The influence of faults on groundwater flow and transport dynamics: the raw fault in the Neogene aquifer, Belgium.

2020 ◽  
Author(s):  
Alberto Casillas-Trasvina ◽  
Bart Rogiers ◽  
Koen Beerten ◽  
Laurent Wouters ◽  
Kristine Walraevens
Keyword(s):  
Radioactive Waste ◽  
Groundwater Flow ◽  
Solute Transport ◽  
Hydraulic Head ◽  
Fault Zones ◽  
Environmental Tracers ◽  
Flow And Transport ◽  
Groundwater Systems ◽  
Neogene Aquifer ◽  
Regional Groundwater

<p>Faults play an important role in flow and transport in regional groundwater systems. The inclusion of faults during the conceptualization of regional groundwater systems and their incorporation during the construction of groundwater models is crucial, particularly during performance assessments of radioactive waste repositories as well as risk assessment for other deep subsurface activities. Faults can act as: i) barriers slowing down groundwater flow, ii) conduits speeding up groundwater flow, or iii) a combination of both. Determining flow and transport behaviors across these structures is difficult since they are rarely exposed on the surface and their hydraulic behavior vary spatially. Environmental tracers may provide valuable information potentially useful to determine flow pathways, travel times, and groundwater age. If these latter are affected by the presence of fault zones, and they can yield important information for the parameterization of faults in groundwater models. For the Neogene aquifer in Flanders, groundwater flow and solute transport models have been developed in the framework of safety and feasibility studies for the underlying Boom Clay Formation as potential host rock for geological disposal of radioactive waste. However, the simulated fluxes and transport parameters of these models are still subject to large uncertainties, as they are typically constrained by hydraulic heads only and their current conceptualization does not differentiate the fault zones from the undisturbed aquifer materials. This study investigates how groundwater flow and solute transport in the sedimentary Neogene aquifer are disturbed by the Rauw fault – a 55 km long normal fault – across the Nete catchment, in Belgium. To this end, we use a combination of hydraulic head observations and several environmental tracers: hydrochemical analyses, stable isotopes, carbon-14 (<sup>14</sup>C), helium-tritium (<sup>3</sup>He-<sup>3</sup>H), helium-4 (<sup>4</sup>He) and temperature-depth (TD) profiles. This will allow us to: i) test our current understanding of the system as well as the corresponding model performance, and ii) decrease the uncertainties on forward model outcomes for future scenarios and inverse models by including an advanced conceptualization. The Rauw fault has a displacement of >7 meters which increases with depth. The observed hydraulic gradient across the fault zone appears significant, with head differences of 1.8-2.0 meters over an horizontal distance of 60 meters. Two sampling campaigns have taken place, in 2016 and 2019, for collection of <sup>3</sup>He-<sup>3</sup>H, <sup>4</sup>He, <sup>14</sup>C, and TD data at a total of 38 selected wells across the Nete river catchment. These will be further used as observations points for the transport modelling. Here, we will present the first results and interpretations of the gathered temperature and environmental tracer data in complementation with hydraulic head levels to evaluate the effects of the Rauw Fault on the hydrogeological system and the implications future conceptualization and numerical modelling.</p>

scholarly journals Groundwater Flow and Transport

2021 ◽  
pp. 9-22
Author(s):  
Chi-Yuen Wang ◽  
Michael Manga
Keyword(s):  
Groundwater Flow ◽  
Solute Transport ◽  
Unsaturated Flow ◽  
Hydraulic Head ◽  
Darcy's Law ◽  
Governing Equations ◽  
Basic Principles ◽  
Flow And Transport ◽  
Groundwater Flow And Transport ◽  
And Storage

AbstractWe summarize the basic principles of, and governing equations for, groundwater flow and transport. Topics covered include the concepts of pressure and hydraulic head, Darcy’s law, permeability, and storage. We compare saturated and unsaturated flow. We provide an introduction to heat and solute transport.

scholarly journals Editorial of Special Issue “Advances in Groundwater Flow and Solute Transport: Pushing the Hidden Boundary”

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 457
Author(s):  
Hongbin Zhan ◽  
Quanrong Wang ◽  
Zhang Wen
Keyword(s):  
Numerical Methods ◽  
Groundwater Flow ◽  
Solute Transport ◽  
Vadose Zone ◽  
Regional Scale ◽  
Chemical Transport ◽  
Low Permeability ◽  
Special Issue ◽  
Flow And Transport ◽  
Wide Range

The theme of this special issue is to explore the new territories beyond conventional subsurface flow and transport theories. We have selected 12 articles in this special issue and these articles cover a wide range of problems including (1) Non-Fickian chemical transport in various environments; (2) Non-Darcian flow; (3) Flow and transport in low-permeability media; (4) Vadose zone process; (5) Regional scale groundwater flow and groundwater-surface interaction; (6) Innovative numerical methods. The major contributions of these papers are summarized in this editorial.

scholarly journals Quantification of anthropogenic impact on groundwater dependent terrestrial ecosystem using geochemical and isotope tools combined with 3-D flow and transport modeling

2014 ◽  
Vol 11 (8) ◽  
pp. 9671-9713
Author(s):  
A. J. Zurek ◽  
S. Witczak ◽  
M. Dulinski ◽  
P. Wachniew ◽  
K. Rozanski ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Terrestrial Ecosystem ◽  
Transport Modeling ◽  
Environmental Tracers ◽  
Groundwater Abstraction ◽  
Flow And Transport ◽  
Wide Range ◽  
The Status ◽  
Water Ph ◽  
Stable Isotopes Of Water

Abstract. A dedicated study was launched in 2010 with the main aim to better understand the functioning of groundwater dependent terrestrial ecosystem (GDTE) located in southern Poland. The GDTE consists of a valuable forest stand (Niepolomice Forest) and associated wetland (Wielkie Bloto fen). A wide range of tools (environmental tracers, geochemistry, geophysics, 3-D flow and transport modeling) was used. The research was conducted along three major directions: (i) quantification of the dynamics of groundwater flow in various parts of the aquifer associated with GDTE, (ii) quantification of the degree of interaction between the GDTE and the aquifer, and (iii) 3-D modeling of groundwater flow in the vicinity of the studied GDTE and quantification of possible impact of enhanced exploitation of the aquifer on the status of GDTE. Environmental tracer data (tritium, stable isotopes of water) strongly suggest that upward leakage of the aquifer contributes significantly to the present water balance of the studied wetland and associated forest. Physico-chemical parameters of water (pH, conductivity, Na / Cl ratio) confirm this notion. Model runs indicate that prolonged groundwater abstraction through the newly-established network of water supply wells, conducted at maximum permitted capacity (ca. 10 000 m3 d−1), may trigger drastic changes in the ecosystem functioning, eventually leading to its degradation.

The Use of Environmental Isotope Techniques together with Conventional Methods in Regional Groundwater Studies

1976 ◽  
Vol 7 (2) ◽  
pp. 81-94
Author(s):  
Guttormur Sigbjarnarson ◽  
Pall Theodorsson ◽  
Bragi Arnason
Keyword(s):  
Groundwater Flow ◽  
Flow Pattern ◽  
Environmental Isotopes ◽  
Geological Exploration ◽  
Environmental Isotope ◽  
Mountain Ranges ◽  
Geological Conditions ◽  
Groundwater Systems ◽  
Regional Groundwater ◽  
Perched Aquifers

Regional hydrological investigations of the subsurface drainage in the neovolcanic area around lake Thorisvatn on the central Icelandic plateau have been carried out as well as geological exploration. Environmental isotopes, deuterium and tritium, proved decisive in finding the groundwater flow pattern and in separating the different groundwater systems and explaining local deviations as barriers and perched aquifers. The regional groundwater flow is only slightly dependent on the. topography but highly on the geological conditions, as it virtually flows under mountain ranges as well as under the river Tungnaa.

Wellenberg, Switzerland: Controls on Groundwater Flow and Solute Transport Derived From Hydrochemical Observations

1997 ◽  
Vol 506 ◽  
Author(s):  
H. N. Waber ◽  
F. J. Pearson ◽  
A. Scholtis
Keyword(s):  
Radioactive Waste ◽  
Groundwater Flow ◽  
Solute Transport ◽  
Host Rock ◽  
Intermediate Level ◽  
Isotopic Data ◽  
The North ◽  
Central Switzerland ◽  
Waste Repository ◽  
Intermediate Level Radioactive Waste

The Wellenberg area, central Switzerland, is under investigation for a potential low and intermediate level radioactive waste repository. The host rock, the Palfris marl, is bounded on the north by Cretaceous limestone units of the Drusberg nappe and is underlain by a sequence of Tertiary to Jurassic sediments (limestones, marls) of the Wissberg-Firrenband-Equivalent. Chemical and isotopic data on groundwaters and rocks show that three essentially independent groundwater flow regimes occur in the area: (1) groundwaters of the Palfris marl, (2) groundwaters of the limestone units of the Drusberg nappe, and (3) groundwaters of the Wissberg-Firrenband Equivalent.

scholarly journals Regional hydraulic model of the Upper Rhine Graben

2019 ◽  
Vol 49 ◽  
pp. 197-206
Author(s):  
Nora Koltzer ◽  
Magdalena Scheck-Wenderoth ◽  
Mauro Cacace ◽  
Maximilian Frick ◽  
Judith Bott
Keyword(s):  
Groundwater Flow ◽  
Flow System ◽  
Hydraulic Head ◽  
Upper Rhine Graben ◽  
Groundwater Dynamics ◽  
Rhine Graben ◽  
Southern Half ◽  
Rhine Valley ◽  
Upper Rhine ◽  
Regional Groundwater

Abstract. In this study we make use of 3-D hydraulic simulations to investigate the regional groundwater flow in the Upper Rhine Graben. The modeling is based on an existing detailed 3-D structural model covering the whole Upper Rhine Graben from the surface down to 14 km of depth. The overall goal of this study is to provide some quantitative analysis on the role of the hydraulic head topology in shaping the underground hydrodynamics by taking into account interactions with the heterogeneous subsurface sedimentary configuration of the basin system. Therefore, the main question addressed by this study can be summarized as follows: does the deep graben flow follow the topographic gradient and the flow direction of the river Rhine from the Alps northward to the northernmost area of the Upper Rhine Graben? Our results demonstrate the presence of a regional subsurface flow in the sedimentary rocks aligning from the graben flanks towards its center and in the southern half of the graben from south to north. The graben-parallel flow velocity is found to be about 1 order of magnitude lower than the velocity predicted perpendicular to the main graben axis. Besides these general trends, the modeling highlights local heterogeneities in the shallow 3-D flow field. Those arise from the interaction between regional groundwater flow and the heterogeneous sedimentary configuration. Within the Cenozoic sediments forming the uppermost aquifer in the model, groundwater flows are driven by imposed hydraulic gradients from recharge areas located at higher elevations in the Black Forest and Vosges Mountains to the discharge region at a lower elevation in the Rhine valley. The presence of a regional aquitard (Keuper) separating the shallow and the deeper aquifer system (Muschelkalk, Buntsandstein, and Rotliegend) hinders hydraulic connection among the two aquifer systems. This is exemplified by the development of a flow system in the deeper aquifers, which shows a more continuous graben-parallel south–north direction. Based on these results we can conclude that both the hydraulic head topology and the level of structuration of the sedimentary sequence exert a 1st-order role in shaping the regional flow system at depth. The regional model predicts a heterogeneous flow system within the upper 4 km of the Upper Rhine Valley, where flow velocities in the graben valley can reach up to 45 mm yr−1 in the upper and lower aquifers. Back to the current conceptual hydrogeological model, the results question the presence of a graben through northward flow, being limited to the southern half of the graben. In the north, the groundwater dynamics turn out to be more complex, being structurally linked to the local geology. This calls for additional studies with a higher level of both structural and stratigraphic attributes in order to arrive at a better quantification of the local to the regional groundwater dynamics in the area.

scholarly journals Reducing the ambiguity of karst aquifer models by pattern matching of flow and transport on catchment scale

2015 ◽  
Vol 19 (2) ◽  
pp. 893-912 ◽  
Author(s):  
S. Oehlmann ◽  
T. Geyer ◽  
T. Licha ◽  
M. Sauter
Keyword(s):  
Groundwater Flow ◽  
Solute Transport ◽  
Karst Aquifer ◽  
Karst Area ◽  
Hydraulic Parameters ◽  
Karst Aquifers ◽  
Flow And Transport ◽  
Model Ambiguity ◽  
Karst Conduit ◽  
Conduit Network

Abstract. Assessing the hydraulic parameters of karst aquifers is a challenge due to their high degree of heterogeneity. The unknown parameter field generally leads to a high ambiguity for flow and transport calibration in numerical models of karst aquifers. In this study, a distributed numerical model was built for the simulation of groundwater flow and solute transport in a highly heterogeneous karst aquifer in south-western Germany. Therefore, an interface for the simulation of solute transport in one-dimensional pipes was implemented into the software COMSOL Multiphysics® and coupled to the three-dimensional solute transport interface for continuum domains. For reducing model ambiguity, the simulation was matched for steady-state conditions to the hydraulic head distribution in the model area, the spring discharge of several springs and the transport velocities of two tracer tests. Furthermore, other measured parameters such as the hydraulic conductivity of the fissured matrix and the maximal karst conduit volume were available for model calibration. Parameter studies were performed for several karst conduit geometries to analyse the influence of the respective geometric and hydraulic parameters and develop a calibration approach in a large-scale heterogeneous karst system. Results show that it is possible not only to derive a consistent flow and transport model for a 150 km2 karst area but also to combine the use of groundwater flow and transport parameters thereby greatly reducing model ambiguity. The approach provides basic information about the conduit network not accessible for direct geometric measurements. The conduit network volume for the main karst spring in the study area could be narrowed down to approximately 100 000 m3.

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