The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Michel Bakalowicz - One of the best experts on this subject based on the ideXlab platform.
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Deep Water Circulation, Residence Time, and Chemistry in a Karst Complex
Groundwater, 2003Co-Authors: Luc Aquilina, Bernard Ladouche, Nathalie Dörfliger, Michel BakalowiczAbstract:We investigated the hydrochemistry of a complex karst hydrosystem made of two carbonate units along a coastal lagoon. Ground water emerges on the lagoon floor from a Submarine Spring. In addition, thermal waters circulate through the limestone and mix with karst water near the lagoon shore. A distinction between the water from the two carbonate units is related to marine influences and human activities. In one of the massifs, the data show an incongruent dissolution of dolomite with time. In the other system, a slight contamination by saline fluids from the thermal reservoir has led to high calcium and magnesium concentrations. 36C1, I4C, and 3H data constrain the residence time of the water, and allow for the distinguishing of four circulation types: (1) shallow surface circulation (primarily above sea level) in the karstic units with short residence times (
Wei Huang - One of the best experts on this subject based on the ideXlab platform.
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The enhancing effect on tidal signals of a Submarine Spring connected to a semi-infinite confined aquifer
Hydrological Sciences Journal, 2012Co-Authors: Yuqiang Xia, Ying Yang, Wei HuangAbstract:Abstract Submarine Springs play an important role in Submarine groundwater discharge (SGD). To investigate the effects of these Springs on the propagation of tidal signals in coastal confined aquifers, this paper considers a general coastal aquifer system with a Submarine Spring on the seabed where the length of the aquifer's offshore extent is finite and its Submarine outlet is covered by an impermeable outlet-capping. An approximate analytical solution is obtained for describing the tidal head fluctuations in the aquifer. Solution analyses indicate that the error of the approximate analytical solution is negligible when both distances from the Spring hole to the coastline and to the Submarine outlet-capping are much greater than the radius of the Spring hole. Sensitivity tests are conducted to investigate the effects of hydraulic properties, tidal and Spring geometric configuration parameters on the tidal signal propagation in the inland aquifer. For aquifers with infinite offshore length, or without su...
Bernard Ladouche - One of the best experts on this subject based on the ideXlab platform.
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Hydraulic and geochemical impact of occasional saltwater intrusions through a Submarine Spring in a karst and thermal aquifer (Balaruc peninsula near Montpellier, France)
2020Co-Authors: Marie-amélie Pétré, Bernard Ladouche, Jean-luc Seidel, Romain Hemelsdaël, Véronique De Montety, Christelle Batiot-guilhe, Claudine LamotteAbstract:Abstract. Submarine Springs are a common discharge feature of the karst aquifers along the Mediterranean coast. In some instances, occasional and localized saltwater intrusions can occur through the Submarine Spring and negatively impact the quality of the groundwater resource. The hydraulic and geochemical behavior of a Submarine Spring discharging into the Thau lagoon just offshore of the Balaruc peninsula near Montpellier, France has been characterized to determine the impacts of such phenomena to better understand the dynamics of a regional karst aquifer and improve its groundwater management. This work is based on both historical and new hydrogeological and geochemical data, illustrating 6 occasional saltwater intrusion events (from 1967 to 2014) in the Thau lagoon area (southern France). Hydraulic perturbation of the aquifer is propagated instantly within the Balaruc-les-Bains peninsula and reaches a distance of about 5 km upgradient within 9 days. Comparison of hydraulic heads during seawater intrusion events in 2010 and 2014 indicates an aggravation of the phenomenon with an increase in hydraulic head variations. In contrast, isotopic tracers (87Sr/86Sr, D/H, 18O/16O,) and Rare Earth Elements (REE) demonstrate that the geochemical impact of these inversac events is only observed at the local scale, but is still perceptible several years after the event. For example, some of the thermal wells had not recovered their initial geochemical state 20 and 40 months after the last two inversac events (2010 and 2014, respectively), suggesting a geochemical legacy of this phenomenon within the complex karst system. By contrast, an adjacent deep karst compartment located south of the study area is not affected by the saltwater intrusion and is characterized by distinctly different hydrodynamic behavior. Overall, this work on occasional and localized saltwater intrusions constitutes a key step in understanding the dynamics of this complex karstic and thermal aquifer and will support the management of the groundwater resource.
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Deep Water Circulation, Residence Time, and Chemistry in a Karst Complex
Groundwater, 2003Co-Authors: Luc Aquilina, Bernard Ladouche, Nathalie Dörfliger, Michel BakalowiczAbstract:We investigated the hydrochemistry of a complex karst hydrosystem made of two carbonate units along a coastal lagoon. Ground water emerges on the lagoon floor from a Submarine Spring. In addition, thermal waters circulate through the limestone and mix with karst water near the lagoon shore. A distinction between the water from the two carbonate units is related to marine influences and human activities. In one of the massifs, the data show an incongruent dissolution of dolomite with time. In the other system, a slight contamination by saline fluids from the thermal reservoir has led to high calcium and magnesium concentrations. 36C1, I4C, and 3H data constrain the residence time of the water, and allow for the distinguishing of four circulation types: (1) shallow surface circulation (primarily above sea level) in the karstic units with short residence times (
Stephen A. Kish - One of the best experts on this subject based on the ideXlab platform.
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Numerical study of groundwater flow cycling controlled by seawater/freshwater interaction in a coastal karst aquifer through conduit network using CFPv2
Journal of contaminant hydrology, 2015Co-Authors: Hal Davis, Stephen A. KishAbstract:In this study, a groundwater flow cycling in a karst Springshed and an interaction between two Springs, Spring Creek Springs and Wakulla Springs, through a subground conduit network are numerically simulated using CFPv2, the latest research version of MODFLOW-CFP (Conduit Flow Process). The Spring Creek Springs and Wakulla Springs, located in a marine estuary and 11 miles inland, respectively, are two major groundwater discharge spots in the Woodville Karst Plain (WKP), North Florida, USA. A three-phase conceptual model of groundwater flow cycling between the two Springs and surface water recharge from a major surface creek (Lost Creek) was proposed in various rainfall conditions. A high permeable subground karst conduit network connecting the two Springs was found by tracer tests and cave diving. Flow rate of discharge, salinity, sea level and tide height at Spring Creek Springs could significantly affect groundwater discharge and water stage at Wakulla Springs simultaneously. Based on the conceptual model, a numerical hybrid discrete-continuum groundwater flow model is developed using CFPv2 and calibrated by field measurements. Non-laminar flows in conduits and flow exchange between conduits and porous medium are implemented in the hybrid coupling numerical model. Time-variable salinity and equivalent freshwater head boundary conditions at the Submarine Spring as well as changing recharges have significant impacts on seawater/freshwater interaction and Springs' discharges. The developed numerical model is used to simulate the dynamic hydrological process and quantitatively represent the three-phase conceptual model from June 2007 to June 2010. Simulated results of two Springs' discharges match reasonably well to measurements with correlation coefficients 0.891 and 0.866 at Spring Creeks Springs and Wakulla Springs, respectively. The impacts of sea level rise on regional groundwater flow field and relationship between the inland Springs and Submarine Springs are evaluated as well in this study.
Michel C. Boufadel - One of the best experts on this subject based on the ideXlab platform.
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Modelling tidal signals enhanced by a Submarine Spring in a coastal confined aquifer extending under the sea
Advances in Water Resources, 2007Co-Authors: David Lockington, Michel C. BoufadelAbstract:Submarine Springs discharge offshore groundwater from confined aquifers extending under the sea. The effects of these Springs on the propagation of tidal oscillations in coastal confined aquifers are not known. This paper presents an approximate analytical solution of tidal head fluctuations in a confined aquifer with one Submarine Spring. The aquifer is assumed to extend in all directions infinitely. The Spring is represented by a permeable round column on the seabed, which penetrates completely the impermeable layer overlying the confined aquifer. The error of the approximate solution is negligible if the distance from the Spring to the coastline is much greater than the radius of the permeable column representing the Spring. Through a hypothetical example, we demonstrate that it is possible to identify the Spring's location using tidal signals observed from inland wells. Tidal groundwater head fluctuations from three inland observation wells at least are needed to determine the 5 model parameters, including the location (2 parameters), the radius of the permeable column representing the Spring, the diffusivity of the aquifer, and the tidal loading efficiency of the system. (c) 2006 Elsevier Ltd. All rights reserved.
