scholarly journals Estimating traveltimes and groundwater flow patterns using 3D time-lapse crosshole ERT imaging of electrical resistivity fluctuations induced by infiltrating river water

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. E239-E250 ◽  
Author(s):  
Ilaria Coscia ◽  
Niklas Linde ◽  
Stewart Greenhalgh ◽  
Tobias Vogt ◽  
Alan Green
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Flow ◽  
River Water ◽  
Preferential Flow ◽  
Tracer Tests ◽  
Time Lapse ◽  
Flow Patterns ◽  
Bank Filtration ◽  
Complex Flow ◽  
Drinking Water Production

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by river water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the river infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantify 3D bank filtration and aquifer dynamics at a high spatial resolution.

scholarly journals Heat as a Proxy to Image Dynamic Processes with 4D Electrical Resistivity Tomography

Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 414 ◽  
Author(s):  
Robert ◽  
Paulus ◽  
Bolly ◽  
Koo Seen Lin ◽  
Hermans
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Flow ◽  
Electrical Resistivity Tomography ◽  
Time Lapse ◽  
Dynamic Processes ◽  
Geophysical Monitoring ◽  
Resistivity Tomography ◽  
Contaminated Aquifer ◽  
Geophysical Measurements ◽  
Do So

Since salt cannot always be used as a geophysical tracer (because it may pollute the aquifer with the mass that is necessary to induce a geophysical contrast), and since in many contaminated aquifer salts (e.g., chloride) already constitute the main contaminants, another geophysical tracer is needed to force a contrast in the subsurface that can be detected from surface geophysical measurements. In this context, we used heat as a proxy to image and monitor groundwater flow and solute transport in a shallow alluvial aquifer (< 10 m deep) with the help of electrical resistivity tomography (ERT). The goal of our study is to demonstrate the feasibility of such methodology in the context of the validation of the efficiency of a hydraulic barrier that confines a chloride contamination to its source. To do so, we combined a heat tracer push/pull test with time-lapse 3D ERT and classical hydrogeological measurements in wells and piezometers. Our results show that heat can be an excellent salt substitution tracer for geophysical monitoring studies, both qualitatively and semi-quantitatively. Our methodology, based on 3D surface ERT, allows to visually prove that a hydraulic barrier works efficiently and could be used as an assessment of such installations.

Studying Effect of Riverbank Filtration (RBF) on Ground Water Using ‘Time-Lapse Electrical Resistivity Imaging’ at Kuala Kangsar, Perak

2015 ◽  
Vol 802 ◽  
pp. 605-610
Author(s):  
Mohd Hanis Mohamad ◽  
Mohd Nawawi ◽  
Mohd Nordin Adlan ◽  
Khiruddin Abdullah
Keyword(s):  
Electrical Resistivity ◽  
Ground Water ◽  
River Water ◽  
Time Lapse ◽  
Pumping Test ◽  
Riverbank Filtration ◽  
Electrical Resistivity Imaging ◽  
Production Well ◽  
Dynamic Changes ◽  
Resistivity Imaging

Riverbank filtration (RBF) is a natural water pre – treatment, safer and cost – effective that uses geology instead of chemicals to pre – treat river water. The process occur during the infiltration process of river water passing through riverbank material towards a production well during a pumping test, where the removal of biological and colloids take place. Abstraction of ground water are required for RBF to occur, hence pumping test were done. As pumping test took place, ground water was in continuous discharging and recharging process throughout time. Objective of this research is to study the dynamic changes of ground water during discharging and recharging process for 72 hours by using time – lapse electrical resistivity imaging (TLERI). Resistivity, which uses current to measure the resistivity of subsurface was used during the pumping test to monitor ground water changes and infiltration of river water during RBF process. Results show significant changes on TLERI data from the first session until the last session. Dynamic changes occurred around the riverbank and production well section while others show less significant changes.

scholarly journals 3D crosshole ERT for aquifer characterization and monitoring of infiltrating river water

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. G49-G59 ◽  
Author(s):  
Ilaria Coscia ◽  
Stewart A. Greenhalgh ◽  
Niklas Linde ◽  
Joseph Doetsch ◽  
Laurent Marescot ◽  
...  
Keyword(s):  
River Water ◽  
Preferential Flow ◽  
Time Lapse ◽  
Water Infiltration ◽  
High Resistivity ◽  
River Flooding ◽  
Main Challenge ◽  
Acquisition Scheme ◽  
Definition Of ◽  
Natural Tracer

The hydrogeological properties and responses of a productive aquifer in northeastern Switzerland are investigated. For this purpose, 3D crosshole electrical resistivity tomography (ERT) is used to define the main lithological structures within the aquifer (through static inversion) and to monitor the water infiltration from an adjacent river. During precipitation events and subsequent river flooding, the river water resistivity increases. As a consequence, the electrical characteristics of the infiltrating water can be used as a natural tracer to delineate preferential flow paths and flow velocities. The focus is primarily on the experiment installation, data collection strategy, and the structural characterization of the site and a brief overview of the ERT monitoring results. The monitoring system comprises 18 boreholes each equipped with 10 electrodes straddling the entire thickness of the gravel aquifer. A multichannel resistivity system programmed to cycle through various four-point electrode configurations of the 180 electrodes in a rolling sequence allows for the measurement of approximately 15,500 apparent resistivity values every 7 h on a continuous basis. The 3D static ERT inversion of data acquired under stable hydrological conditions provides a base model for future time-lapse inversion studies and the means to investigate the resolving capability of our acquisition scheme. In particular, it enables definition of the main lithological structures within the aquifer. The final ERT static model delineates a relatively high-resistivity, low-porosity, intermediate-depth layer throughout the investigated aquifer volume that is consistent with results from well logging and seismic and radar tomography models. The next step will be to define and implement an appropriate time-lapse ERT inversion scheme using the river water as a natural tracer. The main challenge will be to separate the superposed time-varying effects of water table height, temperature, and salinity variations associated with the infiltrating water.

Impact of Preferential Flow Paths on Alluvial Groundwater Flow Patterns and Phosphorus Transport

2010 ◽  
Author(s):  
Derek M Heeren ◽  
Ron B Miller ◽  
Garey A Fox ◽  
Daniel E Storm ◽  
Aaron R Mittelstet ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Preferential Flow ◽  
Flow Patterns ◽  
Phosphorus Transport ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Alluvial Groundwater

Understanding Complex Flow Pathways within Lab-Scale Denitrifying Bioreactors with a Conservative Tracer

2020 ◽  
Vol 63 (2) ◽  
pp. 417-427 ◽  
Author(s):  
William T. Pluer ◽  
M. Todd Walter ◽  
Scott Steinschneider
Keyword(s):  
Time Series ◽  
Cluster Analysis ◽  
Steady Flow ◽  
Removal Efficiency ◽  
Preferential Flow ◽  
Removal Rate ◽  
Flow Patterns ◽  
Storm Events ◽  
Complex Flow ◽  
Flow Models

HighlightsStorm size and media age did not significantly impact removal rate based on simulated storm events in lab bioreactors.Post-hoc cluster analysis of bromide tracer time series identified distributed and preferential flow patterns.Distributed flow cluster had significantly higher removal rate and removal efficiency than preferential cluster.Abstract. Denitrifying bioreactors are designed to reduce excess nitrate (NO3-) pollution from agricultural fields. During storm-induced flow events, flow rate and hydraulic retention time (HRT) can fluctuate widely, which may disturb denitrification within bioreactors in ways not captured by current steady-flow models of NO3- removal rate (RR). This study investigated RR and removal efficiency (RE) during storm flows of variable size and duration to close the gap between existing steady-flow models and real-world flow event conditions. Three simulated storm flow events were run through six lab bioreactors, and RR and RE were calculated during and following each event. Our results show that bioreactors were able to attenuate flow such that event size and duration were not significant explanatory variables of RR. A k-means cluster analysis on characteristics of the outflow bromide tracer time series for each bioreactor during each event identified two major flow patterns. The cluster exhibiting a more distributed bromide load through time had a significantly higher average RR than the cluster with a bromide load time series more characteristic of preferential flow (24.8 and 22.0 g N m-3 d-1, respectively, p = 0.01). Bioreactors did not consistently display a given flow pattern but often changed between events. This suggests that flow patterns within lab bioreactors for each event are a more significant driver of RR than the external factor of the inflow hydrograph. Keywords: Denitrifying bioreactor, k-Means clustering, Stormwater, Tracer.

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