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http://hdl.handle.net/2445/162137
Title: | Time-lapse cross-hole electrical resistivity tomography (CHERT) for monitoring seawater intrusion dynamics in a Mediterranean aquifer |
Author: | Palacios, Andrea Ledo Fernández, Juanjo Linde, Niklas Luquot, Linda Bellmunt Traver, Fabián Folch, Albert Marcuello Pascual, Alejandro Queralt i Capdevila, Pilar Pezard, Philippe A. Martínez, Laura del Val, Laura Bosch Ros, David Carrera, Jesús |
Keywords: | Tomografia Mediterrània (Mar) Hidrologia d'aigües subterrànies Tomography Mediterranean Sea Groundwater hydrology |
Issue Date: | 30-Apr-2020 |
Publisher: | European Geosciences Union (EGU) |
Abstract: | Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but its imaging capabilities are strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease at the depths of interest. The objective of this study is to test the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After 2 years of monitoring, we observe variability of SWI at different timescales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-monotonic salinity profiles in open boreholes (step-wise profiles really reflect the presence of freshwater at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics. |
Note: | Reproducció del document publicat a: https://doi.org/10.5194/hess-24-2121-2020 |
It is part of: | Hydrology and Earth System Sciences, 2020, vol. 24, num. 4, p. 2121-2139 |
URI: | http://hdl.handle.net/2445/162137 |
Related resource: | https://doi.org/10.5194/hess-24-2121-2020 |
ISSN: | 1027-5606 |
Appears in Collections: | Articles publicats en revistes (Dinàmica de la Terra i l'Oceà) |
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