scholarly journals Detecting Macropore Fingering Using Temporal Electrical Resistivity Imaging

2021 ◽  
Vol 37 (5) ◽  
pp. 861-870
Author(s):  
Todd Halihan ◽  
John Paul Hager ◽  
Lucie Guertault ◽  
Garey A. Fox
Keyword(s):  
Electrical Resistivity ◽  
Preferential Flow ◽  
Field Evaluation ◽  
Low Noise ◽  
Riparian Buffers ◽  
Electrical Resistivity Imaging ◽  
List Type ◽  
Soil Matrix ◽  
Resistivity Imaging ◽  
Field Setting

HighlightsSingle macropores can be detected using temporal electrical resistivity imaging under controlled conditions.Macropore flow can be detected based on preferentially wetted fingers of increased conductance.Macropore activation does not appear to require saturated surface conditions to induce preferential flow.Abstract. Riparian soils are uniquely susceptible to the formation of macropores, which are hypothesized to promote fast transport of water and contaminants through upper soil layers. Electrical Resistivity Imaging (ERI) can locate spatial heterogeneities in soil wetting patterns and evaluate differences due to vegetation, thus optimizing the design of riparian buffers. Temporal ERI (TERI) imaging was conducted in a fine and coarse field setting with artificial macropores to evaluate flow under unsaturated simulated rainfall conditions and saturated infiltrometer conditions. While single macropores are detectable using TERI datasets, the results in an average field setting would detect the wetted area surrounding a macropore, not the macropore itself. The results were similar for both the primary fine grain soil site in Oklahoma as well as the coarse grain site in North Carolina. TERI data indicated that without artificial conditions with low noise conditions, a single macropore would not be detected, a wetted zone would be the best detection. In ordinary field evaluation of natural macropores, the TERI technique would detect the wetted zone around a macropore similar to a high hydraulic conductivity zone in a heterogeneous soil matrix. Finally, the results confirmed that macropore activation does not require saturated conditions to generate preferential flow. Keywords: Hydrogeophysics, Preferential flowpaths, Riparian buffers, Temporal electrical resistivity imaging.

Comparative Non-Darcian Modeling of Subsurface Preferential Flow Experimental Observations in a Riparian Buffer

2021 ◽  
Vol 64 (6) ◽  
pp. 1867-1881
Author(s):  
Enrique Orozco-López ◽  
Rafael Muñoz-Carpena
Keyword(s):  
Vadose Zone ◽  
Preferential Flow ◽  
Riparian Buffers ◽  
Riparian Buffer ◽  
Model Parameters ◽  
List Type ◽  
Dispersive Wave ◽  
Macropore Flow ◽  
Modeling Framework ◽  
Soil Matrix

HighlightsHigh ecohydrological activity drives macropore prevalence in riparian buffers.An abundance of macropore flow (MF) was confirmed in a field riparian buffer in Kenya.Source-response (SR) and multilayer kinematic diffusive wave (MKDW) MF models are compared.A novel MKDW modeling framework efficiently identifies and predicts preferential flow in riparian buffers.Abstract. The significant ecohydrological activity typical of riparian buffers makes them potential hotspots of macropores, i.e., structured preferential flow pathways, through the soil vadose zone. The prevalence of these preferential pathways can allow transported contaminants to bypass the soil matrix and quickly reach a seasonal shallow water table and the adjacent surface waterbody. This quick transport can ultimately limit the role of riparian buffers for runoff pollution control. Currently, there are no management tools that incorporate macropore flow (MF) when assessing riparian buffer performance. The objective of this study was to experimentally quantify and mathematically simulate macropore flow and arrival time in a riparian buffer under field conditions. Three infiltration experiments were conducted with a grid of 20 time-domain transmission (TDT) dielectric soil moisture sensors along a field riparian buffer transect in Kenya to quantify the presence of macropore flow and to test two non-Darcian soil MF models, including the source-responsive (SR) model and the modified kinematic-dispersive wave (MKDW) model developed in this study, by adding a user-defined multilayer convection scheme and a new hysteresis function between water flux and content. The abundance of MF in the riparian buffer was corroborated experimentally. Modeling results showed that the MKDW model was an efficient (average NSE of 0.937 and 0.721 for calibration and testing, respectively), flexible, and robust method to identify and represent non-linear and non-sequential MF signals at any soil depth and antecedent conditions. The SR model was computationally inexpensive and provided good calibration results (NSE = 0.867) but required piecemeal recalibration of the travel time and maximum water content at each layer and yielded lower performance in testing. The Akaike (AIC) and Bayesian (BIC) information criteria showed that MKDW outperformed SR when accounting for the trade-off between model complexity and efficiency. The results support further research focused on independent characterization of model parameters at the field scale, and the inclusion of MKDW in holistic riparian buffer management and decision-support tools such as VFSmod. Keywords: Kinematic-dispersive wave, Macropore flow, Numerical modeling, Preferential flow, Riparian vadose zone.

Informed experimental design for electrical resistivity imaging

2011 ◽  
Vol 9 (5) ◽  
pp. 469-482 ◽  
Author(s):  
Vanessa Nenna ◽  
Adam Pidlisecky ◽  
Rosemary Knight
Keyword(s):  
Electrical Resistivity ◽  
Experimental Design ◽  
Electrical Resistivity Imaging ◽  
Resistivity Imaging

scholarly journals Electrical resistivity imaging for the characterization of the Montaguto landslide (southern Italy)

2018 ◽  
Vol 243 ◽  
pp. 272-281 ◽  
Author(s):  
Jessica Bellanova ◽  
Giuseppe Calamita ◽  
Alessandro Giocoli ◽  
Raffaele Luongo ◽  
Maria Macchiato ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Southern Italy ◽  
Electrical Resistivity Imaging ◽  
Resistivity Imaging

scholarly journals The behaviour of six electrode arrays used in electrical resistivity imaging to detect underground cavities: a numerical study

2021 ◽  
Author(s):  
Kamel Hebbache ◽  
Djamel Boubaya
Keyword(s):  
Electrical Resistivity ◽  
Numerical Study ◽  
Electrical Resistivity Imaging ◽  
Good Resolution ◽  
Electrode Arrays ◽  
Resistivity Imaging ◽  
True Resistivity ◽  
Underground Cavities ◽  
Resolution Model ◽  
Synthetic Models

Abstract The aim of this work is to evaluate the efficiency of six electrode arrays used in electrical resistivity imaging. Pole-Pole (PP), Pole-Dipole (PD), Wenner-Alpha (WA), Wenner-Schlumberger (WS), Dipole-Dipole (DD) and multiple Gradient (MG) electrode arrays have been selected to detect underground cavities at shallow depth. Numerical simulation has been made for three synthetic models that have been generated using Res2dmod program. Each model represents three cavities with 2m diameter, spaced 6m from each other and located at a depth of 1.5m from the surface of the ground: 1) air-filled cavity, 2) half-watered cavity and 3) full-watered cavity. The background resistivity of each model was chosen equal to 10, 50 and 250 Ωm respectively. The resistivity of the air and water were set at 106 Ωm and 1 Ωm respectively. The results show that the PD, MG, PP and WS arrays gave good resolutions and clear images, and are less contaminated by noise. The DD array is very sensitive to noise and for this reason, it gave less accurate results for the first and the second synthetic models. An exception is the third synthetic model, where a good resolution model was obtained. This means, that the DD is more efficient in mapping cavities when the background environment is moderately resistive. The shapes of resistive air-filled cavities were found more clearly than those of conductive watered cavities, for the latter, however, the true resistivity values were better estimated than for the air-filled cavities. From the results of the analysis of the inverted synthetic models, the PD, MG, PP and WS arrays show the best results among the other used electrical arrays.

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