ADS)

    Doetsch, J.; Vest Christiansen, A.; Auken, E.; Fiandaca, G.; Graham Cahill, A.

    2013-12-01

    Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface electrical resistivity tomography (ERT) can detect dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5 and 10 m and monitored its migration using 320 electrodes on a 126 m × 20 m surface grid. A fully automated acquisition system continuously collected data and uploaded it into an online database. The large amount of data allows for time-series analysis using geostatistical techniques for noise estimation and data interpolation to compensate for intermittent instrument failure. We estimate a time-dependent noise level for each ERT configuration, taking data variation and measurement frequency into account. A baseline inversion reveals the geology at the site consisting of aeolian sands near the surface and glacial sands below 5 m depth. Directly following the injection, we image the CO2 gas phase in the aquifer as an increase in resistivity and the higher water saturation in the unsaturated zone as a decrease in resistivity. At later times, the 2-D and 3-D time-lapse inversions clearly image the dissolved CO2 plume with decreased electrical resistivity values. We can image the geochemical changes induced by the dissolved CO2 until the end of the acquisition, 120 days after the injection start. During these 120 days, the CO2 migrates about 40 m in the expected groundwater flow direction (towards south-west). Water electrical conductivity (EC) sampling using 68 sensors in 31 wells allows for very good verification of the ERT results. Water EC and ERT results generally agree very well, with the water sampling showing some fine scale variations that cannot be resolved by the ERT. The ERT images have their strength in outlining the plume's shape in three dimensions and in being able to image the plume outside the well field. These results highlight the potential for imaging

  12. The trophic classification of lakes using ERTS multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Blackwell, R. J.; Boland, D. H.

    1975-01-01

    Lake classification methods based on the use of ERTS data are described. Preliminary classification results obtained by multispectral and digital image processing techniques indicate satisfactory correlation between ERTS data and EPA-supplied water analysis. Techniques for determining lake trophic levels using ERTS data are examined, and data obtained for 20 lakes are discussed.

  13. Distribution-based fuzzy clustering of electrical resistivity tomography images for interface detection

    NASA Astrophysics Data System (ADS)

    Ward, W. O. C.; Wilkinson, P. B.; Chambers, J. E.; Oxby, L. S.; Bai, L.

    2014-04-01

    A novel method for the effective identification of bedrock subsurface elevation from electrical resistivity tomography images is described. Identifying subsurface boundaries in the topographic data can be difficult due to smoothness constraints used in inversion, so a statistical population-based approach is used that extends previous work in calculating isoresistivity surfaces. The analysis framework involves a procedure for guiding a clustering approach based on the fuzzy c-means algorithm. An approximation of resistivity distributions, found using kernel density estimation, was utilized as a means of guiding the cluster centroids used to classify data. A fuzzy method was chosen over hard clustering due to uncertainty in hard edges in the topography data, and a measure of clustering uncertainty was identified based on the reciprocal of cluster membership. The algorithm was validated using a direct comparison of known observed bedrock depths at two 3-D survey sites, using real-time GPS information of exposed bedrock by quarrying on one site, and borehole logs at the other. Results show similarly accurate detection as a leading isosurface estimation method, and the proposed algorithm requires significantly less user input and prior site knowledge. Furthermore, the method is effectively dimension-independent and will scale to data of increased spatial dimensions without a significant effect on the runtime. A discussion on the results by automated versus supervised analysis is also presented.

  14. Facies Delineation using Core, Wireline log, Electrical Resistance Tomography, and Electromagnetic Borehole Flowmeter Data

    NASA Astrophysics Data System (ADS)

    Rockhold, M. L.; Chen, X.; Ramanathan, R.; Vermeul, V.; Johnson, T. C.; Murray, C. J.

    2011-12-01

    Multiple data types from the Hanford 300 Area IFRC site and surrounding area were used to delineate and map facies across multiple scales. The data used for facies delineation included grain-size distribution metrics from core samples, spectral gamma logs, ERT, and EBF data. Multivariate analysis and clustering methods were used for facies identification, and transition probability geostatistics were used to generate facies distributions. Simulations of a field-scale flow and tracer transport experiment were performed using facies distributions generated using different combinations of data types and different facies delineation methods to determine which data types and methods were most effective in reproducing the observed flow and transport behavior.

  15. Cartographic quality of ERTS-1 images

    NASA Technical Reports Server (NTRS)

    Welch, R. I.

    1973-01-01

    Analyses of simulated and operational ERTS images have provided initial estimates of resolution, ground resolution, detectability thresholds and other measures of image quality of interest to earth scientists and cartographers. Based on these values, including an approximate ground resolution of 250 meters for both RBV and MSS systems, the ERTS-1 images appear suited to the production and/or revision of planimetric and photo maps of 1:500,000 scale and smaller for which map accuracy standards are compatible with the imaged detail. Thematic mapping, although less constrained by map accuracy standards, will be influenced by measurement thresholds and errors which have yet to be accurately determined for ERTS images. This study also indicates the desirability of establishing a quantitative relationship between image quality values and map products which will permit both engineers and cartographers/earth scientists to contribute to the design requirements of future satellite imaging systems.

  16. ERTS-1 imagery and native plant distributions

    NASA Technical Reports Server (NTRS)

    Musick, H. B.; Mcginnies, W.; Haase, E.; Lepley, L. K.

    1974-01-01

    A method is developed for using ERTS spectral signature data to determine plant community distribution and phenology without resolving individual plants. An Exotech ERTS radiometer was used near ground level to obtain spectral signatures for a desert plant community, including two shrub species, ground covered with live annuals in April and dead ones in June, and bare ground. It is shown that comparisons of scene types can be made when spectral signatures are expressed as a ratio of red reflectivity to IR reflectivity or when they are plotted as red reflectivity vs. IR reflectivity, in which case the signature clusters of each component are more distinct. A method for correcting and converting the ERTS radiance values to reflectivity values for comparison with ground truth data is appended.

  17. Monitoring the geothermal fluid using time lapse electrical resistivity tomography: The Pisciarelli fumarolic field test site (Campi Flegrei, South Italy)

    NASA Astrophysics Data System (ADS)

    Fedele, Alessandro; Giulia Di Giuseppe, Maria; Troiano, Antonio; Somma, Reanto; Caputo, Teresa; Patella, Domenico; Troise, Claudia; De Natale, Giuseppe

    2015-04-01

    Pisciarelli area is a fumarolic field subject to very short time morphological changes. A number of critical problems affect this area, i.e. increase of temperature of the fumaroles above the average background temperature, local seismicity and occurrence of fumaroles mixed with jets of boiling water. The presence of a very shallow aquifer seem to have the control on the behavior and composition of the fumaroles. This fumarolic field is still largely unknown regarding geophysical surveys mainly because of its limited space, surrounded on the eastern side by intense urbanization inside the large Agnano crater (Troiano et al. 2014). Currently is mainly affected by geochemical, thermal and seismic monitoring which may not fully explain the behaviour of fluids surface. Many monitoring or time lapse (TL) applications are discussed in literature (e.g., White, 1994; Daily et al., 1995; Barker and Moore, 1998; Ramirez and Daily, 2001; Carter, 2002; Slater et al., 2002; Singha and Gorelick, 2005; Cassiani et al., 2006; Swarzenski et al., 2006; de Franco et al., 2009). However all these experiments are devoted to the use of the ERT for tracer tests or in contaminant hydrology and are characterized by a short monitoring period due to the complexity and problems of long-time instrument maintenance. We propose and present a first approach of a geophysical monitoring by time lapse electrical resistivity in a fumarolic field. The profiles were acquired in January 2013, in January, March, May, July, September and November 2014 respectively. They cross the Pisciarelli area following approximately the NS direction and were characterized by a 2.5 m electrode spacing and maximum penetration depth of about 20 m. and will supply fundamental evidences on the possible seasonal resistivity fluctuations or if the resistivity changes are indicative of an increase in volcanic gases present in the hydrothermal system.

  18. Diazo Printing of ERTS Color Composites

    NASA Technical Reports Server (NTRS)

    Mcmurtry, G. J.; Petersen, G. W. (Principal Investigator); Kowalik, W. S.

    1975-01-01

    The author has identified the following significant results. ERTS-1 color composites were made with the help of a Diazo developer and printer. Five single channel, density standards were established, using typical ERTS images, in order to determine exposure time. These standards were used to develop a graph from which the exposure time for any transparency can be estimated. Exposure times varied from 3 to 30 minutes, and clear colored polyester sheets from two manufactures were used with slightly different, but equally successful, results.

  19. 2D cross-borehole resistivity tomographies below foundations as a tool to design proper remedial actions in covered karst

    NASA Astrophysics Data System (ADS)

    Deceuster, J.; Delgranche, J.; Kaufmann, O.

    2006-09-01

    To assess the subsurface conditions beneath a 4-floor public building, where sinkhole collapses had already occurred, twenty-three 2D cross-borehole resistivity tomographies were conducted beneath the building foundations in January and February 2004. The aim of these geophysical investigations was to build a model of the complex subsurface geometry in order to estimate and minimize costs of remediation works. In cross-borehole resistivity tomography standard electrode configurations do not exist yet. Thus, preliminary field tests were performed to determine a suitable combination of arrays and to estimate the stability of these measurements on the site. A combination of cross-borehole arrays and single-hole arrays was then selected. The measures were conducted on each panel using this combination of arrays. Over 2500 apparent resistivities were measured on each panel. The inversion problem was solved within the Res2DInv® software. On tomographies weathered zones were clearly identified as low resistivity zones (< 50 Ωm). The strong contrast in resistivities compared to solid limestone ( ρ > 200 Ω m) led to establish a 3D model of the ground conditions. This model showed large variations in buried rockhead depths from 6 to more than 24 m. Four zones of different ranges of depth-to-bedrock were identified inside, which three vertically elongated weathered zones were also delineated. Based on these results, a remediation plan which consisted in underpinning the foundations with about 250 micropiles was designed. The feedback of the remedial works showed that tomographies gave a very accurate overview of the buried rockhead depths (with a precision of about 1 m).

  20. Electro-location, tomography and porosity measurements in geotechnical centrifuge models based on electrical resistivity concepts

    NASA Astrophysics Data System (ADS)

    Li, Zhihua

    This research was focused on the development of electrical techniques for soil characterization and soil dynamic behavior assessment. The research carried out mainly includes (1) development of a needle probe tool for assessment of soil spatial variability in terms of porosity with high-resolution in the centrifuge testing; (2) development of an electro-location technique to accurately detect buried objects' movements inside the soil during dynamic events; (3) collaborative development of a new electrode switching system to implement electrical resistivity tomography, and electro-location with high speed and high resolution. To assess soil spatial variability with high-resolution, electrical needle probes with different tip shapes were developed to measure soil electrical resistivity. After normalizing soil resistivity by pore fluid resistivity, this information can be correlated to soil porosity. Calibrations in laboratory prepared soils were conducted. Loosening due to insertion of needle probes was evaluated. A special needle probe tool, along with data acquisition and data processing tools were developed to be operated by the new NEES robot on the centrifuge. The needle probes have great potential to resolve interfaces between soil layers and small local porosity variations with a spatial resolution approximately equal to the spacing between electrodes (about half of the probe diameter). A new electrode switching system was developed to accurately detect buried objects' movements using a new electro-location scheme. The idea was to establish an electromagnetic field in a centrifuge model by injecting low-frequency alternating currents through pairs of boundary electrodes. The locations of buried objects are related to the potentials measured on them. A closed form expression for the electric field in a rectangular specimen with insulated boundaries was obtained based on the method of images. Effects of sampling parameters on spatial resolution and tradeoffs

  1. Active Layer Thawing and Freeze-Back in Svalbard using DC Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Oswald, A.; Juliussen, H.; Christiansen, H. H.

    2009-04-01

    The thawing of the active layer has an important impact on the permafrost below, since the state of the uppermost soil layers determines how large surface temperature fluctuations are translated to deeper ground. Latent heat and combined liquid water and energy transport during the thawing season influence the energy exchange between permafrost and atmosphere. A first step to a better understanding of these processes is to determine the depth of the active layer and its thermal state the best possible way. Borehole temperatures give a very accurate measure of the ground thermal state but are, like active layer depths from mechanical probing, single point measurements. Geophysical imaging methods, such as DC resistivity tomography, allow for a 2d-image of subsurface soil properties, but should be supplemented with point temperature measurements as the results might be ambiguous. In spring and late summer 2007 electrode arrays have been permanently installed in three different permafrost landforms in Svalbard (a gently sloping solifluction sheet, a valley bottom loess terrace and a vertical sandstone rockwall) as a part of the IPY-project - ‘Permafrost Observatory Project: A Contribution to the Thermal State of Permafrost in Norway and Svalbard' TSP Norway. With a spacing of 20cm and a total array length of 16m this allows for a maximum measurement depth of about 2.5m. During most parts of IPY measurements were carried on a more or less regular basis - ideally in a two weeks interval. While measurements in the rockwall suffered from permanent loosening of the electrodes in the brittle sandstone, the measurements on the loess terrace and the solifluction slope were only interrupted during the very cold spring conditions as grounding errors occurred. Hence field work focused on the loess terrace and the solifluction sheet - the former consisting of silt and fine clay; the latter characterized by its high water content and a rather heterogeneous grain size

  2. Assessment of contamination by intensive cattle activity through electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Sainato, Claudia M.; Losinno, Beatriz N.; Malleville, Horacio J.

    2012-01-01

    The intensive animal production is considered highly risky for groundwater and soil because of high mobility of some contaminants from animal wastes. The aim of this work was to obtain an electrical conductivity image of unsaturated and saturated zones at a feedlot (cattle feeding field) at the surroundings of Buenos Aires city (Argentina) in order to detect the most critical sectors of the field, with regard to contamination by animal wastes. Dipole-dipole electrical soundings (electrical resistivity tomography) were performed at the corral zone and the surroundings. 2D and 3D models of conductivity were obtained. Even if there is a calcareous plate below some parts of the corrals and soil compaction is high, vertical infiltration or subsurface runoff may have occurred since these sites, with high animal charge, show soil conductivities higher than the surroundings. The models showed higher conductivities of saturated zone increasing in the direction of groundwater flow. These results were taken into account for further designs of soil and groundwater sampling. Groundwater conductivity was three times greater downgradient from the corrals with high concentrations of nitrates and phosphorous. A zone of high conductivity was found below a small channel of effluents from the corrals.

  3. Applicability of ERTS-1 to Montana geology

    NASA Technical Reports Server (NTRS)

    Weidman, R. M. (Principal Investigator); Alt, D. D.; Berg, R. A.; Johns, W. M.; Flood, R. E.; Hawley, K. T.; Wackwitz, L. K.

    1973-01-01

    The author has identified the following significant results. A detailed band 7 ERTS-1 lineament map covering western Montana and northern Idaho has been prepared and is being evaluated by direct comparison with geologic maps, by statistical plots of lineaments and known faults, and by field checking. Lineament patterns apparent in the Idaho and Boulder batholiths do not correspond to any known geologic structures. A band 5 mosaic of Montana and adjacent areas has been laid and a lineament annotation prepared for comparison with the band 7 map. All work to date indicates that ERTS-1 imagery is very useful for revealing patterns of high-angle faults, though much less useful for mapping rock units and patterns of low-angle faults. Large-scale mosaics of U-2 photographs of three test sites have been prepared for annotation and comparison with ERTS-1 maps. Mapping of Quaternary deposits in the Glacial Lake Missoula basin using U-2 color infrared transparencies has been successful resulting in the discovery of some deposits not previously mapped. Detailed work has been done for Test Site 354 D using ERTS-1 imagery; criteria for recognition of several rock types have been found. Photogeologic mapping for southeastern Montana suggest Wasatch deposits where none shown of geologic map.

  4. ERTS-1 data applied to strip mining

    NASA Technical Reports Server (NTRS)

    Anderson, A. T.; Schubert, J.

    1976-01-01

    Two coal basins within the western region of the Potomac River Basin contain the largest strip-mining operations in western Maryland and West Virginia. The disturbed strip-mine areas were delineated along with the surrounding geological and vegetation features by using ERTS-1 data in both analog and digital form. The two digital systems employed were (1) the ERTS analysis system, a point-by-point digital analysis of spectral signatures based on known spectral values and (2) the LARS automatic data processing system. These two systems aided in efforts to determine the extent and state of strip mining in this region. Aircraft data, ground-verification information, and geological field studies also aided in the application of ERTS-1 imagery to perform an integrated analysis that assessed the adverse effects of strip mining. The results indicated that ERTS can both monitor and map the extent of strip mining to determine immediately the acreage affected and to indicate where future reclamation and revegetation may be necessary.

  5. Water turbidity detection using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Yarger, H. L.; Mccauley, J. R.; James, G. W.; Magnuson, L. M.; Marzolf, G. R.

    1973-01-01

    ERTS-1 images of two federal reservoirs in Kansas exhibit good correlation with suspended load. The major reservoirs in Kansas, as well as in other Great Plains states, are playing increasingly important roles in flood control, recreation, agriculture, and urban water supply. Satellite imagery may prove useful for acquiring timely low cost water quality data required for optimum management of these fresh water resources.

  6. Hydro-geophysical interpretation of fractured and karstified limestones reservoirs: A case study from Amdoun region (NW Tunisia) using electrical resistivity tomography, digital elevation model (DEM) and hydro-geochemical approaches

    NASA Astrophysics Data System (ADS)

    Redhaounia, Belgacem; Aktarakçi, Hasan; Ilondo, Batobo Ountsche; Gabtni, Hakim; Khomsi, Sami; Bédir, Mourad

    2015-12-01

    Groundwater from fractures and karst in limestone rocks is an important source of drinking water in the semi-arid climatic environment of North-Western Tunisia where cool and rainy seasons alternate with hot dry seasons. Due to varying climatic conditions and anthropogenic interventions the fractured limestone aquifer systems (Abiod and Boudabbous/El Gueria Formations) tend to be complex. The lack of data on the fractured and karstified aquifers in Amdoun region (NW Tunisia) to establish the hydrogeological potential between different rock formations of Upper Cretaceous and Lower Eocene has often discouraged researchers from attempting to model such aquifers. On the SE flank of the Jebel Sabbah anticline, Electrical Resistivity Tomography Data were collected along three different lines of 315 m of length each. The expected vertical penetration depth was 60 m. This hydro-geophysical investigation consisting of geological, structural, and geo-morphological studies, has demonstrated that groundwater in the carbonate rocks, in Amdoun area, occur in fracture zones and weathered parts of the rocks in the karst aquifers. The hydrochemical data (major ion geochemistry) indicate that these groundwaters are characterized by the dominance a Ca-Mg-HCO3 water type. Geochemical pattern is mainly controlled by the dissolution of carbonate minerals. Generally, TDS increases from the Amdoun Monts towards the discharge area (53 < TDS<332 mg l-1). These results are assessed using numerous geophysical data such as ERT imaging and geological knowledge. Finally, we show how these results could be used to improve the management of karst groundwater resources in Amdoun (NW Tunisia) complex terrain.

  7. Resistivity and self-potential tomography applied to groundwater remediation and contaminant plumes: Sandbox and field experiments

    NASA Astrophysics Data System (ADS)

    Mao, D.; Revil, A.; Hort, R. D.; Munakata-Marr, J.; Atekwana, E. A.; Kulessa, B.

    2015-11-01

    Geophysical methods can be used to remotely characterize contaminated sites and monitor in situ enhanced remediation processes. We have conducted one sandbox experiment and one contaminated field investigation to show the robustness of electrical resistivity tomography and self-potential (SP) tomography for these applications. In the sandbox experiment, we injected permanganate in a trichloroethylene (TCE)-contaminated environment under a constant hydraulic gradient. Inverted resistivity tomograms are able to track the evolution of the permanganate plume in agreement with visual observations made on the side of the tank. Self-potential measurements were also performed at the surface of the sandbox using non-polarizing Ag-AgCl electrodes. These data were inverted to obtain the source density distribution with and without the resistivity information. A compact horizontal dipole source located at the front of the plume was obtained from the inversion of these self-potential data. This current dipole may be related to the redox reaction occurring between TCE and permanganate and the strong concentration gradient at the front of the plume. We demonstrate that time-lapse self-potential signals can be used to track the kinetics of an advecting oxidizer plume with acceptable accuracy and, if needed, in real time, but are unable to completely resolve the shape of the plume. In the field investigation, a 3D resistivity tomography is used to characterize an organic contaminant plume (resistive domain) and an overlying zone of solid waste materials (conductive domain). After removing the influence of the streaming potential, the identified source current density had a magnitude of 0.5 A m-2. The strong source current density may be attributed to charge movement between the neighboring zones that encourage abiotic and microbially enhanced reduction and oxidation reactions. In both cases, the self-potential source current density is located in the area of strong resistivity

  8. Characterization of an earth-filled dam through the combined use of electrical resistivity tomography, P- and SH-wave seismic tomography and surface wave data

    NASA Astrophysics Data System (ADS)

    Cardarelli, E.; Cercato, M.; De Donno, G.

    2014-07-01

    The determination of the current state of buildings and infrastructures through non-invasive geophysical methods is a topic not yet covered by technical standards, since the application of high resolution geophysical investigations to structural targets is a relatively new technology. Earth-filled dam investigation is a typical engineering application of this type. We propose the integration of Electrical Resistivity Tomography and P- and SH-wave seismic measurements for imaging the geometry of the dam's body and the underlying soil foundations and to characterize the low strain elastic properties. Because S-wave velocity is closely tied to engineering properties such as shear strength, low-velocity zones in the S-wave velocity models are of particular interest. When acquiring seismic data on earth filled dams, it is not uncommon to encounter highly attenuative surface layers. If only lightweight seismic sources are available, the seismic data generally exhibit a narrow frequency bandwidth: the lack of high frequency components generally prevents from having good quality shallow reflections. If there is no possibility to increase the power as well as the frequency content of the seismic source, the integration of other seismic methods than reflection may be the only available way to achieve a reliable near surface seismic characterization. For these reasons, we combined P- and SH-wave tomography with Multichannel Analysis of Surface Waves to image the internal and the underlying soil foundations of an earth filled dam located in Central Italy. In the presence of moderate velocity contrasts, tomographic methods have proven successful in imaging near surface variations along both the horizontal and vertical directions. On the other hand, body wave propagation is severely affected by attenuation under the previously described conditions, so that the quality of picked traveltimes dramatically decreases with offset and, consequently, the tomographic investigation

  9. Seismic refraction and electrical resistivity tomography to investigate subsurface controls on vegetation distribution in a mountain watershed

    NASA Astrophysics Data System (ADS)

    Donnelly, W.; Bradford, J. H.; Seyfried, M. S.

    2014-12-01

    The objective of this work is to investigate subsurface controls on the distribution of vegetation at two sites located within the Reynolds Creek Critical Zone Observatory (CZO). Located in southwestern Idaho, the Reynolds Creek CZO extends over a steep elevation-climatic gradient (mean annual precipitation 250 - 1100 mm/yr, mean annual temperature 5.5 °C to 11°C). The existing, publically available hydroclimatic data are long-term and spatially extensive, including precipitation (>50 yr), snow course SWE (>50 yr), temperature (30-50 yr), soil moisture and temperature (>10 yr), and some soil depth data. Both sites we investigated were at elevation greater than 2000m, and both sites showed abrupt changes in vegetation with no surface expression of changes in the underlying geology. The first site, termed Dry Meadow (DM), consists of a grassy meadow that transitions from being saturated to the surface during the spring runoff to dry with a water table at a depth of 4-6m in the late summer. The grassy meadow transitions abruptly to sage brush dominated terrain with no significant change in elevation. The second site, termed the Aspen Grove (AG), shows an abrupt transition from dry grassy terrain to an Aspen grove along a constant, and low gradient hill slope. At both sites we acquired high density seismic refraction data (1m receiver spacing) along transects that ranged from 95 to 160 m. Additionally we acquired 107 m long electrical resistivity profiles in both dipole-dipole and Wenner arrays with 2 m electrode spacing. At both sites, both seismic and ERT data indicate a distinct and abrupt drop in depth to the top of the weathered rock surface of 10-15 m. These topographic lows in the bedrock may be either erosional or structurally controlled, but in either case create accommodation space for the accumulation of sediment and an altered groundwater distribution that can accommodate a shift in the dominant vegetation type.

  10. Modeling of shaft tombs in western Mexico by mean of resistive tomography

    NASA Astrophysics Data System (ADS)

    Alatorre-Zamora, M. A.; Gutierrez-Peña, Q. J.; Gomez-Gomez, G.; Rosas-Elguera, J.

    2013-05-01

    The archaeological affluence of Mexico is huge. However, the western part of the country is viewed as lacking of important prehispanic constructions. Discoveries since 1970 have exposed an ancient culture that has been termed as Teuchitlan Tradition. This culture is characterized by ceremonial centers formed with circular pyramids and several rectangular platforms surrounding them, and tombs below any of these structures. The tombs in turn are typically composed of a vertical shaft and one to three horizontal chambers, where bodies were placed. Due to this character is also referred to as Shaft Tombs Culture. The tombs are located mainly in low cohesion pumice, welded tephras and volcanic ash deposits. The vertical shafts were usually filled, and there was always the camera. Two major centers developed by this culture are found in Teuchitlan and El Arenal, in the western state of Jalisco. The former has been rebuilt and is currently open to tourism, while the latter is not restored yet. The latter apparently has two ceremonial centers located at two different altitudes. We conducted a survey in both sites with resistive tomography. The first study was conducted in Teuchitlan, on a circular platform. In this structure there are already located three shaft tombs. The results obtained using the Wenner alpha array with equidistance of 0.5 and 1 meter, are successful. The data have been modeled using the program RES2DINV, and models obtained show the presence of a boot-shaped tomb and other like bottle. The graves are identified with higher resistivity values, while values lower than 30 ohm-m indicate moisture leaks at the ends of the structure. Theoretical modeling of the tombs and the building was carried out, which is compared with the actual sections and their inversion models. Coincidences are appreciable. With this results, were conducted two lines in ceremonial centers of El Arenal, to identify the occurrence of shaft tombs. The two centers are separated by

  11. Ert Applied to the Characterization of Subsidence in Mexico City: Ancient Structures Affecting Urban Utilities

    NASA Astrophysics Data System (ADS)

    Arango, C.; Chavez, R. E.; Cifuentes-Nava, G.; Hernández-Quintero, E.

    2013-05-01

    The problem of subsidence in Mexico City is basically due to the rapid extraction of groundwater for water supply in addition to the geological conditions. The most typical manifestations of the phenomena are presented as cracks and fractures due to compaction of ancient lake clayish sediments. This phenomenon has caused major affectations to city infrastructure because of the differential subsidence. Fractured buildings, sinkholes, among others manifestations, are potentially sources of collapses, which exposes the population to a serious risk. A small portion of Iztacalco County is being affected by this problem, specifically, in a crossroad formed by two important avenues: La Viga and Plutarco Elias Calles, where the area apparently increases its topographical level. The Electrical Resistivity Tomography technique was selected in order to obtain a resistivity image of the subsoil, which allows identify the main features associated to the terrain uprising. Three (ERT) profiles 200 m, were deployed on the mentioned crossroad in order to characterize the subsurface structures affecting the topographical level of the avenues. A big resistivity anomaly (~ 1000 ohm-m) could be observed towards the central part of the crossroad, coinciding with the major lifting level on surface. This feature appears at 15 m deep in all the profiles and depicts an approximate extension of 100 m in the E-W direction and 60 m in N-S axis. On the other hand, the surrounding material seems to correspond to a higher-saturated environment (lacustrine sediments <10 ohm-m). Shallow anomalies were also detected related to urban artifacts (pipes, sewers, etcetera). The apparently terrain uprising can be associated to a differential subsidence. However, the mentioned avenues were ancient water channels since pre-Hispanic times, where the caudal was enough to allow small steam boating at late nineteenth century. These waterways served as main routes for the exchange of goods during colonial times

  12. Monitoring coastal water properties and current circulation with ERTS-1

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Otley, M.; Wethe, C.; Rogers, R. H.

    1977-01-01

    Imagery and digital tapes from nine successful ERTS-1 passes over Delaware Bay during different portions of the tidal cycle were analyzed with special emphasis on turbidity, current circulation, waste disposal plumes, and convergent boundaries between different water masses. ERTS-1 image radiance correlated well with Secchi depth and suspended sediment concentration. Circulation patterns observed by ERTS-1 during different parts of the tidal cycle, agreed well with predicted and measured currents throughout Delaware Bay.

  13. ERTS-B imagery interpretation techniques in the Tennessee Valley

    NASA Technical Reports Server (NTRS)

    Gonzalez, R. C. (Principal Investigator)

    1973-01-01

    There are no author-identified significant results in this report. The proposed investigation is a continuation of an ERTS-1 project. The principal missions are to serve as the principal supporter on computer and image processing problems for the multidisciplinary ERTS effort of the University of Tennessee, and to carry out research in improved methods for the computer processing, enhancement, and recognition of ERTS imagery.

  14. Automated thematic mapping and change detection of ERTS-1 images

    NASA Technical Reports Server (NTRS)

    Gramenopoulos, N. (Principal Investigator); Alpaugh, H.

    1972-01-01

    The author has identified the following significant results. An ERTS-1 image was compared to aircraft photography and maps of an area near Brownsville, Texas. In the coastal region of Cameron County, natural and cultural detail were identified in the ERTS-1 image. In Hidalgo County, ground truth was located on the ERTS-1 image. Haze and 50% cloud cover over Hidalgo County reduced the usefulness of multispectral techniques for recognizing crops.

  15. Applicability of ERTS-1 to Montana geology

    NASA Technical Reports Server (NTRS)

    Weidman, R. M. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Geologic maps of four test sites were compiled at 1/250,000. Band 7 prints enlarged to 1/500,000 scale are the best for the purpose, and negative prints provide a valuable supplement. More than 100 mapped lineaments represent most of the major faults of the area and a large number of suspected faults, including many of northeast trend. Under ideal conditions dip slopes may be recognized, laccoliths outlined, and axial traces drawn for narrow, plunging folds. Use of ERTS-1 imagery will greatly facilitate construction of a needed tectonic map of Montana. From ERTS-1 imagery alone, it was possible to identify up-turned undivided Paleozoic and Mesozoic strata and to map the boundaries of mountain glaciation, intermontane basins, a volcanic field, and an area of granitic rocks. It was also possible to outline clay pans associated with bentonite. However, widespread recognition of gross rock types will be difficult.

  16. ERTS: Surveying Earth's Resources from Space.

    PubMed

    Maugh, T H

    1973-06-01

    Several errors occurred in the Research News story "ERTS: Surveying earth's resources from space" (6 Apr. 1973) by Thomas H. Maugh II. In column 3, page 50, the statement, "It thus maps an area of about 6.5 km(2) every day," should read "6.5 x 10(6) km(2)." In Fig. 3, the land masses are identified as Manhattan and Staten Island; actually, the spit at the left of the figure is Sandy Hook, New Jersey, and the barrier beaches further north are Rockaway, Long Beach, and Jones Beach, from left to right. The negative for Fig. 4 was inadvertently flipped over so that the illustration is a mirror image of the actual picture. It has also since been brought to the author's attention that " the previously unsuspected difference in salinity" in the Great Salt Lake described in the caption of Fig. 2 was, in fact, well known before the ERTS picture was taken. PMID:17806578

  17. Application of ERTS imagery to geological mapping

    NASA Technical Reports Server (NTRS)

    Fernandez, A.; Aranibar, O.; Ballon, P.

    1973-01-01

    The author has identified the following significant results. In comparing the interpretation of the imagery with that of photomosaics, the following results were derived. The drainage networks of the RBV images show information in greater detail than the photomosaics, and maps, yet maintain scale differences. However, for the basins the mosaics and maps provide better information. The geomorphology is best interpreted in the images of the ERTS-1, not only for the regional countryside, but also for the morphological formations. It was concluded that the satellite images offer the better possibility for identifying the alignment of joints and faults. In the images the relation is 4 to 1. The considered N-S alignments were identified in both systems with a ratio of 2 to 1. The E-W alignments for the areas considered in the ERTS-1 images show a basic Paleozoic formation not previously detected.

  18. Regional agriculture surveys using ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Draeger, W. C.; Nichols, J. D.; Benson, A. S.; Larrabee, D. G.; Jenkus, W. M.; Hay, C. M.

    1974-01-01

    The Center for Remote Sensing Research has conducted studies designed to evaluate the potential application of ERTS data in performing agricultural inventories, and to develop efficient methods of data handling and analysis useful in the operational context for performing large area surveys. This work has resulted in the development of an integrated system utilizing both human and computer analysis of ground, aerial, and space imagery, which has been shown to be very efficient for regional crop acreage inventories. The technique involves: (1) the delineation of ERTS images into relatively homogeneous strata by human interpreters, (2) the point-by-point classification of the area within each strata on the basis of crop type using a human/machine interactive digital image processing system; and (3) a multistage sampling procedure for the collection of supporting aerial and ground data used in the adjustment and verification of the classification results.

  19. Water depth estimation with ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Ross, D. S.

    1973-01-01

    Contrast-enhanced 9.5 inch ERTS-1 images were produced for an investigation on ocean water color. Such images lend themselves to water depth estimation by photographic and electronic density contouring. MSS-4 and -5 images of the Great Bahama Bank were density sliced by both methods. Correlation was found between the MSS-4 image and a hydrographic chart at 1:467,000 scale, in a number of areas corresponding to water depth of less than 2 meters, 5 to 10 meters and 10 to about 20 meters. The MSS-5 image was restricted to depths of about 2 meters. Where reflective bottom and clear water are found, ERTS-1 MSS-4 images can be used with density contouring by electronic or photographic methods for estimating depths to 5 meters within about one meter.

  20. Agricultural applications of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Draeger, W. C.

    1973-01-01

    In an attempt to evaluate the usefulness of ERTS imagery for the production of land use stratifications as a preliminary step in the crop inventory process, all land within San Joaquin County was delineated into broad land use and crop category classes based on their appearance on the ERTS-1 Color composite image. The stratification of the agricultural land use categories proved to be a relatively simple task, taking each of three interpreters approximately 30 minutes to complete. The three interpretations were quite similar requiring only minor revisions to produce a consensus stratification. A total of 13 different agricultural strata were recognized, differing both in general field size and relative proportions of crop types and degree of irrigation. Upon comparing these interpretations, it was concluded that nearly all boundaries were truly representative of differing cropping practices. In a number of cases, the stratifications agreed almost exactly with soil type boundaries as drawn by earlier soils surveys.

  1. Studies of images of short lived events using ERTS data

    NASA Technical Reports Server (NTRS)

    Deutschman, W. A. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The program to study short-lived events with the ERTS-1 satellite has evaluated 97 events reported by the Center for Short-Lived Phenomena. Forty-eight of these events were listed as candidates for ERTS-1 coverage and 8 of these were considered significant enough to immediately alert the ERTS operation staff by telephone. Studies of the images received from six events indicate that useful data on short-lived events can be obtained from ERTS-1 that would be difficult or impossible to obtain by other methods.

  2. Application of ERTS imagery to environmental studies of Lake Champlain

    NASA Technical Reports Server (NTRS)

    Lind, A. O.

    1974-01-01

    ERTS Imagery has provided data relating to a number of environmental and limnological concerns such as water quality, lake flooding and lake ice formation. Pollution plume data provided by ERTS was recently used in the Supreme Court case involving the States of Vermont and New York and a paper company. Flooding of lowland tracts has been a major concern due to a repetitive pattern of high lake levels over the past three years, and ERTS imagery is being used to construct the first series of flood maps of the affected areas. Lake ice development and turbidity patterns have also been studied from ERTS, since these have significance for shore erosion studies.

  3. Machine processing of ERTS and ground truth data

    NASA Technical Reports Server (NTRS)

    Rogers, R. H. (Principal Investigator); Peacock, K.

    1973-01-01

    The author has identified the following significant results. Results achieved by ERTS-Atmospheric Experiment PR303, whose objective is to establish a radiometric calibration technique, are reported. This technique, which determines and removes solar and atmospheric parameters that degrade the radiometric fidelity of ERTS-1 data, transforms the ERTS-1 sensor radiance measurements to absolute target reflectance signatures. A radiant power measuring instrument and its use in determining atmospheric parameters needed for ground truth are discussed. The procedures used and results achieved in machine processing ERTS-1 computer -compatible tapes and atmospheric parameters to obtain target reflectance are reviewed.

  4. Electrical tomography and magnetic imaging of Zeida's abandoned mine tailings (Morocco)

    NASA Astrophysics Data System (ADS)

    Lachhab, A.; Dekayir, A.; Benyassine, E. M.; Rouai, M.; Parisot, J. C.; Mathé, P. E.

    2014-12-01

    The Zeida (Pb-Zn) mine was closed since 1985 and contains huge dams of mine waste deposited without adjustment or remediation. These tailings contain large amount of Pb (3000 ppm) and Zn (140 ppm) expressed mainly as galena, wulfenite and barite. The subsurface of the studied area is constituted mainly by weathered granite coved in some places by Triassic red formations. A geophysical survey was conducted by using Electrical Resistivity Tomography (ERT) combined with Magnetic Imagery to explore the subsurface area and understand how the mine waste is interacting with the groundwater. Two-Dimensional ERT revealed the occurrence of rounded structures with high resistivity values corresponding to spherical boulders of weathered granite. Resistivity values within the boulders decrease gradually from the center toward the outer layers. This granite was found to be covered by highly conductive materials from the tailings of the mine reaching a depth extending up to 60 m. Magnetic maps revealed local magnetic anomalies reaching 400 nT due to old buried pipes at the mine site of Zeida. These anomalies correspond to the presence of faults used as pathways to recharge the groundwater reservoir

  5. Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

    NASA Astrophysics Data System (ADS)

    Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

    2014-05-01

    The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

  6. Combined ERT-TDEM measurements for studying submarine groundwater discharge (SGD) at Dor Beach, Israel

    NASA Astrophysics Data System (ADS)

    Levi, E.; Goldman, M.; Weinstein, Y.; Yechieli, Y.

    2008-12-01

    During last years, Dor Beach became a major test site for hydrogeological, geochemical and geophysical investigations of the SGD phenomenon in Israel. The high resolution time-series ERT measurements using 112-m long cable carried out at the site in 2006 have provided important information regarding shallow coastal hydrogeology up to the maximum exploration depth of approximately 20 m (Swarzenski et al, 2006). In a recent experiment (summer 2008), we focused on deeper parts of the site. This goal was achieved by using roughly two times longer shore diagonal and shore perpendicular ERT lines accompanied by onshore TDEM measurements. Such a combination allowed obtaining reliable information regarding the distribution of electrical resistivity up to a maximum depth of approximately 100 m. As a result, an additional high resistivity structure has been detected at a depth of approximately 63 m, which most likely represents the underlying Carmel Cretaceous aquifer saturated with water of lower than seawater salinity. Two saline/freshwater interfaces were detected at depths of approximately 17 m and 49 m. The upper interface between fresh and brackish water was detected by both ERT and TDEM, while the lower fresh/seawater interface was detected by TDEM alone.

  7. Assessment of a design to monitor the influence of crop residue management on the dynamics of soil water content with ERT

    NASA Astrophysics Data System (ADS)

    Chelin, Marie; Hiel, Marie-Pierre; Hermans, Thomas; Binley, Andrew; Garre, Sarah

    2016-04-01

    Choices related to crop residue management affect the soil structure. As a consequence, they may determine the spatio-temporal dynamics of water content and eventually the crop yields. In order to better understand the influence of these strategies on hydraulic processes occurring at the plot scale, we opted for the use electrical resistivity tomography (ERT). This approach presents the advantage to limit soil disturbance but is still faced to important challenges when applied in an agricultural field context. Especially changing soil-electrode contact has to be considered, as it can lead to bad quality data, especially for setups with small electrodes and small inter-electrode distance. The objective of this study was to test the efficiency of a high-resolution 3-D field measurement design to properly assess the dynamics of soil water content. ERT measurements were conducted in a Cutanic Siltic Luvisol in Gembloux, Belgium, on two plots of 2m2 ploughed in Oct 2014 at a depth of 25 cm and sown with maize in April 2015. The plants were removed on one of the plots in order to obtain a bare soil reference. A grid of 98 surface stainless steel electrodes was layed-out on each plot and four sticks supporting each eight stainless steel electrodes were vertically inserted into the soil up to 1.20 m to get more detailed information in depth. The experiments were performed between Jul and Oct 2015, in order to get measurements both in dry and wet periods. For surface and borehole monitoring, a dipole-dipole array configuration including in-line and cross-line measurements was adopted. Normal and reciprocal measurements were performed systematically to assess the data quality: only the datasets with a mean reciprocal error lower than 3% were considered for the data inversion. This contribution will show the first inverted results showing the complexity of experimental design and data analysis for high-resolution, timelapse ERT in field conditions. Based on these results, we

  8. Monitoring and modelling of soil-plant interactions: the joint use of ERT, sap flow and Eddy Covariance data to characterize the volume of an orange tree root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Vanella, D.; Perri, M. T.; Consoli, S.

    2014-12-01

    Mass and energy exchanges between soil, plants and atmosphere control a number of key environmental processes involving hydrology, biota and climate. The understanding of these exchanges also play a critical role for practical purposes e.g. in precision agriculture. In this paper we present a methodology based on coupling innovative data collection and models in order to obtain quantitative estimates of the key parameters of such complex flow system. In particular we propose the use of hydro-geophysical monitoring via 4-D Electrical Resistivity Tomography (ERT) in conjunction with measurements of plant transpiration via sap flow and evapotranspiration from Eddy Covariance (EC). This abundance of data is fed to a spatially distributed soil model in order to characterize the distribution of active roots. We conducted experiments in an orange orchard in Eastern Sicily (Italy), characterized by the typical Mediterranean semi-arid climate. The subsoil dynamics, particularly influenced by irrigation and root uptake, were characterized mainly by the ERT setup, consisting of 48 buried electrodes on 4 instrumented micro boreholes (about 1.2 m deep) placed at the corners of a square (about 1.3 m in side) surrounding the orange tree, plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. During the monitoring, we collected repeated ERT and TDR soil moisture measurements, soil water samples, sap flow measurements from the orange tree and EC data. We conducted a laboratory calibration of the soil electrical properties as a function of moisture content and pore water electrical conductivity. Irrigation, precipitation, sap flow and ET data are available allowing knowledge of the system's long term forcing conditions on the system. This information was used to calibrate a 1-D Richards' equation model representing the dynamics of the volume monitored via 3-D ERT. Information on the soil hydraulic properties was collected from laboratory and field experiments. The

  9. Monitoring and modelling of soil-plant interactions: the joint use of ERT, sap flow and eddy covariance data to characterize the volume of an orange tree root zone

    NASA Astrophysics Data System (ADS)

    Cassiani, G.; Boaga, J.; Vanella, D.; Perri, M. T.; Consoli, S.

    2015-05-01

    Mass and energy exchanges between soil, plants and atmosphere control a number of key environmental processes involving hydrology, biota and climate. The understanding of these exchanges also play a critical role for practical purposes e.g. in precision agriculture. In this paper we present a methodology based on coupling innovative data collection and models in order to obtain quantitative estimates of the key parameters of such complex flow system. In particular we propose the use of hydro-geophysical monitoring via "time-lapse" electrical resistivity tomography (ERT) in conjunction with measurements of plant transpiration via sap flow and evapotranspiration (ET) from eddy covariance (EC). This abundance of data is fed to spatially distributed soil models in order to characterize the distribution of active roots. We conducted experiments in an orange orchard in eastern Sicily (Italy), characterized by the typical Mediterranean semi-arid climate. The subsoil dynamics, particularly influenced by irrigation and root uptake, were characterized mainly by the ERT set-up, consisting of 48 buried electrodes on 4 instrumented micro-boreholes (about 1.2 m deep) placed at the corners of a square (with about 1.3 m long sides) surrounding the orange tree, plus 24 mini-electrodes on the surface spaced 0.1 m on a square grid. During the monitoring, we collected repeated ERT and time domain reflectometry (TDR) soil moisture measurements, soil water sampling, sap flow measurements from the orange tree and EC data. We conducted a laboratory calibration of the soil electrical properties as a function of moisture content and porewater electrical conductivity. Irrigation, precipitation, sap flow and ET data are available allowing for knowledge of the system's long-term forcing conditions on the system. This information was used to calibrate a 1-D Richards' equation model representing the dynamics of the volume monitored via 3-D ERT. Information on the soil hydraulic properties was

  10. Exploitation of ERTS-1 imagery utilizing snow enhancement techniques

    NASA Technical Reports Server (NTRS)

    Wobber, F. J.; Martin, K. R.

    1973-01-01

    Photogeological analysis of ERTS-simulation and ERTS-1 imagery of snowcovered terrain within the ERAP Feather River site and within the New England (ERTS) test area provided new fracture detail which does not appear on available geological maps. Comparative analysis of snowfree ERTS-1 images has demonstrated that MSS Bands 5 and 7 supply the greatest amount of geological fracture detail. Interpretation of the first snow-covered ERTS-1 images in correlation with ground snow depth data indicates that a heavy blanket of snow (more than 9 inches) accentuates major structural features while a light "dusting", (less than 1 inch) accentuates more subtle topographic expressions. An effective mail-based method for acquiring timely ground-truth (snowdepth) information was established and provides a ready correlation of fracture detail with snow depth so as to establish the working limits of the technique. The method is both efficient and inexpensive compared with the cost of similarly scaled direct field observations.

  11. Geological and environmental applications of the ERTS data

    NASA Technical Reports Server (NTRS)

    Schnetzler, C. C.

    1974-01-01

    The significant results from geological investigations made with the aid of the ERTS spacecraft can be grouped into four broad categories: mapping, land form analysis, structural studies, and the search for mineral deposits. Illustrations of how ERTS has been used in such studies are given, including photomosaics of Nevada and of southern Morocco, and a photogeological interpretation of the Rhodesian craton. Environmental applications of ERTS are illustrated by an ERTS update of an Indiana strip mine map, an ERTS image of Lake Michigan showing particulate plumes and their effect on the weather, and an image of the New York Bight area showing the location and extent of an acid-iron wastes dump and a sewage sludge dump.

  12. Effective use of ERTS multisensor data in the Great Plains

    NASA Technical Reports Server (NTRS)

    Myers, V. I. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. One unique advantage of ERTS imagery for delineating soil associations is the large area that can be scanned with one photo. Although soil associations usually are published at scales of 1:500,000 or 1:1,000,000, the delineations are drawn on much larger scale maps covering small pieces of the scene and then pieced together. Alluvial areas are usually swollen out of proportion to other soil areas. ERTS imagery puts alluvial areas into their proper size. A second feature of ERTS imagery is that a soil association map constructed with its aid assures that the cartographic level of the associations is more nearly the same. Another advantage of ERTS imagery is that the actual shape and configuration of soil associations are apparent. Also with ERTS imagery significant new delineations may become apparent which were missed when constructing soil association maps from conventional large scale photos.

  13. Calibration of electrical impedance tomography

    SciTech Connect

    Daily, W; Ramirez, A

    2000-05-01

    Over the past 10 years we have developed methods for imaging the electrical resistivity of soil and rock formations. These technologies have been called electrical resistance tomography of ERT (e.g. Daily and Owen, 1991). Recently we have been striving to extend this capability to include images of electric impedance--with a new nomenclature of electrical impedance tomography or EIT (Ramirez et al., 1999). Electrical impedance is simply a generalization of resistance. Whereas resistance is the zero frequency ratio of voltage and current, impedance includes both the magnitude and phase relationship between voltage and current at frequency. This phase and its frequency behavior is closely related to what in geophysics is called induced polarization or (Sumner, 1976). Why is this phase or IP important? IP is known to be related to many physical phenomena of importance so that image of IP will be maps of such things as mineralization and cation exchange IP (Marshall and Madden, 1959). Also, it is likely that IP, used in conjunction with resistivity, will yield information about the subsurface that can not be obtained by either piece of information separately. In order to define the accuracy of our technologies to image impedance we have constructed a physical model of known impedance that can be used as a calibration standard. It consists of 616 resistors, along with some capacitors to provide the reactive response, arranged in a three dimensional structure as in figure 1. Figure 2 shows the construction of the network and defines the coordinate system used to describe it. This network of components is a bounded and discrete version of the unbounded and continuous medium with which we normally work (the subsurface). The network has several desirable qualities: (1) The impedance values are known (to the accuracy of the component values). (2) The component values and their 3D distribution is easily controlled. (3) Error associated with electrode noise is eliminated. (4

  14. Electrical resistivity tomography for studying liquefaction induced by the May 2012 Emilia-Romagna earthquake (Mw = 6.1, North Italy)

    NASA Astrophysics Data System (ADS)

    Giocoli, A.; Quadrio, B.; Bellanova, J.; Lapenna, V.; Piscitelli, S.

    2013-10-01

    This work shows the result of an Electrical Resistivity Tomography survey carried out for imaging and characterizing the shallow subsurface affected by the coseismic effects of the Mw = 6.1 Emilia-Romagna (North Italy) earthquake occurred on 20 May 2012. The most characteristic coseismic effects were ground failure, lateral spreading and liquefaction that occurred extensively along the paleo-Reno river in the urban areas of San Carlo, a hamlet of Sant'Agostino municipality, and of Mirabello (south-western portion of the Ferrara Province). Totally, six Electrical Resistivity Tomography were performed and calibrated with surface geological surveys, exploratory borehole and aerial photo interpretations. This was one of the first applications of the Electrical Resistivity Tomography method in investigating coseismic liquefaction.

  15. Station Readiness Test for the Earth Resources Technology Satellite (ERTS) Mission

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The purpose of this SRT is to establish testing procedures which will verify that ERTS supporting stations can effectively support the ERTS mission. This SRT is applicable to all supporting stations for the ERTS-A and ERTS-B mission.

  16. Digital rectification of ERTS multispectral imagery

    NASA Technical Reports Server (NTRS)

    Rifman, S. S.

    1973-01-01

    Rectified ERTS multispectral imagery have been produced utilizing all digital techniques, as the first step toward producing precision corrected imagery. Errors arising from attitude and ephemeris sources have been corrected, and the resultant image is represented in a meter/meter mapping utilizing an intensity resampling technique. Early results from available data indicate negligible degradation of the photometric and resolution properties of the source data as a consequence of the geometric correction process. Work utilizing ground control points to produce precision rectified imagery, and including photometric corrections resulting from available sensor calibration data, is currently in progress.

  17. In situ spectroradiometric quantification of ERTS data

    NASA Technical Reports Server (NTRS)

    Yost, E. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Additive color photographic analysis of ERTS-1 multispectral imagery indicates that the presence of soil moisture in playas (desert dry lakes) can be readily detected from space. Time sequence additive color presentations in which 600-700 nm bands taken at three successive 18-day cycles show that changes in soil moisture of playas with time can be detected as unique color signatures and can probably be quantitatively measured using photographic images of multispectral scanner data.

  18. Author index to published ERTS-1 reports

    USGS Publications Warehouse

    Bidwell, Timothy C.; Mitchell, Cheryl A.

    1975-01-01

    This index has been compiled to assist the reader in locating and obtaining reports on the 334 scientific experiments conducted under the National Aeronautics and Space Administration (NASA) Earth Resources Technology Satellite-1 (ERTS-1) (renamed Landsat) program.  Each NASA-designated experimenter was required to submit written reports on his investigation: these were designated type 1, type 2, and type 3 reports.  Type 1 reports were periodic (monthly or bimonthly) progress summaries; type 2 were comprehensive scientific and technical reports; and type 3 were final report.  Investigators were also encourage to present their more significant findings in professional or technical journals and proceedings of symposia.

  19. Remote detection of aerosol pollution by ERTS

    NASA Technical Reports Server (NTRS)

    Copeland, G. E.; Brandy, A. R.; Kindle, E. C.; Blais, R. N.; Hilton, G. M.

    1973-01-01

    Photogrammetric and densitometric examination of ERTS-1 MSS imagery of Eastern Virginia coupled with extensive ground truth air quality and meteorological data has shown that the identification and surveying of fixed particulate emitters (smoke plumes) is feasible. A description of the ground truth network is included. The quantitative monitoring of smoke stacks from orbital altitudes over state size regions appears possible when tied to realistic plume models and minimal ground truth. Contrast reductions over urban areas can possibly be utilized to produce isopleths of particulates when supplemented by local measurements.

  20. Remote detection of aerosol pollution by ERTS

    NASA Technical Reports Server (NTRS)

    Copeland, G. E. (Principal Investigator); Bandy, A. R.; Kindle, E. C.; Blais, R. N.; Hilton, G. M.

    1973-01-01

    The author has identified the following significant results. Photogrammetric and densitometric examination of ERTS-1 MSS imagery of eastern Virginia coupled with extensive ground truth air quality and meteorological data has shown that the identification and surveying of fixed particulate emitters (smoke plumes) is feasible. A description of the ground truth network is included. The quantitative monitoring of smoke stacks from orbital altitudes over state-size regions appears possible when tied to realistic plume models and minimal ground truth. Contrast reductions over urban areas can possibly be utilized to produce isopleths of particulates when supplemented by local measurements.

  1. Time-lapse 2D electrical resistivity tomographies for investigating the Picerno landslide (Basilicata Region, southern Italy)

    NASA Astrophysics Data System (ADS)

    Luongo, Raffaele; de Bari, Claudia; Calamita, Giuseppe; Loperte, Antonio; Perrone, Angela; Satriani, Antonio; Votta, Mario; Lapenna, Vincenzo

    2010-05-01

    The rainwater infiltration into the soil and the increase of pore water pressure in the vadose zone can be considered the main causes of shallow landslides triggering. The standard techniques used to measure the water content of the soil and the piezometric levels in areas of potential instability are the TDR method and the piezometric measurements, respectively. These techniques, while allowing to obtain direct information of the considered parameter, provide a punctual information about the specific hydrological characteristics of the investigated soil. Recently, the literature reports many examples of applications of indirect methods for the study and the estimate of water content in the first layers of the subsoil. In particular, the 2D electrical resistivity tomography has been applied for obtaining information about the temporal and spatial patterns of water infiltration processes. This paper reports the results obtained in the area affected by the Picerno landslide (Basilicata Region, Southern Italy), which represents one of the test sites of Morfeo project (Monitoraggio e Rischio da Frana mediante dati EO) funded by the Italian Space Agency (ASI). The studied slope has been frequently involved in reactivation phenomena the most recent of which occurred on March 2006. In the area, we have installed a prototype system for time-dependent analysis of electrical resistivity images and TDR measurements. The geophysical results are opportunely integrated with the piezometric data. The system is composed of a 48-channel cable connected to the georesistivimeter Syscal Pro Switch 48, the electrodes are placed at a distance of 1 m. Two holes used to measure the piezometric level and another four equipped with TDR probes are located along the acquisition profile. The electrical resistivity tomographies and the water content measurements are performed with time intervals selected by considering the rainfall intensity and frequency. The first preliminary result of this

  2. Structural lineaments of Gaspe from ERTS imagery

    NASA Technical Reports Server (NTRS)

    Steffensen, R.

    1973-01-01

    A test study was conducted to assess the value of ERTS images for mapping geologic features of the Gaspe Peninsula, Quebec. The specific objectives of the study were: 1) to ascertain the best procedure to follow in order to obtain valuable geologic data as a result of interpretation; and 2) to indicate in which way these data could relate to mineral exploration. Of the four spectral bands of the Multispectral scanner, the band from 700 to 800 nanometers, which seems to possess the best informational content for geologic study, was selected for analysis. The original ERTS image at a scale of 1:3,700,000 was enlarged about 15 times and reproduced on film. Geologically meaningful lines, called structural lineaments, were outlined and classified according to five categories: morpho-lithologic boundaries, morpho-lithologic lineaments, fault traces, fracture zones and undefined lineaments. Comparison with the geologic map of Gaspe shows that morpho-lithologic boundaries correspond to contacts between regional stratigraphic units. Morpholithologic lineaments follow bedding trends, whereas fracture traces appear as sets of parallel lineaments, intersecting at high angles the previous category of lineaments. Fault traces mark more precisely the location of faults already mapped and spot the presence of presumable faults, not indicated on the geologic map.

  3. All-digital precision processing of ERTS images

    NASA Technical Reports Server (NTRS)

    Bernstein, R. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Digital techniques have been developed and used to apply precision-grade radiometric and geometric corrections to ERTS MSS and RBV scenes. Geometric accuracies sufficient for mapping at 1:250,000 scale have been demonstrated. Radiometric quality has been superior to ERTS NDPF precision products. A configuration analysis has shown that feasible, cost-effective all-digital systems for correcting ERTS data are easily obtainable. This report contains a summary of all results obtained during this study and includes: (1) radiometric and geometric correction techniques, (2) reseau detection, (3) GCP location, (4) resampling, (5) alternative configuration evaluations, and (6) error analysis.

  4. Ground control requirements for precision processing of ERTS images

    USGS Publications Warehouse

    Burger, Thomas C.

    1972-01-01

    When the first Earth Resources Technology Satellite (ERTS-A) flies in 1972, NASA expects to receive and bulk-process 9,000 images a week. From this deluge of images, a few will be selected for precision processing; that is, about 5 percent will be further treated to improve the geometry of the scene, both in the relative and absolute sense. Control points are required for this processing. This paper describes the control requirements for relating ERTS images to a reference surface of the earth. Enough background on the ERTS-A satellite is included to make the requirements meaningful to the user.

  5. 3D modeling and inversion of the electrical resistivity tomography using steel cased boreholes as long electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-Ying; Liu, De-Jun; Ai, Qing-Hui; Qin, Min-Jun

    2014-10-01

    Electrical resistivity tomography using a steel cased borehole as a long electrode is an advanced technique for geoelectrical survey based on the conventional mise-à-la-masse measurement. In most previous works, the steel casing is simplified as a transmission line current source with an infinitely small radius and constant current density. However, in practical stratified formations with different resistivity values, the current density along the casing cannot be constant. In this study, the steel casing is modeled by a conductive physical volume that the casing occupies in the finite element mesh. The current supply point is set on the center of the top surface of the physical volume. Synthetic modeling, using both a homogenous and layered formation, demonstrates reasonability of the forward modeling method proposed herein. Based on this forward modeling method, the inversion procedure can be implemented by using a freeware R3t (Lancaster University, UK). Inversion results of synthetic modeling data match fairly well with the defined target location and validate that the method works on the inversion of the casing-surface electrical resistivity data. Finally, a field example of Changqing oil field in China is carried out using the inversion method to image water flooding results and to discover wells with great potential to enhance residual oil recovery.

  6. Electrical Resistivity Tomographies on the detection of adobe buried archaeological structures in Piramide Sur in Cahuachi (Peru)

    NASA Astrophysics Data System (ADS)

    Capozzoli, L.; Masini, N.; Rizzo, E.; Lasaponara, R.; Orefici, G.

    2012-04-01

    During the last two decades of excavations, adobe pyramids dating back from the 6th century B.C. to the 4th century A.D have been unearthed in the ancient Ceremonial Centre of Cahuachi near Nasca (Peru) by an Italian-Peruvian mission directed by Giuseppe Orefici. One of the archaeological sectors, called sector A, has been almost excavated and restored. To complete sector A only a terraced mound named "Piramide Sur" needs to be excavated. In order to provide useful information on the presence of buried structures and platforms as well on the geological stratigraphy a multi-scale approach based on the integration of satellite remote sensing with geophysical techniques was employed. Such investigations were carried out by the Italian mission ITACA, funded by the Italian Ministry Affairs and composed of researchers of two institutes of CNR (IMAA and IBAM), which provides a scientific support for archaeological research, since 2007. In particular, the subsurface features were investigated by Geoelectrical prospecting, performed by using a georesistivimeter for tomography which observe the resistivity value along sections. Several tomographies were carried out to investigate the shallow and deep structure of the pyramid both along the main flank at Nord and on the top. Finally, the integration of all data acquired by the different remote sensing techniques allowed for spatially characterizing the archaeological features, thus providing important information for the planning of the next archaeological campaign.

  7. Is fully coupled hydrogeophysical inversion really better than uncoupled? A comparison study using ensemble Kalman filter assimilation of ERT-monitored tracer test data. (Invited)

    NASA Astrophysics Data System (ADS)

    Camporese, M.; Cassiani, G.; Deiana, R.; Salandin, P.; Binley, A. M.

    2013-12-01

    Recent advances in geophysical methods have been increasingly exploited as inverse modeling tools in groundwater hydrology. In particular, several attempts to constrain the hydrogeophysical inverse problem to reduce inversion error have been made using time-lapse geophysical measurements through both coupled and uncoupled inversion approaches. On one hand, the main advantage of coupled approaches is that the numerical models for the geophysical and hydrological processes are linked together such that the geophysical data are inverted directly for the hydrological properties of interest, avoiding artifacts related to the classical geophysical inversions. On the other hand, uncoupled approaches, relying upon a geophysical inversion that is carried out before estimating the hydrological variable of interest, could reveal something about the process that is not accounted for in a model, i.e., they are not constrained by the conceptualization of the hydrological model. In spite of the appeal and popularity of fully coupled inversion approaches, their superiority over more traditional uncoupled methods still needs to be objectively proven; the aim of this work is to shed some light on this debate. An approach based on the Lagrangian formulation of transport and the ensemble Kalman filter (EnKF) is here applied to assess the spatial distribution of hydraulic conductivity (K) by assimilating time-lapse cross-hole electrical resistivity tomography (ERT) data generated for a synthetic tracer test in a heterogeneous aquifer. In the coupled version of the proposed inverse modeling approach, the K distribution is retrieved by assimilating raw ERT resistance data without the need for a preliminary geoelectrical inversion. In the uncoupled version, K is estimated by assimilating electrical conductivity data derived from a previously performed classical geophysical inversion of the same resistance dataset. We compare the performance of the two approaches in a number of simulation

  8. Investigation of suspected gulls in the Jurassic limestone strata of the Cotswold Hills, Gloucestershire, England using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Barron, A. J. M.; Uhlemann, S.; Pook, G. G.; Oxby, L.

    2016-09-01

    An electrical resistivity tomography survey has clearly indicated the presence of substantial vertical zones of contrasting material beneath a set of conspicuous linear surface hollows that cut across a spur forming part of the Cotswold Hills escarpment in Gloucestershire. These zones are compared with nearby quarry exposures and are inferred to be gulls - graben-like structures at least 80 m deep filled with collapsed blocks of bedrock with intervening air-filled spaces, lying within areas of relatively undisrupted gently dipping strata, and which under some circumstances would present a significant geohazard. Our results confirm the great potential of this non-invasive and rapid survey technique for investigating such phenomena, and provide an exemplar for comparison with surveys elsewhere, to assist identification of similar features.

  9. Electrical Resistivity Monitoring of an Active Hydrothermal Degassing Area at Solfatara, Phlegrean Fields.

    NASA Astrophysics Data System (ADS)

    Vandemeulebrouck, J.; Byrdina, S.; Grangeon, J.; Lebourg, T.; Bascou, P.; Mangiacapra, A.

    2015-12-01

    Campi Flegrei caldera (CFc) is an active volcanic complex covering a ~100 km² densely populated area in the western part of Naples (Italy) that is presently showing clear signs of unrest. Solfatara volcano, a tuff cone crater formed ~4000 yrs B.P. ago by phreato-magmatic eruptions represents the main degassing outflow of CFc. Magmatic gases which are exsolved from a ~8 km deep magmatic reservoir mix at 4 km depth with meteoric hydrothermal fluids then reach the surface in the Solfatara area. These hydrothermal and magmatic gases, mainly H2O and CO2, are released through both diffuse degassing structures and fumaroles. In the frame of the MedSuv (Mediterranean Supervolcanoes) FP7 european project , we are performing a time-lapse electrical resistivity monitoring of an active degassing area of Solfatara. Using a 500-m-long cable and 48 electrodes, an electrical resistivity tomography (ERT) is performed on a two-day basis since May 2013. The time-lapse inversion of the ERT gives an image of the temporal variations of resistivity up to 100 m depth that can be compared with the variations of ground deformation, CO2 flux, soil temperature and seismic ambient noise. Resistivity variations can originate from fluid composition, gas ratio and temperature. For example, the abrupt change of resistivity that was observed mid-2014 during a period of uplift and gas flux increase, could be associated with the rise of hydrothermal fluids.

  10. Applicability of ERTS for surveying Antarctic iceberg resources

    NASA Technical Reports Server (NTRS)

    Hult, J. L. (Principal Investigator); Ostrander, N. C.

    1973-01-01

    The author has identified the following significant results. This investigation explores the applicability of ERTS to (1) determine the Antarctic sea ice and environmental behavior that may influence the harvesting of icebergs, and (2) monitor iceberg locations, characteristics, and evolution. From image sampling, it is found that the potential applicability of ERTS to the research, planning, and harvesting operations can contribute importantly to the promise derived from broader scope studies for the use of Antarctic iceberg to relieve fresh Thermal sensor bands will provide coverage in daylight and darkness. Several years of comprehensive monitoring will be necessary to characterize sea ice and environmental behavior and iceberg evolution. Live ERTS services will assist harvesting control and claming operations and offer a means for harmonizing entitlements to iceberg resources. The valuable ERTS services will be more cost effective than other means and will be easily justified and borne by the iceberg harvesting operation.

  11. Glaciation of northwestern Wyoming interpreted from ERTS-1

    NASA Technical Reports Server (NTRS)

    Breckenridge, R. M.

    1973-01-01

    Analysis of ERTS Imagery has shown a number of alpine glacial features can be recognized and mapped successfully. Although the Wyoming mountains are generally regarded as the type locality for Rocky Mountain glaciation some areas have not been studied from a glacial standpoint because of inaccessibility or lack of topographic control. ERTS imagery provides an excellent base for this type of regional geomorphic study. A map of maximum extent of Wisconsin Ice, flow directions and major glacial features was compiled from interpretation of the ERTS imagery. Features which can be mapped are large moraines, outwash fans and terraces. Present-day glaciers and snowfields are easily discriminated and mapped. Glaciers and glacial deposits which serve as aquifers play a significant role in the hydrologic cycle and are important because of the increasing demand placed on our water resources. ERTS provides a quick and effective method for change detection and inventory of these vital resources.

  12. Assessment of Southern California environment from ERTS-1

    NASA Technical Reports Server (NTRS)

    Bowden, L. W.; Viellenave, J. H.

    1973-01-01

    ERTS-1 imagery is a useful source of data for evaluation of earth resources in Southern California. The improving quality of ERTS-1 imagery, and our increasing ability to enhance the imagery has resulted in studies of a variety of phenomena in several Southern California environments. These investigations have produced several significant results of varying detail. They include the detection and identification of macro-scale tectonic and vegetational patterns, as well as detailed analysis of urban and agricultural processes. The sequential nature of ERTS-1 imagery has allowed these studies to monitor significant changes in the environment. In addiation, some preliminary work has begun directed toward assessing the impact of expanding recreation, agriculture and urbanization into the fragile desert environment. Refinement of enhancement and mapping techniques and more intensive analysis of ERTS-1 imagery should lead to a greater capability to extract detailed information for more precise evaluations and more accurate monitoring of earth resources in Southern California.

  13. Use of ERTS data for mapping Arctic sea ice

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (Principal Investigator); Bowley, C. J.

    1973-01-01

    The author has identified the following significant results. Data from ERTS passes crossing the Bering Sea in early March have been correlated with ice observations collected in the Bering Sea Experiment (BESEX). On two flights of the NASA CV-990 aircraft, the ice conditions in the vicinity of St. Lawrence Island reported by the onboard observer are in close agreement with the ice conditions mapped from the corresponding ERTS imagery. The ice features identified in ERTS imagery and substantiated by the aerial observer include the locations of boundaries between areas consisting of mostly grey ice and of mostly first and multi-year ice, the existence of shearing leads, and the occurrence of open water with the associated development of stratus cloud streaks. The BESEX correlative ice formation verifies the potential of practical applications of ERTS data.

  14. An ERTS multispectral scanner experiment for mapping iron compounds

    NASA Technical Reports Server (NTRS)

    Vincent, R. K. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. An experimental plan for enhancing spectral features related to the chemical composition of geological targets in ERTS multispectral scanner data is described. The experiment is designed to produce visible-reflective infrared ratio images from ERTS-1 data. Iron compounds are promising remote sensing targets because they display prominent spectral features in the visible-reflective infrared wavelength region and are geologically significant. The region selected for this ERTS experiment is the southern end of the Wind River Range in Wyoming. If this method proves successful it should prove useful for regional geologic mapping, mineralogical exploration, and soil mapping. It may also be helpful to ERTS users in scientific disciplines other than geology, especially to those concerned with targets composed of mixtures of live vegetation and soil or rock.

  15. ERTS-1 views the Great Lakes

    NASA Technical Reports Server (NTRS)

    Lyons, W. A.; Pease, S. R.

    1973-01-01

    The meteorological content of ERTS images, particularly mesoscale effects of the Great Lakes and air pollution dispersion is summarized. Summertime lake breeze frontal clouds and various winter lake-effect convection patterns and snow squalls are revealed in great detail. A clear-cut spiral vortex over southern Lake Michigan is related to a record early snow storm in the Chicago area. Marked cloud changes induced by orographic and frictional effects on Lake Michigan's lee shore snow squalls are seen. The most important finding, however, is a clear-cut example of alterations in cumulus convection by anthropogenic condensation and/or ice nuclei from northern Indiana steel mills during a snow squall situation. Jet aircraft condensation trails are also found with surprising frequency.

  16. Applicability of ERTS-1 to Montana geology

    NASA Technical Reports Server (NTRS)

    Weidman, R. M. (Principal Investigator); Alt, D. D.; Berg, R.; Johns, W.; Flood, R.; Hawley, K.; Wackwitz, L.

    1976-01-01

    The author has identified the following significant results. Late autumn imagery provides the advantages of topographic shadow enhancement and low cloud cover. Mapping of rock units was done locally with good results for alluvium, basin fill, volcanics, inclined Paleozoic and Mesozoic beds, and host strata of bentonite beds. Folds, intrusive domes, and even dip directions were mapped where differential erosion was significant. However, mapping was not possible for belt strata, was difficult for granite, and was hindered by conifers compared to grass cover. Expansion of local mapping required geologic control and encountered significant areas unmappable from ERTS imagery. Annotation of lineaments provided much new geologic data. By extrapolating test site comparisons, it is inferred that 27 percent of some 1200 lineaments mapped from western Montana represent unknown faults. The remainder appear to be localized mainly by undiscovered faults and sets of minor faults or joints.

  17. Seasonal vegetation differences from ERTS imagery

    NASA Technical Reports Server (NTRS)

    Ashley, M. D.; Rea, J.

    1975-01-01

    Knowledge of the times when crop and forest vegetation experience seasonally related changes in development is important in understanding growth and yield relationships. This article describes how densitometry of earth resources technology satellite (ERTS-1) multispectral scanner (MSS) imagery can be used to identify such phenological events. Adjustments for instrument calibration, aperture size, gray-scale differences between overpasses, and normalization of changing solar elevation are considered in detail. Seasonal vegetation differences can be identified by densitometry of band 5 (0.6-0.7 microns) and band 7 (0.8-1.1 microns) MSS imagery. Band-to-band ratios of the densities depicted the changes more graphically than the individual band readings.

  18. Ability of High-Resolution Resistivity Tomography to Detect Fault and Fracture Zones: Application to the Tournemire Experimental Platform, France

    NASA Astrophysics Data System (ADS)

    Gélis, C.; Noble, M.; Cabrera, J.; Penz, S.; Chauris, H.; Cushing, E. M.

    2016-02-01

    located at depth between two fault zones. This zone could be correlated with the fractured zones identified at 250-m depth in underground works. This study highlights the interest of multi-scale approaches to image complex heterogeneous near subsurface layers. Finally, this study shows that the electrical resistivity tomography is a useful and powerful tool to detect fault and fracture zones in upper limestones. Such a method is complementary to other geophysical and geological data.

  19. Use of ERTS data for mapping Arctic sea ice

    NASA Technical Reports Server (NTRS)

    Barnes, J. C.; Bowley, C. J.

    1973-01-01

    This investigation is to evaluate the application of ERTS data for detecting and mapping Arctic sea ice. The specific objectives are to determine the spectral bands most suitable for detecting ice, to measure the scale and types of ice features that can be detected, and to develop interpretive techniques for differentiating ice from clouds and for mapping ice concentrations. The ERTS data are being analyzed primarily for three Arctic areas, the eastern Beaufort Sea, Baffin Bay, and the Greenland Sea.

  20. The use of ERTS imagery in reservoir management and operation

    NASA Technical Reports Server (NTRS)

    Cooper, S. (Principal Investigator)

    1973-01-01

    There are no author-identified significant results in this report. Preliminary analysis of ERTS-1 imagery suggests that the configuration and areal coverage of surface waters, as well as other hydrologically related terrain features, may be obtained from ERTS-1 imagery to an extent that would be useful. Computer-oriented pattern recognition techniques are being developed to help automate the identification and analysis of hydrologic features. Considerable man-machine interaction is required while training the computer for these tasks.

  1. Monitoring vegetation systems in the Great Plains with ERTS

    NASA Technical Reports Server (NTRS)

    Rouse, J. W., Jr.; Haas, R. H.; Schell, J. A.; Deering, D. W.

    1974-01-01

    The Great Plains Corridor rangeland project utilizes natural vegetation systems as phenological indicators of seasonal development and climatic effects upon regional growth conditions. A method has been developed for quantitative measurement of vegetation conditions over broad regions using ERTS-1 MSS data. Radiance values recorded in ERTS-1 spectral bands 5 and 7, corrected for sun angle, are used to compute a band ratio parameter which is shown to be correlated with aboveground green biomass on rangelands.

  2. ERTS-1 applications to Minnesota land use mapping

    NASA Technical Reports Server (NTRS)

    Brown, D.; Gamble, J.; Prestin, S.; Trippler, D.; Meyer, M. P.; Ulliman, J. J.; Eller, R. G.

    1973-01-01

    Land use class definitions that can be operationally employed with ERTS-1 imagery are being developed with the cooperation of personnel from several state, regional, and federal agencies with land management responsibilities within the state and the University of Minnesota. Investigations of urban, extractive, forest, and wetlands areas indicate that it is feasible to subdivide each of these classes into several sub-classes with the use of ERTS-1 images from one or more time periods.

  3. Facilitating the exploitation of ERTS imagery using snow enhancement techniques

    NASA Technical Reports Server (NTRS)

    Wobber, F. J. (Principal Investigator); Martin, K. R.; Sheffield, C.; Russell, O.; Amato, R. V.

    1972-01-01

    The author has identified the following significant results. Analysis of all available (Gemini, Apollo, Nimbus, NASA aircraft) small scale snow covered imagery has been conducted to develop and refine snow enhancement techniques. A detailed photographic interpretation of ERTS-simulation imagery covering the Feather River/Lake Tahoe area was completed and the 580-680nm. band was determined to be the optimum band for fracture detection. ERTS-1 MSS bands 5 and 7 are best suited for detailed fracture mapping. The two bands should provide more complete fracture detail when utilized in combination. Analysis of early ERTS-1 data along with U-2 ERTS simulation imagery indicates that snow enhancement is a viable technique for geological fracture mapping. A wealth of fracture detail on snow-free terrain was noted during preliminary analysis of ERTS-1 images 1077-15005-6 and 7, 1077-15011-5 and 7, and 1079-15124-5 and 7. A direct comparison of data yield on snow-free versus snow-covered terrain will be conducted within these areas following receipt of snow-covered ERTS-1 imagery.

  4. Task 10: an ERTS Experiment for Mapping Iron Compounds, 1383

    NASA Technical Reports Server (NTRS)

    Vincent, R. K. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Preliminary results of a spectral ratioing technique are shown for a region at the southern end of the Wind River Range, Wyoming. Digital ratio graymaps and analog ratio images have been produced for the test site, but ground truth is not yet available for thorough interpretation of these products. ERTS-1 analog ratio images were found generally better than either ERTS-1 single channel images or high altitude aerial photos for the discrimination of vegetation from non-vegetation in the test site region. Some linear geological features smaller than the ERTS-1 spatial resolution are seen as well in ERTS-1 ratio and single channel images as in high altitude aerial photography. Geochemical information appears to be extractable from ERTS-1 data. Good preliminary quantitative agreement between ERTS-1 derived ratios and laboratory derived reflectance ratios of rocks and minerals encourage plans to use lab data as training sets for a simple ratio gating logic approach to automatic recognition maps. Empirical atmospheric corrections indicate that atmospheric corrections are needed to make the ratio method, and possibly other types of data processing, consistent over large geographical and temporal displacements.

  5. Spatial variability in free phase gas dynamics in a Northern peatland using surface resistivity and GPR tomography

    NASA Astrophysics Data System (ADS)

    Terry, N.; Slater, L. D.; Comas, X.; Parsekian, A.; Schafer, K. V.; Reeve, A. S.

    2011-12-01

    Recent research suggests peatlands play a vital role in greenhouse gas exchange between the atmosphere and the terrestrial environment. However, scientific understanding of the mechanisms governing this exchange remains limited, and quantitative data regarding free phase fluxes between peatlands and the atmosphere, particularly those associated with large-scale ebullition events, is largely unavailable. To study these fluxes, recent geophysical techniques, such as ground penetrating radar (GPR), DC resistivity, and electromagnetic induction, have demonstrated potential to monitor 2D or 3D gas dynamics in peatlands non-invasively and in situ. In this research, we acquired bi-daily resistivity and tomographic GPR data over the course of ten days at a field site in Caribou Bog, Maine. Two boreholes spaced approximately 4 m apart and 6.5 m deep to the underlying mineral soil were utilized for the collection of tomographic and zero offset GPR data. Surrounding this area, eight direct current resistivity lines, with line spacing of approximately 4 m and electrode spacing of 1.25 m, were used to create a comprehensive electrical imaging dataset. In addition, continuous pressure and temperature data were collected at varying depths near the resistivity array, and surface gas flux chamber measurements were obtained using a fast methane analyzer (Li7700) located on site. Inversion of the GPR and resistivity data provides evidence for a correlation between free phase gas production and release, and atmospheric pressure and temperature. In this study, we demonstrate the utility of capturing subsurface gas evolution and ebullition in 2D at multiple spatial scales using different geophysical techniques. On the one hand, GPR tomography provides a tool for monitoring the spatial distribution of free phase gas at high resolution in 2D. In contrast, resistivity is a rapid, more autonomous method that samples at coarser resolution. These results spur construction of a stochastic

  6. High-resolution Electrical Resistivity Tomography monitoring of a tracer test in a confined aquifer

    NASA Astrophysics Data System (ADS)

    Wilkinson, P. B.; Meldrum, P. I.; Kuras, O.; Chambers, J. E.; Holyoake, S. J.; Ogilvy, R. D.

    2010-04-01

    A permanent geoelectrical subsurface imaging system has been installed at a contaminated land site to monitor changes in groundwater quality after the completion of a remediation programme. Since the resistivities of earth materials are sensitive to the presence of contaminants and their break-down products, 4-dimensional resistivity imaging can act as a surrogate monitoring technology for tracking and visualising changes in contaminant concentrations at much higher spatial and temporal resolution than manual intrusive investigations. The test site, a municipal car park built on a former gasworks, had been polluted by a range of polycyclic aromatic hydrocarbons and dissolved phase contaminants. It was designated statutory contaminated land under Part IIA of the UK Environmental Protection Act due to the risk of polluting an underlying minor aquifer. Resistivity monitoring zones were established on the boundaries of the site by installing vertical electrode arrays in purpose-drilled boreholes. After a year of monitoring data had been collected, a tracer test was performed to investigate groundwater flow velocity and to demonstrate rapid volumetric monitoring of natural attenuation processes. A saline tracer was injected into the confined aquifer, and its motion and evolution were visualised directly in high-resolution tomographic images in near real-time. Breakthrough curves were calculated from independent resistivity measurements, and the estimated seepage velocities from the monitoring images and the breakthrough curves were found to be in good agreement with each other and with estimates based on the piezometric gradient and assumed material parameters.

  7. Accurate modeling and inversion of electrical resistivity data in the presence of metallic infrastructure with known location and dimension

    SciTech Connect

    Johnson, Timothy C.; Wellman, Dawn M.

    2015-06-26

    Electrical resistivity tomography (ERT) has been widely used in environmental applications to study processes associated with subsurface contaminants and contaminant remediation. Anthropogenic alterations in subsurface electrical conductivity associated with contamination often originate from highly industrialized areas with significant amounts of buried metallic infrastructure. The deleterious influence of such infrastructure on imaging results generally limits the utility of ERT where it might otherwise prove useful for subsurface investigation and monitoring. In this manuscript we present a method of accurately modeling the effects of buried conductive infrastructure within the forward modeling algorithm, thereby removing them from the inversion results. The method is implemented in parallel using immersed interface boundary conditions, whereby the global solution is reconstructed from a series of well-conditioned partial solutions. Forward modeling accuracy is demonstrated by comparison with analytic solutions. Synthetic imaging examples are used to investigate imaging capabilities within a subsurface containing electrically conductive buried tanks, transfer piping, and well casing, using both well casings and vertical electrode arrays as current sources and potential measurement electrodes. Results show that, although accurate infrastructure modeling removes the dominating influence of buried metallic features, the presence of metallic infrastructure degrades imaging resolution compared to standard ERT imaging. However, accurate imaging results may be obtained if electrodes are appropriately located.

  8. Electrical resistivity tomography, VES and magnetic surveys for dam site characterization, Wukro, Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Haile, Tigistu; Atsbaha, Solomun

    2014-09-01

    Geophysical surveys involving the techniques of electrical resistivity imaging, electrical sounding and magnetics were employed to characterize the ground conditions at a proposed dam site at Hizaeti-Afras, Wukro, North Ethiopia. The techniques were utilized to map the depth to the competent formations, their relative suitability for foundation work and the presence and extent of weak zones in the subsurface. The work has mapped the different lithologic units of the subsurface and determined the depth to the basement rocks in the area. Through correlation of the inverse model resistivity sections of the imaging surveys, the geoelectric section of the sounding survey and the magnetic profile plots with available borehole lithologic logs, it is shown that the results very well supplement the geotechnical point data in addition to providing a wider coverage in mapping areas of weak ground that could otherwise be missed with widely spaced borehole information. The combined results of the survey show the proposed dam axis to be unsuitable. The power of the electrical resistivity imaging technique and its potential to map the shallow subsurface with adequate resolution are illustrated. The result is a strong suggestion that geophysical techniques can be used to assist and extrapolate borehole geotechnical data especially when large area is to be used for development of large infrastructure.

  9. Effect of surface fissure on apparent resistivity measurements

    NASA Astrophysics Data System (ADS)

    Sailhac, P.; Gance, J.; Malet, J.

    2013-12-01

    Fissures are features of interest, prone to create preferential flow path, modifying locally the soil hydrogeological behavior. Electrical Resistivity Tomography (ERT) is a suitable tool to monitor such preferential flow path. However, this technique is not efficient in the presence of surface fissure, due to a bad resistivity recovering around the fissure vicinity during the inversion process. Therefore, we propose a description of fissure effect on raw apparent resistivity on three resistivity arrays. The purposes of the study are multiple. First, we aim at making ERT users aware of surface fissure effect, and propose a first help to interpret basically resistivity pseudo sections. Second, we propose to ERT users to automatically conduct a surface fissure survey on the studied profile, in order to consider each fissure in a forward DC model and to suppress their effect. Finally, this study is only a first step toward 2D fissure shape inversion, and time-lapse monitoring of fissure drying and filling. In this study, we create a fissure model based on different geomorphological descriptors. After describing the FEM-DC forward modeling strategy, we investigate the fissure effect on pseudo section of apparent resistivity for a Wenner-Schlumberger (WS), a dipole-dipole (DD) and a gradient (GRAD) array. We determine a fissure detectability threshold for each array and perform a sensitivity analysis on the different fissure parameters (position, width, depth, dip angles...). The crack filling or drying effect is also investigated. The possibility to remove fissure effect and to propose a first interpretation of time-lapse data is illustrated on real data. This study show again the higher sensitivity of the DD array compared to the GRAD and WS arrays. Not only the maximal amplitude in the pseudo section is higher for the DD array, but also the anomaly pattern created by the fissure is much larger for this acquisition geometry. The minimal depth detectable for the DD

  10. The ERTS-1 investigation (ER-600). Volume 5: ERTS-1 urban land use analysis

    NASA Technical Reports Server (NTRS)

    Erb, R. B.

    1974-01-01

    The Urban Land Use Team conducted a year's investigation of ERTS-1 MSS data to determine the number of Land Use categories in the Houston, Texas, area. They discovered unusually low classification accuracies occurred when a spectrally complex urban scene was classified with extensive rural areas containing spectrally homogeneous features. Separate computer processing of only data in the urbanized area increased classification accuracies of certain urban land use categories. Even so, accuracies of urban landscape were in the 40-70 percent range compared to 70-90 percent for the land use categories containing more homogeneous features (agriculture, forest, water, etc.) in the nonurban areas.

  11. Three-dimensional resistivity tomography in extreme coastal terrain amidst dense cultural signals: application to cliff stability assessment at the historic D-Day site

    NASA Astrophysics Data System (ADS)

    Udphuay, Suwimon; Günther, Thomas; Everett, Mark E.; Warden, Robert R.; Briaud, Jean-Louis

    2011-04-01

    Pointe du Hoc overlooking the English Channel in Normandy, France was host to one of the most important military engagements of World War II but is vulnerable to cliff collapses that threaten important German fortifications including the forward observation post (OP) and Rudder's command post. The objective of this study is to apply advanced 3-D resistivity tomography towards a detailed site stability assessment with special attention to the two at-risk buildings. 3-D resistivity tomography data sets at Pointe du Hoc in the presence of extreme topography and dense cultural clutter have been successfully acquired, inverted and interpreted. A cliff stability hazard assessment scheme has been designed in which regions of high resistivity are interpreted as zones of open, dry fractures with a moderate mass movement potential. Regions of low resistivity are zones of wet, clay-filled fractures with a high mass movement potential. The OP tomography results indicate that the highest mass movement hazard appears to be associated with the marine caverns at the base of the cliff that are positioned at the point of strongest wave attack. These caverns likely occupy the future site of development of a sea arch that will threaten the OP building. The mass movement potential at the Rudder's command post area is low to moderate. The greatest risk there is associated with soil wedge failures at the top of the cliffs.

  12. Lithostratigraphic interpretation from joint analysis of seismic tomography and magnetotelluric resistivity models using self-organizing map techniques

    NASA Astrophysics Data System (ADS)

    Bauer, K.; Muñoz, G.; Moeck, I.

    2012-12-01

    The combined interpretation of different models as derived from seismic tomography and magnetotelluric (MT) inversion represents a more efficient approach to determine the lithology of the subsurface compared with the separate treatment of each discipline. Such models can be developed independently or by application of joint inversion strategies. After the step of model generation using different geophysical methodologies, a joint interpretation work flow includes the following steps: (1) adjustment of a joint earth model based on the adapted, identical model geometry for the different methods, (2) classification of the model components (e.g. model blocks described by a set of geophysical parameters), and (3) re-mapping of the classified rock types to visualise their distribution within the earth model, and petrophysical characterization and interpretation. One possible approach for the classification of multi-parameter models is based on statistical pattern recognition, where different models are combined and translated into probability density functions. Classes of rock types are identified in these methods as isolated clusters with high probability density function values. Such techniques are well-established for the analysis of two-parameter models. Alternatively we apply self-organizing map (SOM) techniques, which have no limitations in the number of parameters to be analysed in the joint interpretation. Our SOM work flow includes (1) generation of a joint earth model described by so-called data vectors, (2) unsupervised learning or training, (3) analysis of the feature map by adopting image processing techniques, and (4) application of the knowledge to derive a lithological model which is based on the different geophysical parameters. We show the usage of the SOM work flow for a synthetic and a real data case study. Both tests rely on three geophysical properties: P velocity and vertical velocity gradient from seismic tomography, and electrical resistivity

  13. A study of the utilization of ERTS-1 data from the Wabash River Basin

    NASA Technical Reports Server (NTRS)

    Landgrebe, D. A. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. The identification and area estimation of crops experiment tested the usefulness of ERTS data for crop survey and produced results indicating that crop statistics could be obtained from ERTS imagery. Soil association mapping results showed that strong relationships exist between ERTS data derived maps and conventional soil maps. Urban land use analysis experiment results indicate potential for accurate gross land use mapping. Water resources mapping demonstrated the feasibility of mapping water bodies using ERTS imagery.

  14. ERTS evaluation for land use inventory

    NASA Technical Reports Server (NTRS)

    Hardy, E. E. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The feasibility of accomplishing a general inventory of any given region based on spectral categories from satellite data has been demonstrated in a pilot study for an area of 6300 square kilometers in central New York State. This was accomplished by developing special processing techniques to improve and balance contrast and density for each spectral band of an image scene to compare with a standard range of density and contrast found to be acceptable for interpretation of the scene. Diazo film transparencies were made from enlarged black and white transparencies of each spectral band. Color composites were constructed from these diazo films in combinations of hue and spectral bands to enhance different spectral features in the scene. Interpretation and data takeoff was accomplished manually by translating interpreted areas onto an overlay to construct a spectral map. The minimum area interpreted was 25 hectares. The minimum area geographically referenced was one square kilometer. The interpretation and referencing of data from ERTS-1 was found to be about 88% accurate for eight primary spectral categories.

  15. Mineral exploration potential of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Brewer, W. A. (Principal Investigator); Erskine, M. C., Jr.; Prindle, R. O.

    1972-01-01

    The author has identified the following significant results. Preliminary analysis of a mosaic composing eight individual ERTS frames (1:1,000,000) extending well beyond the test site has revealed a number of tectonic structural trends that are controlled by regional lineations. So far most of the regional lineations fall into three general directions: east by northeast, northwest, and north-south. From preliminary examination, it appears that the older Precambrian basement predominates in the NE-bearing structural trends, whereas the predominate NW trend is most likely associated with the Texas Structural Zone, and the north-south trend being the Utah-Arizona belt and/or part of the southern Basin and Range Province. One major lineation, made up of many parallel lineations, is noticeable just north of Lake Pleasant which extends for approximately 100 miles in a northern direction out of the target area. This feature corresponds to a Precambrian schist formation shown on the USGS geologic map of Arizona.

  16. Permafrost Changes along the Alaska Highway Corridor, Southern Yukon, from Ground Temperature Measurements and DC Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Duguay, M. A.; Lewkowicz, A. G.; Smith, S.

    2011-12-01

    A natural gas pipeline running across permafrost terrain from Prudhoe Bay, Alaska, through Canada to US markets was first proposed more than 30 years ago. In the intervening period, mean annual air temperatures in the region have risen by 0.5-1.0°C and it is probable that the ground has also warmed. Renewed interest in the pipeline has meant that information on permafrost and geotechnical conditions within the Alaska Highway Corridor of the southern Yukon must be updated for engineering design and the assessment of environmental impacts. To accomplish this goal, results from 1977-1981 drilling and ground temperature monitoring programs within the proposed pipeline corridor were used in combination with air photo analysis to select sites potentially sensitive to climate change. The sites are distributed across the extensive and sporadic discontinuous permafrost zones over a distance of 475 km between Beaver Creek and Whitehorse. To date, 11 targeted boreholes with permafrost have been found and cased to permit renewed ground temperature monitoring. By the end of summer 2011, it is expected that another 7 will have been instrumented. Measurable temperature increases relative to the 1970s are expected, except where values were previously just below 0°C. In the latter case, if the sites are still in permafrost, latent heat effects may have substantially moderated the temperature increase. Electrical resistivity tomography surveys are also being conducted to characterize the local permafrost distribution and geotechnical conditions. These 2D resistivity profiles will be used with the ground temperatures to examine current conditions and response to climate change and vegetation disturbance.

  17. ERTS-1 data collection system: Status and performance

    NASA Technical Reports Server (NTRS)

    Painter, J. E.

    1975-01-01

    The Data Collection System flown on the first Earth Resources Technology Satellite (ERTS-1) relays earth resources data from remotely located in-situ sensors to Goddard Space Flight Center. Data is received at Goddard at least twice each day from every sensor installation and is distributed to users (who operate the sensors and transmitters) by mail and teletype. The system consists of a data formatting and transmitting unit, called the Data Collection Platform (DCP), a receiver and a retransmitter aboard ERTS-1; and receiving, demodulating and decoding equipment located at the Goldstone, California and Goddard data acquisition stations. Data is transmitted from the data acquisition stations to the ERTS Control Center at Goddard, then to the NASA (ERTS) Data Processing Facility (NDPF) where it is processed and distributed to users. Experience to date indicates that the design of the ERTS-1 Data Collection System is adequate for operational use for 50% of the users and, with minor modifications, could meet the requirements of 75%. Some users will have to augment the system by other data collection techniques to meet their operational requirements.

  18. Estrogen replacement therapy (ERT) in high-risk cancer patients.

    PubMed Central

    Hutchinson-Williams, K. A.; Gutmann, J. N.

    1991-01-01

    Menopausal estrogens are now being prescribed not only for symptom relief, but also to prevent the long-term sequelae of estrogen deficiency, namely osteoporosis and atherosclerotic disease. The well-established association between endometrial cancer and estrogen replacement therapy (ERT) has become less of a clinical concern due to the recognition of the protective effect of progestogens in this setting. A small literature has emerged suggesting that extending ERT to the woman with a history of endometrial carcinoma imposes no increased risk of recurrence and may improve survival. Candidates for ERT should be women with a better prognostic profile with reference to their cancer. The relationship between ERT and breast cancer remains a topic of intense debate and investigation. Overall, the current literature finds no significant increase in risk among healthy women without a family history of breast cancer. There are no guidelines with reference to the woman with a history of breast cancer and the use of ERT. The most prudent approach with this population is to consider alternative treatments until more is known. PMID:1810102

  19. Plant-soil interactions in salt marsh environments: Experimental evidence from electrical resistivity tomography in the Venice Lagoon

    NASA Astrophysics Data System (ADS)

    Boaga, Jacopo; D'Alpaos, Andrea; Cassiani, Giorgio; Marani, Marco; Putti, Mario

    2014-09-01

    The role of root water uptake in regulating soil water saturation in salt marshes is controversial. Modeling studies suggest that soil aeration is improved by transpiration, with implications for the distribution of vegetation species and of the associated topographic features controlling the hydraulic regime of the marshland and eventually its survival. Marsh vegetation plays a key role in the preservation of such critical environment, which represents unique marker for climatic change and impact studies. However, the direct quantification of space-time aeration patterns has remained elusive, in part, because of the limitations posed by high salinity to conventional observation techniques such as time or frequency domain reflectometry. Here we show that time-lapse microscale electrical resistivity tomography, coupled with tensiometric observations, allows the identification of variably saturated zones and the characterization of space-time soil moisture dynamics in a salt marsh in the Venice Lagoon (Italy). This is the first quantitative observational experiment which confirms that periodically flooded plants are capable of producing a persistently aerated layer below the flooded surface when transpiration proceeds at a sufficiently high rate. The experimental results are compared against previously published model predictions.

  20. Electrical resistivity tomography to characterize a karstic Vauclusian spring: Fontaine d'Orbe (Pyrénées, France)

    NASA Astrophysics Data System (ADS)

    Sirieix, C.; Riss, J.; Rey, F.; Prétou, F.; Lastennet, R.

    2014-06-01

    The study site lies on a karst system in the Pyrénées (France) that crosses the Urgonian limestones. Organic matter was dumped on the west bank of the River Vert d'Arette, which polluted a spring (the Fontaine d'Orbe) situated on the east bank. Electrical resistivity tomography was utilised in order to understand the geometry of this karst outlet. After tests with the pole-pole array, the ideal electrode spacing was found to be less than 3 m. A conduit, a little less than 10 m wide, was discovered, which proved to be the terminal conduit of the karst system. It was established that the conduit traverses both banks of the River Vert d'Arette, thus presenting a hydraulic link between the two sides. Moreover, this conduit, which is totally submerged, passes under the riverbed and goes upwards to the spring. In addition to the geophysical measurements, hydrogeological measurements and observations were made. Based on the characterisation of the geometry of the karst network's terminal conduit, and the fact that is completely full of water and inclined, it is concluded that the Fontaine d'Orbe spring is of the Vauclusian variety.

  1. Comparison of a networks-of-zones fluid mixing model for a baffled stirred vessel with three-dimensional electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Rodgers, T. L.; Siperstein, F. R.; Mann, R.; York, T. A.; Kowalski, A.

    2011-10-01

    Reliable models for the simulation of mixing vessels are important for the understanding of real-life mixing problems. To achieve these models, information about the mixing in the system must be measured to compare with the predicted values. Electrical resistance tomography has the capability to measure spatial and temporal changes within a vessel in three dimensions even in optically inaccessible environments. This paper discusses the creation of a network-of-zones model for the prediction of mixing within a vessel with a Cowles disc-type agitator. Solving of the network-of-zones simplified transport equations for the vessel predicts the concentration distribution of an inert tracer added to the vessel. The change in this distribution with time is calculated and compared with visual inspection of the vessel. The concentration distribution inside the vessel is also measured using electrical resistance tomography and shows good agreement with the predicted values.

  2. Reconstruction of landslide movements by inversion of 4-D electrical resistivity tomography monitoring data

    NASA Astrophysics Data System (ADS)

    Wilkinson, Paul; Chambers, Jonathan; Uhlemann, Sebastian; Meldrum, Philip; Smith, Alister; Dixon, Neil; Loke, Meng Heng

    2016-02-01

    Reliable tomographic inversion of geoelectrical monitoring data from unstable slopes relies critically on knowing the electrode positions, which may move over time. We develop and present an innovative inverse method to recover movements in both surface directions from geoelectrical measurements made on a grid of monitoring electrodes. For the first time, we demonstrate this method using field data from an active landslide to recover sequences of movement over timescales of days to years. Comparison with GPS measurements demonstrated an accuracy of within 10% of the electrode spacing, sufficient to correct the majority of artifacts that would occur in subsequent image reconstructions if incorrect positions are used. Over short timescales where the corresponding subsurface resistivity changes were smaller, the constraints could be relaxed and an order-of-magnitude better accuracy was achievable. This enabled the onset and acceleration of landslide activity to be detected with a temporal resolution of a few days.

  3. ERTS-B (Earth Resources Technology Satellite). [spacecraft design remote sensor description, and technology utilization

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Mission plans and objectives of the ERTS 2 Satellite are presented. ERTS 2 follow-on investigations in various scientific disciplines including agriculture, meteorology, land-use, geology, water resources, oceanography, and environment are discussed. Spacecraft design and its sensors are described along with the Delta launch vehicle and launch operations. Applications identified from ERTS 1 investigations are summarized.

  4. Comparison of measuring strategies for the 3-D electrical resistivity imaging of tumuli

    NASA Astrophysics Data System (ADS)

    Tsourlos, Panagiotis; Papadopoulos, Nikos; Yi, Myeong-Jong; Kim, Jung-Ho; Tsokas, Gregory

    2014-02-01

    Artificial erected hills like tumuli, mounds, barrows and kurgans comprise monuments of the past human activity and offer opportunities to reconstruct habitation models regarding the life and customs during their building period. These structures also host features of archeological significance like architectural relics, graves or chamber tombs. Tumulus exploration is a challenging geophysical problem due to the complex distribution of the subsurface physical properties, the size and burial depth of potential relics and the uneven topographical terrain. Geoelectrical methods by means of three-dimensional (3-D) inversion are increasingly popular for tumulus investigation. Typically data are obtained by establishing a regular rectangular grid and assembling the data collected by parallel two-dimensional (2-D) tomographies. In this work the application of radial 3-D mode is studied, which is considered as the assembly of data collected by radially positioned Electrical Resistivity Tomography (ERT) lines. The relative advantages and disadvantages of this measuring mode over the regular grid measurements were investigated and optimum ways to perform 3-D ERT surveys for tumuli investigations were proposed. Comparative test was performed by means of synthetic examples as well as by tests with field data. Overall all tested models verified the superiority of the radial mode in delineating bodies positioned at the central part of the tumulus while regular measuring mode proved superior in recovering bodies positioned away from the center of the tumulus. The combined use of radial and regular modes seems to produce superior results in the expense of time required for data acquisition and processing.

  5. Using a new multichannel GPR and ERT method for high resolution archaeological mapping: application to a buried Gallo-Roman site in Normandy, France

    NASA Astrophysics Data System (ADS)

    Antoine, Raphael; Fauchard, Cyrille; Beaucamp, Bruno; Guilbert, Vincent

    2014-05-01

    We report on successful geophysical observations above a buried Gallo-Roman theatre in Normandy, France. The main objective of this study was to complete the previous archaeological surveys in order to localize the structure and precise its depth. The 100 m diameter theatre, lying between 50 cm and 3 m depth, was investigated using 1) a new multichannel Ground Penetrating Radar (GPR); 2) a 2D Electric Resistivity Tomography (ERT) and 3) geotechnical soundings. The multichannel GPR (IDS Stream X) is composed of 7 antennas working at a frequency of 200 MHz and with a spacing of 12 cm. Therefore, such system is well adapted to large-scale high-resolution surveys. In our case, the GPR was able to investigate the entire zone (1600 m2) in few hours. This survey led to the characterization of the subsurface up to 3 m depth. To complete the information obtained with the GPR, seven ERT profiles were acquired longitudinally and transversally to the structure. A Terrameter LS imaging system (ABEM) was used with a dipole-dipole configuration; as such protocol is sensitive to vertical structures. Three profiles are 32 m with a spacing of 1 m between electrodes, 2 profiles are 16 m with a 0.5 m spacing between electrodes, 1 profile is 19.20 m with a spacing of 0.6 m between electrodes and 1 profile is 64 m with a spacing of 1 m between electrodes. Such approach allowed to inverse the electric data up to a depth in the range 4-10 m. An excellent correlation is obtained between both methods, allowing us to propose a precise 3D visualisation of the Gallo-Roman theatre, in agreement with a partial model obtained from the previous archaeological surveys. Moreover, this study led to the discovery of other structures (confirmed by geotechnical soundings) and thus to complete the current archaeological model of the site. The Multichannel GPR clearly offers new potentials for the large-scale imaging of the subsurface. Combined with other geophysical and archaeological methods, it is a

  6. Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution-dependent limitations

    USGS Publications Warehouse

    Day-Lewis, F. D.; Singha, K.; Binley, A.M.

    2005-01-01

    Geophysical imaging has traditionally provided qualitative information about geologic structure; however, there is increasing interest in using petrophysical models to convert tomograms to quantitative estimates of hydrogeologic, mechanical, or geochemical parameters of interest (e.g., permeability, porosity, water content, and salinity). Unfortunately, petrophysical estimation based on tomograms is complicated by limited and variable image resolution, which depends on (1) measurement physics (e.g., electrical conduction or electromagnetic wave propagation), (2) parameterization and regularization, (3) measurement error, and (4) spatial variability. We present a framework to predict how core-scale relations between geophysical properties and hydrologic parameters are altered by the inversion, which produces smoothly varying pixel-scale estimates. We refer to this loss of information as "correlation loss." Our approach upscales the core-scale relation to the pixel scale using the model resolution matrix from the inversion, random field averaging, and spatial statistics of the geophysical property. Synthetic examples evaluate the utility of radar travel time tomography (RTT) and electrical-resistivity tomography (ERT) for estimating water content. This work provides (1) a framework to assess tomograms for geologic parameter estimation and (2) insights into the different patterns of correlation loss for ERT and RTT. Whereas ERT generally performs better near boreholes, RTT performs better in the interwell region. Application of petrophysical models to the tomograms in our examples would yield misleading estimates of water content. Although the examples presented illustrate the problem of correlation loss in the context of near-surface geophysical imaging, our results have clear implications for quantitative analysis of tomograms for diverse geoscience applications. Copyright 2005 by the American Geophysical Union.

  7. Trimethoprim/sulfamethoxazole-resistant Nocardia asteroides causing multiple hepatic abscesses. Successful treatment with ampicillin, amikacin, and limited computed tomography-guided needle aspiration.

    PubMed

    Cockerill, F R; Edson, R S; Roberts, G D; Waldorf, J C

    1984-09-01

    Hepatic abscesses are rarely encountered in disseminated Nocardia infections. Sulfonamides alone or trimethoprim/sulfamethoxazole is often efficacious in treating infections caused by Nocardia asteroides. In vitro resistance of N. asteroides to trimethoprim/sulfamethoxazole is occasionally present. The patient described in this report had disseminated nocardiosis initially manifesting as multiple subcapsular hepatic abscesses. In vitro susceptibility studies demonstrated resistance to trimethoprim/sulfamethoxazole. Subsequent treatment with ampicillin and amikacin in conjunction with computed tomography-guided needle aspiration of several of the hepatic abscesses, surgical drainage of a right pleural empyema, and eventual discontinuation of use of corticosteroids resulted in cure of the infection.

  8. Vegetation density as deduced from ERTS-1 MSS response

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Gausman, H. W.; Cuellar, J. A.; Gerbermann, A. H.; Richardson, A. J.

    1974-01-01

    Reflectance from vegetation increases with increasing vegetation density in the 0.75- to 1.35 micron wavelength interval. Therefore, ERTS-1 bands 6 (0.7 to 0.8 micron) and 7 (0.8 to 1.1 micron) contain information that should relate to the probable yield of crops and the animal carrying capacity of rangeland. The results of an experiment designed specifically to test the relations among leaf area index (LAI), plant population, plant cover and plant height, and the ERTS-1 MSS responses for 3 corn, 10 sorghum, and 10 cotton fields are given. Plant population was as useful as LAI for characterizing the sorghum and corn fields, and plant height was as good as LAI for characterizing cotton fields. These findings generally support the utility of ERTS-1 data for explaining variability in green biomass, harvestable forage and other indicators of productivity.

  9. ERTS-1 Role in land management and planning in Minnesota

    NASA Technical Reports Server (NTRS)

    Sizer, J. E.; Brown, D. A.

    1974-01-01

    Research on applications of ERTS-1 imagery to land use has focused on evaluating the ability of ERTS-1 imagery to update and refine the detail of land use information in the Minnesota Land Management Information System. Work has been directed toward defining the capabilities of the ERTS-1 system to provide information about surface cover by identifying forest, water, and wetland resources; urban and agricultural development: and testing and evaluating data input and output procedures. As capabilities were developed, meetings were held with administrators and resource information users from various agencies of government to identify their information needs. A full scale systems test for several selected pilot areas in the state is nearly complete. Users have been identified for each test area and they have been instrumental in identifying data requirements and analysis needs for administrative purposes. Users have both rural and urban orientations and provide a basis for evaluation of the results.

  10. Mapping a recent forest fire with ERTS-1 MSS data

    NASA Technical Reports Server (NTRS)

    Hitchcock, H. C.; Hoffer, R. M.

    1974-01-01

    Accurate fire boundary delineation provides essential information to forest managers in allocating suppression costs and planning regeneration efforts. The objective of this study was to test the capability of computer-aided analysis of ERTS-1 MSS data to accurately define the boundary of a recent forest fire and to discriminate spectral classes within the perimeter. Two frames of ERTS-1 MSS data were selected for analysis of the Moccasin Mesa Fire in Mesa Verde National Park. Data sets were collected one-half growing season and one full growing season after the fire. Results indicate that computer-aided analysis of ERTS-1 MSS data has the capability for accurately delineating fire boundaries and determining acreage of the burned area. Distinct spectral classes may also be defined within the fire perimeter.

  11. Evaluation of ERTS data for certain hydrological uses

    NASA Technical Reports Server (NTRS)

    Wiesnet, D. R. (Principal Investigator); Mcginnis, D. F.

    1973-01-01

    The author has identified the following significant results. Melting ice has been detected in Lake Erie by comparison of visible and near infrared differential reflectance. This melting condition is confirmed by meteorological ground truth data and concurrent NOAA-2 thermal infrared data. Using near-synchronous ERTS-1 data, it was possible to determine the approximate ground resolution of NOAA-2 very high resolution radiometer by comparing the smallest identifiable ice crack in the imagery and measuring the same crack on the ERTS-1 image. It was determined that photointerpretation and analysis of a single Lake Erie image can, under certain conditions, provide meaningful data on ice dynamics. ERTS-1 imagery is effective for icepack monitoring of the Great Lakes, but the sampling interval of 18 days imposes a severe limitation. Maps of the snow cover in the American River basin for 16 March 1973 have been prepared using all four bands.

  12. Water-management models in Florida from ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Higer, A. L. (Principal Investigator); Rogers, R. H.; Coker, A. E.; Cordes, E. H.

    1975-01-01

    The author has identified the following significant results. The usefullness of ERTS 1 to improving the overall effectiveness of collecting and disseminating data was evaluated. ERTS MSS imagery and in situ monitoring by DCS were used to evaluate their separate and combined capabilities. Twenty data collection platforms were established in southern Florida. Water level and rainfall measurements were collected and disseminated to users in less than 2 hours, a significant improvement over conventional techniques requiring 2 months. ERTS imagery was found to significantly enhance the utility of ground measurements. Water stage was correlated with water surface areas from imagery in order to obtain water stage-volume relations. Imagery provided an economical basis for extrapolating water parameters from the point samples to unsampled data and provided a synoptic view of water mass boundaries that no amount of ground sampling or monitoring could provide.

  13. Environmental study of ERTS-1 imagery: Lake Champlain and Vermont

    NASA Technical Reports Server (NTRS)

    Lind, A. O.; Henson, E. B.; Pelton, J. O.

    1973-01-01

    Environmental concerns of the State of Vermont currently being stressed include water quality in Lake Champlain and a state-wide land use and capability plan. Significant results obtained from ERTS-1 relate directly to the above concerns. Industrial water pollution and turbidity in Lake Champlain have been identified and mapped and the ERTS pollution data will be used in the developing court suit which Vermont has initiated against the polluters. ERTS imagery has also provided a foundation for updating and revising land use inventories. Major classes of land use have been identified and mapped, and substantial progress has been made toward the mapping of such land use divisions as crop and forest type, and wetlands.

  14. ERTS Applications in earthquake research and mineral exploration in California

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M.; Silverstein, J.

    1973-01-01

    Examples that ERTS imagery can be effectively utilized to identify, locate, and map faults which show geomorphic evidence of geologically recent breakage are presented. Several important faults not previously known have been identified. By plotting epicenters of historic earthquakes in parts of California, Sonora, Mexico, Arizona, and Nevada, we found that areas known for historic seismicity are often characterized by abundant evidence of recent fault and crustal movements. There are many examples of seismically quiet areas where outstanding evidence of recent fault movements is observed. One application is clear: ERTS-1 imagery could be effectively utilized to delineate areas susceptible to earthquake recurrence which, on the basis of seismic data alone, may be misleadingly considered safe. ERTS data can also be utilized in planning new sites in the geophysical network of fault movement monitoring and strain and tilt measurements.

  15. Calculations of water depth from ERTS-MSS data

    NASA Technical Reports Server (NTRS)

    Polcyn, F. C.; Lyzenga, D. R.

    1973-01-01

    ERTS-1 MSS data taken on October 10, 1972 of the Little Bahama Bank are being used to demonstrate the use of ERTS-1 data for mapping of shallow water features for the purpose of upgrading world navigation charts. Marked reflectance differences occur for the shallow water areas in Bands 4, 5, and 6. Digital processing of two adjacent data tapes within the ERTS frame covering an area of about 40 by 40 miles has been completed. Correlation of depth measurements to 5 meters has been successful. A mathematical model for depth measurements using ratio of voltages in Band 4 and 5 has been successfully developed and is being tested for accuracy. Additional studies for areas near Puerto Rico and in Northern Lake Michigan will be undertaken. Satellite data will also provide geographical evidence for verifying existence or nonexistence of doubtful shoal waters now appearing on world charts and considered to be hazardous to shipping.

  16. The first Earth Resources Technology Satellite (ERTS-1)

    NASA Technical Reports Server (NTRS)

    Nordberg, W.

    1973-01-01

    The first Earth Resources Technology Satellite (ERTS-1) makes images of the earth's surface in four portions of the electromagnetic spectrum with sufficient spatial resolution and with a minimum of geometric distortions, so that these images may be applied experimentally to the study of geophysical processes relating to earth resources, to the exploration and conservation of these resources, and to the assessments of environmental stresses. During the first six months of operation, ERTS-1 has imaged 6.5 million square kilometers of the earth's surface every day, covering most major land masses and coastal zones as well as both polar regions of this planet. These images as well as the results of their analyses are available to all people throughout the world. Scientific investigators of all countries have been invited to participate in the utilization of ERTS-1 observations. Many of them have already demonstrated the great efficiency, economy, and reliability of making earth surveys from space.

  17. Evaluation of stress and saturation effects on seismic velocity and electrical resistivity - laboratory testing of rock samples

    NASA Astrophysics Data System (ADS)

    Vilhelm, Jan; Jirků, Jaroslav; Slavík, Lubomír; Bárta, Jaroslav

    2016-04-01

    Repository, located in a deep geological formation, is today considered the most suitable solution for disposal of spent nuclear fuel and high-level waste. The geological formations, in combination with an engineered barrier system, should ensure isolation of the waste from the environment for thousands of years. For long-term monitoring of such underground excavations special monitoring systems are developed. In our research we developed and tested monitoring system based on repeated ultrasonic time of flight measurement and electrical resistivity tomography (ERT). As a test site Bedřichov gallery in the northern Bohemia was selected. This underground gallery in granitic rock was excavated using Tunnel Boring Machine (TBM). The seismic high-frequency measurements are performed by pulse-transmission technique directly on the rock wall using one seismic source and three receivers in the distances of 1, 2 and 3 m. The ERT measurement is performed also on the rock wall using 48 electrodes. The spacing between electrodes is 20 centimeters. An analysis of relation of seismic velocity and electrical resistivity on water saturation and stress state of the granitic rock is necessary for the interpretation of both seismic monitoring and ERT. Laboratory seismic and resistivity measurements were performed. One series of experiments was based on uniaxial loading of dry and saturated granitic samples. The relation between stress state and ultrasonic wave velocities was tested separately for dry and saturated rock samples. Other experiments were focused on the relation between electrical resistivity of the rock sample and its saturation level. Rock samples with different porosities were tested. Acknowledgments: This work was partially supported by the Technology Agency of the Czech Republic, project No. TA 0302408

  18. Application of ERTS-1 imagery in coastal studies

    NASA Technical Reports Server (NTRS)

    Magoon, O. T.; Berg, D. W.; Hallermeier, R. J.

    1973-01-01

    The basic ERTS output is four black-and-white photographs presenting the same scene recorded in each multispectral scanner band. Mosaics covering large regions at a 1:250,000 scale can be compiled from these photographs. Office study of the image of each band separately, in combination with other bands, and in conjunction with other available data (navigation charts, tide tables, etc.) permits extraction of data useful in coastal engineering planning and coastal processes studies. Specific examples in which significant information on regional shoreline configuration or nearshore water movements has been obtained from unenhanced ERTS imagery are: (1) tidal inlet configuration; (2) navigation information; and (3) nearshore water movements.

  19. Evaluation of ERTS-1 data for certain hydrological uses

    NASA Technical Reports Server (NTRS)

    Wiesnet, D. R. (Principal Investigator); Mcginnis, D. F.; Mcmillan, M. C.

    1974-01-01

    The author has identified the following significant results. ERTS-1 MSS data have been used in a variety of hydrologic research including snow-extent mapping; studies of snowmelt, snowmelt runoff, spectral reflectance of snow for assessing snowpack conditions, and snow albedo; lake ice formation, breakup, and migration; lake current measurements; multispectral studies of lake ice; and flood studies. MSS sensing of soil moisture over a well-vegetated test site was unsuccessfully attempted. Although a powerful research tool, ERTS-1 has very limited use as an operational system for hydrologic communities because of its 18-day revisit cycle and its lack of a quick look capability.

  20. Environmental studies of Iceland with ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Williams, R. S., Jr.; Boovarsson, A.; Frioriksson, S.; Thorsteinsson, I.; Palmason, G.; Rist, S.; Saemundsson, K.; Sigtryggsson, H.; Thorarinsson, S.

    1974-01-01

    Imagery from the ERTS-1 satellite can be used to study geological and geophysical phenomena which are important in relation to Iceland's natural resources. Multispectral scanner (MSS) imagery can be used to map areas of altered ground, intense thermal emission, fallout from volcanic eruptions, lava flows, volcanic geomorphology, erosion or build-up of land, snow cover, the areal extent of glaciers and ice caps, etc. At least five distinct vegetation types and barren areas can be mapped using MSS false-color composites. Stereoscopic coverage of iceland by side-lapping ERTS imagery permits precise analysis of various natural phenomena.

  1. ERTS-1 applications in hydrology and water resources

    NASA Technical Reports Server (NTRS)

    Salomonson, V. V.; Rango, A.

    1973-01-01

    After having been in orbit for less than one year, the Earth Resources Technology Satellite (ERTS-1) has shown that it provides very applicable data for more effective monitoring and management of surface water features over the globe. Mapping flooded areas, snowcover, and wetlands and surveying the size, type, and response of glaciers to climate are among the specific areas where ERTS-1 data were applied. In addition the data collection system has proven to be a reliable tool for gathering hydrologic data from remote regions. Turbidity variations in lakes and rivers were also observed and related to shoreline erosion, industrial plant effluent, and overall water quality.

  2. Facilitating the exploitation of ERTS imagery using snow enhancement techniques

    NASA Technical Reports Server (NTRS)

    Wobber, F. J. (Principal Investigator); Martin, K. R.; Amato, R. V.

    1973-01-01

    The author has identified the following significant results. Detection and analysis of fracture systems can be more effectively conducted utilizing snow cover as an enhancement tool. From analysis within the Great Barrington Test Site it appears that the use of aeromagnetic data effectively supplements lineament data acquired using ERTS imagery. Coincidence of lineaments derived from aeromagnetics with lineaments interpreted from ERTS imagery apparently indicate the presence of mineralized fracture systems and dikes. Utilizing both tools can increase the speed and efficiency of mineral exploration and geological mapping in areas where bedrock is obscured by a thick unconsolidated sediment cover.

  3. Statistical Analysis of Resistivity Anomalies Caused by Underground Caves

    NASA Astrophysics Data System (ADS)

    Frid, V.; Averbach, A.; Frid, M.; Dudkinski, D.; Liskevich, G.

    2015-05-01

    Geophysical prospecting of underground caves being performed on a construction site is often still a challenging procedure. Estimation of a likelihood level of an anomaly found is frequently a mandatory requirement of a project principal due to necessity of risk/safety assessment. However, the methodology of such estimation is not hitherto developed. Aiming to put forward such a methodology the present study (being performed as a part of an underground caves mapping prior to the land development on the site area) consisted of application of electrical resistivity tomography (ERT) together with statistical analysis utilized for the likelihood assessment of underground anomalies located. The methodology was first verified via a synthetic modeling technique and applied to the in situ collected ERT data and then crossed referenced with intrusive investigations (excavation and drilling) for the data verification. The drilling/excavation results showed that the proper discovering of underground caves can be done if anomaly probability level is not lower than 90 %. Such a probability value was shown to be consistent with the modeling results. More than 30 underground cavities were discovered on the site utilizing the methodology.

  4. The ERTS-1 investigation (ER-600). Volume 1: ERTS-1 agricultural analysis

    NASA Technical Reports Server (NTRS)

    Erb, R. B.

    1974-01-01

    The Agriculture Analysis Team of the Johnson Space Center conducted a 1-year-long investigation of ERTS-1 multispectral data to evaluate how well features of agricultural importance could be detected, identified, and located; and their areal extent measured. Six study areas were selected in cooperation with the U.S. Department of Agriculture. Two basic analytical approaches were used to meet the objectives. The conventional image interpretation technique revealed that a particular color was an indication of the density of vegetative cover, not an indication of crop classification. Computer-aided techniques were used to classify crop types (i.e., small grains, truck farm crops, grasses, summer fallow) to accuracies as high as 95 percent on large (12 hectares or more) well-defined fields. A further breakdown into crop species (wheat, barley, soybeans, oats, corn) reduced the accuracy to 70 to 80 percent for single-date observations.

  5. ERTS data user no. 119: Effective use of ERTS multisensor data in the Great Plains. ERTS-1 MSS imagery: A tool for identifying soil associations

    NASA Technical Reports Server (NTRS)

    Myers, V. I. (Principal Investigator); Westin, F. C.

    1973-01-01

    The author has identified the following significant results. Soil association maps show the spatial relationships of land units developed in unique climatic, geologic, and topographic environments, and having characteristic slopes, soil depths, textures, available water capacities, permeabilities, and the like. ERTS-1 imagery was found to be a useful tool in the identification of soil associations since it provides a synoptic view of an 8 million acre scene, which is large enough so that the effect can be seen on soils of climate, topography, and geology. A regional view also allows soil associations to be observed over most, if not all, of their extent. ERTS-1 MSS imagery also provides four spectral bands taken every 18 days which give data on relief, hydrology, and vegetation, all of which bear on the delineation and interpretation of soil associations. Enlarged prints derived from the individual spectral bands and shown in gray tones were useful for identifying soil associations.

  6. Environmental surveys in Alaska based upon ERTS data

    NASA Technical Reports Server (NTRS)

    Miller, J. M.

    1974-01-01

    Alaskan applications of ERTS data are summarized. Areas discussed are: (1) land use; (2) archaeology; (3) vegetation mapping; (4) ice reporting and mapping; (5) permafrost; (6) mineral and oil exploration; (7) geological surveys; (8) seismology; (9) geological faults and structures; (10) hydrology and water resources; (11) glaciology; (12) water circulation in Cook Inlet; and (13) fish and mammal populations.

  7. Evaluation of ERTS data for certain hydrological uses

    NASA Technical Reports Server (NTRS)

    Wiesnet, D. R.; Mcginnis, D. F. (Principal Investigator); Matson, M.

    1973-01-01

    The author has identified the following significant results. Mapping of snow cover using ERTS-1 data proved to be six times faster than that done from U-2 photography. However, NOAA-2 VHRR snow cover mapping was almost as fast as ERTS-1, and it is available more frequently. Ice conditions in the Great Lakes can be readily determined by ERTS-1. Ice features characteristic of thawing conditions such as rotten ice, lack of pressure ridges, brash belts, and compacted ice edges can be identified. A great decrease in apparent reflectivity in band 7 as compared to band 4 also indicated melting conditions. Using sidelap from two successive ERTS-1 images of Lake Erie (February 17 and 18, 1973) a measure of ice movement was made, agreeing closely with the estimate from conventional methods. The same imagery permitted tentative identification of the following features: shuga, light and dark nilas, fast ice, icefoot, ice breccia, brash ice, fracturing, ridging, rafting, sastrugi, thaw holes, rotten ice, ice islands, dried ice puddles, hummocked ice, and leads.

  8. Utilization of ERTS-1 data in the Houston area

    NASA Technical Reports Server (NTRS)

    Erb, R. B. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Using clustering techniques, several large lakes in Texas have been accurately delineated in computer printout graymaps. It was also found that small bodies of water (one to two acres in size) could be detected by searching for small reflectance values in the infrared data. A graymap printout of a lake described a shore outline that was not consistent with available maps. Field examination revealed that the actual level of the lake was below that for which the map was drawn. The current lake configuration agrees in shape and relative size with the ERTS-1 data printout. Water turbidity causes reflectance changes which are detectable in ERTS-1 band 7 data. A comparison has been made of the Monterey Bay, California area using 1971 aerial color infrared photography and a 1972 ERTS-1 band 7 infrared image. This comparison revealed that some event has occurred to impound a significant amount of water in the area since the infrared photography was taken. Data values in the ERTS-1 infrared image exhibit detectable changes in brightness at inflow points, where high turbidity would be present. Researchers had not expected to detect water turbidity patterns in band 7 (800 to 1100 nanometers).

  9. ERTS-1, a new window on our planet

    USGS Publications Warehouse

    Williams, Richard S.; Carter, William Douglas

    1976-01-01

    The launch, on July 23, 1972, of the first Earth Resources Technology Satellite (ERTS-1) by the National Aeronautics and Space Administration was a major step forward in extending man 's ability to inventory the Earth 's resources and to evaluate objectively his impact upon the environment. ERTS spacecraft represent the first step in merging space and remote-sensing technologies into a system for inventorying and managing the Earth 's resources. Examples presented in this book demonstrate ERTS ' vast potential for inventorying resources, monitoring environmental conditions, and measuring changes. Such information is essential for the full evaluation of the Federal lands and determining their future use, as well as for improved planning of overall land use throughout the United States and the world. Ten bureaus of the U.S. Department of Interior have roles in the ERTS project. Nearly all of these participating bureaus are represented in almost 100 papers included in this book. Chapter 3 is entitled ' Applications to Water Resources ' and contains 23 separate sections. (Woodard-USGS)

  10. Coastal applications of the ERTS-1 satellite imagery

    NASA Technical Reports Server (NTRS)

    Magoon, O. T. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. Samples are given of the possible applications of ERTS-1 imagery to coastal and nearshore studies. Briefly discussed are: (1) obtaining regional views of extended coastal areas; (2) distribution of sediments; (3) coastal configurations and changes; (4) barrier islands; (5) underwater penetration, and (6) coastal waves.

  11. Agricultural utilization of ERTS-1 data in Thailand

    NASA Technical Reports Server (NTRS)

    Cheosakul, P.; Indrambarya, B.; Morgan, J. O.; Vibulsresth, S.

    1974-01-01

    Recent advances made in three disciplinary areas that are of major importance to Thailand are briefly discussed. These areas are; (1) agriculture, (2) forestry, and (3) land use. Preliminary investigations of the ERTS-1 data have been so successful that the Thai Government has decided to develop a remote sensing data handling and research center.

  12. Geological evaluation and applications of ERTS-1 imagery over Georgia

    NASA Technical Reports Server (NTRS)

    Pickering, S. M.; Jones, R. C.

    1974-01-01

    ERTS-1 70mm and 9 x 9 film negatives are being used by conventional and color enhancement methods as a tool for geologic investigation. Geologic mapping and mineral exploration by conventional methods is very difficult in Georgia. Thick soil cover and heavy vegetation cause outcrops of bed rock to be small, rare and obscure. ERTS imagery, and remote sensing in general have helped delineate: (1) major tectonic boundaries; (2) lithologic contacts; (3) foliation trends; (4) topographic lineaments; and (5) faults. The ERTS-1 MSS imagery yields the greatest amount of geologic information on the Piedomont, Blue Ridge, and Valley and Ridge Provinces of Georgia where topography is strongly controlled by the bedrock geology. ERTS imagery, and general remote sensing techniques, have provided us with a powerful tool to assist geologic research; have significantly increased the mapping efficiency of our field geologists; have shown new lineaments associated with known shear and fault zones; have delineated new structural features; have provided a tool to re-evaluate our tectonic history; have helped to locate potential ground water sources and areas of aquifer recharge; have defined areas of geologic hazards; have shown areas of heavy siltation in major reservoirs; and by its close interval repetition, have aided in monitoring surface mine reclamation activities and the environmental protection of our intricate marshland system.

  13. Electrical resistance tomography with constrained sine wave solutions for impact damage identification in glass fiber/epoxy/carbon black laminate composites

    NASA Astrophysics Data System (ADS)

    Tallman, T. N.

    2016-04-01

    Electrical impedance tomography (EIT) has incredible potential for structural health monitoring (SHM) when applied to structures in which mechanical damage is coupled with changes in electrical conductivity. Practically, however, the potential of EIT for SHM is largely nullified by requiring both non-negligible computational resources and accurate initial conductivity estimates. By working in resistivity instead of conductivity and constraining the change in resistivity to be a series of two-dimensional sine waves, a novel resistivity-based EIT formulation is herein developed that significantly abates the computational requirements of EIT and is independent of initial estimates. This approach is explored analytically and then demonstrated experimentally by locating impact damage to a glass fiber/epoxy/carbon black laminate.

  14. Assessing clogging processes caused by biofilm growth and organic particle accumulation in constructed wetlands using time-lapse electrical resistivity tomography method

    NASA Astrophysics Data System (ADS)

    Mahjoub, Himi; Tapias, Josefina C.; Lovera, Raúl; Rivero, Lluís; Font, Xavier; Casas, Albert

    2016-04-01

    Constructed wetlands for removing pollutants from wastewater in small communities are growing rapidly in many regions of the world. The advantages over conventional mechanical sanitation systems, where land availability is not a limiting factor, are low energy requirements, easy operation and maintenance, low sludge production and cost-effectivity. Nevertheless, with time the cleaning process can result in gradual clogging of the porous layer by suspended solids, bacterial film, chemical precipitates and compaction. The clogging development causes decrease of hydraulic conductivity, reduced oxygen supply and further leads to a rapid decrease of the treatment performance. As the investment involved in reversing clogging can represent a substantial fraction of the cost of a new system it is essential to assess in advance the evolution of clogging process and detect potential failures in the system. Since there is a lack of experiences for monitoring the functionality of constructed wetlands time-lapse electrical resistivity tomography studies have been conducted at horizontal sub-surface flow municipal wastewater treatment wetlands of Catalonia (Spain). The results of this research show that electrical resistivity tomography can be a very useful technique for assessing the extent of silting up processes that clog the subsurface flow constructed wetlands through the gravel layer. In the unsaturated zone, the electrical resistivity is greater at the end of the filter, since the pores contains air which is dielectric, while at the beginning of the filter the resistivity is lower because the electrical conduction of organic matter around the mineral grains. Conversely, in the saturated zone, the electrical resistivity is lower at the end of the filter, since pores contain a higher proportion of high ionic conductivity wastewater, while at the beginning of the filter the electrical resistivity is higher because of the lower porosity due to the clogging process.

  15. Hydrostratigraphy of a Sand Aquifer from Combined ERT and GPR

    NASA Astrophysics Data System (ADS)

    Papadimitrios, K. S.; Ferris, G.; Bank, C.

    2015-12-01

    Overlapping resistivity and ground-penetrating radar transects were collected on a shallow sand aquifer. The study area covers about 150 by 150 m, and the water table depth in that area ranges from as shallow as 30 cm to over 2m. Electric resistivity tomography shows layers of resistances which we relate to the vadose zone (above 1200 Ohm.m), the saturated zone (approx. 300 Ohm.m), and underlying aquitard (above 1200 Ohm.m, made of glacial till). The resistivity sections fail to capture the topography of the sand-till boundary seen in collected radargrams (e.g., from 80 to 120 ns over a 30 m horizontal distance). Converting radar travel times to thickness of the aquifer requires knowledge of water table depth as well as radar velocity in both the saturated and unsaturated sands. Water table depth can be taken from resistivity pseudosections as well as local piezometers. Radar velocities can be estimated based on the properties of the local sand and assuming 100% saturation. In merging the results from the two datasets we are able to map local hydrostratigraphy and aquifer geometry.

  16. An Improved ERT Approach for the Investigation of Subsurface Structures

    NASA Astrophysics Data System (ADS)

    Lu, De-Bao; Wang, Feng; Chen, Xiao-Dong; Ou, Jian; Wang, Hui

    2016-08-01

    The joint use of multiple geophysical data types has been proven to be a powerful tool to both improve subsurface imaging and help in the interpretation process. The main goal of this paper is to develop a multi-geophysical approach for subsurface experimental investigations in which seismic data are used to improve electrical resistivity tomography quality. The basic philosophy of the method is that seismic travel time data will be used to construct the prior model for the resistivity inversion. Synthetic data were employed to demonstrate the improvements enabled by the use of this strategy. Afterwards, the scheme was applied successfully on field data from northwestern China. The outcomes reveal that the multi-geophysical approach improves the interpretation of the subsurface over a single source.

  17. Modelling the electrical resistivity response to CO2 plumes generated in a laboratory, cylindrical sandbox

    NASA Astrophysics Data System (ADS)

    Kremer, T.; Maineult, A. J.; Binley, A.; Vieira, C.; Zamora, M.

    2012-12-01

    CO2 capture and storage into deep geological formations is one of the main solutions proposed to reduce the concentration of anthropic CO2 in the atmosphere. The monitoring of injection sites is a crucial issue to assess for the long term viability of CO2 storage. With the intention of detecting potential leakages, we are investigating the possibility of using electrical resistivity tomography (ERT) techniques to detect CO2 transfers in the shallow sub-surface. ERT measurements were performed during a CO2 injection in a cylindrical tank filled with Fontainebleau sand and saturated with water. Several measurements protocols were tested. The inversion of the resistances measured with the software R3T (Binley and Kemna (2005)) clearly showed that the CO2 injection induces significant changes in the resistivity distribution of the medium, and that ERT has a promising potential for the detection and survey of CO2 transfers through unconsolidated saturated media. We modeled this experiment using Matlab by building a 3D cellular automaton that describes the CO2 spreading, following the geometric and stochastic approach described by Selker et al. (2007). The CO2 circulation is described as independents, circular and continuous gas channels whose horizontal spread depends on a Gaussian probability law. From the channel distribution we define the corresponding gas concentration distribution and calculate the resistivity of the medium by applying Archie's law for unsaturated conditions. The forward modelling was performed with the software R3T to convert the resistivity distribution into resistances values, each corresponding to one of the electrode arrays used in the experimental measurements. Modelled and measured resistances show a good correlation, except for the electrode arrays located at the top or the bottom of the tank. We improved the precision of the model by considering the effects due to CO2 dissolution in the water which increases the conductivity of the

  18. Digital photogrammetric analysis and electrical resistivity tomography for investigating a landslide located in Basilicata region (southern Italy).

    NASA Astrophysics Data System (ADS)

    de Bari, C.; Lapenna, V.; Perrone, A.; Puglisi, C.; Sdao, F.

    2009-04-01

    estimated by multiplying the difference of altimetry by reduced or accumulated area sizes for every couple of years. The results obtained allowed both a geometric characterization of the landslide body and the dynamic development of the one. In the landslide area, some electrical resistivity tomographies have been carried out to reconstruct the geometrical setting of the subsoil, then to detect the sliding surface and estimate the thickness of the landslide that could be involved in future reactivation. This information is very useful and necessary to better plan the mitigation operations.

  19. Internal Structure of Periglacial Landforms: Assessment using 3D Electrical Resistivity Imaging (ERI)

    NASA Astrophysics Data System (ADS)

    Emmert, Adrian; Kneisel, Christof

    2015-04-01

    The occurrence of internal heterogeneities within periglacial landforms (e.g. frost table topography or varying ice content) is in most cases not inferable from the surface. Hence, to develop an enhanced understanding of the interaction between surface and subsurface processes, it is necessary to analyse the internal structure of different periglacial landforms and landform elements. The assessment of the internal structure is provided by the application of three-dimensional Electrical Resistivity Imaging (ERI). ERI is the technique of merging datum points from several parallel and perpendicular performed two-dimensional ERT (Electrical Resistivity Tomography) measurements and inverting the data set with a 3D inversion algorithm (sometimes also referred to as quasi-3D ERT). The application of this method has proven to be a valuable tool for mapping the spatial extent of isolated permafrost bodies and associated subsurface conditions. In this contribution, we present results from four ERI measurements, carried out in summer 2014 at different investigation sites in the Swiss Alps: Three measurements were performed on pebbly rockglaciers of different size and topographical position and one measurement was performed on a solifluction slope. Each of the 3D survey grids consists of 17 to 32 single 2D ERT surveys (Dipol-Dipol or Wenner-Schlumberger array) and covers an area of between 6000 m² and 7000 m², depending on the specific survey grid set-up. The inversions of the data sets were performed using the two different inversion algorithms of the software products "RES3DINV" and "BERT" (Boundless Electrical Resistivity Tomography) for a comparative analysis and to further support the geomorphological interpretation of the geophysical models. Each of the resulting resistivity models shows strong small-scale spatial heterogeneities between the investigated landforms but also within landform elements. For the investigated rockglacier sites, these structures include

  20. Geologic and mineral and water resources investigations in western Colorado using ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Knepper, D. H., Jr. (Compiler)

    1973-01-01

    The author has identified the following significant results. Geologic interpretation of ERTS-1 imagery is dependent on recognition of the distribution, continuity, trend, and geometry of key surface features. In the examination of ERTS-1 imagery, lithology must be interpreted largely from the geomorphic expression of the terrain. ERTS-1 imagery is extremely useful in detecting local structures. Most mapped structures are topographically-expressed. Consequently, ERTS-1 imagery acquired during mid-winter, when the solar illumination angle is low, provides the largest amount of structural information. Stereoscopic analyses of ERTS-1 images significantly aid geologic interpretation. Positive transparencies of ERTS-1 images (1:1,000,000) commonly contain more geologic information than can be adequately annotated during geologic interpretation.

  1. Monitoring coastal water properties and current circulation with ERTS-1. [Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Otley, M.; Wethe, C.; Rogers, R.

    1974-01-01

    Imagery and digital tapes from nine successful ERTS-1 passes over Delaware Bay during different portions of the tidal cycle have been analyzed with special emphasis on turbidity, current circulation, waste disposal plumes and convergent boundaries between different water masses. ERTS-1 image radiance correlated well with Secchi depth and suspended sediment concentration. Circulation patterns observed by ERTS-1 during different parts of the tidal cycle, agreed well with predicted and measured currents throughout Delaware Bay. Convergent shear boundaries between different water masses were observed from ERTS-1. In several ERTS-1 frames, waste disposal plumes have been detected 36 miles off Delaware's Atlantic coast. The ERTS-1 results are being used to extend and verify hydrodynamic models of the bay, developed for predicting oil slick movement and estimating sediment transport.

  2. Sea truth and environmental characterization studies of Mobile Bay, Alabama, utilizing ERTS-1, data collection platforms

    NASA Technical Reports Server (NTRS)

    Schroeder, W. W.

    1977-01-01

    The paper reports on the scientific results obtained during a feasibility study that evaluated the potential of using ERTS data collection platforms (DCPs) in the coastal environment of Mobile Bay, Alabama. The utility of instrumented buoys operated in a coastal marine environment as ERTS DCPs is demonstrated. It is shown that these platforms are capable of providing both sea-truth data for ERTS imagery studies and time-series data for event monitoring and/or environmental characterization studies.

  3. Exploration for fossil and nuclear fuels from orbital altitudes. [results of ERTS program for oil exploration

    NASA Technical Reports Server (NTRS)

    Short, N. M.

    1974-01-01

    Results from the ERTS program pertinent to exploration for oil, gas, and uranium are discussed. A review of achievements in relevant geological studies from ERTS, and a survey of accomplishments oriented towards exploration for energy sources are presented along with an evaluation of the prospects and limitations of the space platform approach to fuel exploration, and an examination of continuing programs designed to prove out the use of ERTS and other space system in exploring for fuel resources.

  4. Interpretation of ERTS-MSS images of a Savanna area in eastern Colombia

    NASA Technical Reports Server (NTRS)

    Elberson, G. W. W.

    1973-01-01

    The application of ERTS-1 imagery for extrapolating existing soil maps into unmapped areas of the Llanos Orientales of Colombia, South America is discussed. Interpretations of ERTS-1 data were made according to conventional photointerpretation techniques. Most units delineated in the existing reconnaissance soil map at a scale of 1:250,000 could be recognized and delineated in the ERTS image. The methods of interpretation are described and the results obtained for specific areas are analyzed.

  5. Interpretation of Pennsylvania agricultural land use from ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Mcmurtry, G. J.; Petersen, G. W. (Principal Investigator); Wilson, A. D.

    1974-01-01

    The author has identified the following significant results. To study the complex agricultural patterns in Pennsylvania, a portion of an ERTS scene was selected for detailed analysis. Various photographic products were made and were found to be only of limited value. This necessitated the digital processing of the ERTS data. Using an unsupervised classification procedure, it was possible to delineate the following categories: (1) forest land with a northern aspect, (2) forest land with a southern aspect, (3) valley trees, (4) wheat, (5) corn, (6) alfalfa, grass, pasture, (7) disturbed land, (8) builtup land, (9) strip mines, and (10) water. These land use categories were delineated at a scale of approximately 1:20,000 on the line printer output. Land use delineations were also made using the General Electric IMAGE 100 interactive analysis system.

  6. ERTS-1 - Teaching us a new way to see.

    NASA Technical Reports Server (NTRS)

    Mercanti, E. P.

    1973-01-01

    The ERTS-1 payload is discussed, giving attention to three television cameras, which view the same area in three different spectral bands. The payload includes also a multispectral scanner subsystem and a data collection system which collects information from some 150 remote, unattended, instrumented ground platforms. Many government agencies use ERTS-1 data as integral parts of their ongoing programs. Through its EROS program, the Interior Department represents the largest single recipient and user agency of data obtained from NASA aircraft and spacecraft designed to gather repetitive information related to a wide variety of earth-science and natural-resources disciplines. Questions of environmental impact are considered together with applications in agriculture, forestry, marine resources, geography, and the survey of water resources.

  7. ERTS-1: Automated land-use mapping in lake watersheds

    NASA Technical Reports Server (NTRS)

    Chase, P. E. (Principal Investigator); Rogers, R. H.; Reed, L. E.; Smith, V. E.

    1974-01-01

    The author has identified the following significant results. ERTS-1 computer compatible tapes were used as a basis to generate land use maps in lake watersheds in southeastern Michigan. These maps, generated on a repetitive basis, provide information essential to governmental agencies concerned with planning and control of lake eutrophication. The ERTS mapping products included geometrically current land use map overlays at 1:250,000 and 1:48,000 scale and area measurement printouts. The printouts provide, within the watershed boundaries and by land use category, a quantitative measure of the amount of land, in square kilometers and acres. This quantitative measure of land use in watersheds is essential to the development and application of deterministic models, which compute nutrient flows into lakes and establish lake eutrophication rates.

  8. Arctic and subarctic environmental analyses utilizing ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Anderson, D. M. (Principal Investigator); Mckim, H. L.; Gatto, L. W.; Haugen, R. K.; Crowder, W. K.; Slaughter, C. W.; Marlar, T. L.

    1974-01-01

    The author has identified the following significant results. ERTS-1 imagery provides a means of distinguishing and monitoring estuarine surface water circulation patterns and changes in the relative sediment load of discharging rivers on a regional basis. Physical boundaries mapped from ERTS-1 imagery in combination with ground truth obtained from existing small scale maps and other sources resulted in improved and more detailed maps of permafrost terrain and vegetation for the same area. Snowpack cover within a research watershed has been analyzed and compared to ground data. Large river icings along the proposed Alaska pipeline route from Prudhoe Bay to the Brooks Range have been monitored. Sea ice deformation and drift northeast of Point Barrow, Alaska have been measured during a four day period in March and shore-fast ice accumulation and ablation along the west coast of Alaska have been mapped for the spring and early summer seasons.

  9. Applications of ERTS data to resource surveys of Alaska

    NASA Technical Reports Server (NTRS)

    Belon, A. E.; Miller, J. M.

    1974-01-01

    ERTS data affords a unique opportunity to perform urgently needed resource surveys and land use planning at a critical juncture in the history of Alaska's social and economic development. The available facilities for photographic, optical and digital processing of ERTS data are described, along with the interpretive techniques which have been developed. Examples of the applications of these facilities and techniques are given for three environmental disciplines: vegetation mapping for potential archeological sites; marine and sea ice surveys on the Alaskan continental shelf for the determination of surface circulation and sedimentation patterns and their effects on navigation, pollution assessment, fisheries, location of habors and construction of off-shore structures; snow surveys for inventories of water resources and flood potential in Alaska watersheds.

  10. Application of ERTS-1 Imagery to Flood Inundation Mapping

    NASA Technical Reports Server (NTRS)

    Hallberg, G. R.; Hoyer, B. E.; Rango, A.

    1973-01-01

    Ground data and a variety of low-altitude multispectral imagery were acquired for the East Nishnabotna River on September 14 and 15. This successful effort concluded that a near-visible infrared sensor could map inundated areas in late summer for at least three days after flood recession. ERTS-1 multispectral scanner subsystem (MSS) imagery of the area was obtained on September 18 and 19. Analysis of MSS imagery by IGSRSL, USGS, and NASA reinforced the conclusions of the low-altitude study while increasing the time period critical for imagery acquisition to at least 7 days following flood recession. The capability of satellite imagery to map late summer flooding at a scale of 1:250,000 is exhibited by the agreement of interpreted flood boundaries obtained from ERTS-1 imagery to boundaries mapped by low-altitude imagery and ground methods.

  11. Semi-automatic crop inventory from sequential ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Johnson, C. W.; Coleman, V. B.

    1973-01-01

    The detection of a newly introduced crop into the Imperial (California) Valley by sequential ERTS-1 imagery is proving that individual crop types can be identified by remote sensing techniques. Initial results have provided an extremely useful product for water agencies. A system for the identification of field conditions enables the production of a statistical summary within two to three days of receipt of the ERTS-1 imagery. The summary indicates the total acreage of producing crops and irrigated planted crops currently demanding water and further indicates freshly plowed fields that will be demanding water in the near future. Relating the field conditions to the crop calendar of the region by means of computer techniques will provide specific crop identification for the 8000 plus fields.

  12. Mapping of soil banks using ERTS-1 pictures

    NASA Technical Reports Server (NTRS)

    Ahmad, M. U.; Kantner, D. A.; Antalovich, J. W.

    1973-01-01

    Earth Resources Technology Satellite (ERTS-1) pictures of different wavelengths (MSS 4,5,6,7) were used in the study of two strip mine areas in southeastern Ohio. The first area was near Piedmont Lake and the second area was near New Lexington. Prints were examined under a binocular microscope and the gray tone was correlated with the actual ground conditions at several sites. For the New Lexington area, color infrared pictures taken at an elevation of 18,000 feet were also used for correlation with the ERTS-1 imagery. The results indicate that MSS 5 and 7 are most useful in defining the stripped land and show that the hydrological and soil characteristics are remarkably different than the surrounding lands.

  13. Mapping Atlantic coastal marshlands, Maryland, Georgia, using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Anderson, R. R.; Carter, V. L.; Mcginness, J. W., Jr.

    1973-01-01

    Eastern coastal marshes are the most extensive and productive in the United States. A relatively low cost, moderately accurate method is needed to map these areas for management and protection. Groundbased and low-altitude aircraft methods for mapping are time-consuming and quite expensive. The launch of NASA's Earth Resources Technology Satellite has provided an opportunity to test the feasibility of mapping wetlands using small scale imagery. The test sites selected were in Chesapeake Bay, Maryland, and Ossabaw Island, Georgia. Results of the investigation indicate that the following may be ascertained from ERTS imagery, enlarged to 1:250,000: (1) upper wetland boundary; (2) drainage pattern in the wetland; (3) plant communities; (4) ditching activities associated with agriculture; and (5) lagooning for water-side home development. Conclusions are that ERTS will be an excellent tool for many types of coastal wetland mapping.

  14. Application of NASA ERTS-1 satellite imagery in coastal studies

    NASA Technical Reports Server (NTRS)

    Magoon, O. T.; Berg, D. W. (Principal Investigator); Hallermeier, R. J.

    1973-01-01

    There are no author-identified significant results in this report. Review of ERTS-1 imagery indicates that it contains information of great value in coastal engineering studies. A brief introduction is given to the methods by which imagery is generated, and examples of its application to coastal engineering. Specific applications discussed include study of the movement of coastal and nearshore sediment-laden water masses and information for planning and construction in remote areas of the world.

  15. Cartographic evaluation of ERTS orbit and attitude data

    NASA Technical Reports Server (NTRS)

    Mcewen, R. B. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. Return beam vidicon corrected (bulk) images have been precisely enlarged and rectified to control at a scale of 1:500,000. The results closely approach National Map Accuracy Standards. A MSS scene corrected (precision) image has been prepared and printed by color lithography. This Lake Tahoe area scene is the first cartographic product from ERTS that was available for economical distribution to the public in large numbers.

  16. Environmental monitoring via the ERTS-1 Data Collection System.

    NASA Technical Reports Server (NTRS)

    Painter, J. E.; Seitner, J. E.

    1973-01-01

    The Data Collection System (DCS) provides users with near real-time environmental data from earth-based sensors relayed via the Earth Resources Technology Satellite (ERTS-1) to Goddard Space Flight Center. Data is received at Goddard at least twice per day from each sensor and distributed to users (who operate the sensors and transmitters) by mail and teletype. Data collection platforms are discussed together with DCS equipment and the ground receiving and processing equipment.

  17. Delineation of major soil associations using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Parks, W. L.; Bodenheimer, R. E.

    1973-01-01

    The delineation of a major soil association in the loess region of Obion County has been accomplished using ERTS-1 imagery. Channel 7 provides the clearest differentiation. The separation of other smaller soil associations in an intensive row crop agricultural area is somewhat more difficult. Soil differentiation has been accomplished visually as well as electronically using a scanning microdensitometer. Lower altitude aircraft imagery permits a more refined soil association identification and where imagery is of sufficient scale, even individual soils may be identified.

  18. Corrections of surface fissure effect on apparent resistivity measurements

    NASA Astrophysics Data System (ADS)

    Gance, J.; Sailhac, P.; Malet, J.-P.

    2015-02-01

    Electrical resistivity tomography (ERT) is a useful tool to detect and track water flow paths in the subsoil. However, measurements are strongly affected by subsurface heterogeneities such as fissures of different sizes and genesis (shrinking-swelling, macropores and deformation). In this work, we focus on surface fissures characterized by dimensions lower than the interelectrode spacing and correct their effect on apparent resistivity pseudo-sections by incorporating fissure geometry in the topography. We show that fissures with depths greater than 0.10 times the interelectrode spacing for a dipole-dipole array and equal to 0.16 for the gradient array and the Wenner-Schlumberger arrays create significant anomalies (greater than 5 per cent) in the pseudo-section. Surface fissure widths and dip angles have little effect with respect to the fissure depths which can increase the apparent resistivity up to 200 per cent. The clogging of the fissures with water or soil material decreases the anomaly effect linearly with the percentage of filling. The correction of apparent resistivity values is possible for relatively simple fissure geometries and only requires a manual survey of the surface fissures. It allows to improve the quality of the inverted resistivity section by mitigating the inversion artefacts and therefore a better interpretation.

  19. Combining human and computer interpretation capabilities to analyze ERTS imagery

    NASA Technical Reports Server (NTRS)

    Nichols, J. D.

    1973-01-01

    The human photointerpreter and the computer have complementary capabilities that are exploited in a computer-based data analysis system developed at the Forestry Remote Sensing Laboratory, University of California. This system is designed to optimize the process of extracting resource information from ERTS images. The human has the ability to quickly delineate gross differences in land classes, such as wildland, urban, and agriculture on appropriate ERTS images, and to further break these gross classes into meaningful subclasses. The computer, however, can more efficiently analyze point-by-point spectral information and localized textural information which can result in a much more detailed agricultural or wildland classification based on species composition and/or plant association. These human and computer capabilities have been integrated through the use of an inexpensive small scale computer dedicated to the interactive preprocessing of the human inputs and the display of raw ERTS images and computer classified images. The small computer is linked to a large scale computer system wherein the bulk of the statistical work and the automatic point-by-point classification is done.

  20. ERTS imagery applied to Alaskan coastal problems. [surface water circulation

    NASA Technical Reports Server (NTRS)

    Wright, F. F.; Sharma, G. D.; Burbank, D. C.; Burns, J. J.

    1974-01-01

    Along the Alaska coast, surface water circulation is relatively easy to study with ERTS imagery. Highly turbid river water, sea ice, and fluvial ice have proven to be excellent tracers of the surface waters. Sea truth studies in the Gulf of Alaska, Cook Inlet, Bristol Bay, and the Bering Strait area have established the reliability of these tracers. ERTS imagery in the MSS 4 and 5 bands is particularly useful for observing lower concentrations of suspended sediment, while MSS 6 data is best for the most concentrated plumes. Ice features are most clearly seen on MSS 7 imagery; fracture patterns and the movement of specific floes can be used to map circulation in the winter when runoff is restricted, if appropriate allowance is made for wind influence. Current patterns interpreted from satellite data are only two-dimensional, but since most biological activity and pollution are concentrated near the surface, the information developed can be of direct utility. Details of Alaska inshore circulation of importance to coastal engineering, navigation, pollution studies, and fisheries development have been clarified with satellite data. ERTS has made possible the analysis of circulation in many parts of the Alaskan coast.

  1. Facilitating the exploitation of ERTS imagery using snow enhancement techniques

    NASA Technical Reports Server (NTRS)

    Wobber, F. J. (Principal Investigator); Martin, K. R.; Amato, R. V.

    1973-01-01

    The author has identified the following significant results. New fracture detail within New England test area has been interpreted from ERTS-1 images. Comparative analysis of snow-free imagery (1096-15065 and 1096-15072) has demonstrated that MSS bands 5 and 7 supply the greatest amount of geological fracture detail. Interpretation of the first snow-covered ERTS-1 images (1132-15074 and 1168-15065) in correlation with ground snow depth data indicates that a heavy blanket of snow (less than 9 inches) accentuates major structural features while a light dusting (greater than 1 inch) accentuates more subtle topographic expressions. Snow cover was found to accentuate drainage patterns which are indicative of lithological and/or structural variations. Snow cover provided added enhancement for viewing and detecting topographically expressed fractures and faults. A recent field investigation was conducted within the New England test area to field check lineaments observed from analysis of ERTS-1 imagery, collect snow depth readings, and obtain structural joint readings at key locations in the test area.

  2. ERTS-1 data applications to Minnesota forest land use classification

    NASA Technical Reports Server (NTRS)

    Sizer, J. E. (Principal Investigator); Eller, R. G.; Meyer, M. P.; Ulliman, J. J.

    1973-01-01

    The author has identified the following significant results. Color-combined ERTS-1 MSS spectral slices were analyzed to determine the maximum (repeatable) level of meaningful forest resource classification data visually attainable by skilled forest photointerpreters for the following purposes: (1) periodic updating of the Minnesota Land Management Information System (MLMIS) statewide computerized land use data bank, and (2) to provide first-stage forest resources survey data for large area forest land management planning. Controlled tests were made of two forest classification schemes by experienced professional foresters with special photointerpretation training and experience. The test results indicate it is possible to discriminate the MLMIS forest class from the MLMIS nonforest classes, but that it is not possible, under average circumstances, to further stratify the forest classification into species components with any degree of reliability with ERTS-1 imagery. An ongoing test of the resulting classification scheme involves the interpretation, and mapping, of the south half of Itasca County, Minnesota, with ERTS-1 imagery. This map is undergoing field checking by on the ground field cooperators, whose evaluation will be completed in the fall of 1973.

  3. Analysis of ERT data of geoelectrical permafrost monitoring on Hoher Sonnblick (Austrian Central Alps)

    NASA Astrophysics Data System (ADS)

    Pfeiler, Stefan; Schöner, Wolfgang; Reisenhofer, Stefan; Ottowitz, David; Jochum, Birgit; Kim, Jung-Ho; Hoyer, Stefan; Supper, Robert; Heinrich, Georg

    2016-04-01

    In the Alps infrastructure facilities such as roads, routes or buildings are affected by the changes of permafrost, which often cause enormous reparation costs. Investigation on degradation of Alpine Permafrost in the last decade has increased, however, the understanding of the permafrost changes inducing its atmospheric forcing processes is still insufficient. Within the project ATMOperm the application of the geoelectrical method to estimate thawing layer thickness for mountain permafrost is investigated near the highest meteorological observatory of Austria on the Hoher Sonnblick. Therefore, it is necessary to further optimize the transformation of ERT data to thermal changes in the subsurface. Based on an innovative time lapse inversion routine for ERT data (Kim J.-H. et al 2013) a newly developed data analysis software tool developed by Kim Jung-Ho (KIGAM) in cooperation with the Geophysics group of the Geological Survey of Austria allows the statistical analysis of the entire sample set of each and every data point measured by the geoelectrical monitoring instrument. This gives on the one hand of course an enhanced opportunity to separate between „good" and „bad" data points in order to assess the quality of measurements. On the other hand, the results of the statistical analysis define the impact of every single data point on the inversion routine. The interpretation of the inversion results will be supplemented by temperature logs from selected boreholes along the ERT profile as well as climatic parameters. KIM J.-H., SUPPER R., TSOURLOS P. and YI M.-J.: Four-dimensional inversion of resistivity monitoring data through Lp norm minimizations. - Geophysical Journal International, 195(3), 1640-1656, 2013. Doi: 10.1093/gji/ggt324. (No OA) Acknowledgments: The geoelectrical monitoring on Hoher Sonnblick has been installed and is operated in the frame of the project ATMOperm (Atmosphere - permafrost relationship in the Austrian Alps - atmospheric extreme

  4. An interdisciplinary analysis of ERTS data for Colorado mountain environments using ADP techniques. An early analysis of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Hoffer, R. M.; Landgrebe, D. A. (Principal Investigator); Goodrick, F. E.

    1972-01-01

    There are no author-identified significant results in this report. The principal problem encountered has been the lack of good quality, small scale baseline photography for the test areas. Analysis of the ERTS-1 data for the San Juan Site will emphasize development of a preliminary spectral classification defining grass cover categories, and then selection of subframes for intensive investigation of the forestry, geologic, and hydrologic properties of the area. Primary work has been devoted to the selection and digitization of areas for topographic modeling, and compilation of ground based data maps necessary for computer analysis. Study effort has emphasized: geomorphic features; macro-vegetation; micro-vegetation; snow-hydrology; insect/disease damage; and blow-down. Analysis of a frame of the Lake Texoma area indicates a great deal of potential in the analysis and interpretation of ERTS imagery. Preliminary results of investigations of geologic, forest, range, cropland, and water resources of the area are summarized.

  5. Artic and subarctic environmental analyses utilizing ERTS-1 imagery. Cold regions environmental analysis based on ERTS-1 imagery (preprint)

    NASA Technical Reports Server (NTRS)

    Anderson, D. M. (Principal Investigator); Haugen, R. K.; Gatto, L. W.; Slaughter, C. W.; Marlar, T. L.; Mckim, H. L.

    1972-01-01

    There are no author-identified significant results in this report. An overriding problem in arctic and subarctic environmental research has been the absence of long-term observational data and the sparseness of geographical coverage of existing data. A first look report is presented on the use of ERTS-1 imagery as a major tool in two large area environmental studies: (1) investigation of sedimentation and other nearshore marine processes in Cook Inlet, Alaska; and (2) a regional study of permafrost regimes in the discontinuous permafrost zone of Alaska. These studies incorporate ground truth acquisition techniques that are probably similar to most ERTS investigations. Studies of oceanographic processes in Cook Inlet will be focused on seasonal changes in nearshore bathymetry, tidal and major current circulation patterns, and coastal sedimentation processes, applicable to navigation, construction, and maintenance of harbors. Analyses will be made of the regional permafrost distribution and regimes in the Upper Koyukuk-Kobuk River area located in NW Alaska.

  6. Assessment of the Efficiency of Consolidation Treatment through Injections of Expanding Resins by Geotechnical Tests and 3D Electrical Resistivity Tomography

    PubMed Central

    Apuani, T.; Giani, G. P.; d'Attoli, M.; Fischanger, F.; Morelli, G.; Ranieri, G.; Santarato, G.

    2015-01-01

    The design and execution of consolidation treatment of settled foundations by means of injection of polyurethane expanding resins require a proper investigation of the state of the foundation soil, in order to better identify anomalies responsible for the instability. To monitor the injection process, a procedure has been developed, which involves, in combination with traditional geotechnical tests, the application of a noninvasive, geophysical technique based on the electrical resistivity, which is strongly sensitive to presence of water or voids. Three-dimensional electrical resistivity tomography is a useful tool to produce effective 3D images of the foundation soils before, during, and after the injections. The achieved information allows designing the consolidation scheme and monitoring its effects on the treated volumes in real time. To better understand the complex processes induced by the treatment and to learn how variations of resistivity accompany increase of stiffness, an experiment was carried out in a full-scale test site. Injections of polyurethane expanding resin were performed as in real worksite conditions. Results confirm that the experimented approach by means of 3D resistivity imaging allows a reliable procedure of consolidation, and geotechnical tests demonstrate the increase of mechanical stiffness. PMID:26167521

  7. Assessment of the Efficiency of Consolidation Treatment through Injections of Expanding Resins by Geotechnical Tests and 3D Electrical Resistivity Tomography.

    PubMed

    Apuani, T; Giani, G P; d'Attoli, M; Fischanger, F; Morelli, G; Ranieri, G; Santarato, G

    2015-01-01

    The design and execution of consolidation treatment of settled foundations by means of injection of polyurethane expanding resins require a proper investigation of the state of the foundation soil, in order to better identify anomalies responsible for the instability. To monitor the injection process, a procedure has been developed, which involves, in combination with traditional geotechnical tests, the application of a noninvasive, geophysical technique based on the electrical resistivity, which is strongly sensitive to presence of water or voids. Three-dimensional electrical resistivity tomography is a useful tool to produce effective 3D images of the foundation soils before, during, and after the injections. The achieved information allows designing the consolidation scheme and monitoring its effects on the treated volumes in real time. To better understand the complex processes induced by the treatment and to learn how variations of resistivity accompany increase of stiffness, an experiment was carried out in a full-scale test site. Injections of polyurethane expanding resin were performed as in real worksite conditions. Results confirm that the experimented approach by means of 3D resistivity imaging allows a reliable procedure of consolidation, and geotechnical tests demonstrate the increase of mechanical stiffness. PMID:26167521

  8. An image reconstruction framework based on boundary voltages for ultrasound modulated electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Song, Xizi; Xu, Yanbin; Dong, Feng

    2016-11-01

    A new image reconstruction framework based on boundary voltages is presented for ultrasound modulated electrical impedance tomography (UMEIT). Combining the electric and acoustic modalities, UMEIT reconstructs the conductivity distribution with more measurements with position information. The proposed image reconstruction framework begins with approximately constructing the sensitivity matrix of the imaging object with inclusion. Then the conductivity is recovered from the boundary voltages of the imaging object. To solve the nonlinear inverse problem, an optimization method is adopted and the iterative method is tested. Compared with that for electrical resistance tomography (ERT), the newly constructed sensitivity matrix is more sensitive to the inclusion, even in the center of the imaging object, and it contains more effective information about the inclusions. Finally, image reconstruction is carried out by the conjugate gradient algorithm, and results show that reconstructed images with higher quality can be obtained for UMEIT with a faster convergence rate. Both theory and image reconstruction results validate the feasibility of the proposed framework for UMEIT and confirm that UMEIT is a potential imaging technique.

  9. An ECT/ERT dual-modality sensor for oil-water two-phase flow measurement

    SciTech Connect

    Wang, Pitao; Wang, Huaxiang; Sun, Benyuan; Cui, Ziqiang; Huang, Wenrui

    2014-04-11

    This paper presents a new sensor for ECT/ERT dual-modality system which can simultaneously obtain the permittivity and conductivity of the materials in the pipeline. Quasi-static electromagnetic fields are produced by the inner electrodes array sensor of electrical capacitance tomography (ECT) system. The results of simulation show that the data of permittivity and conductivity can be simultaneously obtained from the same measurement electrode and the fusion of two kinds of data may improve the quality of the reconstructed images. For uniform oil-water mixtures, the performance of designed dual-modality sensor for measuring the various oil fractions has been tested on representative data and the results of experiments show that the designed sensor broadens the measurement range compared to single modality.

  10. Comparison of soil thickness in a zero-order basin in the Oregon Coast Range using a soil probe and electrical resistivity tomography

    USGS Publications Warehouse

    Morse, Michael S.; Lu, Ning; Godt, Jonathan W.; Revil, André; Coe, Jeffrey A.

    2012-01-01

    Accurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration. One important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding. In this paper, we investigate the direct current (DC) resistivity method as a tool for quickly estimating soil thickness over a steep (33–40°) zero-order basin in the Oregon Coast Range, a landslide prone region. Point measurements throughout the basin showed bedrock depths between 0.55 and 3.2 m. Resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92%. Resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70%. Results from the laboratory measurements and point-depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil-bedrock interface. A decreasing-with-depth resistivity contrast was apparent at the interface in the modeling results. At the field site, three transects were surveyed where coincident ground truth measurements of bedrock depth were available, to test the accuracy of the method. The same decreasing-with-depth resistivity trend that was apparent in the model was also present in the survey data. The resistivity contour of between 1,000 and 2,000 Ωm that marked the top of the contrast was our interpreted bedrock depth in the survey data. Kriged depth-to-bedrock maps were created from both the field-measured ground truth obtained with a soil probe and interpreted depths from the resistivity tomography, and these were compared for accuracy graphically. Depths were interpolated as far as 16.5 m laterally from the resistivity survey lines with root mean squared error (RMSE) = 27 cm between the measured and interpreted depth at those locations. Using several transects and analysis of the subsurface

  11. Shallow subsurface imaging of the Piano di Pezza active normal fault (central Italy) by high-resolution refraction and electrical resistivity tomography coupled with time domain electromagnetic data

    NASA Astrophysics Data System (ADS)

    Villani, Fabio; Tulliani, Valerio; Fierro, Elisa; Sapia, Vincenzo; Civico, Riccardo

    2015-04-01

    The Piano di Pezza fault is the north-westernmost segment of the >20 km long Ovindoli-Pezza active normal fault-system (central Italy). Although existing paleoseismic data document high vertical Holocene slip rates (~1 mm/yr) and a remarkable seismogenic potential of this fault, its subsurface setting and Pleistocene cumulative displacement are still poorly known. We investigated for the first time by means of high-resolution seismic and electrical resistivity tomography coupled with time domain electromagnetic (TDEM) measurements the shallow subsurface of a key section of the Piano di Pezza fault. Our surveys cross a ~5 m-high fault scarp that was generated by repeated surface-rupturing earthquakes displacing some Late Holocene alluvial fans. We provide 2-D Vp and resistivity images which clearly show significant details of the fault structure and the geometry of the shallow basin infill material down to 50 m depth. We can estimate the dip (~50°) and the Holocene vertical displacement of the master fault (~10 m). We also recognize in the hangingwall some low-velocity/low-resistivity regions that we relate to packages of colluvial wedges derived from scarp degradation, which may represent the record of several paleo-earthquakes older than the Late Holocene events previously recognized by paleoseismic trenching. Conversely, due to the limited investigation depth of seismic and electrical tomography, the estimation of the cumulative amount of Pleistocene throw is hampered. Therefore, to increase the depth of investigation, we performed 7 TDEM measurements along the electrical profile using a 50 m loop size both in central and offset configuration. The recovered 1-D resistivity models show a good match with 2-D resistivity images in the near surface. Moreover, TDEM inversion results indicate that in the hangingwall, ~200 m away from the surface fault trace, the carbonate pre-Quaternary basement may be found at ~90-100 m depth. The combined approach of electrical and

  12. A study on the erosion of Niigata Beach from ERTS-A imagery

    NASA Technical Reports Server (NTRS)

    Maruyasu, T.

    1973-01-01

    Coastal erosion of Niigata Beach, Japan as a result of construction works is discussed. The application of ERTS-1 imagery for defining and monitoring the extent of the erosion is described. The contribution of ERTS-1 data to studies leading to effective erosion control methods are reported.

  13. Utilization of ERTS-1 data in North Carolina. [forested wetlands, water management, and land use

    NASA Technical Reports Server (NTRS)

    Welby, C. W. (Principal Investigator); Lammi, J. O.; Carson, R. J., III

    1973-01-01

    The author has identified the following significant results. ERTS-1 imagery has been used to study forested wetlands, dynamic processes off Coastal North Carolina, and land use patterns in the Wilmington, North Carolina area. The thrust of the investigation is still involvement of state and regional agencies in the use of ERTS-1 imagery in solving some of their day-to-day problems.

  14. Utilizing ERTS imagery to detect plant diseases and nutrient deficiencies, soil types and soil moisture levels

    NASA Technical Reports Server (NTRS)

    Parks, W. L. (Principal Investigator); Sewell, J. I.; Hilty, J. W.; Rennie, J. C.

    1973-01-01

    The author has identified the following significant results. The delineation of soil associations and detection of drainage patterns, erosion and sedimentation through the use of ERTS-1 imagery are shown. Corn blight and corn virus could not be detected from ERTS-1 and detection of forest composition was at a very low probability.

  15. Mapping coastal vegetation, land use and environmental impact from ERTS-1. [Delaware Bay area

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Vegetation map overlays at a scale of 1:24,000 compiled by multispectral analysis from NASA aircraft imagery for all of Delaware's wetlands are being used as ground truth for ERTS-1 mapping and by state agencies for wetlands management. Six major vegetation species were discriminated and mapped, including percentages of minor species. Analogue enhancements of wetlands vegetation and dredge-fill operations have been produced using General Electric's GEMS data processing and ERTS-1 false color composites. Digital, thematic land use, and vegetation mapping of entire Delaware Bay area is in progress using Bendix Corporation's Earth Resources Data System and ERTS-1 digital tapes. Statistical evaluation of target-group selection reliability has been completed. Three papers have been published on ERTS-1 coastal vegetation and land use. Local and state officials are participating in the ERTS-1 program as co-investigators.

  16. Land use mapping and change detection using ERTS imagery in Montgomery County, Alabama

    NASA Technical Reports Server (NTRS)

    Wilms, R. P.

    1973-01-01

    The feasibility of using remotely sensed data from ERTS-1 for mapping land use and detecting land use change was investigated. Land use information was gathered from 1964 air photo mosaics and from 1972 ERTS data. The 1964 data provided the basis for comparison with ERTS-1 imagery. From this comparison, urban sprawl was quite evident for the city of Montgomery. A significant trend from forestland to agricultural was also discovered. The development of main traffic arteries between 1964 and 1972 was a vital factor in the development of some of the urban centers. Even though certain problems in interpreting and correlating land use data from ERTS imagery were encountered, it has been demonstrated that remotely sensed data from ERTS is useful for inventorying land use and detecting land use change.

  17. Geologic hypotheses of Lake Tanganyika region, Zaire, drawn from ERTS imagery

    NASA Technical Reports Server (NTRS)

    Wolyce, U.; Ilunga, S.

    1974-01-01

    Based on initial work in the Lake Tanganyika area of eastern Zaire, it has been concluded that ERTS imagery is extremely useful for reconnaissance level geologic mapping and analysis in this region of the humid tropics. In particular, ERTS imagery has proven useful for recognizing and mapping regional structural units, for recognizing major structural features, and for arriving at some preliminary hypotheses about the mineral potential of the area. Results so far indicate that ERTS imagery can make a major contribution to the development of the mineral resources of the country. Research has concentrated on applications of ERTS imagery in the field of cartography, geology, forestry, hydrology and agriculture. For the work in geology, a test site was chosen in eastern Zaire on the shore of Lake Tanganyika in the vicinity of the Lukuga River. This area was selected because of its varied geology and the existence of two frames of cloud-free ERTS imagery.

  18. Combining indoors thermo-hygric survey, thermal imaging and Electrical Resistivity Tomography through GIS for the characterization of moisture in historic buildings

    NASA Astrophysics Data System (ADS)

    Gomez-Heras, Miguel; Garcia-Morales, Soledad; Lopez-Gonzalez, Laura; Ortiz de Cosca, Raquel Otero

    2015-04-01

    This paper presents the results of the combination, through a GIS, of environmental indoors thermo-hygric parameters and Electrical Resistivity Tomography in the hermit of "Humilladero", a small historic building in the city of Avila (Spain). The Hermit of "humilladero" was built 1548 - 1550 and it underwent several refurbishment works throughout its history until the present day. The hermit is formed by two rooms and a basement: The hermit per se, a sacristy which was added at a later stage towards the east of the hermit and the basement excavated under the sacristy in 1990. The south wall is nowadays half buried by the adjacent street pavement and a staircase attached to the east wall. The walls are built with granite ashlars and the whole building displays severe moisture-related damage, including granular disaggregation of mortars and some ashlars. The most affected areas are the ones buried under the street towards the south and the staircase towards the east where liquid water appears from time to time due to infiltrations through the ground. A mesh of thermo-hygric measurements of the indoors environment of the hermit was carried out to detect the humidity focal points, in addition to Electrical Resistivity Tomography and Infrared thermography on the walls. All these data was uploaded to a GIS (ArcGIS) together with a photogrammetric model of the decayed areas. The combination of the information in the GIS improved decay maps and allowed a better diagnosis of the building moisture distribution and causes. Research funded by Geomateriales 2 S2013/MIT-2914 and CEI Moncloa (UPM, UCM, CSIC) through a PICATA contract and the equipment from RedLAbPAt Network

  19. Fluid circulation pattern inside La Soufrière volcano (Guadeloupe) inferred from combined electrical resistivity tomography, self-potential, soil temperature and diffuse degassing measurements

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Finizola, A.; Peltier, A.; Delcher, E.; Komorowski, J.-C.; Di Gangi, F.; Borgogno, G.; Passarella, M.; Trovato, C.; Legendre, Y.

    2014-11-01

    After a drastic decline in 1983, hydrothermal activity at La Soufrière lava dome (Guadeloupe, Lesser Antilles) has been progressively increasing in the summit area since 1992, raising the threat of a renewed eruptive activity. To better constrain the geometry of the hydrothermal system, an extensive high-resolution self-potential survey was performed on the dome and three multi-method profiles combining electrical resistivity tomography, self-potential, ground thermometry and soil CO2 diffuse degassing measurements were carried out to cover its southern periphery in January 2011. Results indicate that hydrothermal ascending flows are currently restricted to a proximal area including the dome and its very vicinity. The extension of hydrothermal alteration inferred from electrical resistivity tomography reflects the presence of a heat source just below the dome. A first-order correction of topography-related self-potential variations allows the identification of major hydrothermal fluid circulations pathways, as well as significant meteoric infiltration zones. Local shifting of hydrothermal fluids towards the dome periphery is favored by the presence of major axes. The regional La Ty fault appears as the major axis draining large volumes of hydrothermal and magmatic fluids. However hydrothermal activity remains confined inside a collapse structure surrounding the dome, that formed in the last 9000 years as a result of recurrent edifice collapses, the latest occurring at the onset of the 1530 AD eruption. The combination of these qualitative results with structural analysis leads to a synthetic model of magmatic and hydrothermal fluids circulation inside the dome, which may be useful for the assessment of potential hazards associated with a renewal of fluid pressurization, and a possibly associated partial flank-failure.

  20. Non-stationarity of electrical resistivity and soil moisture relationship in heterogeneous soil system: a case study

    NASA Astrophysics Data System (ADS)

    Michot, D.; Thomas, Z.; Adam, I.

    2015-09-01

    Root uptake is the most decisive key in water transfer involving soil and vegetation. It depends on water availability which can be evaluated by punctual measurements. Additionally, surface geophysical methods such as Electrical Resistivity Tomography (ERT) provide larger spatial scales. This paper focuses on investigating temporal and spatial soil moisture changes, along a toposequence crossed by a hedgerow, using ERT and punctual measurements. 10 ERT were performed over the studied period for a 28 m long transect and compared to matric potential and groundwater level measurements. Soil Volumetric Water Content (VWC) was predicted using two methods (i) from ER using Waxman and Smits model (ii) and from matric potential using experimental retention curve fitted by Van Genuchten model. Probability Density Functions (Pdfs) of our set of data show that the largest change, in mean values of ER as well as matric potential, was observed in the topsoil layer. We then analyzed the consistency between ER and punctual measurements in this layer by extracting the arrays in the junction between ER grids and punctual measurements. Pdfs of ER maps at each monitoring time (from T01 to T10) were also calculated to select the more contrasted distributions corresponding to the wettest (T06) and driest states (T10). Results of ER were consistent with matric potential measurements with two different behaviors for locations inside and outside the root zone. A strong correlation (r = 0.9) between VWC values from Waxman and Smits model and those obtained from retention curve was observed outside the root zone. The heterogeneous soil system inside the root zone shows a different pattern in this relationship. The shift in the relationship between ER and soil moisture for the locations outside and inside the root zone highlights the non-stationarity in heterogeneous soil system. Such systems were actually related to the high hedgerow root density and also to a particular topographical

  1. Skylab S192 data evaluation: Comparisons with ERTS-1 results. [classification results using ERTS-1 and Skylab MSS data over Holt County, Nebraska agricultural area

    NASA Technical Reports Server (NTRS)

    Chang, C. Y.

    1974-01-01

    The author has identified the following significant results. The Skylab S192 data was evaluated by: (1) comparing the classification results using S192 and ERTS-1 data over the Holt County, Nebraska agricultural study area, and (2) investigating the impact of signal-to-noise ratio on classification accuracies using registered S192 and ERTS-1 data. Results indicate: (1) The classification accuracy obtained on S192 data using its best subset of four bands can be expected to be as high as that on ERTS-1 data. (2) When a subset of four S192 bands that are spectrally similar to the ERTS-1 bands was used for classification, an obvious deterioration in the classification accuracy was observed with respect to the ERTS-1 results. (3) The thermal bands 13 and 14 as well as the near IR bands were found to be relatively important in the classification of agricultural data. Although bands 11 and 12 were highly correlated, both were invariably included in the best subsets of the band sizes, four and beyond, according to the divergence criterion. (4) The differentiation of corn from popcorn was difficult on both S192 and ERTS-1 data acquired at an early summer date. (5) The results on both sets of data indicate that it was relatively easy to differentiate grass from any other class.

  2. Multidisciplinary applications of ERTS and Skylab data in Ohio

    NASA Technical Reports Server (NTRS)

    Sweet, D. C.; Pincura, P. G.; Meier, C. J.; Garrett, G. B.; Herd, L. O.; Dowdy, J. M.; Anderson, D. M.; Wukelic, G. E.; Stephan, J. G.; Smail, H. E.

    1974-01-01

    Experimental studies of ERTS-1 and Skylab earth resources data, in combination with correlative aircraft and on-site data, for environmental quality, land use, and resource management applications in Ohio show several areas of operational promise. Prime data use candidates demonstrated to date include definition and enforcement of surface mining (all minerals) legislation; Lake Erie modeling/management; land use classification and mapping studies at state, regional, and localized levels; and resources' inventories particularly of forested areas on both regional (multicounty) and localized scales.

  3. Quantitative water quality with ERTS-1. [Kansas water resources

    NASA Technical Reports Server (NTRS)

    Yarger, H. L.; Mccauley, J. R.; James, G. W.; Magnuson, L. M.; Marzolf, G. R.

    1974-01-01

    Analyses of ERTS-1 MSS computer compatible tapes of reservoir scenes in Kansas along with ground truth show that MSS bands and band ratios can be used for reliable prediction of suspended loads up to at least 900 ppm. The major reservoirs in Kansas, as well as in other Great Plains states, are playing increasingly important roles in flood control, recreation, agriculture, and urban water supply. Satellite imagery is proving useful for acquiring timely low cost water quality data required for optimum management of these fresh water resources.

  4. ERTS-C (Landsat 3) cryogenic heat pipe experiment definition

    NASA Technical Reports Server (NTRS)

    Brennan, P. J.; Kroliczek, E. J.

    1975-01-01

    A flight experiment designed to demonstrate current cryogenic heat pipe technology was defined and evaluated. The experiment package developed is specifically configured for flight aboard an ERTS type spacecraft. Two types of heat pipes were included as part of the experiment package: a transporter heat pipe and a thermal diode heat pipe. Each was tested in various operating modes. Performance data obtained from the experiment are applicable to the design of cryogenic systems for detector cooling, including applications where periodic high cooler temperatures are experienced as a result of cyclic energy inputs.

  5. Facilitating the exploitation of ERTS imagery using snow enhancement techniques

    NASA Technical Reports Server (NTRS)

    Wobber, F. J. (Principal Investigator); Martin, K. R.; Sheffield, C.; Russell, O.; Amato, R. V.

    1973-01-01

    The author has identified the following significant results. EarthSat has established an effective mail-based method for obtaining timely ground truth (snow depth) information over an extensive area. The method is both efficient and inexpensive compared with the cost of a similarly scaled direct field checking effort. Additional geological information has been acquired which is not shown in geological maps in the area. Excellent quality snow-free ERTS-1 transparencies of the test areas have been received and are being analyzed.

  6. An ERTS-1 investigation for Lake Ontario and its basin

    NASA Technical Reports Server (NTRS)

    Polcyn, F. C.; Falconer, A. (Principal Investigator); Wagner, T. W.; Rebel, D. L.

    1975-01-01

    The author has identified the following significant results. Methods of manual, semi-automatic, and automatic (computer) data processing were evaluated, as were the requirements for spatial physiographic and limnological information. The coupling of specially processed ERTS data with simulation models of the watershed precipitation/runoff process provides potential for water resources management. Optimal and full use of the data requires a mix of data processing and analysis techniques, including single band editing, two band ratios, and multiband combinations. A combination of maximum likelihood ratio and near-IR/red band ratio processing was found to be particularly useful.

  7. Geology and forestry classification from ERTS-1 digital data

    NASA Technical Reports Server (NTRS)

    Lawrence, R. D.; Herzog, J. H.

    1975-01-01

    Computer classifications into seven and ten classes of two areas in central Oregon of interest to geology and forestry demonstrate the extraction of information from ERTS-1 data. The area around Newberry Caldera was classified into basalt, rhyolite obsidian, pumice flats, Newberry pumice, ponderosa pine, lodgepole pine, and water classes. The area around Mt. Washington was classified into two basalts, three forest, two clearcut, burn, snow, and water classes. Both also include an unclassified category. Significant details that cannot be extracted from photographic reconstitutions of the data emerge from these classifications, such as moraine locations and paleowind directions. Spectral signatures for the various rocks are comparable to those published elsewhere.

  8. Automated strip mine and reclamation mapping from ERTS. [Ohio coal

    NASA Technical Reports Server (NTRS)

    Pettyjohn, W. A.; Rogers, R. H.; Reed, L. E.

    1974-01-01

    In response to the urgent need for a faster and more economical means of generating strip mine and reclamation maps, a study was conducted to evaluate the suitability of using ERTS computer compatible tape for automatic mapping. The procedure uses computer target spectral recognition techniques as a basis for classification. The area encompassed by this investigation includes five counties in eastern Ohio that comprise nearly 7,500 square kilometers (3,000 square miles). The counties have been disrupted by coal mining since the early 1800's, and strip mining has been practiced in all of them. The environmental effects of strip mining are also discussed.

  9. Automatic interpretation of ERTS data for forest management

    NASA Technical Reports Server (NTRS)

    Kirvida, L.; Johnson, G. R.

    1973-01-01

    Automatic stratification of forested land from ERTS-1 data provides a valuable tool for resource management. The results are useful for wood product yield estimates, recreation and wild life management, forest inventory and forest condition monitoring. Automatic procedures based on both multi-spectral and spatial features are evaluated. With five classes, training and testing on the same samples, classification accuracy of 74% was achieved using the MSS multispectral features. When adding texture computed from 8 x 8 arrays, classification accuracy of 99% was obtained.

  10. Natural resources inventory and monitoring in Oregon with ERTS imagery

    NASA Technical Reports Server (NTRS)

    Simonson, G. H.; Paine, D. P.; Poulton, C. E.; Lawrence, R. D.; Sherzog, J. H.; Murray, R. J.

    1973-01-01

    Multidiscipline team interpretation of ERTS satellite and highflight imagery is providing resource and land use information needed for land use planning in Oregon. A coordinated inventory of geology, soil-landscapes, forest and range vegetation, and land use for Crook County, illustrates the value of this approach for broad area and state planning. Other applications include mapping fault zones, inventory of forest clearcut areas, location of forest insect damage, and monitoring irrigation development. Computer classification is being developed for use in conjunction with visual interpretation.

  11. Lake eutrophication as indicated by ERTS satellite imagery

    NASA Technical Reports Server (NTRS)

    Scherz, J. P.; Van Domelen, J. F.; Holtje, K.; Johnson, W.

    1975-01-01

    Light reflectance from water in the laboratory always correlates to the water quality parameter of turbidity. This turbidity is caused by suspended solids in the water and for a particular type of material there is a good correlation between the weight of these suspended solids and turbidity. However, this correlation is different for different types of material. When this suspended material is living green matter as in an eutrophic lake, the changes in reflectance can be detected as changes in brightness on a particular aerial image. Two test sites have shown that there is indeed a good correlation between the brightness on an ERTS image and lake eutrophication.

  12. Oceanic turbidity and chlorophyll as inferred from ERTS-1 observations

    NASA Technical Reports Server (NTRS)

    Curran, R. J.

    1973-01-01

    Spectral signatures of phytoplankton and other obscuring effects are considered in order to determine how to best use satellite data. The results of this study were then used to analyze the spectral data obtained from the ERTS-1 multispectral scanner (MSS). The analyzed satellite data were finally compared with surface ship measurements of chlorophyll concentration. It was found that the effects of water turbidity on the multispectral imagery can be discriminated by rationing the two shortest wavelength channels so that the effect of phytoplankton is enhanced.

  13. Mapping a Pristine Glaciofluvial Aquifer on the Canadian Shield Using Ground-Penetrating Radar and Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Graves, L. W.; Shirokova, V.; Bank, C.

    2013-12-01

    Our study aims to construct a 3D structural model of an unconfined pristine aquifer in Laurentian Hills, Ontario, Canada. The stratigraphy of the study site, which covers about 5400 square meters, features reworked glaciofluvial sands and glacial till on top of Canadian Shield bedrock. A network of 25 existing piezometers provides ground-truth. We used two types of geophysical surveys to map the water table and the aquifer basin. Ground-penetrating radar (GPR) collected 40 profiles over distances up to 140 meters using 200MHz and 400MHz antennas with a survey wheel. The collected radargrams show a distinct reflective layer, which can be mapped to outcrops of glacial till within the area. This impermeable interface forms the aquitard. Depths of the subsurface features were calculated using hyperbolic fits on the radargrams in Matlab by determining wave velocity then converting measured two-way-time to depth. Electrical resistivity was used to determine the water table elevations because the unconfined water table did not reflect the radar waves. 20 resistivity profiles were collected in the same area using Wenner-Alpha and dipole-dipole arrays with both 24 and 48 electrodes and for 0.5, 0.75, 1.0 and 2.0 meter spacing. The inverted resistivity models show low resistivity values (<1000 Ohm.m) below 2 to 5 meter depths and higher resistivity values (2000-6000 Ohm.m) above 1 to 2 meter depths. These contrasting resistivity values correspond to saturated and wet sand (lower resistivity) to dry sand (higher resistivity); a correlation we could verify with several bore-hole logs. The water table is marked on the resistivity profiles as a steep resistivity gradient, and the depth can be added to the comprehensive 3D model. This model also incorporates hydrogeological characteristics and geochemical anomalies found within the aquifer. Ongoing seasonal and annual monitoring of the aquifer using geophysical methods will bring a fourth dimension to our understanding of this

  14. Analysis study of multispectral data, ERTS-A, from an area in West Pakistan

    NASA Technical Reports Server (NTRS)

    Schmidt, R. G. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Geomorphic features related to a known porphyry copper deposit at Saindak, western Chagai District, Pakistan, are easily distinguished on ERTS-1 images. No new prospecting sites were recognized on the basis of the images alone, but new information from the images was used in conjunction with known geology to evaluate two previously known speculative areas and to suggest one additional one. The study showed that Saindak-type deposits are less likely in some extensive areas of the Chagai District than formerly believed. The Saindak deposit is in an area of relatively soft folded sedimentary and volcanic rocks. The deposit is characterized by a linear zone of easily eroded sulfide-rich rock surrounded by a resistant rim of hornfels and propylitically altered rock. Both this rim and the central sulfide-rich valley are conspicuous features on the images. Swarms of dikes are probably useful for distinguishing real rims from other resistant rock types, but there is no expression of them on the image, although they are easily seen on aerial photographs of the Saindak rim. During field mapping, patches of strong red and yellow hue related to the mineral natrojarosite were noted in the central valley. Attempts to detect a color anomaly using simple false color composites were not successful.

  15. Estimate of winter wheat yield from ERTS-1. [southwest Kansas

    NASA Technical Reports Server (NTRS)

    Morain, S. A.; Williams, D. W.

    1974-01-01

    A model for estimating wheat yield per acre has been applied to acreage estimates derived from ERTS-1 imagery to project the 1973 wheat yields for a ten county area in southwest Kansas. The results (41.04 million bushels) are within 3 per cent of the preharvest estimates for the same area prepared by the USDA Statistical Reporting Service (39.91 million bushels). The projection from ERTS data is based on a visual enumeration of all detectable wheat fields in the study area and was completed while the harvest was in progress. Visual identification of winter wheat is readily achieved by using a temporal sequence of images (band 5 for Sept.-Oct.; band 5 for Dec.-Jan.; and band 5 and 7 for March-April). Identification can be improved by stratifying the project area into subregions having more or less homogeneous agricultural practices and crop mixes. By doing this, small changes in the spectral appearance of wheat related to soil type, irrigation, etc. can be accounted for. The interpretation rules developed by visual analysis can be automated for rapid computer surveys.

  16. ERTS-1, earthquakes, and tectonic evolution in Alaska

    NASA Technical Reports Server (NTRS)

    Gedney, L.; Vanwormer, J.

    1974-01-01

    In comparing seismicity patterns in Alaska with ERTS-1 imagery, it is striking to see the frequency with which earthquake epicenters fall on, or near, lineaments visible on the imagery. Often these lineaments prove to be tectonics faults which have been mapped in the field. But equally as often, existing geologic and tectonic maps show no evidence of these features. The remoteness and inaccessibility of most of Alaska is responsible, in large part, for the inadequacy of the mapping. ERTS-1 imagery is filling a vital need in providing much of the missing information, and is pointing out many areas of potential earthquake hazard. Earthquakes in central and south-central Alaska result when the northeastern corner of the north Pacific lithospheric plate underthrusts the continent. North of Mt. McKinley, the seismicity is continental in nature and of shallow origin, with earthquakes occurring on lineaments, and frequently at intersections of lineaments. The shallower events tend to align themselves with lineaments visible on the imagery.

  17. Relevance of ERTS to the State of Ohio

    NASA Technical Reports Server (NTRS)

    Sweet, D. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. A significant result was the fabrication of an image transfer and comparison device. To avoid problems and high costs encountered in manual drafting methods, Battelle staff members have fabricated an inexpensive, yet effective, technique for transferring ERTS-1 analysis displays from the Spatial Data 32-Color Viewer to maps and/or aircraft imagery. In brief, the image transfer-comparison device consists of a 2-way mirror which functions similar to a zoom transfer scope. However, the device permits multiuser viewing and real time photographic recording (35-mm and Polaroid) of enhanced ERTS-1 imagery superimposed over maps and aircraft photography. Thirty-five mm, 70 mm, and 4 in. x 5 in. photographs are taken of 80% of the TV screen of the Spatial Data Density Slicing Viewer. The resulting black and white and color imagery is then used in transparent overlays, viewgraphs, 35-mm and 70-mm transparencies, and paper prints for reports and publications. Annotations can be added on the TV screen or on the finished product.

  18. Pollution detection in Lake Champlain using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Lind, A. O. (Principal Investigator); Henson, E. B.

    1972-01-01

    The author has identified the following significant results. A major waste water discharge plume generated by a large paper mill along the New York shore of Lake Champlain was visually detected on ERTS-1 imagery. The plume is best displayed in 9.5 inch positive transparencies of MSS bands 4 and 5. Observation of the magnitude and extent of this plume is feasible, under magnification of 4 times. The chemical parameters of this plume have been documented by limnological studies. An enhancement technique useful for documenting the presence of waste water discharge plumes in Lake Champlain utilizes Polaroid MP-3 copy camera equipment and Spectral Data Corporation's multispectral viewer. The 9.5 inch, ERTS-1, positive transparency is enlarged using the Polaroid MP-3 copy camera to produce an enlarged lantern slide size positive transparency. These are projected through the multispectral viewer for enhancement and the scene is viewed directly on the screen or copied by an additional photographic step. The technique is simple and produces rapid results.

  19. Pollution monitoring in Lake Champlain using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Lind, A. O. (Principal Investigator); Henson, E. B.

    1973-01-01

    The author has identified the following significant results. Band 4 imagery of April 7 and 25 show contrasting pollution effects due to seasonal and discharge variations. The pollution plume emanating from the International Paper Co. mill just north of Fort Ticonderoga was first detected on October 10 ERTS-1 imagery and now has been documented during spring high lake level conditions. The plume was observed extending further to the north and east than under low water conditions of October 10. This northward extension reflects a stronger northward current flow expected in the turbid southern leg of Lake Champlain. The extensive plume of April 25 represents full plant operation while the April 5 scene shows some plume traces directly over the submerged diffuser, discharge pipe representing minimal discharge during weekend plant operation. The ERTS-1 documentation will be used in developing a model of plume behavior under varying environmental conditions and will hopefully serve to assist in a major resource decision pending at U.S. Supreme Court level.

  20. Analysis of ERTS-1 linear features in New York State

    NASA Technical Reports Server (NTRS)

    Isachsen, Y. W. (Principal Investigator); Fakundiny, R. H.; Forster, S. W.

    1974-01-01

    The author has identified the following significant results. All ERTS-1 linears confirmed to date have topographic expression although they may appear as featureless tonal linears on the imagery. A bias is unavoidably introduced against any linears which may parallel raster lines, lithological trends, or the azimuth of solar illumination. Ground study of ERTS-1 topographic lineaments in the Adirondacks indicates: outcrops along linears are even more rare than expected, fault breccias are found along some NNE lineaments, chloritization and slickensiding without brecciation characterize one EW lineament whereas closely-spaced jointing plus a zone of plastic shear define another. Field work in the Catskills suggests that the prominent new NNE lineaments may be surface manifestations of normal faulting in the basement, and that it may become possible to map major joint sets over extensive plateau regions directly on the imagery. Fall and winter images each display some unique linears, and long linears on the fall image commonly appear as aligned segments on the winter scene. A computer-processed color composite image permitted the extraction or additional information on the shaded side of mountains.

  1. Real-time 4D ERT monitoring of river water intrusion into a former nuclear disposal site using a transient warping-mesh water table boundary (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, T.; Hammond, G. E.; Versteeg, R. J.; Zachara, J. M.

    2013-12-01

    The Hanford 300 Area, located adjacent to the Columbia River in south-central Washington, USA, is the site of former research and uranium fuel rod fabrication facilities. Waste disposal practices at site included discharging between 33 and 59 metric tons of uranium over a 40 year period into shallow infiltration galleries, resulting in persistent uranium contamination within the vadose and saturated zones. Uranium transport from the vadose zone to the saturated zone is intimately linked with water table fluctuations and river water intrusion driven by upstream dam operations. As river stage increases, the water table rises into the vadose zone and mobilizes contaminated pore water. At the same time, river water moves inland into the aquifer, and river water chemistry facilitates further mobilization by enabling uranium desorption from contaminated sediments. As river stage decreases, flow moves toward the river, ultimately discharging contaminated water at the river bed. River water specific conductance at the 300 Area varies around 0.018 S/m whereas groundwater specific conductance varies around 0.043 S/m. This contrast provides the opportunity to monitor groundwater/river water interaction by imaging changes in bulk conductivity within the saturated zone using time-lapse electrical resistivity tomography. Previous efforts have demonstrated this capability, but have also shown that disconnecting regularization constraints at the water table is critical for obtaining meaningful time-lapse images. Because the water table moves with time, the regularization constraints must also be transient to accommodate the water table boundary. This was previously accomplished with 2D time-lapse ERT imaging by using a finely discretized computational mesh within the water table interval, enabling a relatively smooth water table to be defined without modifying the mesh. However, in 3D this approach requires a computational mesh with an untenable number of elements. In order to

  2. Seasonal ERT monitoring of subsurface processes connected to freezing, thawing, snow accumulation and melt cycles

    NASA Astrophysics Data System (ADS)

    Krzeminska, Dominika; Starkloff, Torsten; Bloem, Esther; Stolte, Jannes

    2016-04-01

    For a better understanding of processes that influence snowmelt infiltration and runoff, and their consequences on soil erosion during spring periods, we established a long-term winter-spring ERT transect in the Gryteland catchment (Norway). The ERT transect is 71 m long, with 1 m spacing between the electrodes. It covers a depression with a north and south facing slope. The readings are collected once a week and, if needed, after a sudden change in weather conditions. Additionally, the soil transect is equipped with six TDR profiles, which register soil moisture and soil temperature every thirty minutes, at five depths (5, 10, 20, 30, 40 cm), for quantifying the ERT readings. The measurements performed during winter 2014/2015 gave promising results and showed the potential of ERT monitoring for understanding the soil thermal and hydraulic processes occurring during a winter and early spring. Moreover, there are visible differences in temporal trends and spatial variations in observed ERT patterns on the opposite facing slopes, which are of special interest. With the on-going experiment, we are aiming to understand the reoccurrence of the observed processes as well as to quantify soil moisture patterns. Herein, we would like to present the preliminary result of two ERT experiments (2014/2015 and 2015/2016) and discuss the advantages and limitations of our experiments. Moreover, we would like to stimulate the discussion about the potential of ERT for spatial and temporal monitoring of soil hydraulic and thermal processes and indirect measurements of soil water content.

  3. A method for recording resistance changes non-invasively during neuronal depolarization with a view to imaging brain activity with electrical impedance tomography.

    PubMed

    Gilad, Ori; Ghosh, Anthony; Oh, Dongin; Holder, David S

    2009-05-30

    Electrical impedance tomography (EIT) is a recently developed medical imaging method which has the potential to produce images of fast neuronal depolarization in the brain. The principle is that current remains in the extracellular space at rest but passes into the intracellular space during depolarization through open ion channels. As current passes into the intracellular space across the capacitance of cell membranes at higher frequencies, applied current needs to be below 100 Hz. A method is presented for its measurement with subtraction of the contemporaneous evoked potentials which occur in the same frequency band. Neuronal activity is evoked by stimulation and resistance is recorded from the potentials resulting from injection of a constant current square wave at 1 Hz with amplitude less than 25% of the threshold for stimulating neuronal activity. Potentials due to the evoked activity and the injected square wave are removed by subtraction. The method was validated with compound action potentials in crab walking leg nerve. Resistance changes of -0.85+/-0.4% (mean+/-SD) occurred which decreased from -0.97+/-0.43% to -0.46+/-0.16% with spacing of impedance current application electrodes from 2 to 8 mm but did not vary significantly with applied currents of 1-10 microA. These tallied with biophysical modelling, and so were consistent with a genuine physiological origin. This method appears to provide a reproducible and artefact free means for recording resistance changes during neuronal activity which could lead to the long-term goal of imaging of fast neural activity in the brain.

  4. Determine utility of ERTS-1 to detect and monitor area strip mining and reclamation. [southeastern Ohio

    NASA Technical Reports Server (NTRS)

    Rogers, R. H. (Principal Investigator); Pettyjohn, W. A.

    1975-01-01

    The author has identified the following significant results. Computer techniques were applied to process ERTS tapes acquired over coal mining operations in southeastern Ohio on 21 August 1972 and 3 September 1973. ERTS products obtained included geometrically correct map overlays showing stripped earth, partially reclaimed earth, water, and natural vegetation. Computer-generated tables listing the area covered by each land-water category in square kilometers and acres were produced. By comparing these mapping products, the study demonstrates the capability of ERTS to monitor changes in the extent of stripping, success of reclamation, and the secondary effects of mining on the environment.

  5. Forestry, geology and hydrological investigations from ERTS-1 imagery in two areas of Ecuador, South America

    NASA Technical Reports Server (NTRS)

    Moreno, N. V. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. In the Oriente area, well-drained forests containing commercially valuable hardwoods can be recognized confidently and delineated quickly on the ERTS imagery. In the tropical rainforest, ERTS can provide an abundance of inferential information about large scale geologic structures. ERTS imagery is better than normal aerial photography for recognizing linears. The imagery is particularly useful for updating maps of the distributary system of the Guagas River Basin and of any other river with a similarly rapid changing channel pattern.

  6. Relevance of ERTS-1 to the State of Ohio. [environmental monitoring and resources management

    NASA Technical Reports Server (NTRS)

    Sweet, D. C.; Pincura, P. G.; Wukelic, G. E. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. During the first year of project effort the ability of ERTS-1 imagery to be used for mapping and inventorying strip-mined areas in southeastern Ohio, the potential of using ERTS-1 imagery in water quality and coastal zone management in the Lake Erie region, and the extent that ERTS-1 imagery could contribute to localized (metropolitan/urban), multicounty, and overall state land use needs were experimentally demonstrated and reported as significant project results.

  7. Application of ERTS imagery to geologic mapping in the volcanic terrane of northwest Wyoming

    NASA Technical Reports Server (NTRS)

    Breckenridge, R. M.

    1973-01-01

    The author has identified the following significant results. ERTS-1 image interpretations in the Yellowstone/Absaroka volcanic province indicate that the ERTS-1 imagery can be successfully employed in mapping large-scale structures and gross lithologic differences within the volcanic rocks. The volcanic rocks are readily separable from the sedimentary and crystalline rocks but the various volcanic units are seldom distinguishable unless they exhibit a characteristic morphology. Color anomalies were detected on the ERTS-1 imagery and found to be related to zones of alteration and mineralization. High altitude aircraft imagery provided a means of checking and improving the interpretations.

  8. Correlation of coastal water turbidity and current circulation with ERTS-1 and Skylab imagery

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Otley, M.; Philpot, W.; Wethe, C.; Rogers, R.; Shah, N.

    1974-01-01

    The article reviews investigations of current circulation patterns, suspended sediment concentration, coastal frontal systems, and waste disposal plumes based on visual interpretation and digital analysis of ERTS-1 and Skylab/EREP imagery. Data on conditions in the Delaware Bay area were obtained from 10 ERTS-1 passes and one Skylab pass, with simultaneous surface and airborne sensing. The current patterns and sediments observed by ERTS-1 correlated well with ground-based observations. Methods are suggested which would make it possible to identify certain pollutants and sediment types from multispectral scanner data.

  9. Fracture mapping and strip mine inventory in the Midwest by using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Wier, C. W.; Wobber, F. J.; Russell, O. R.; Amato, R. V.

    1973-01-01

    Analysis of the ERTS-1 imagery and high-altitude infrared photography indicates that useful fracture data can be obtained in Indiana and Illinois despite a glacial till cover. ERTS MSS bands 5 and 7 have proven most useful for fracture mapping in coal-bearing rocks in this region. Preliminary results suggest a reasonable correlation between image-detected fractures and mine roof-fall accidents. Information related to surface mined land, such as disturbed area, water bodies, and kind of reclamation, has been derived from the analysis of ERTS imagery.

  10. Preliminary analysis of ERTS-relayed water resources data in the Delaware River Basin

    NASA Technical Reports Server (NTRS)

    Paulson, R. W.

    1973-01-01

    Preliminary analysis of ERTS-DCS data from water-resources stations in the Delaware River Basin indicates that the Data-Collection System is performing well. Data-Collections Platforms have been successfully interfaced with five stream-gaging station and three ground-water observation wells and are being interfaced with 12 water-quality monitors in the basin. Data are being relayed during four or five ERTS orbital passes per day, which is within the design specifications of the ERTS-DCS.

  11. Electrical resistivity and Seismic Refraction Tomography to Detect Heavy Metals Pathways in the Tailings of the Abandoned Mine of Zeïda, Morocco

    NASA Astrophysics Data System (ADS)

    Dekayir, A.; Lachhab, A.; Rouai, M.; Benyassine, E. M.; Boujamaoui, M.; Parisot, J. C.

    2015-12-01

    The abandoned mine Zeïda (Pb) located at the center of the High Moulouya watershed is believed to have produced a total of 640,000 tons of concentrated Pb within 14 years of activities (1972-1985). Today, the mine has been abandoned with one of the largest tailings pits in Morocco without supervision and concern of environmental impacts. Several studies have shown the existence of high levels of heavy metals (Pb, Zn, Cu, Cr, Co, Cd and Ni) in samples (water and soil) taken from and around the tailings (Laghlimi et al, 2014, Benyassine et al, 2013, Iavarzzo, 2012, Makhoukh et al, 2011, Baghdad et al, 2008, Bouabdli et al, 2005). In this study, several electrical and seismic tomography profiles were taken to explore the thickness of the tailings and the potential pathways of contaminants to the aquifer. Because heavy metals were found in the surrounding areas of the tailings, there are concerns about their seepage into the groundwater aquifer. A total of 6 electric resistivity profiles together with another 16 seismic refraction profiles were completed over the 3 major mining waste piles to study this contamination. Analysis of both electric and seismic tomography profiles showed: 1) the thickness of tailings range from few cm to above 20m depending on where the survey was performed, 2) the contamination pathways of heavy metal pollutants occur predominantly right above the thickest areas of sandstone formation, and 3) water ponds at the surface of the tailing piles forms directly above the thickest part of the sandstone layer

  12. Use of ERTS-1 data: Summary report of work on ten tasks. [solving natural resources and environmental quality problems using ERTS-1 MSS data

    NASA Technical Reports Server (NTRS)

    Thomson, F. J.; Polcyn, F. C.; Bryan, M. L.; Sattinger, I. J.; Malila, W. A.; Nalepka, R. F.; Wezernak, C. T.; Horvath, R.; Vincent, R. K. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Depth mapping's for a portion of Lake Michigan and at the Little Bahama Bank test site have been verified by use of navigation charts and on-site visits. A thirteen category recognition map of Yellowstone Park has been prepared. Model calculation of atmospheric effects for various altitudes have been prepared. Radar, SLAR, and ERTS-1 data for flooded areas of Monroe County, Michigan are being studied. Water bodies can be reliably recognized and mapped using maximum likelihood processing of ERTS-1 digital data. Wetland mapping has been accomplished by slicing of single band and/or ratio processing of two bands for a single observation date. Both analog and digital processing have been used to map the Lake Ontario basin using ERTS-1 data. Operating characteristic curves were developed for the proportion estimation algorithm to determine its performance in the measurement of surface water area. The signal in band MSS-5 was related to sediment content of waters by modelling approach and by relating surface measurements of water to processed ERTS data. Radiance anomalies in ERTS-1 data could be associated with the presence of oil on water in San Francisco Bay, but the anomalies were of the same order as those caused by variations in sediment concentration and tidal flushing.

  13. A study of the utilization of ERTS-1 data from the Wabash River Basin

    NASA Technical Reports Server (NTRS)

    Landgrebe, D. A. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Nine projects are defined, five ERTS data applications experiments and four supporting technology tasks. The most significant applications results were achieved in the soil association mapping, earth surface feature identification, and urban land use mapping efforts. Four soil association boundaries were accurately delineated from ERTS-1 imagery. A data bank has been developed to test surface feature classifications obtained from ERTS-1 data. Preliminary forest cover classifications indicated that the number of acres estimated tended to be greater than actually existed by 25%. Urban land use analysis of ERTS-1 data indicated highly accurate classification could be obtained for many urban catagories. The wooded residential category tended to be misclassified as woods or agricultural land. Further statistical analysis revealed that these classes could be separated using sample variance.

  14. Mapping soils, crops, and rangelands by machine analysis of multitemporal ERTS-1 data. [Kansas and Texas

    NASA Technical Reports Server (NTRS)

    Baumgardner, M. F.; Henderson, J. A., Jr.

    1974-01-01

    ERTS-1 data, obtained during the period 25 August 1972 to 5 September 1973 over a range of test sites in the Central United States, have been used for identifying and mapping differences in soil patterns, species and conditions of cultivated crops, and conditions of rangelands. Multispectral scanner data from multiple ERTS passes over certain test sites have provided the opportunity to study temporal changes in the scene. Multispectral classifications delineating soils boundaries in different test sites compared well with existing soil association maps prepared by conventional means. Spectral analysis of ERTS data was used to identify, maps, and make areal measurements of wheat in western Kansas. Multispectral analysis of ERTS-1 data provided patterns in rangelands which can be related to soils differences, range management practices, and the extent of infestation of grasslands by mesquite (prosopis fuliflora) and juniper (juniperus spp.).

  15. A summary of selected early results from the ERTS-1 menhaden experiment

    NASA Technical Reports Server (NTRS)

    Stevenson, W. H. (Principal Investigator); Kemmerer, A. J.; Benigno, J. A.; Reese, G. B.; Minkler, F. C.

    1973-01-01

    The author has identified the following significant results. Imagery from ERTS-1 satellite was used in conjunction with aerial photographically-sensed menhaden distribution information, sea truth oceanographic measurements, and commercial fishing information from a 8685 square kilometer study area in the north-central portion of the Gulf of Mexico to demonstrate relationships between selected oceanographic parameters and menhaden distribution, ERTS-1 imagery and menhaden distribution, and ERTS-1 imagery and oceanographic parameters. ERTS-1, MSS band 5 imagery density levels correlated with photographically detected menhaden distribution patterns and could be explained based on sea truth Secchi disc transparency and water depth measurements. These two parameters, together with surface salinity, Forel-Ule color, and chlorophyll-a also were found to correlate significantly with menhaden distribution. Eight empirical models were developed which provided menhaden distribution predictions for the study area on combinations of Secchi disc transparency, water depth, surface salinity, and Forel-Ule color measurements.

  16. Effect of enzyme replacement therapy (ERT) added to Home Mechanical Ventilation (HMV) in Adult Pompe disease.

    PubMed

    Sayeed, Nadia; Sharma, Pooja; Abdelhalim, Manahil; Mukherjee, Rahul

    2015-12-01

    Adult Pompe disease/acid maltase deficiency is an autosomal recessive disorder resulting in accumulation of glycogen in skeletal muscles, leading to myopathy frequently involving respiratory muscles. This involvement can cause respiratory insufficiency that may present as acute hypercapnic respiratory failure. Enzyme replacement therapy (ERT) with alpha - glucosidase alfa, the only disease-specific treatment, has been available as treatment option since 2006. ERT has shown efficacy concerning muscle strength and pulmonary function in adult patients as well as positive association with survival. We present two cases where addition of ERT to Home Mechanical Ventilation (HMV) showed improvements in lung function and gas exchange that may not be entirely attributable to nocturnal HMV and therefore may further indicate the beneficial role of ERT in conjunction with HMV in Adult Pompe disease. PMID:26740886

  17. Geologic and mineral and water resources investigations in western Colorado using ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Knepper, D. H. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Most of the geologic information in ERTS-1 imagery can be extracted from bulk processed black and white transparencies by a skilled interpreter using standard photogeologic techniques. In central and western Colorado, the detectability of lithologic contacts on ERTS-1 imagery is closely related to the time of year the imagery was acquired. Geologic structures are the most readily extractable type of geologic information contained in ERTS images. Major tectonic features and associated minor structures can be rapidly mapped, allowing the geologic setting of a large region to be quickly accessed. Trends of geologic structures in younger sedimentary appear to strongly parallel linear trends in older metamorphic and igneous basement terrain. Linears and color anomalies mapped from ERTS imagery are closely related to loci of known mineralization in the Colorado mineral belt.

  18. Interpretation and mapping of gypsy moth defoilation from ERTS (LANDSAT)-1 temporal composites

    NASA Technical Reports Server (NTRS)

    Mcmurtry, G. J.; Petersen, G. W. (Principal Investigator); Kowalik, W. S.

    1975-01-01

    The author has identified the following significant results. Photointerpretation of temporally composited color Diazo transparencies of ERTS(LANDSAT) images is a practical method for detecting and locating levels of widespread defoliation. ERTS 9 x 9 inch images are essentially orthographic and are produced at a nearly constant 1:1,000,000 scale. This allows direct superposition of scenes for temporal composites. ERTS coverage provides a sweeping 180 km (110 mile) wide view, permitting one interpreter to rapidly delineate defoliation in an area requiring days and weeks of work by aerial surveys or computerized processing. Defoliation boundaries can be located on the images within maximum errors on the order of hundreds of meters. The enhancement process is much less expensive than aerial surveys or computerized processing. Maps produced directly from interpretation are manageable working products. The 18 day periodic coverage of ERTS is not frequent enough to replace aerial survey mapping because defoliation and refoliation move as waves.

  19. Applicability of ERTS to Antarctic iceberg resources. [harvesting sea ice for fresh water

    NASA Technical Reports Server (NTRS)

    Hult, J. L. (Principal Investigator); Ostrander, N. C.

    1973-01-01

    The author has identified the following significant results. This investigation explorers the applicability of ERTS to (1) determine the Antarctic sea ice and environmental behavior that may influence the harvesting of icebergs, and (2) monitor iceberg locations, characteristics, and evolution. Imagery has shown that the potential applicability of ERTS to the research, planning, and harvesting operations can contribute importantly to the glowing promise derived from broader scope studies for the use of Antarctic icebergs to relieve a growing global thirst for fresh water. Several years of comprehensive monitoring will be necessary to characterize sea ice and environmental behavior and iceberg evolution. Live ERTS services will assist harvesting control and claiming operations and offer a means of harmonizing entitlements of iceberg resources. The valuable ERTS services will be more cost effective than other means will be easily justified and borne by the iceberg harvesting operations.

  20. Impact of ERTS-1 images on management of New Jersey's coastal zone

    NASA Technical Reports Server (NTRS)

    Feinberg, E. B.; Yunghans, R. S.; Stitt, J. A.; Mairs, R. L.

    1974-01-01

    The thrust of New Jersey's ERTS investigation is development of procedures for operational use of ERTS-1 data by the Department of Environmental Protection in the management of the State's coastal zone. Four major areas of concern were investigated: detection of land use changes in the coastal zone; monitoring of offshore waste disposal; siting of ocean outfalls; and allocation of funds for shore protection. ERTS imagery was not useful for shore protection purposes; it was of limited practical value in the evaluation of offshore waste disposal and ocean outfall siting. However, ERTS imagery shows great promise for operational detection of land use changes in the coastal zone. Some constraints for practical change detection have been identified.

  1. Utilization of ERTS data to detect plant diseases and nutrient deficiencies, soil types and moisture levels

    NASA Technical Reports Server (NTRS)

    Parks, W. L.; Sewell, J. I.; Hilty, J. W.; Rennie, J. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The separation of the Mississippi Delta from the Memphis Association (Loess) is clearly defined in ERTS-1 imagery covering west Tennessee and Mississippi.

  2. Detecting disturbances in a forest environment. [ERTS land use surveys

    NASA Technical Reports Server (NTRS)

    Aldrich, R. C.

    1975-01-01

    The interchange between forest and nonforest land and most man-made and natural forest disturbances can be detected on 1:120,000-scale color-infrared film. Bulk multispectral scanner imagery from the Earth Resources Technology Satellite combined and enhanced at a scale of 1:1,000,000 shows major changes in forest and nonforest land-use categories, many timber harvested areas, and some natural disturbances. Late fall to late spring is the best period of the year for detecting forest disturbances. In a study in Georgia, 79 percent of the disturbances in one county were detected on an ERTS color composite for April 1973 with only 12 percent commission error.

  3. Utilization of ERTS-1 data in North Carolina

    NASA Technical Reports Server (NTRS)

    Welby, C. W. (Principal Investigator); Lammi, J. O.; Carson, R. J., III

    1973-01-01

    The author has identified the following significant results. A wide range of potential uses for ERTS-1 imagery is described. Special emphasis has been placed upon studies in the Coastal Plain of North Carolina. Soil groups, water quality, and suspended sediment patterns in estuaries and offshore have been studied. A phytoplankton bloom has possibly been detected. The usefulness of the imagery in coastal landform surveys has been demonstrated as has its usefulness in monitoring developmental activity in the forests. Planners appear hesitant to use the imagery because of its small scale, but it is felt that as they become familiar with the imagery they will find it useful and time-saving for many purposes.

  4. Engineering analysis of ERTS data for rice in the Philippines

    NASA Technical Reports Server (NTRS)

    Mcnair, A. J. (Principal Investigator); Heydt, H. L.

    1973-01-01

    The author has identified the following significant results. Rice is an important food worldwide. Worthwhile goals, particularly for developing nations, are the capability to recognize from satellite imagery: (1) areas where rice is grown, and (2) growth status (irrigation, vigor, yield). A two-step procedure to achieve this is being investigated. Ground truth, and ERTS-1 imagery (four passes) covering 80% of a rice growth cycle for some Philippine sites, have been analyzed. One-D and three-D signature extraction, and synthesis of an initial site recognition/status algorithm have been performed. Results are encouraging. but additional passes and sites must be analyzed. Good position information for extracted data is a must.

  5. Use of ERTS-1 imagery in forest inventory

    NASA Technical Reports Server (NTRS)

    Rennie, J. C.; Birth, E. E.

    1974-01-01

    The utility of ERTS-1 imagery when combined with field observations and with aircraft imagery and field observations is evaluated. Satellite imagery consisted of 9-1/2 inch black and white negatives of four multispectral scanner bands taken over Polk County, Tennessee. Aircraft imagery was obtained by a C-130 flying at 23,000 ft over the same area and provided the basis for locating ground plots for field observations. Correspondence between aircraft and satellite imagery was somewhat inaccurate due to seasonal differences in observations and lack of good photogrammetry with the data processing system used. Better correspondence was found between satellite imagery and ground observations. Ways to obtain more accurate data are discussed, and comparisons between aircraft and satellite observations are tabulated.

  6. Crop identification and acreage measurement utilizing ERTS imagery

    NASA Technical Reports Server (NTRS)

    Vonsteen, D. H. (Principal Investigator)

    1972-01-01

    There are no author-identified significant results in this report. The microdensitometer will be used to analyze data acquired by ERTS-1 imagery. The classification programs and software packages have been acquired and are being prepared for use with the information as it is received. Photo and digital tapes have been acquired for coverage of virtually 100 percent of the test site areas. These areas are located in South Dakota, Idaho, Missouri, and Kansas. Hass 70mm color infrared, infrared, black and white high altitude aerial photography of the test sites is available. Collection of ground truth for updating the data base has been completed and a computer program written to count the number of fields and give total acres by size group for the segments in each test site. Results are given of data analysis performed on digitized data from densitometer measurements of fields of corn, sugar, beets, and alfalfa in Kansas.

  7. ERTS-1 data user investigation of wetlands ecology

    NASA Technical Reports Server (NTRS)

    Anderson, R. R. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. ERTS-1 imagery (enlarged to 1:250,000) is an excellent tool by which large area coastal marshland mapping may be undertaken. If states can sacrifice some accuracy (amount unknown at this time) in placing of boundary lines, the technique may be used to do the following: (1) estimate extent of man's impact on marshes by ditching and lagooning and accelerated successional trends; (2) place boundaries between wetland and upland and hence estimate amount of coastal marshland remaining in the state; (3) distinguish among relatively large zones of various plant species including high and low growth S. alterniflora, J. roemerianus, and S. cynosuroides; and (4) estimate marsh plant species productivity when ground based information is available.

  8. Automatic classification of soils and vegetation with ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Landgrebe, D. A.

    1972-01-01

    Preliminary results of a test of a computerized analysis method using ERTS 1 data are presented. The method consisted of a four-spectral-band supervised, maximum likelihood, Gaussian classifier with training statistics derived through a combination of clustering and manual methods. The multivariate analysis method leads to the assignment of each resolution element of the data to one of a preselected set of discrete classes. The data frame was an area over the Texas-Oklahoma border including Lake Texoma. The study suggests that multispectral scanner data coupled with machine processing shows promise for earth surface cover surveys. Futhermore, the processing time is short and consequently the costs are low; a full frame can be analyzed completely within 48 hours.

  9. Ground control requirements for precision processing of ERTS images

    USGS Publications Warehouse

    Burger, Thomas C.

    1973-01-01

    With the successful flight of the ERTS-1 satellite, orbital height images are available for precision processing into products such as 1:1,000,000-scale photomaps and enlargements up to 1:250,000 scale. In order to maintain positional error below 100 meters, control points for the precision processing must be carefully selected, clearly definitive on photos in both X and Y. Coordinates of selected control points measured on existing ½ and 15-minute standard maps provide sufficient accuracy for any space imaging system thus far defined. This procedure references the points to accepted horizontal and vertical datums. Maps as small as 1:250,000 scale can be used as source material for coordinates, but to maintain the desired accuracy, maps of 1:100,000 and larger scale should be used when available.

  10. ERTS-1 MSS imagery - A tool for identifying soil associations.

    NASA Technical Reports Server (NTRS)

    Westin, F. C.

    1973-01-01

    Soil association maps show the spatial relationships of land units developed in unique climatic, geologic, and topographic environments, and having characteristic slopes, soil depths, textures, available water capacities, permeabilities, and the like. From these characteristics of the soil, broad interpretations can be made such as how the soil is suited for various agronomic and engineering uses. ERTS-1 imagery was found to be a useful tool in the identification of soil associations since it provides a synoptic view of an 8 million acre scene, which is large enough so that the effect can be seen on soils of climate, topography, and geology. A regional view also allows soil associations to be observed over most, if not all, of their extent. This aids in selecting typical sampling sites and provides a check on the homogeniety of the associations.

  11. Utilization of ERTS-1 data in North Carolina

    NASA Technical Reports Server (NTRS)

    Welby, C. W. (Principal Investigator); Lammi, J. O.; Carson, R. J.

    1972-01-01

    The author has identified the following significant results. Initial study and interpretation of ERTS-1 imagery indicates its usefulness for regional land use planning purposes in North Carolina. Quarries, many secondary roads, and the existence of urbanization as well as changes in urban areas may be mapped. Differences in spectral response for various parts of the major cities suggests that the type of activity in urbanized areas may be monitored. Geological mapping at a scale of 1:250,000 may be possible. The major unfavorable comment from various organizations and agencies who are potential users has been to the relatively small scale. The imagery is a powerful illustrative tool for the several state agencies cooperating in the investigation.

  12. Geologic applications of ERTS images on the Colorado Plateau, Arizona

    NASA Technical Reports Server (NTRS)

    Goetz, A. F. H.; Billingsley, F. C.; Elston, D. P.; Lucchitta, I.; Shoemaker, E. M.

    1974-01-01

    Three areas in central and northern Arizona centered on the (1) Verde Valley, (2) Coconino Plateau, and (3) Shivwits Plateau were studied using ERTS photography. Useful applications results include: (1) upgrading of the existing state geologic map of the Verde Valley region; (2) detection of long NW trending lineaments in the basalt cap SE of Flagstaff which may be favorable locations for drilling for new water supplies; (3) tracing of the Bright Angel and Butte faults to twice their previously known length and correlating the extensions with modern seismic events, showing these faults to be present-day earthquake hazards; (4) discovering and successfully drilling perched sandstone aquifers in the Kaibab Limestone on the Coconino Plateau; and (5) determining the relationship between the Shivwits lavas and the formation of the lower Grand Canyon and showing that the lavas should be an excellent aquifer, as yet untapped.

  13. A summary of ERTS-1 data collection system applications

    NASA Technical Reports Server (NTRS)

    Salomonson, V. V.

    1975-01-01

    Geographically, applications were made over nearly the entire area where direct readout could be accomplished using the data acquisition stations in the ERTS-1 system. The extreme areas included Iceland, the Canadian Arctic, Alaska, Hawaii and Central America. In the discipline sense the majority of applications were in the water resources area with other applications being formally and informally reported in meteorology, oceanography, volcano surveillance and forestry. Installation and maintenance of the data collection platforms, as is true with nearly all new systems, was not accomplished without difficulty. On the whole, however, it has gone well enough so that it is agreed that it is a system which is amenable to installation in a variety of physical situations and the installation is accomplished with an ease commensurate with eventual use in an operational system.

  14. Remote sensing of ocean currents using ERTS imagery

    NASA Technical Reports Server (NTRS)

    Maul, G. A.

    1973-01-01

    Major ocean currents such as the Loop Current in the eastern Gulf of Mexico have surface manifestations which can be exploited for remote sensing. Surface chlorophyll-a concentrations, which contribute to the shift in color from blue to green in the open sea, were found to have high spatial variability; significantly lower concentrations were observed in the current. The cyclonic edge of the current is an accumulation zone which causes a peak in chlorophyll concentration. The dynamics also cause surface concentrations of algae, which have a high reflectance in the near infrared. Combining these observations gives rise to an edge effect which can show up as a bright lineation on multispectral imagery delimiting the current's boundary under certain environmental conditions. When high seas introduce bubbles, white caps, and foam, the reflectance is dominated by scattering rather than absorption. This has been detected in ERTS imagery and used for current location.

  15. Geology of Utah and Nevada by ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Jensen, M. L.

    1973-01-01

    Repetitive ERTS-1 imagery covering Utah and Nevada is studied as an aid in structural geology, mineral exploration, and limnological and hydrological aspects. Limnological features of algal blooms and varying biological activities in Utah Lake and the Great Salt Lake are grossly evident on the imagery with more subtle details detected on the different bands. Major structural breaks, lineages, or trends are abundant throughout the area of study. The correlation of positive aeromagnetic anomalies with the trends suggests near surface intrusive bodies, not yet exposed at the surface, that can be tested for possible associated mineralization by collecting soil-gas at the surface which is analyzed for mercury that is (1) apparently associated with mineralization, (2) escapes as a vapor, and (3) can be readily measured in extremely low amounts of less than 1 ppb by absorption.

  16. Investigating a damaging buried sinkhole cluster in an urban area (Zaragoza city, NE Spain) integrating multiple techniques: Geomorphological surveys, DInSAR, DEMs, GPR, ERT, and trenching

    NASA Astrophysics Data System (ADS)

    Carbonel, Domingo; Rodríguez-Tribaldos, Verónica; Gutiérrez, Francisco; Galve, Jorge Pedro; Guerrero, Jesús; Zarroca, Mario; Roqué, Carles; Linares, Rogelio; McCalpin, James P.; Acosta, Enrique

    2015-01-01

    This contribution analyses a complex sinkhole cluster buried by urban elements in the mantled evaporite karst of Zaragoza city, NE Spain, where active subsidence has caused significant economic losses (~ 0.3 million Euro). The investigation, conducted after the development of the area, has involved the application of multiple surface and subsurface techniques. A detailed map of modern surface deformation indicates two active coalescing sinkholes, whereas the interpretation of old aerial photographs reveals the presence of two additional dormant sinkholes beneath human structures that might reactivate in the near future. DInSAR (Differential Interferometry Synthetic Aperture Radar) displacement data have limited spatial coverage mainly due to high subsidence rates and surface changes (re-pavement), and the Electrical Resistivity Tomography (ERT) and trenching investigations were severely restricted by the presence of urban elements. Nonetheless, the three techniques consistently indicate that the area affected by subsidence is larger than that defined by surface deformation features. The performance of the Ground Penetrating Radar (GPR) technique was adversely affected by the presence of highly conductive and massive anthropogenic deposits, but some profiles reveal that subsidence in the central sector of one of the sinkholes is mainly accommodated by sagging. The stratigraphic and structural relationships observed in a trench dug across the topographic margin of one of the sinkholes may be alternatively interpreted by three collapse events of around 0.6 m that occurred after 290 yr BP, or by progressive fault displacement combined with episodic anthropogenic excavation and fill. Average subsidence rates of > 6.6 mm/yr and 40 mm/yr have been calculated using stratigraphic markers dated by the radiocarbon method and historical information, respectively. This case study illustrates the need of conducting thorough investigations in sinkhole areas during the pre

  17. Electrical Resistivity and Ground Penetrating Radar Investigation of Presence and Extent of Hardpan Soil Layers

    NASA Astrophysics Data System (ADS)

    Thao, S. J.; Plattner, A.

    2015-12-01

    Farming in the San Joaquin Valley in central California is often impeded by a shallow rock-hard layer of consolidated soil commonly referred to as hardpan. To be able to successfully farm, this layer, if too shallow, needs to be removed either with explosives or heavy equipment. It is therefore of great value to obtain information about depth and presence of such a layer prior to agricultural operations. We tested the applicability of electrical resistivity tomography and ground penetrating radar in hardpan detection. On our test site of known hardpan depth (from trenching) and local absence (prior dynamiting to plant trees), we successfully recovered the known edge of a hardpan layer with both methods, ERT and GPR. The clay-rich soil significantly reduced the GPR penetration depth but we still managed to map the edges at a known gap where prior dynamiting had removed the hardpan. Electrical resistivity tomography with a dipole-dipole electrode configuration showed a clear conductive layer at expected depths with a clearly visible gap at the correct location. In our data analysis and representation we only used either freely available or in-house written software.

  18. Use of ERTS-1 images in the search for porphyry copper deposits in Pakistani Baluchistan

    NASA Technical Reports Server (NTRS)

    Schmidt, R. G.

    1973-01-01

    Geomorphic features related to a known porphyry copper deposit at Saindak, western Chagai District, Pakistan, are easily distinguished on ERTS-1 images. New geologic information from the images was used in conjunction with known geology to evaluate one previously known prospect area and to suggest two additional ones, but no new prospects were recognized on the basis of the images alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District. The Saindak deposit is in an area of relatively easily eroded folded sedimentary and volcanic rocks. The deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by this rim and the central sulfide-rich valley are conspicuous features on the images. Swarms of dikes are probably useful for distinguishing real rims from other resistant rock types, but there is no expression of them on the image, although they are easily seen on aerial photographs of the Saindak rim.

  19. Precision annotation of predetermined primary sampling units on ERTS-1 MSS images

    NASA Technical Reports Server (NTRS)

    Vanroessel, J. W.; Langley, P. G.

    1973-01-01

    Resectioning programs were developed for projecting the boundary corners of sample units, management units, and counties into U2 RC-10 and ERTS-1 MSS images. The technique used includes corrections for earth curvature, terrain elevation, and MSS distortions. The minimum standard error obtained was about 0.15 mm or 150 meters on the ground. This technique now makes it possible to include land ownership as an integral part of forest resource sampling plans using ERTS imagery.

  20. ERTS-A data as a teaching and research tool in the Department of Geology

    NASA Technical Reports Server (NTRS)

    Grybeck, D. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The ERTS-1 materials continue to be used in a number of courses including Geology of Alaska, Economic Geology, and Structural Geology. In addition, specific talks about the ERTS-1 material were given at a seminar at the Geophysical Institute, to the Geology Department, to numerous individuals, and were extensively used in a popularized talk on the Geology of Alaska to the local Historical Society.

  1. Evaluation of commercial utility of ERTS-A imagery in structural reconnaissance for minerals and petroleum

    NASA Technical Reports Server (NTRS)

    Saunders, D. F. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The only area that has been analyzed to date is Area 3 where results have already been reported. However, work progressing in Area 1 and 2 seem to indicate a good correlation between lineament zones previously reported, mineralized areas and lineaments currently being picked from ERTS-1 imagery. There also appear to be many lineaments on ERTS-1 imagery in these areas which have not been reported in any other literature.

  2. Preliminary assessment of geological applications of ERTS-1 imagery from selected areas of the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Gregory, A. F.

    1973-01-01

    An assessment of geological applications of ERTS-1 imagery from selected areas of the Canadian Arctic is presented. The three levels of interpretation which may be recognized and employed to derive information from a single image or data format are outlined. It is stated that one immediate benefit from ERTS will be improved efficiency in planning for and operation of programs of regional geological mapping. Imagery of various areas of Canada are presented to show applications to regional mapping.

  3. Skylab and ERTS-1 investigations of coastal land-use and water properties in Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Bartlett, D.; Rogers, R.

    1974-01-01

    Study of coastal land use and water properties of Delaware Bay using digital and visual analysis of enhanced imagery from NASA's Earth Resources Technology Satellite (ERTS) and from the Skylab Earth Resources Experimental Package (EREP). ERTS is shown to have the advantage of repetitive coverage of the test site which facilitates change detection experiments by gathering data under a variety of tidal, seasonal, and atmospheric conditions. Skylab-EREP data, on the other hand, are superior in both spatial and spectral resolution.

  4. The use of ERTS imagery for lake classification. [turbidity due to phytoplankton

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Wade, R. E.; Fisher, L. T.

    1975-01-01

    The feasibility of using photographic representations of the ERTS imagery to classify lakes in the State of Wisconsin as to their trophic level was studied. Densitometric readings in band 5 of ERTS 70 mm imagery were taken for all the lakes in Wisconsin greater than 100 acres (approximately 1000 lakes). An algorithm has been developed from ground truth measurements to predict from satellite imagery an indicator of trophic status.

  5. Regional geology subprogram: Geological interpretation of ERTS imagery of the occidental region of Bolivia

    NASA Technical Reports Server (NTRS)

    Brockmann, C. E. (Principal Investigator); Ayllon, R. B.

    1973-01-01

    The author has identified the following significant results. Using ERTS-1 imagery, it is possible to delimit great lithological units, folds, lineaments, faults, and in lesser degree unconformities. In the morphological aspect, the images show clearly the relief necessary for geological interpretation. The ERTS-1 images are important for the preparation of the geological and tectonic map of Bolivia, on a 1:1 million scale, if conventional methods of work are used as a base.

  6. A technique for correcting ERTS data for solar and atmospheric effects

    NASA Technical Reports Server (NTRS)

    Rogers, R. H.; Peacock, K.; Shah, N. J.

    1974-01-01

    A technique is described by which ERTS investigators can obtain and utilize solar and atmospheric parameters to transform spacecraft radiance measurements to absolute target reflectance signatures. A radiant power measuring instrument (RPMI) and its use in determining atmospheric paramaters needed for ground truth are discussed. The procedures used and results achieved in processing ERTS CCTs to correct for atmospheric parameters to obtain imagery are reviewed. Examples are given which demonstrate the nature and magnitude of atmospheric effects on computer classification programs.

  7. Water quality determinations in the Virgin Islands from ERTS-A data.

    NASA Technical Reports Server (NTRS)

    Egan, W. G.

    1973-01-01

    The characterization of water quality in terms of absolute color values, using imagery from the ERTS-A satellite, imagery from aircraft, and ground truth measurements is discussed. The establishment of photometric standards resolvable by the ERTS-A sensors, as a means of determining atmospheric effects (which generally vary on sequential overpasses) is examined. The application of these techniques is demonstrated for the harbor of Charlotte Amalie on St. Thomas, Virgin Islands, which is characterized by the presence of many poluting factors.-

  8. Principles of cost-benefit analysis for ERTS experiments, volumes 1 and 2

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The basic elements of a cost-benefit study are discussed along with special considerations for ERTS experiments. Elements required for a complete economic analysis of ERTS are considered to be: statement of objectives, specification of assumptions, enumeration of system alternatives, benefit analysis, cost analysis nonefficiency considerations, and final system selection. A hypothetical cost-benefit example is presented with the assumed objective of an increase in remote sensing surveys of grazing lands to better utilize available forage to lower meat prices.

  9. A combined methodology using electrical resistivity tomography, ordinary kriging and porosimetry for quantifying total C trapped in carbonate formations associated with natural analogues for CO2 leakage

    NASA Astrophysics Data System (ADS)

    Prado-Pérez, A. J.; Aracil, E.; Pérez del Villar, L.

    2014-06-01

    Currently, carbon deep geological storage is one of the most accepted methods for CO2 sequestration, being the long-term behaviour assessment of these artificial systems absolutely essential to guarantee the safety of the CO2 storage. In this sense, hydrogeochemical modelling is being used for evaluating any artificial CO2 deep geological storage as a potential CO2 sinkhole and to assess the leakage processes that are usually associated with these engineered systems. Carbonate precipitation, as travertines or speleothems, is a common feature in the CO2 leakage scenarios and, therefore, is of the utmost importance to quantify the total C content trapped as a stable mineral phase in these carbonate formations. A methodology combining three classical techniques such as: electrical resistivity tomography, geostatistical analysis and mercury porosimetry is described in this work, which was developed for calculating the total amount of C trapped as CaCO3 associated with the CO2 leakages in Alicún de las Torres natural analogue (Granada, Spain). The proposed methodology has allowed estimating the amount of C trapped as calcite, as more than 1.7 Mt. This last parameter, focussed on an artificial CO2 deep geological storage, is essential for hydrogeochemical modellers when evaluating whether CO2 storages constitute or not CO2 sinkholes. This finding is extremely important when assessing the long-term behaviour and safety of any artificial CO2 deep geological storage.

  10. Analysis of ERTS-1 imagery and its application to evaluation of Wyoming's natural resources

    NASA Technical Reports Server (NTRS)

    Marrs, R. W.

    1973-01-01

    The author has identified the following significant results. A summary of the significant results of the studies completed during the July-August, 1973 period includes: (1) ERTS-1 image brightness contrasts can be related to important contrasts in rangeland and forest vegetation communities of the Laramie Basin. (2) Stereoscopic viewing is essential for correct structural interpretation in outcrop patterns in some areas. (3) Complex fracture patterns which may have exerted a controlling influence on intrusive activity in the Absaroka Mountains can be mapped from ERTS. (4) Volcanic lithologies of the Yellowstone region are often differentiated on the basis of their textures, and cannot be successfully mapped by photogeologic interpretation of ERTS-1 imagery. Ground spectral readings confirm a general lack of contrast between these lithologies in the four ERTS-1 MSS bands. (5) Major dune fields can be recognized and defined from ERTS-1 image interpretations and recognition of differences in stabilizing plant communities (some of which may be mappable from ERTS-1) yields information about migration history of the dune fields.

  11. Application of ecological, geological and oceanographic ERTS-1 imagery to Delaware's coastal resources planning

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Communities containing five different coastal vegetation species, developed marshlands, and fresh water impoundments have been identified in ERTS-1 images. Suspended sediment and circulation patterns in imagery from five ERTS-1 passes over Delaware Bay have been enhanced and correlated with predicted current patterns. Conclusions reached are: (1) ERTS-1 is suitable platform for observing suspended sediment patterns and water masses synoptically over large areas. (2) Suspended sediment acts as a natural tracer allowing photointerpreters to deduce gross current circulation patterns from ERTS-1 imagery. (3) Under atmospheric conditions encountered along the East Coast of the United States MSS band 5 seems to give the best representation of sediment load in upper one meter of water column. (4) In the ERTS-1 imagery the sediment patterns are delineated by three to four neighboring shades of grey. (5) Negative transparencies of the ERTS-1 images give better contrast whenever the suspended sediment tones fall within the first few steps of the grey scale. (6) Color density slicing helps delineate the suspended sediment patterns more clearly and differentiate turbidity levels.

  12. The ERTS-1 investigation (ER-600). Volume 2: ERTS-1 coastal/estuarine analysis. [Galveston Bay, Texas

    NASA Technical Reports Server (NTRS)

    Erb, R. B.

    1974-01-01

    The Coastal Analysis Team of the Johnson Space Center conducted a 1-year investigation of ERTS-1 MSS data to determine its usefulness in coastal zone management. Galveston Bay, Texas, was the study area for evaluating both conventional image interpretation and computer-aided techniques. There was limited success in detecting, identifying and measuring areal extent of water bodies, turbidity zones, phytoplankton blooms, salt marshes, grasslands, swamps, and low wetlands using image interpretation techniques. Computer-aided techniques were generally successful in identifying these features. Aerial measurement of salt marshes accuracies ranged from 89 to 99 percent. Overall classification accuracy of all study sites was 89 percent for Level 1 and 75 percent for Level 2.

  13. The ERTS-1 investigation (ER-600): A compendium of analysis results of the utility of ERTS-1 data for land resources management

    NASA Technical Reports Server (NTRS)

    Erb, R. B.

    1974-01-01

    The results of the ERTS-1 investigations conducted by the Earth Observations Division at the NASA Lyndon B. Johnson Space Center are summarized in this report, which is an overview of documents detailing individual investigations. Conventional image interpretation and computer-aided classification procedures were the two basic techniques used in analyzing the data for detecting, identifying, locating, and measuring surface features related to earth resources. Data from the ERTS-1 multispectral scanner system were useful for all applications studied, which included agriculture, coastal and estuarine analysis, forestry, range, land use and urban land use, and signature extension. Percentage classification accuracies are cited for the conventional and computer-aided techniques.

  14. Evaluation of the application of ERTS-1 data to the regional land use planning process. [Northeast Wisconsin

    NASA Technical Reports Server (NTRS)

    Clapp, J. L. (Principal Investigator); Green, T., III; Hanson, G. F.; Kiefer, R. W.; Niemann, B. J., Jr.

    1974-01-01

    The author has identified the following significant results. Employing simple and economical extraction methods, ERTS can provide valuable data to the planners at the state or regional level with a frequency never before possible. Interactive computer methods of working directly with ERTS digital information show much promise for providing land use information at a more specific level, since the data format production rate of ERTS justifies improved methods of analysis.

  15. The use of ERTS-1 data for the inventory of critical land resources for regional land use planning

    NASA Technical Reports Server (NTRS)

    Clapp, J. L.; Kiefer, R. W.; Mccarthy, M. M.; Niemann, B. J., Jr.

    1973-01-01

    Computer-generated spatial and statistical comparisons of critical land resource data derived from conventional sources, RB-57 photographs, and ERTS images, for an eastern Wisconsin test site, suggest that certain critical land resource data can be mapped from ERTS images on a statewide basis. This paper presents one of the biotic resources, wetlands, as an example of the use of ERTS imagery to inventory land resources.

  16. Quasi-3D Resistivity Imaging - Results from Geophysical Mapping and Forward Modeling

    NASA Astrophysics Data System (ADS)

    Schwindt, D.; Kneisel, C.

    2009-04-01

    2D resistivity tomography has proven to be a reliable tool in detecting, characterizing and mapping of permafrost, especially in joint application with other geophysical methods, e.g. seismic refraction. For many permafrost related problems a 3D image of the subsurface is of interest. Possibilities of quasi-3D imaging by collating several 2D ERT files into one quasi-3D file were tested. Data acquisition took place on a vegetated scree slope with isolated permafrost lenses in the Bever Valley, Swiss Alps. 21 2D-electrical arrays were applied with an electrode spacing of 5 m and a parallel spacing of 20 and 30 m using the Wenner electrode configuration. Refraction seismic was applied parallel to every second ERT array, with a geophone spacing of 5 m for validation. Results of quasi-3D imaging indicate that the most important factors influencing data quality are parallel spacing and number of right-angled crossing profiles. While the quasi-3D images generated of 2D-files with a parallel spacing of 20 m provide an interpretable image, 30 m spacing results in a blurred illustration of resistivity structures. To test the influence of crossing profiles quasi-3D images were inverted using only parallel measured data files as well as images containing right-angled crossing transects. Application of crossing profiles is of great importance, because the number of model blocks with interpolated resistivity values between parallel profiles is minimized. In case of two adjacent high resistivity anomalies a quasi-3D image consisting of parallel measured transects only illustrates one anomaly. A crossing profile provides information to differentiate the anomalies. Forward modeling was used to prove these assumptions and to improve the application of 2D ERT with regard to quasi-3D imaging. Main focus was on electrode and parallel spacing, the influence of crossing transects and the applicability of different array types. A number of 2D ERT profiles were generated, using the forward

  17. Isolation of Novel CreERT2-Driver Lines in Zebrafish Using an Unbiased Gene Trap Approach

    PubMed Central

    Jungke, Peggy; Hammer, Juliane; Hans, Stefan; Brand, Michael

    2015-01-01

    Gene manipulation using the Cre/loxP-recombinase system has been successfully employed in zebrafish to study gene functions and lineage relationships. Recently, gene trapping approaches have been applied to produce large collections of transgenic fish expressing conditional alleles in various tissues. However, the limited number of available cell- and tissue-specific Cre/CreERT2-driver lines still constrains widespread application in this model organism. To enlarge the pool of existing CreERT2-driver lines, we performed a genome-wide gene trap screen using a Tol2-based mCherry-T2a-CreERT2 (mCT2aC) gene trap vector. This cassette consists of a splice acceptor and a mCherry-tagged variant of CreERT2 which enables simultaneous labeling of the trapping event, as well as CreERT2 expression from the endogenous promoter. Using this strategy, we generated 27 novel functional CreERT2-driver lines expressing in a cell- and tissue-specific manner during development and adulthood. This study summarizes the analysis of the generated CreERT2-driver lines with respect to functionality, expression, integration, as well as associated phenotypes. Our results significantly enlarge the existing pool of CreERT2-driver lines in zebrafish and combined with Cre–dependent effector lines, the new CreERT2-driver lines will be important tools to manipulate the zebrafish genome. PMID:26083735

  18. Overall evaluation of ERTS-1 imagery for cartographic application. [Australia, Antarctica, U.S., and U.S.S.R.

    NASA Technical Reports Server (NTRS)

    Covocoresses, A. P. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. The conclusion reached is that an ERTS-type satellite has widespread cartographic application for scales of 1:250,000 and smaller. ERTS imagery also indicates those areas requiring revision at larger scales. For optimum cartographic application, ERTS must be flown continuously as temporal change (seasonal and long term) detection requires comparative coverage. ERTS is the first imagery system that lends itself to automated mapping wherein cartographic products may be produced in a matter of days rather than in months or years.

  19. Isolation of Novel CreERT2-Driver Lines in Zebrafish Using an Unbiased Gene Trap Approach.

    PubMed

    Jungke, Peggy; Hammer, Juliane; Hans, Stefan; Brand, Michael

    2015-01-01

    Gene manipulation using the Cre/loxP-recombinase system has been successfully employed in zebrafish to study gene functions and lineage relationships. Recently, gene trapping approaches have been applied to produce large collections of transgenic fish expressing conditional alleles in various tissues. However, the limited number of available cell- and tissue-specific Cre/CreERT2-driver lines still constrains widespread application in this model organism. To enlarge the pool of existing CreERT2-driver lines, we performed a genome-wide gene trap screen using a Tol2-based mCherry-T2a-CreERT2 (mCT2aC) gene trap vector. This cassette consists of a splice acceptor and a mCherry-tagged variant of CreERT2 which enables simultaneous labeling of the trapping event, as well as CreERT2 expression from the endogenous promoter. Using this strategy, we generated 27 novel functional CreERT2-driver lines expressing in a cell- and tissue-specific manner during development and adulthood. This study summarizes the analysis of the generated CreERT2-driver lines with respect to functionality, expression, integration, as well as associated phenotypes. Our results significantly enlarge the existing pool of CreERT2-driver lines in zebrafish and combined with Cre-dependent effector lines, the new CreERT2-driver lines will be important tools to manipulate the zebrafish genome. PMID:26083735

  20. In Vivo Performance and Properties of Tamoxifen Metabolites for CreERT2 Control

    PubMed Central

    Dolbois, Aymeric; Blazkova, Kristyna; Hess, Christopher; Low, Larry W. L.; Burger, Sibylle; Samson, Natasha; Carney, Tom J.; Bartunek, Petr; Nevado, Cristina

    2016-01-01

    Mutant Estrogen Receptor (ERT2) ligand-binding domain fusions with Cre recombinase are a key tool for spatio-temporally controlled genetic recombination with the Cre/lox system. CreERT2 is efficiently activated in a concentration-dependent manner by the Tamoxifen metabolite trans-4-OH-Tamoxifen (trans-4-OHT). Reproducible and efficient Cre/lox experimentation is hindered by the gradual loss of CreERT2 induction potency upon prolonged storage of dissolved trans-4-OHT, which potentially results from gradual trans-to-cis isomerization or degradation. Here, we combined zebrafish CreERT2 recombination experiments and cell culture assays to document the gradual activity loss of trans-4-OHT and describe the alternative Tamoxifen metabolite Endoxifen as more stable alternative compound. Endoxifen retains potent activation upon prolonged storage (3 months), yet consistently induces half the ERT2 domain fusion activity compared to fresh trans-4-OHT. Using 1H-NMR analysis, we reveal that trans-4-OHT isomerization is undetectable upon prolonged storage in either DMSO or Ethanol, ruling out isomer transformation as cause for the gradual loss of trans-4-OHT activity. We further establish that both trans-4-OHT and Endoxifen are insensitive to light exposure under regular laboratory handling conditions. We attribute the gradual loss of trans-4-OHT potency to precipitation over time, and show that heating of aged trans-4-OHT aliquots reinstates their CreERT2 induction potential. Our data establish Endoxifen as potent and reproducible complementary compound to 4-OHT to control ERT2 domain fusion proteins in vivo, and provide a framework for efficient chemically controlled recombination experiments. PMID:27077909

  1. In Vivo Performance and Properties of Tamoxifen Metabolites for CreERT2 Control.

    PubMed

    Felker, Anastasia; Nieuwenhuize, Susan; Dolbois, Aymeric; Blazkova, Kristyna; Hess, Christopher; Low, Larry W L; Burger, Sibylle; Samson, Natasha; Carney, Tom J; Bartunek, Petr; Nevado, Cristina; Mosimann, Christian

    2016-01-01

    Mutant Estrogen Receptor (ERT2) ligand-binding domain fusions with Cre recombinase are a key tool for spatio-temporally controlled genetic recombination with the Cre/lox system. CreERT2 is efficiently activated in a concentration-dependent manner by the Tamoxifen metabolite trans-4-OH-Tamoxifen (trans-4-OHT). Reproducible and efficient Cre/lox experimentation is hindered by the gradual loss of CreERT2 induction potency upon prolonged storage of dissolved trans-4-OHT, which potentially results from gradual trans-to-cis isomerization or degradation. Here, we combined zebrafish CreERT2 recombination experiments and cell culture assays to document the gradual activity loss of trans-4-OHT and describe the alternative Tamoxifen metabolite Endoxifen as more stable alternative compound. Endoxifen retains potent activation upon prolonged storage (3 months), yet consistently induces half the ERT2 domain fusion activity compared to fresh trans-4-OHT. Using 1H-NMR analysis, we reveal that trans-4-OHT isomerization is undetectable upon prolonged storage in either DMSO or Ethanol, ruling out isomer transformation as cause for the gradual loss of trans-4-OHT activity. We further establish that both trans-4-OHT and Endoxifen are insensitive to light exposure under regular laboratory handling conditions. We attribute the gradual loss of trans-4-OHT potency to precipitation over time, and show that heating of aged trans-4-OHT aliquots reinstates their CreERT2 induction potential. Our data establish Endoxifen as potent and reproducible complementary compound to 4-OHT to control ERT2 domain fusion proteins in vivo, and provide a framework for efficient chemically controlled recombination experiments. PMID:27077909

  2. In Vivo Performance and Properties of Tamoxifen Metabolites for CreERT2 Control.

    PubMed

    Felker, Anastasia; Nieuwenhuize, Susan; Dolbois, Aymeric; Blazkova, Kristyna; Hess, Christopher; Low, Larry W L; Burger, Sibylle; Samson, Natasha; Carney, Tom J; Bartunek, Petr; Nevado, Cristina; Mosimann, Christian

    2016-01-01

    Mutant Estrogen Receptor (ERT2) ligand-binding domain fusions with Cre recombinase are a key tool for spatio-temporally controlled genetic recombination with the Cre/lox system. CreERT2 is efficiently activated in a concentration-dependent manner by the Tamoxifen metabolite trans-4-OH-Tamoxifen (trans-4-OHT). Reproducible and efficient Cre/lox experimentation is hindered by the gradual loss of CreERT2 induction potency upon prolonged storage of dissolved trans-4-OHT, which potentially results from gradual trans-to-cis isomerization or degradation. Here, we combined zebrafish CreERT2 recombination experiments and cell culture assays to document the gradual activity loss of trans-4-OHT and describe the alternative Tamoxifen metabolite Endoxifen as more stable alternative compound. Endoxifen retains potent activation upon prolonged storage (3 months), yet consistently induces half the ERT2 domain fusion activity compared to fresh trans-4-OHT. Using 1H-NMR analysis, we reveal that trans-4-OHT isomerization is undetectable upon prolonged storage in either DMSO or Ethanol, ruling out isomer transformation as cause for the gradual loss of trans-4-OHT activity. We further establish that both trans-4-OHT and Endoxifen are insensitive to light exposure under regular laboratory handling conditions. We attribute the gradual loss of trans-4-OHT potency to precipitation over time, and show that heating of aged trans-4-OHT aliquots reinstates their CreERT2 induction potential. Our data establish Endoxifen as potent and reproducible complementary compound to 4-OHT to control ERT2 domain fusion proteins in vivo, and provide a framework for efficient chemically controlled recombination experiments.

  3. Computed Tomography

    NASA Astrophysics Data System (ADS)

    Castellano, Isabel; Geleijns, Jacob

    After its clinical introduction in 1973, computed tomography developed from an x-ray modality for axial imaging in neuroradiology into a versatile three dimensional imaging modality for a wide range of applications in for example oncology, vascular radiology, cardiology, traumatology and even in interventional radiology. Computed tomography is applied for diagnosis, follow-up studies and screening of healthy subpopulations with specific risk factors. This chapter provides a general introduction in computed tomography, covering a short history of computed tomography, technology, image quality, dosimetry, room shielding, quality control and quality criteria.

  4. ERTS-1 imagery use in reconnaissance prospecting: Evaluation of commercial utility of ERTS-1 imagery in structural reconnaissance for minerals and petroleum

    NASA Technical Reports Server (NTRS)

    Saunders, D. F.; Thomas, G. E. (Principal Investigator); Kinsman, F. E.; Beatty, D. F.

    1973-01-01

    The author has identified the following significant results. This study was performed to investigate applications of ERTS-1 imagery in commercial reconnaissance for mineral and hydrocarbon resources. ERTS-1 imagery collected over five areas in North America (Montana; Colorado; New Mexico-West Texas; Superior Province, Canada; and North Slope, Alaska) has been analyzed for data content including linears, lineaments, and curvilinear anomalies. Locations of these features were mapped and compared with known locations of mineral and hydrocarbon accumulations. Results were analyzed in the context of a simple-shear, block-coupling model. Data analyses have resulted in detection of new lineaments, some of which may be continental in extent, detection of many curvilinear patterns not generally seen on aerial photos, strong evidence of continental regmatic fracture patterns, and realization that geological features can be explained in terms of a simple-shear, block-coupling model. The conculsions are that ERTS-1 imagery is of great value in photogeologic/geomorphic interpretations of regional features, and the simple-shear, block-coupling model provides a means of relating data from ERTS imagery to structures that have controlled emplacement of ore deposits and hydrocarbon accumulations, thus providing a basis for a new approach for reconnaissance for mineral, uranium, gas, and oil deposits and structures.

  5. An observational study of the association among interatrial adiposity by computed tomography measure, insulin resistance, and left atrial electromechanical disturbances in heart failure

    PubMed Central

    Hung, Chung-Lieh; Yun, Chun-Ho; Lai, Yau-Huei; Sung, Kuo-Tzu; Bezerra, Hiram G.; Kuo, Jen-Yuan; Hou, Charles Jia-Yin; Chao, Tze-Fan; Bulwer, Bernard E.; Yeh, Hung-I.; Shih, Shou-Chuan; Lin, Shing-Jong; Cury, Ricardo C.

    2016-01-01

    Abstract Excessive visceral adiposity, hypothesized to be a key mediator in metabolic derangements, has recently been shown to exert toxic effects on cardiac structure and function. Data regarding the mechanistic link between regional adiposity, left atrial (LA) electromechanical remodeling, and heart failure with preserved ejection fraction (HFpEF) have been lacking. Various visceral adiposity measures, including pericardial fat (PCF), thoracic periaortic (TAT) fat, regional inter-atrial fat (IAF), and atrioventricular groove fat (AV Groove Fat), were assessed by multidetector computed tomography in 2 study cohorts (an annual health survey cohort and an outpatient cohort). We related such measures to cardiometabolic profiles in health survey cohort and LA electromechanical indices in our outpatient cohort, with Cox proportional hazards performed to examine the temporal trends of heart failure (HF). In our annual health survey cohort (n = 362), all 4 adiposity measures were positively related to unfavorable anthropometrics and systemic inflammation (high-sensitivity C-reactive protein) (all P < 0.05). In addition, both greater IAF and AV Groove Fat were positively associated with higher fasting glucose, HbA1c levels, and insulin resistance (all P < 0.05). In the outpatient cohort, the HFpEF group demonstrated the greatest adiposity measures, with greater IAF (≥8.2 mm, hazard ratio: 4.11, 95% confidence interval: 1.50–11.32) associated with reduced LA strain (ß-coef: –0.28), higher LA stiffness (ß-coef: 0.23), and longer P wave duration (ß-coef: 0.23) in multivariate models (all P < 0.05), and further related to higher HF hospitalization during follow-up. We therefore propose a possible pathophysiologic link among greater visceral adiposity, systemic inflammation, cardiometabolic risks, and HFpEF. Regional adiposity, especially IAF, was tightly linked to altered LA electromechanical properties and likely plays a key role in HF prognosis. PMID

  6. The antiepileptic drug mephobarbital is not transported by P-glycoprotein or multidrug resistance protein 1 at the blood-brain barrier: a positron emission tomography study

    PubMed Central

    Mairinger, Severin; Bankstahl, Jens P.; Kuntner, Claudia; Römermann, Kerstin; Bankstahl, Marion; Wanek, Thomas; Stanek, Johann; Löscher, Wolfgang; Müller, Markus; Erker, Thomas; Langer, Oliver

    2013-01-01

    Summary Aim of this study was to determine whether the carbon-11-labelled antiepileptic drug [11C]mephobarbital is a substrate of P-glycoprotein (Pgp) and can be used to assess Pgp function at the blood-brain barrier (BBB) with positron emission tomography (PET). We performed paired PET scans in rats, wild-type (FVB) and Mdr1a/b(−/−) mice, before and after intravenous administration of the Pgp inhibitor tariquidar (15 mg/kg). Brain-to-blood AUC0-60 ratios in rats and brain AUC0-60 values of [11C]mephobarbital in wild-type and Mdr1a/b(−/−) mice were similar in scan 1 and scan 2, respectively, suggesting that in vivo brain distribution of [11C]mephobarbital is not influenced by Pgp efflux. Absence of Pgp transport was confirmed in vitro by performing concentration equilibrium transport assay in cell lines transfected with MDR1 or Mdr1a. PET experiments in wild-type mice, with and without pretreatment with the multidrug resistance protein (MRP) inhibitor MK571 (20 mg/kg), and in Mrp1(−/−) mice suggested that [11C]mephobarbital is also not transported by MRPs at the murine BBB, which was also supported by in vitro transport experiments using human MRP1-transfected cells. Our results are surprising as phenobarbital, the N-desmethyl derivative of mephobarbital, has been shown to be a substrate of Pgp, which suggests that N-methylation abolishes Pgp affinity of barbiturates. PMID:22342565

  7. An observational study of the association among interatrial adiposity by computed tomography measure, insulin resistance, and left atrial electromechanical disturbances in heart failure.

    PubMed

    Hung, Chung-Lieh; Yun, Chun-Ho; Lai, Yau-Huei; Sung, Kuo-Tzu; Bezerra, Hiram G; Kuo, Jen-Yuan; Hou, Charles Jia-Yin; Chao, Tze-Fan; Bulwer, Bernard E; Yeh, Hung-I; Shih, Shou-Chuan; Lin, Shing-Jong; Cury, Ricardo C

    2016-06-01

    Excessive visceral adiposity, hypothesized to be a key mediator in metabolic derangements, has recently been shown to exert toxic effects on cardiac structure and function. Data regarding the mechanistic link between regional adiposity, left atrial (LA) electromechanical remodeling, and heart failure with preserved ejection fraction (HFpEF) have been lacking.Various visceral adiposity measures, including pericardial fat (PCF), thoracic periaortic (TAT) fat, regional inter-atrial fat (IAF), and atrioventricular groove fat (AV Groove Fat), were assessed by multidetector computed tomography in 2 study cohorts (an annual health survey cohort and an outpatient cohort). We related such measures to cardiometabolic profiles in health survey cohort and LA electromechanical indices in our outpatient cohort, with Cox proportional hazards performed to examine the temporal trends of heart failure (HF).In our annual health survey cohort (n = 362), all 4 adiposity measures were positively related to unfavorable anthropometrics and systemic inflammation (high-sensitivity C-reactive protein) (all P < 0.05). In addition, both greater IAF and AV Groove Fat were positively associated with higher fasting glucose, HbA1c levels, and insulin resistance (all P < 0.05). In the outpatient cohort, the HFpEF group demonstrated the greatest adiposity measures, with greater IAF (≥8.2 mm, hazard ratio: 4.11, 95% confidence interval: 1.50-11.32) associated with reduced LA strain (ß-coef: -0.28), higher LA stiffness (ß-coef: 0.23), and longer P wave duration (ß-coef: 0.23) in multivariate models (all P < 0.05), and further related to higher HF hospitalization during follow-up.We therefore propose a possible pathophysiologic link among greater visceral adiposity, systemic inflammation, cardiometabolic risks, and HFpEF. Regional adiposity, especially IAF, was tightly linked to altered LA electromechanical properties and likely plays a key role in HF prognosis. PMID:27310996

  8. Towards electrical resistivity soundings in eco-engineering: A non-invasive and fast method to model the near-subsurface characteristics on stabilized alpine slopes.

    NASA Astrophysics Data System (ADS)

    Bast, Alexander; Meyer, Christine; Meier, Wolfgang; Wilcke, Wolfgang; Lüscher, Peter; Graf, Frank; Gärtner, Holger

    2014-05-01

    The observation and monitoring of the aboveground plant development is a common practice in eco-engineering to estimate the plant's influence on the stabilization process. In contrast to this aboveground "sphere", the near subsurface is invisible and therefore difficult to address. To get an impression of the near subsurface and to model slope stability, (soil)samples are taken or a soil profile is dug and root traits (e.g., tensile strength) are determined. Other parameters as rooting depth, root length density, root clustering or the type of root in general are also of interest. However, soil samples or soil profiles only provide limited point-by-point data, alter parts of the study site, and are often time-consuming and expensive. The development of plants results a complex spatial and temporal distribution of the root network along a slope. This network causes shear strength variations and hydrological heterogeneities in the near subsurface within short distances. In contrast to the common point data, geophysical methods provide minimally-invasive, spatial and, via a time-lapse approach (monitoring), also temporal information of the near subsurface conditions. Hence, by measuring physical properties of the near subsurface, the root system, i.e. root distribution and rooting depth can be modeled. Furthermore, if a correlation between root traits and the measured physical properties is determined, the corresponding root trait can be estimated. To test this approach we applied electrical resistivity tomography (ERT) in a subalpine catchment in the Prättigau valley/Eastern Swiss Alps. Different ERT-soundings were conducted using varying electrode spacings (5cm, 25cm, 50cm and 100cm), electrode arrays (Wenner and Wenner-Schlummberger) and locations (eco-engineered slopes, stabilized two, three and 17 years ago; two forest stands of different stand densities). Furthermore, we took soil samples along the electrical profiles, and dug out several soil profiles to

  9. Geology of Utah and Nevada by ERTS imagery

    NASA Technical Reports Server (NTRS)

    Jensen, M. L. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Two ancient watercourses have been observed on ERTS-1 imagery. These lie in the Waterpocket Fold area, north of the Marble Canyon section of the Colorado River, in Arizona and Utah. A third old watercourse of interest is an ancient canyon of the Colorado and is located on image no. 1156-17260. Image no. 1051-17414 contains some very useful information concerning the hydrology, sedimentology, and biology of Great Salt Lake and Bear Lake in Utah. In Great Salt Lake, there is a sharp line between the portion of the lake north of the railroad causeway and that south of the causeway. There is a marked difference in salinity across the causeway, and this is reflected in different algal species. On the same image, sediment plumes in Bear Lake clearly delineate the circulation pattern, and provide excellent indications of bottom contours over much of the area. Image no. 1051-17420 contains part of Great Salt Lake and all of Utah Lake. The latter displays a very interesting surface pattern which is probably due to an algal bloom which has been swirled into a spiral by the circulation of the lake.

  10. Automated strip-mine and reclamation mapping from ERTS

    NASA Technical Reports Server (NTRS)

    Rogers, R. H. (Principal Investigator); Reed, L. E.; Pettyjohn, W. A.

    1974-01-01

    The author has identified the following significant results. Computer processing techniques were applied to ERTS-1 computer-compatible tape (CCT) data acquired in August 1972 on the Ohio Power Company's coal mining operation in Muskingum County, Ohio. Processing results succeeded in automatically classifying, with an accuracy greater than 90%: (1) stripped earth and major sources of erosion; (2) partially reclaimed areas and minor sources of erosion; (3) water with sedimentation; (4) water without sedimentation; and (5) vegetation. Computer-generated tables listing the area in acres and square kilometers were produced for each target category. Processing results also included geometrically corrected map overlays, one for each target category, drawn on a transparent material by a pen under computer control. Each target category is assigned a distinctive color on the overlay to facilitate interpretation. The overlays, drawn at a scale of 1:250,000 when placed over an AMS map of the same area, immediately provided map locations for each target. These mapping products were generated at a tenth of the cost of conventional mapping techniques.

  11. Identification and interpretation of tectonic features from ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. An important fault zone, which is strongly suspected of being seismically active, was identified on RBV images, ERTS E-1013-17305 (101, 201, and 301), in northeastern Utah. This fault zone is not shown on the Geological Map of the United States nor on the Tectonic Map of North America. When the epicenters of historic earthquakes and their magnitudes were plotted on an overlay corresponding to the scene, a major earthquake cluster up to magnitude 4.9 was found through which the fault zone passes. This suspected active fault zone runs in a northwest-southwest direction cutting across the Patmos Mountains and the southwestern side of the East Tavaputs Plateau from near the junction of the Colorado River with the Dolores River to and beyond the town of Dragerton, Utah. The fault zone which will subsequently be referred to as the Dragerton fault zone appears to be an element of a major tectonic lineament which includes the Moab fault, Salt Valley, Spanish and Lisbon Valleys. Because of the limited imagery coverage received so far, the extent of this lineament or its tectonic significance cannot be ascertained. It is suspected, however, that it constitutes a major crustal break in the Colorado Plateau.

  12. Fracture trends identified by ERTS-1 imagery in Utah and Nevada

    NASA Technical Reports Server (NTRS)

    Jensen, M. L. (Principal Investigator); Erickson, M. P.; Smith, M. R.

    1973-01-01

    The author has identified the following significant results. In the Utah-Nevada area, linear structural trends recorded on ERTS-1 imagery conform in part to previously recognized structures. In addition, the ERTS-1 imagery reveals cryptic structures not previously identified and not readily apparent in other imagery. These structures are illustrated by prominent east-west trending structures which appear to be concentrated in pre-volcanic rocks. This suggests that the structures are older than many of those with other trends which are equally prominent in volcanic and non-volcanic terrain. Since the older east-west structures may have controlled early Tertiary emplacement of magma or the ascent of mineralizing fluids, their recognition is important in minerial exploration. Soil-gas sampling and analysis for mercury content is being continued over structures, and projected trends of buried structures which appear, from studies of ERTS-1 imagery, to be favorable to mineralization. Comparison of ERTS-1 and Skylab imagery indicated that ERTS-1 imagery records more previously unrecognized linear structures than the Skylab imagery. In differentiating and identifying different rock types, the Skylab imagery appears to be more effective.

  13. Application of ERTS-1 data to the protection and management of New Jersey's coastal environment

    NASA Technical Reports Server (NTRS)

    Yunghans, R. S. (Principal Investigator); Feinberg, E. B.; Stitt, J. A.; Mairs, R. L.; Wobber, F. J.; Macomber, R. T.; Stanczuk, D. T.; Thibult, D.

    1974-01-01

    The author has identified the following significant results. Quasi-operational information products for coastal zone management have been prepared using ERTS-1 imagery and collateral aerial photography. These products were applied to the practical regulation, protection, and management of New Jersey's coastal environment. Procedures were developed for the operational use of ERTS-1 data products within New Jersey's Department of Environmental Protection. Successful analysis and product preparation for operational needs centered on four major coastal resource problem areas: (1) detection of environmental changes in coastal areas, (2) siting of ocean outfalls, (3) monitoring of offshore waste disposal, and (4) calculation of recession rates along the Atlantic Shore. The utility and monetary benefits derived from ERTS and aircraft imagery for each problem area have been determined. The NJDEP estimates the possibility of $620,000 yearly savings through the use of an operational ERTS system and a one-time savings of $2.8 million on current or planned projects if a truly operational ERTS type satellite were available.

  14. Evaluate the application of ERTS-A data for detecting and mapping snow cover

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Analysis of ERTS-1 data covering the test sites in the western United States indicate that the MSS-4 and 5 spectral bands are the most useful for detecting and mapping snow cover. Of these two bands, the MSS-5 is the most consistently useful, as snow-covered areas in some MSS-4 images are nearly saturated causing some loss of detail. Snow can be readily detected and can be distinguished from clouds through a number of interpretive keys. At the ERTS-1 resolution, numerous terrestrial features not visible in lower resolution meteorological satellite data can be detected. In addition to various natural features, man-made features such as roads, electric power lines, cultivated fields, and timber cuts are visible. In two cases analyzed for the Salt-Verde Watershed in Arizona, good agreement is observed between the location of the snowline as mapped from the ERTS-1 data and as depicted on aerial snow survey charts compiled within a few days of the ERTS-1 passage. Results indicate that the snowline can be mapped in more detail from ERTS-1 imagery than can be achieved by current aerial survey methods.

  15. ERIM progress report on use of ERTS-1 data: Summary report of work on ten tasks

    NASA Technical Reports Server (NTRS)

    Thomson, F. J. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Several of the tasks have produced significant results which are summarized: (1) Absolute water depth can be calculated from a ratio of signals from bands MSS 4 and MSS 5. (2) A 13 category terrain feature classification map of Yellowstone National Park has been produced using supervised pattern recognition techniques. (3) ERTS-1 data has been shown to provide a detection and monitoring capability for a number of water quality problems associated with off-shore ocean dumping sites and inland lakes. (4) A corrected ratio of bands MSS-5 and MSS-7 signals has been formed. (5) A concise format has been devised for storing the ratio signatures of geologic rock and mineral materials determined from laboratory reflectance spectra. (6) Results of work in information extraction demonstrate: signal variability exists among ERTS-1 detectors in any one spectral band that will impact users doing quantitative analysis on successive ERTS-1 images; a newly developed computer-aided procedure for correlating ERTS-1 pixels to ground features; the strong influence of atmospheric effects in ERTS-1 data; and area estimation accuracies are better using the ERIM proportion estimation algorithm than for conventional recognition techniques.

  16. Monitoring coastal water properties and circulation from ERTS-1. [Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Imagery and digital tapes from nine successful ERTS-1 passes over Delaware Bay during different portions of the tidal cycle have been analyzed with special emphasis on turbidity, current circulation, waste disposal plumes, and convergent boundaries between different water masses. ERTS-1 image radiance correlated well with Secchi depth and suspended sediment concentration. MSS band 5 seemed to give the best representation of sediment load in the upper one meter of the water column. Circulation patterns observed by ERTS-1 during different parts of the tidal cycle, agreed well with predicted and measured currents throughout Delaware Bay. During flood tide the suspended sediment as visible from ERTS-1 also correlated well with the depth profile. Convergent shear boundaries between different water masses were observed from ERTS-1, with foam lines containing high concentrations of lead, mercury, and other toxic substances. Several fronts have been seen. Those near the mouth of the bay are associated with the tidal intrusion of shelf water. Fronts in the interior of the bay on the Delaware side appear to be associated with velocity shears induced by differences in bottom topography. Waste disposal plumes have benn detected 36 miles offshore.

  17. ERTS-1 flood hazard studies in the Mississippi River Basin. [Missouri, Mississippi, and Arkansas

    NASA Technical Reports Server (NTRS)

    Rango, A.; Anderson, A. T.

    1974-01-01

    The Spring 1973 Mississippi River flood was investigated using remotely sensed data from ERTS-1. Both manual and automatic analyses of the data indicate that ERTS-1 is extremely useful as a regional tool for flood and floodplain management. The maximum error of such flood area measurements is conservatively estimated to be less than five percent. Change detection analysis indicates that the flood had major impacts on soil moisture, land pattern stability, and vegetation stress. Flood hazard identification was conducted using photointerpretation techniques in three study areas along the Mississippi River using pre-flood ERTS-1 imagery down to 1:100,000 scale. Flood prone area boundaries obtained from ERTS-1 were generally in agreement with flood hazard maps produced by the U.S. Army Corps of Engineers and the U.S. Geological Survey although the latter are somewhat more detailed because of their larger scale. Initial results indicate that ERTS-1 digital mapping of the flood-prone areas can be performed at least 1:62,500 which is comparable to conventional flood hazard map scales.

  18. Comparative evaluation of ERTS imagery for resource inventory in land use planning

    NASA Technical Reports Server (NTRS)

    Simonson, G. H. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Numerous previously unmapped faults in central Oregon have been distinguished on ERTS-1 imagery. Tectonic mapping of fault-controlled linears demonstrates the utility of ERTS-1 imagery as a mean of illustrating and studying the regional tectonics of the state. Soil colors observed on ERTS-1 frame 1075-18150-5 at the eastern end of the Columbia basin correlate very well with those from descriptions of soils from that area. Digital output from frame 1021-18151 has shown the enhanced ability to interpret such features as joint patterns, shadowed landslide blocks, bottomlands, and drainage patterns. Widespread use of wheat-fallow rotation in northern Umatilla County, Oregon, insures that nearly one-half of the cultivated soil is devoid of vegetation much of the time. On ERTS-1 imagery, fallow fields are only slightly darker than fields of wheat stubble at the western end of the transect. Similar climate-related contrasts in soil color are visible on ERTS-1 Imagery from several other portions of the Columbia Basin. Absence of steep topography in the area mentioned, however, minimizes the disturbing effect caused by shadows.

  19. Application of ERTS-1 satellite imagery for land use mapping and resource inventories in the central coastal region of California

    NASA Technical Reports Server (NTRS)

    Estes, J. E.; Thaman, R. R.; Senger, L. W.

    1974-01-01

    ERTS-1 satellite imagery has proved a valuable data source for land use as well as natural and cultural resource studies on a regional basis. ERTS-1 data also provide an excellent base for mapping resource related features and phenomena. These investigations are focused on a number of potential applications which are already showing promise of having operational utility.

  20. Relevance of ERTS-1 to the State of Ohio. [agriculture, forestry, land use, mining, and environmental quality management

    NASA Technical Reports Server (NTRS)

    Sweet, D. C.; Pincura, P. G.; Wukelic, G. E. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. During the first year of project effort the ability of ERTS-1 imagery to be used for mapping and inventorying strip-mined areas in south eastern Ohio, the potential of using ERTS-1 imagery in water quality and coastal zone management in the Lake Erie region, and the extent that ERTS-1 imagery could contribute to localized (metropolitan/urban), multicounty, and overall state land use needs were experimentally demonstrated and reported as significant project results. Significant research accomplishments were achieved in the technological development of manual and computerized methods to extract multi-feature information as well as singular feature information from ERTS-1 data as is exemplified by the forestry transparency overlay. Fabrication of an image transfer device to superimpose ERTS-1 data onto existing maps and other data sources was also a significant analytical accomplishment.

  1. Inventory and monitoring of natural vegetation and related resources in an arid environment: A comparative evaluation of ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Schrumpf, B. J. (Principal Investigator); Johnson, J. R.; Mouat, D. A.; Pyott, W. T.

    1973-01-01

    The author has identified the following significant results. A comparative evaluation of an ERTS-1 MSS color reconstitution and an Apollo 6 and Gemini 4 color photograph for information content was conducted. A greater variety of image detail was indicated for the Apollo 6 imagery. A study of terrain feature variable-vegetation relationships has been concluded. However, there were no substantial differences among space photo types when macrorelief classes were interpreted. Vegetation distribution is influenced in varying degrees by characteristics of the terrain, some of which are quite apparent on ERTS-1 imagery and, therefore, provide the means for inferring possible vegetation types for a specified location. Spectral signatures have been determined for some natural vegetation systems from the ERTS-1 MSS data. Those signatures have been used to classify ERTS-1 data for a portion of the study area. Work continues on multistage sampling for natural vegetation, terrain feature identification of ERTS-1 photographs, plant phenology, and spectral signature studies.

  2. Application of ERTS-1 data to analysis of agricultural crops and forests in Michigan

    NASA Technical Reports Server (NTRS)

    Safir, G. R.; Myers, W. L.; Malila, W. A.; Morgenstern, J. P.

    1973-01-01

    The results reported are based on analysis of ERTS Frame 1033-15580 collected over southwestern Lower Michigan on August 25, 1972. Major agricultural crops such as corn and soybeans were approaching maturity at this data and forest canopies were dense. Extensive ground truth information was gathered by detailed field study of test strips. This detailed information was supplemented over larger areas by interpretation of RB-57 and C-47 photography and MSS imagery. Recognition processing of ERTS-1 MSS data was carried out on a digital computer. Fields and forest stands were selected as training sets and test areas. Aerial imagery was essential for locating the positions of these selected areas on ERTS digital tapes. The recognition process was successful for each type of vegetation which had a dense green canopy such as forests, corn, and soybeans. Bare soil was also recognizable as a category.

  3. User oriented ERTS-1 images. [vegetation identification in Canada through image enhancement

    NASA Technical Reports Server (NTRS)

    Shlien, S.; Goodenough, D.

    1974-01-01

    Photographic reproduction of ERTS-1 images are capable of displaying only a portion of the total information available from the multispectral scanner. Methods are being developed to generate ERTS-1 images oriented towards special users such as agriculturists, foresters, and hydrologists by applying image enhancement techniques and interactive statistical classification schemes. Spatial boundaries and linear features can be emphasized and delineated using simple filters. Linear and nonlinear transformations can be applied to the spectral data to emphasize certain ground information. An automatic classification scheme was developed to identify particular ground cover classes such as fallow, grain, rape seed or various vegetation covers. The scheme applies the maximum likelihood decision rule to the spectral information and classifies the ERTS-1 image on a pixel by pixel basis. Preliminary results indicate that the classifier has limited success in distinguishing crops, but is well adapted for identifying different types of vegetation.

  4. Significant techniques in the processing and interpretation of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Cousin, S. B.; Anderson, A. C.; Paris, J. F.; Potter, J. F.

    1973-01-01

    The discipline oriented investigations underway at the Johnson Space Center (JSC) using ERTS-1 data provide an appropriate framework for the systematic evaluation of the various elements comprising a prototype multispectral data processing and analysis system. In particular such a system may be thought of as the integration of: (1) a preprocessing subsystem; (2) a spectral clustering subsystem, (3) a correlation and classification subsystem; (4) mensuration subsystem; and (5) an information management subsystem. Specific elements of this system are already operational at JSC. It is in the context of this system that technique development and application is being pursued at JSC. Aircraft, ERTS and EREP data will be utilized to refine the subsystem elements for each of the data acquisition systems or system combinations that are optimally suited for a specific Earth Resources application. The techniques reported are those that have been developed to date during the utilization of ERTS-1 data in this processing and analysis system.

  5. A comparison of Gemini and ERTS imagery obtained over southern Morocco

    NASA Technical Reports Server (NTRS)

    Blodget, H. W.; Anderson, A. T.

    1973-01-01

    A mosaic constructed from three ERTS MSS band 5 images enlarged to 1:500,000 compares favorably with a similar scale geologic map of southern Morocco, and a near-similar scale Gemini 5 photo pair. A comparative plot of lineations and generalized geology on the three formats show that a significantly greater number of probable fractures are visible on the ERTS imagery than on the Gemini photography, and that both orbital formats show several times more lineaments than were previously mapped. A plot of mineral occurrences on the structural overlays indicates that definite structure-mineralization relationships exist; this finding is used to define underdeveloped areas which are prospective for mineralization. More detailed mapping is possible using MSS imagery than on Gemini 5 photographs, and in addition, the ERTS format is not restricted to limited coverage.

  6. Stratigraphic Subdivision of the Transvaal Dolomite from ERTS imagery. [South Africa

    NASA Technical Reports Server (NTRS)

    Grootenboer, J.; Eriksson, K.; Truswell, J.

    1974-01-01

    ERTS imagery has revealed the presence of broad stratigraphic subdivisions in the previously undifferentiated Transvaal Dolomite of the western Tranvaal, Republic of South Africa. While detailed field mapping in areas of good outcrop, as well as borehole logging has recently led to the recognition of a stratigraphy in the Transvaal Dolomite of the central Transvaal, poor outcrop in the western Transvaal has to date prevented this. The ERTS-imagery, however, clearly reveals the presence of six, and in the far west seven, distinct stratigraphic zones extending along strike for a distance of at least 200 km. The investigation clearly demonstrates the potential applications of ERTS-imagery in geological studies, even in a country where the geology is supposedly well known.

  7. Evaluation of surface water resources from machine-processing of ERTS multispectral data

    NASA Technical Reports Server (NTRS)

    Mausel, P. W.; Todd, W. J.; Baumgardner, M. F.; Mitchell, R. A.; Cook, J. P.

    1976-01-01

    The surface water resources of a large metropolitan area, Marion County (Indianapolis), Indiana, are studied in order to assess the potential value of ERTS spectral analysis to water resources problems. The results of the research indicate that all surface water bodies over 0.5 ha were identified accurately from ERTS multispectral analysis. Five distinct classes of water were identified and correlated with parameters which included: degree of water siltiness; depth of water; presence of macro and micro biotic forms in the water; and presence of various chemical concentrations in the water. The machine processing of ERTS spectral data used alone or in conjunction with conventional sources of hydrological information can lead to the monitoring of area of surface water bodies; estimated volume of selected surface water bodies; differences in degree of silt and clay suspended in water and degree of water eutrophication related to chemical concentrations.

  8. Film/chemistry selection for the earth resources technology satellite /ERTS/ ground data handling system

    NASA Technical Reports Server (NTRS)

    Shaffer, R. M.

    1973-01-01

    A detailed description is given of the methods of choose the duplication film and chemistry currently used in the NASA-ERTS Ground Data Handling System. The major ERTS photographic duplication goals are given as background information to justify the specifications for the desirable film/chemistry combination. Once these specifications were defined, a quantitative evaluation program was designed and implemented to determine if any recommended combinations could meet the ERTS laboratory specifications. The specifications include tone reproduction, granularity, MTF and cosmetic effects. A complete description of the techniques used to measure the test response variables is given. It is anticipated that similar quantitative techniques could be used on other programs to determine the optimum film/chemistry consistent with the engineering goals of the program.

  9. SO2 damage to forests recorded by ERTS-1. [Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Murtha, P. A.

    1974-01-01

    Sulfur dioxide fumes have been affecting the forests around Wawa, Ontario, which have been under surveillance for a number of years and were recently covered by ultra-small-scale (1:160,000) air photography for damage-assessment purposes. Image interpretation supported by electronic color enhancement was used to delineate on ERTS imagery three damage zones (total-kill, heavy-kill and medium-damage zones). The zones delineated on ERTS imagery are similar to the results of aerial sketch-mapping and air photo interpretation. Band 5 provided the greatest detail for assessing the damage to the forests, followed in successive order by bands 4, 6 and 7. Comparison with ERTS images obtained in the winter showed that even though the total-kill could be separated from heavy-kill damage zones, total-kill could not be consistently separated from clear-cut logging, burned areas, frozen lakes and bogs.