Modeling the electrical conductivity of hydrogeological strata using joint-inversion of loop-loop electromagnetic data

In coastal-estuarine agricultural landscapes that are inherently rich in sulfidic sediments and saline water-tables, natural resource management data need to be collected to describe the heterogeneous nature of the soil, underlying regolith, and interactions with groundwater. Geophysical methods, such as electromagnetic (EM) induction instruments, are increasingly being used. This is because they measure apparent soil electrical conductivity [Formula: see text], which has previously been successfully used to map the areal distribution of soil (e.g., salinity) and hydrological (e.g., water-table depth) properties. We explored the potential of a next-generation DUALEM-421 and EM34 to be used independently and in conjunction with each other to provide information we can use to represent the pedological and hydrogeological setting of alluvial and estuarine sediments. A 1D laterally constrained joint-inversion algorithm can account for the nonlinearity of large [Formula: see text] (i.e., [Formula: see text]). We applied this algorithm to develop 2D cross sections of electrical conductivity ([Formula: see text]) from DUALEM-421 and EM34 [Formula: see text] data acquired across an estuarine landscape and situated within Quaternary fluvial sediments adjacent to Rocky Mouth Creek on the far north coast of New South Wales, Australia. We compared this joint-inversion model with inversions of the DUALEM-421 and EM34 [Formula: see text] data independently of each other. For the most part, the general patterns of the inverted models of [Formula: see text] compare favorably with existing pedological and hydrogeological interpretations, based on results achieved during a previous geoelectrical survey. However, the joint-inversion provides a more realistic model of the location and extent of a saline water-table and associated with the location of sulfidic sediments.

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Resolving the spatial distribution of the true electrical conductivity with depth using EM38 and EM31 signal data and a laterally constrained inversion model

Soil Research ◽

10.1071/sr09149 ◽

2010 ◽

Vol 48 (5) ◽

pp. 434 ◽

Cited By ~ 50

Author(s):

J. Triantafilis ◽

F. A. Monteiro Santos

Keyword(s):

Electrical Conductivity ◽

Spatial Distribution ◽

Vadose Zone ◽

Root Zone ◽

Joint Inversion ◽

Geophysical Methods ◽

Exchange Capacity ◽

Saturated Soil ◽

Cotton Field ◽

Inversion Algorithm

The ability to map the spatial distribution of average soil property values using geophysical methods at the field and district level has been well described. This includes the use of electromagnetic (EM) instruments which measure bulk soil electrical conductivity (σa). However, soil is a 3-dimensional medium. In order to better represent the spatial distribution of soil properties with depth, various methods of inverting EM instrument data have been attempted and include Tikhonov regularisation and layered earth models. In this paper we employ a 1-D inversion algorithm with 2-D smoothness constraints to predict the true electrical conductivity (σ) using σa data collected along a transect in an irrigated cotton field in the lower Namoi valley. The primary σa data include the root-zone measuring EM38 and the vadose-zone sensing EM31, in the vertical (v) and horizontal (h) dipole modes and at heights of 0.2 and 1.0 m, respectively. In addition, we collected σa with the EM38 at heights of 0.4 and 0.6 m. In order to compare and contrast the value of the various σa data we carry out individual inversions of EM38v and EM38h collected at heights of 0.2, 0.4, and 0.6 m, and EM31v and EM31h at 1.0 m. In addition, we conduct joint inversions of various combinations of EM38 σa data available at various heights (e.g. 0.2 and 0.4 m). Last we conduct joint inversions of the EM38v and EM38h σa data at 0.2, 0.4, and 0.6 m with the EM31v and EM31h at 1.0 m. We find that the values of σ achieved along the transect studied represent the duplex nature of the soil. In general, the EM38v and EM38h collected at a height of 0.2, 0.4, and 0.6 m assist in resolving solum and root-zone variability of the cation exchange capacity (cmol(+)/kg of soil solids) and the electrical conductivity of a saturated soil paste extract (ECe, dS/m), while the use of the EM31v and EM31h at 1.0 m assists in characterising the vadose zone and the likely location of a shallow perched-water table. In terms of identifying an optimal set of EM σa data for inversion we found that a joint inversion of the EM38 at a height of 0.6 m and EM31 signal data provided the best correlation with electrical conductivity of a saturated soil paste (ECp, dS/m) and ECe (respectively, 0.81 and 0.77) closely followed by a joint inversion of all the EM38 and EM31 σa data available (0.77 and 0.56).

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

Geophysics ◽

10.1190/geo2019-0754.1 ◽

2020 ◽

Vol 85 (6) ◽

pp. H97-H113 ◽

Cited By ~ 1

Author(s):

Diego Domenzain ◽

John Bradford ◽

Jodi Mead

Keyword(s):

Electrical Conductivity ◽

Electrical Resistivity ◽

Ground Penetrating Radar ◽

Joint Inversion ◽

Geophysical Methods ◽

Data Types ◽

Full Waveform ◽

Electrical Permittivity ◽

Ground Penetrating ◽

Subsurface Geometry

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

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Mapping cation exchange capacity using a quasi-3d joint-inversion of EM38 and EM31 data

10.5194/egusphere-egu2020-918 ◽

2020 ◽

Author(s):

Dongxue Zhao ◽

John Triantafilis

Keyword(s):

Electrical Conductivity ◽

Cation Exchange ◽

Cation Exchange Capacity ◽

Joint Inversion ◽

Exchange Capacity ◽

Damping Factor ◽

Inversion Algorithm ◽

Good Concordance ◽

Value Add ◽

Leave One Out

The cation exchange capacity (CEC, cmol(+)/kg) is a measure of soil&#8217;s capacity to retain exchangeable cations. However, it is expensive to collect CEC across a heterogenous field and at different depths. To value-add to limited data, proximal sensed electromagnetic (EM) data has been coupled to CEC through linear regression (LR) models, because they measure apparent soil electrical conductivity (ECa, mS/m). However, these LRs have been depth-specific. This approach was compared with one universal LR between estimates of true electrical conductivity (s, mS/m) and CEC from various depths, including topsoil (0-0.3 m), subsurface (0.3-0.6 m), shallow subsoil (0.6-0.9 m) and deeper subsoil (0.9-2.1 m). We estimated s from inversion of EM38 and EM31 ECa either alone or in combination (joint-inversion), in horizontal (ECah) and vertical (ECav) modes, using a quasi-3d (q3-d) inversion software (EM4Soil) and various parameters, including EM38 at two different heights (i.e. 0.2 or 0.4 m). In terms of performance, the LR correlation (R2 > 0.60) was largest between deeper subsoil CEC and EM38 ECah at 0.2 m. However, the LR was unsatisfactory for CEC calibration in the topsoil (0.31), subsurface (0.37) and shallow subsoil (0.52). In comparison, a universal LR between CEC and &#963; was well correlated (0.72), when both EM38 (0.2 m) and EM31 ECa in both modes, were inverted using a forward model (CF), inversion algorithm (S2) and small damping factor (&#955; = 0.03). The calibrations tested using a leave-one-out cross validation, showed CEC prediction was precise (RMSE, 2.35 cmol(+)/kg), unbiased (ME, -0.002 cmol(+)/kg) with good concordance (Lin&#8217;s, 0.83). To improve areal prediction, closer spaced transects need to be collected, while improved vertical resolution of CEC prediction we recommend DUALEM-421 ECa data be acquired.&#160;

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Pareto Joint Inversion of 2D magnetometric and gravity data- synthetic study

E3S Web of Conferences ◽

10.1051/e3sconf/201913301009 ◽

2019 ◽

Vol 133 ◽

pp. 01009

Author(s):

Tomasz Danek ◽

Andrzej Leśniak ◽

Katarzyna Miernik ◽

Elżbieta Śledź

Keyword(s):

Pareto Front ◽

Joint Inversion ◽

Gravity Data ◽

Group Analysis ◽

Geophysical Methods ◽

Model Parameters ◽

Data Sets ◽

Inversion Algorithm ◽

Promising Tool ◽

Real Model

Pareto joint inversion for two or more data sets is an attractive and promising tool which eliminates target functions weighing and scaling, providing a set of acceptable solutions composing a Pareto front. In former author’s study MARIA (Modular Approach Robust Inversion Algorithm) was created as a flexible software based on global optimization engine (PSO) to obtain model parameters in process of Pareto joint inversion of two geophysical data sets. 2D magnetotelluric and gravity data were used for preliminary tests, but the software is ready to handle data from more than two geophysical methods. In this contribution, the authors’ magnetometric forward solver was implemented and integrated with MARIA. The gravity and magnetometry forward solver was verified on synthetic models. The tests were performed for different models of a dyke and showed, that even when the starting model is a homogeneous area without anomaly, it is possible to recover the shape of a small detail of the real model. Results showed that the group analysis of models on the Pareto front gives more information than the single best model. The final stage of interpretation is the raster map of Pareto front solutions analysis.

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Joint Inversion of Seismic and Audio Magnetotelluric Data with Structural Constraint for Metallic Deposit

Journal of Environmental and Engineering Geophysics ◽

10.2113/jeeg23.2.159 ◽

2018 ◽

Vol 23 (2) ◽

pp. 159-169

Author(s):

Xuan Feng ◽

Enhedelihai Nilot ◽

Cai Liu ◽

Minghe Zhang ◽

Hailong Yu ◽

...

Keyword(s):

Partial Information ◽

Joint Inversion ◽

Waveform Inversion ◽

Geophysical Methods ◽

P Wave ◽

Real Field ◽

Sulfide Deposit ◽

Inversion Algorithm ◽

Data Types ◽

Magnetotelluric Data

Audio magnetotelluric (AMT) and seismic methods are widely used to detect metallic deposits. However, each geophysical method only provides partial information of the underground target. Besides, individual methods have inherent limitations and ambiguity which leads to non-uniqueness when solving the inverse problem. To obtain a more robust and consistent ore deposit model, it is best to integrate different geophysical methods and data types. Towards this effort, we propose a joint inversion algorithm using cross-gradient constraint to build a connection between seismic and AMT data, and simultaneously invert for a resistivity and P-wave velocity model. Compared with separate AMT Gauss–Newton inversion and seismic Full waveform inversion (FWI) method, we can get more detailed and robust inversion results. In addition, frequency domain FWI with the Limited-Memory-Broyden–Fletcher–Goldfarb–Shanno (L-BFGS) algorithm provides an effective way to reduce computer memory usage and improve convergence speed. This joint inversion algorithm has been tested using simple synthetic models with two cross targets. The results obtained with separate inversions were compared with those obtained with joint inversion. Then, we applied the algorithm to geophysical models of the Jinchuan sulfide deposit. The AMT results obtained with joint inversion of seismic data were better than those obtained with separate AMT inversion. The joint inversion approach appears more robust than the traditional separate FWI inversion and it is recommended that the proposed algorithm be considered in future projects of real field data.

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Mapping the Pollution Plume Using the Self-Potential Geophysical Method: Case of Oum Azza Landfill, Rabat, Morocco

Water ◽

10.3390/w13070961 ◽

2021 ◽

Vol 13 (7) ◽

pp. 961

Author(s):

Meryem Touzani ◽

Ismail Mohsine ◽

Jamila Ouardi ◽

Ilias Kacimi ◽

Moad Morarech ◽

...

Keyword(s):

Electrical Conductivity ◽

Water Table ◽

Soil Surface ◽

The Self ◽

Drainage Network ◽

Geophysical Method ◽

Direct Measurements ◽

Sandy Material ◽

The City ◽

Self Potential

The main landfill in the city of Rabat (Morocco) is based on sandy material containing the shallow Mio-Pliocene aquifer. The presence of a pollution plume is likely, but its extent is not known. Measurements of spontaneous potential (SP) from the soil surface were cross-referenced with direct measurements of the water table and leachates (pH, redox potential, electrical conductivity) according to the available accesses, as well as with an analysis of the landscape and the water table flows. With a few precautions during data acquisition on this resistive terrain, the results made it possible to separate the electrokinetic (~30%) and electrochemical (~70%) components responsible for the range of potentials observed (70 mV). The plume is detected in the hydrogeological downstream of the discharge, but is captured by the natural drainage network and does not extend further under the hills.

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Quasi-2D inversion of DCR and TDEM data for shallow investigations

Geophysics ◽

10.1190/1.3587218 ◽

2011 ◽

Vol 76 (4) ◽

pp. F239-F250 ◽

Cited By ~ 10

Author(s):

Fernando A. Monteiro Santos ◽

Hesham M. El-Kaliouby

Keyword(s):

Joint Inversion ◽

Synthetic Data ◽

Data Sets ◽

Complex Environments ◽

Inversion Algorithm ◽

2D Inversion ◽

New Approach ◽

Earth Models ◽

Time Domain Electromagnetic ◽

Inversion Techniques

Joint or sequential inversion of direct current resistivity (DCR) and time-domain electromagnetic (TDEM) data commonly are performed for individual soundings assuming layered earth models. DCR and TDEM have different and complementary sensitivity to resistive and conductive structures, making them suitable methods for the application of joint inversion techniques. This potential joint inversion of DCR and TDEM methods has been used by several authors to reduce the ambiguities of the models calculated from each method separately. A new approach for joint inversion of these data sets, based on a laterally constrained algorithm, was found. The method was developed for the interpretation of soundings collected along a line over a 1D or 2D geology. The inversion algorithm was tested on two synthetic data sets, as well as on field data from Saudi Arabia. The results show that the algorithm is efficient and stable in producing quasi-2D models from DCR and TDEM data acquired in relatively complex environments.

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Formation of ‘Crioula’ guava rootstock under saline water irrigation and nitrogen doses

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v20n8p739-745 ◽

2016 ◽

Vol 20 (8) ◽

pp. 739-745 ◽

Cited By ~ 4

Author(s):

Leandro de P. Souza ◽

Reginaldo G. Nobre ◽

Evandro M. da Silva ◽

Geovani S. de Lima ◽

Francisco W. A. Pinheiro ◽

...

Keyword(s):

Electrical Conductivity ◽

Salt Stress ◽

Experimental Design ◽

Deleterious Effect ◽

Saline Water ◽

Dry Weight ◽

Saline Water Irrigation ◽

N Dose

ABSTRACT The objective of this research was to evaluate the growth and formation of fresh and dry weight of ‘Crioula’ guava rootstock irrigated with waters of different saline levels and nitrogen (N) doses, in an experiment conducted in plastic tubes under greenhouse conditions. The experimental design was randomized blocks, in a 5 x 4 factorial scheme with four replicates, and the treatments consisted of five levels of water electrical conductivity - ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four N doses (70, 100, 130 and 160% of the N dose recommended for the cultivation of guava seedlings, cv. ‘Paluma’). The dose referring to 100% corresponds to 773 mg of N dm-3. The highest growth of ‘Crioula’ guava rootstock was obtained with ECw of 0.3 dS m-1 and fertilization of 541.1 mg N dm-3 of soil; increasing N doses did not reduce the deleterious effect of the salt stress on the growth and phytomass formation of ‘Crioula’ guava rootstock; irrigation with water of up to 1.75 dS m-1, in the production of guava rootstocks, promotes acceptable reduction of 10% in growth and quality of the seedlings.

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Emergence and biomass accumulation in seedlings of rice cultivars irrigated with saline water

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v22n7p471-475 ◽

2018 ◽

Vol 22 (7) ◽

pp. 471-475

Author(s):

Márcio H. da C. Freire ◽

Geocleber G. de Sousa ◽

Maria V. P. de Souza ◽

Emanuel D. R. de Ceita ◽

Jamili N. Fiusa ◽

...

Keyword(s):

Electrical Conductivity ◽

Dry Matter ◽

Saline Water ◽

Biomass Accumulation ◽

The Other ◽

Saline Stress ◽

Rice Cultivars ◽

Saline Water Irrigation ◽

Emergence Percentage ◽

Mean Time

ABSTRACT The objective of this study was to evaluate the performance of three rice cultivars under saline water irrigation. The experiment was carried out in full sun at the Experimental Farm of the Unilab, in Redenção, Ceará, Brazil, in January 2016. The experimental design was completely randomized (CRD), in a 5 x 3 factorial scheme [irrigation water electrical conductivity (ECw: 0.5, 1.0, 2.0, 3.0 and 4.0 dS m-1) versus three rice cultivars (C1 - Ligeirinho, C2 - Casado and C3 - Meruinho)], totaling 15 treatments, with 4 replicates of 30 seeds per cultivar. After 21 days, the following variables were evaluated: emergence percentage (EP), emergence speed index (ESI), mean time of emergence (MTE), mean speed of emergence (MSE), shoot dry matter (SDM), root dry matter (RDM) and total dry matter (TDM). The cultivar Ligeirinho showed higher tolerance to saline stress with respect to the emergence percentage, emergence speed index and mean speed of emergence. The cultivar Casado showed higher tolerance to saline stress for shoot dry matter, root dry matter and total dry matter in comparison to the other cultivars.

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Production of Pityrocarpa moniliformis (Benth.) Luckow & R.W. Jobson (Fabaceae) seedlings irrigated with saline water

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v25n3p182-188 ◽

2021 ◽

Vol 25 (3) ◽

pp. 182-188

Author(s):

Adriana dos S. Ferreira ◽

Caio C. P. Leal ◽

Bruno da S. Guirra ◽

Salvador B. Torres ◽

Marco Porceddu ◽

...

Keyword(s):

Electrical Conductivity ◽

Irrigation Water ◽

Saline Water ◽

Block Design ◽

Soluble Sugars ◽

Dry Mass ◽

Initial Growth ◽

Saline Irrigation ◽

Total Soluble Sugars ◽

Chlorophylls A And B

ABSTRACT Saline irrigation water at high levels causes disturbance in the growth of more sensitive plants. The objective of this research was to evaluate the initial growth of Pityrocarpa moniliformis seedlings under different electrical conductivity in irrigation water through physiological and biochemical analyses. The experiment was conducted in a greenhouse with five water electrical conductivities (0.5, 2.0, 4.0, 6.0 and 8.0 dS m-1) and four repetitions of 20 plants each, arranged in a randomized block design. Application of the treatments with irrigation water containing NaCl began at 30 days after sowing. To determine the behaviour of the species, the following variables were analysed: stem diameter, plant height, number of leaves, leaf area, Dickson quality index, shoot dry mass, root dry mass and total dry mass, as well as the biochemical variables, such as the concentrations of total soluble sugars, free proline and chlorophylls a and b. The increase in irrigation water salinity hampered the growth of P. moniliformis seedlings, with electrical conductivity of 0.5 dS m-1 being the limit for maximum production. The results also indicated that the deleterious effects of salt stress on P. moniliformis seedlings variables increase in concentrations of proline, total soluble sugars and betaine glycine.

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