scholarly journals Improved Geoarchaeological Mapping with Electromagnetic Induction Instruments from Dedicated Processing and Inversion

2016 ◽  
Vol 8 (12) ◽  
pp. 1022 ◽  
Author(s):  
Anders Christiansen ◽  
Jesper Pedersen ◽  
Esben Auken ◽  
Niels Søe ◽  
Mads Holst ◽  
...  
Keyword(s):  
Electromagnetic Induction ◽  
And Inversion

Soil salinity monitoring and detection of obstructed drainage pipes in the B-XII irrigation district (SW Spain) using electromagnetic induction sensing and inversion. 

2021 ◽  
Author(s):  
Mario Ramos ◽  
Mohhamad Farzamian ◽  
José Luis Gómez ◽  
Alfonso González ◽  
Benito Salvatierra ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Salinity ◽  
Electromagnetic Induction ◽  
Drainage System ◽  
State Agency ◽  
Irrigation District ◽  
Sw Spain ◽  
Hard Soil ◽  
Moisture Conditions ◽  
And Inversion

<p>Inversion of electromagnetic induction (EMI) signals is increasingly used for monitoring soil salinity in irrigated fields. In the B-XII irrigation district (SW Spain) the build-up of high salt concentrations in the topsoil is often related with a deficient performance of the underlying drainage system resulting in higher-than-average soil moisture conditions and salinization. This work aims at using EMI sensing and inversion to identify and localize problems (<em>e.g</em>. obstruction) with the drainage system in a 12.5 ha irrigated field in the B-XII irrigation district. The identified salinity hotspots in the EMI images are further validated using remotely sensed NDVI data and detailed information obtained during the cleaning of the drainage system, in addition to hard soil data. This study shows that EMI sensing and inversion can pinpoint problems with the drainage system that result in salinity hotspots and identify areas where the drainage system should be cleaned or substituted.</p><p> </p><p>This work is funded by the Spanish State Agency for Research through grants PID2019-104136RR-C21 and PID2019-104136RR-C22 and by IFAPA/FEDER through grant AVA2019.018.</p>

Monitoring changes in salinity and sodicity in a tile-drained field in the B-XII irrigation district (SW Spain) using electromagnetic induction sensing and inversion.

2021 ◽  
Author(s):  
José Luis Gómez Flores ◽  
Mario Ramos Rodriguez ◽  
Alfonso González Jiménez ◽  
Mohammad Farzamian ◽  
Juan Francisco Herencia Galán ◽  
...  
Keyword(s):  
Electromagnetic Induction ◽  
Saline Water ◽  
Drainage System ◽  
State Agency ◽  
Irrigation District ◽  
Irrigated Agriculture ◽  
Sw Spain ◽  
Strong Relation ◽  
Parameters Inversion ◽  
And Inversion

<p>Continuous monitoring of soil salinity/sodicity is of prime importance in environments such as the B-XII irrigation district (SW Spain) where a shallow saline water table and intensive irrigated agriculture create a fragile equilibrium between salt accumulation and leaching in the topsoil. We evaluate to which extend electromagnetic induction (EMI) sensing and inversion with limited calibration can be used to accomplish such monitoring purposes, given that widespread soil sampling and laboratory analyses are prohibitive for economic and technical reasons.</p><p>Detailed EMI surveys were performed in 2017 and 2020 in a 4-ha tile-drained field with a heavy clay soil. Soil samples were taken at different locations and depths along a transect and analyzed for salinity/sodicity-related parameters. Inversion of the EMI signals along the investigated transect yielded consistent conductivity images for both years and showed a strong relation (R<sup>2</sup><0.95) with saturated paste extract conductivity. The observed spatial conductivity patterns persisted from 2017 to 2020, although the obtained absolute values of the salinity/sodicity parameters changed slightly. This indicates that salinity hotspots persist in time and are mainly associated with wet locations, where salt movement towards the topsoil is promoted, possibly as a result of deficiencies in the performance of the drainage system.</p><p>Our results show that inversion of EMI signals offers a powerful means for accurately monitoring spatial and temporal changing salinity/sodicity under the specific conditions of the B-XII irrigation district.</p><p> </p><p><strong>Acknowledgement</strong></p><p>This work is funded by the Spanish State Agency for Research through grant PID2019-104136RR-C21 and by IFAPA/FEDER through grant AVA2019.018.</p><p> </p>

Digital regolith mapping of clay across the Ashley irrigation area using electromagnetic induction data and inversion modelling

Geoderma ◽  
2019 ◽  
Vol 346 ◽  
pp. 18-29 ◽  
Author(s):  
Xueyu Zhao ◽  
Jie Wang ◽  
Dongxue Zhao ◽  
Nan Li ◽  
Ehsan Zare ◽  
...  
Keyword(s):  
Electromagnetic Induction ◽  
Irrigation Area ◽  
And Inversion ◽  
Inversion Modelling

Simultaneous calibration and inversion algorithm for multiconfiguration electromagnetic induction data acquired at multiple elevations

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. EN1-EN14 ◽  
Author(s):  
Xihe Tan ◽  
Achim Mester ◽  
Christian von Hebel ◽  
Egon Zimmermann ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electromagnetic Induction ◽  
Synthetic Data ◽  
Ground Surface ◽  
Acquisition Time ◽  
Inversion Algorithm ◽  
Transect Line ◽  
Promising Tool ◽  
Reference Measurements ◽  
And Inversion

Electromagnetic induction (EMI) is a contactless and fast geophysical measurement technique. Frequency-domain EMI systems are available as portable rigid booms with fixed separations up to approximately 4 m between the transmitter and the receivers. These EMI systems are often used for high-resolution characterization of the upper subsurface meters (up to depths of approximately 1.5 times the maximum coil separation). The availability of multiconfiguration EMI systems, which measure multiple apparent electrical conductivity ([Formula: see text]) values of different but overlapping soil volumes, enables EMI data inversions to estimate electrical conductivity ([Formula: see text]) changes with depth. However, most EMI systems currently do not provide absolute [Formula: see text] values, but erroneous shifts occur due to calibration problems, which hinder a reliable inversion of the data. Instead of using physical soil data or additional methods to calibrate the EMI data, we have used an efficient and accurate simultaneous calibration and inversion approach to avoid a possible bias of other methods while reducing the acquisition time for the calibration. By measuring at multiple elevations above the ground surface using a multiconfiguration EMI system, we simultaneously obtain multiplicative and additive calibration factors for each coil configuration plus an inverted layered subsurface electrical conductivity model at the measuring location. Using synthetic data, we verify our approach. Experimental data from five different calibration positions along a transect line showed similar calibration results as the data obtained by more elaborate vertical electrical sounding reference measurements. The synthetic and experimental results demonstrate that the multielevation calibration and inversion approach is a promising tool for quantitative electrical conductivity analyses.

scholarly journals Calibration, Conversion, and Quantitative Multi-Layer Inversion of Multi-Coil Rigid-Boom Electromagnetic Induction Data

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4753 ◽  
Author(s):  
von Hebel ◽  
van der Kruk ◽  
Huisman ◽  
Mester ◽  
Altdorff ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Induction ◽  
Depth Range ◽  
Electrode Arrays ◽  
Average Value ◽  
Bulk Electrical Conductivity ◽  
Electrical Conductivities ◽  
Electrical Soundings ◽  
And Inversion

Multi-coil electromagnetic induction (EMI) systems induce magnetic fields below and above the subsurface. The resulting magnetic field is measured at multiple coils increasingly separated from the transmitter in a rigid boom. This field relates to the subsurface apparent electrical conductivity (σa), and σa represents an average value for the depth range investigated with a specific coil separation and orientation. Multi-coil EMI data can be inverted to obtain layered bulk electrical conductivity models. However, above-ground stationary influences alter the signal and the inversion results can be unreliable. This study proposes an improved data processing chain, including EMI data calibration, conversion, and inversion. For the calibration of σa, three direct current resistivity techniques are compared: Electrical resistivity tomography with Dipole-Dipole and Schlumberger electrode arrays and vertical electrical soundings. All three methods obtained robust calibration results. The Dipole-Dipole-based calibration proved stable upon testing on different soil types. To further improve accuracy, we propose a non-linear exact EMI conversion to convert the magnetic field to σa. The complete processing workflow provides accurate and quantitative EMI data and the inversions reliable estimates of the intrinsic electrical conductivities. This improves the ability to combine EMI with, e.g., remote sensing, and the use of EMI for monitoring purposes.

The Fine Structure of the Sheath of Volvox Carteri f. Weismannia

1977 ◽  
Vol 35 ◽  
pp. 346-347
Author(s):  
Regina Birchem
Keyword(s):  
Developmental Stages ◽  
Ruthenium Red ◽  
Sulfated Polysaccharides ◽  
Volvox Carteri ◽  
High Voltage Electron Microscopy ◽  
Ultrastructural Studies ◽  
Voltage Electron ◽  
Sheath Formation ◽  
And Inversion ◽  
Sheath Material

Spheroids of the green colonial alga Volvox consist of biflagellate Chlamydomonad-like cells embedded in a transparent sheath. The sheath, important as a substance through which metabolic materials, light, and the sexual inducer must pass to and from the cells, has been shown to have an ordered structure (1,2). It is composed of both protein and carbohydrate (3); studies of V. rousseletii indicate an outside layer of sulfated polysaccharides (4).Ultrastructural studies of the sheath material in developmental stages of V. carteri f. weismannia were undertaken employing variations in the standard fixation procedure, ruthenium red, diaminobenzidine, and high voltage electron microscopy. Sheath formation begins after the completion of cell division and inversion of the daughter spheroids. Golgi, rough ER, and plasma membrane are actively involved in phases of sheath synthesis (Fig. 1). Six layers of ultrastructurally differentiated sheath material have been identified.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Sign in / Sign up

Export Citation Format

Share Document