scholarly journals Hydraulic behavior of subsidence-induced surface discontinuities in the hydrogeology of the Aguascalientes valley

2020 ◽  
Vol 382 ◽  
pp. 589-594
Author(s):  
Lilia Guerrero-Martínez ◽  
Martín Hernández-Marín ◽  
Ángel Eduardo Muñoz-Zavala
Keyword(s):  
Groundwater Flow ◽  
Fault Plane ◽  
Fault Zones ◽  
Hydraulic Behavior ◽  
Fault Behavior ◽  
Mapping Analysis ◽  
The Impact ◽  
Surface Discontinuities ◽  
Hydraulic Barriers ◽  
Aguascalientes Valley

Abstract. The impact of faults and fissures (discontinuities) on the groundwater flow has become important in several parts of the world because the heterogeneous and anisotropic distribution of permeability in fault zones is difficult to characterize. Based on this, we propose an analysis of patterns of parameters measured in groundwater, under the premise that the observed anomalies can be indicators of the hydraulic behavior of the flow in the direction perpendicular to the fault plane. In this context, if the discontinuities are sealed, they behave as hydraulic barriers, causing variation in the continuity of the parameters across the fault plane. Conversely, when faults are a conduit, they appear to have a small or null variation in the distribution of the parameter measurements. The impact of discontinuities in groundwater flow in a zone with a large number of faults and fissures such as that of the Aguascalientes valley is being studied using a graphical-correlation analysis with the revision of 230 wells, through the measurement of parameters such as temperature and static levels across discontinuities, in order to determine the hydraulic behavior of the faults. This investigation considered values over 4 ∘C for geothermal variations and 10 m for hydraulic-head changes to define fault behavior. Results show three zones through mapping analysis, where the fault presents barrier behavior and where the hanging block represents high values; these anomalies are much higher than the average across the valley and indicate the propensity for the fault to restrict horizontal flow. In conclusion, the Oriente fault presents complex behavior of a barrier–conduct system along the fault. This analysis gives a robust way to describe fault behavior without referring to elaborate and invasive hydrological investigations.

Groundwater Lowering for Construction of the Kilsby Tunnel – Geological and Geotechnical Interpretation

2021 ◽  
pp. 1-14
Author(s):  
Martin Preene ◽  
Mike Chrimes
Keyword(s):  
Groundwater Flow ◽  
Theoretical Understanding ◽  
Stress Theory ◽  
Glacial Origin ◽  
Buried Channel ◽  
Geological Information ◽  
Ground Conditions ◽  
Glacial Processes ◽  
The Impact ◽  
Groundwater Lowering

The Kilsby Tunnel, constructed in the 1830s, faced severe problems when a section of the tunnel, almost 400 m long, encountered unstable ‘quicksand’ conditions. The engineer for the project, Robert Stephenson, developed an extensive groundwater lowering scheme, unique for the time, using steam engines pumping from multiple shafts, to overcome the quicksand. Modern geological information indicates most of the tunnel was in Middle Lias bedrock, but the ‘quicksand’ section passed through a buried channel of water-bearing sand of glacial origin. In the early 19th century the impact of glacial processes on British geology was not widely accepted and, based on contemporary geological knowledge, Stephenson’s problems appear to be genuine unforeseen ground conditions, not predicted by his experienced advisers. It seems just random chance that trial borings missed the buried channel of sand. The work at Kilsby was two decades before Darcy’s law established the theoretical understanding for groundwater flow, and 90 years before Terzaghi’s effective stress theory described how reducing pore water pressures changed ‘quicksand’ into a stable and workable material. Despite the lack of existing theories, Stephenson used careful observations and interpretation of groundwater flow in the ‘quicksand’ to navigate the tunnel project to a successful conclusion.

Partitioned Permeability Diagram: an innovative way to estimate Fault Zones hydraulics.

2021 ◽  
Author(s):  
Irène Aubert ◽  
Juliette Lamarche ◽  
Philippe Leonide
Keyword(s):  
Fault Zone ◽  
Damage Zone ◽  
Fault Zones ◽  
Matrix Permeability ◽  
Vertical Fault ◽  
Core Permeability ◽  
The Impact ◽  
Evolution With Time ◽  
Fluid Pathway

<p>Understanding the impact of fault zones on reservoir trap properties is a major challenge for a variety of geological ressources applications. Fault zones in cohesive rocks are complex structures, composed of 3 components: rock matrix, damage zone fractures and fault core rock. Despite the diversity of existing methods to estimate fault zone permeability/drain properties, up to date none of them integrate simultaneously the 3 components of fracture, fault core and matrix permeability, neither their evolution with time. We present a ternary plot that characterizes the fault zones permeability as well as their drainage properties. The ternary plot aims at (i) characterizing the fault zone permeability between the three vertices of matrix, fractures and fault core permeability ; and at (ii) defining the drain properties among 4 possible hydraulic system: (I) good horizontal and vertical, fault-perpendicular and -parallel; (II) moderate parallel fluid pathway; (III) good parallel fault-core and (IV) good parallel fractures. The ternary plot method is valid for 3 and 2 components fault zones. The application to the Castellas Fault case study show the simplicity and efficiency of the plot for studying underground and/or fossil, simple or polyphase faults in reservoirs with complete or limited permeability data.</p>

The interplay of Malm carbonate permeability, gravity-driven groundwater flow, and paleoclimate – implications for the geothermal field and potential in the Molasse Basin (Southern Germany), a foreland-basin play

2021 ◽  
Author(s):  
Tom Vincent Schintgen ◽  
Inga Sigrun Moeck
Keyword(s):  
Groundwater Flow ◽  
Geothermal Energy ◽  
Foreland Basin ◽  
Geothermal Field ◽  
Molasse Basin ◽  
Carbonate Aquifer ◽  
Foreland Basins ◽  
Gravity Driven ◽  
The Impact ◽  
Subsurface Temperatures

Abstract The Molasse Basin in Southern Germany is part of the North Alpine Foreland Basin and hosts the largest accumulation of deep geothermal production fields in Central Europe. Despite the vast development of geothermal energy utilization projects especially in the Munich metropolitan region, the evolution of and control factors on the natural geothermal field are still debated. Especially seismic and deep well data from extensive oil and gas exploration in the Molasse Basin led to conceptual hydrogeological and thermal-hydraulic models. Corrected borehole-temperature data helped to constrain subsurface temperatures by geostatistical interpolation and facilitated the set-up of 3D temperature models. However, within the geothermally used Upper Jurassic (Malm) carbonate aquifer, temperature anomalies such as the Wasserburg Trough anomaly to the east of Munich and their underlying physical processes are yet poorly understood. From other foreland basins like the Alberta Basin in Western Canada, it is known that climate during the last ice age has a considerable effect even on subsurface temperatures up to two kilometres depth. Therefore, we study the impact of paleoclimatic changes on the Molasse Basin during the last 130 ka including the Würm glaciation. We consider the hydraulic and thermal effects of periglacial conditions like permafrost formation and the impact of the numerous glacial advances onto the Molasse Basin. The major difference between the thermal-hydraulic regime in the western and eastern parts of the Southern German Molasse Basin are delineated by calculating two contrasting permeability scenarios of the heterogeneously karstified Malm carbonate aquifer. Thermal-hydraulic modelling reveals the effect of recurrent glacial periods on the geothermally drillable subsurface, which is minor compared to the effect of permeability-related, continuous gravity-driven groundwater flow as a major heat transport mechanism. Practically, the results might help to reduce the exploration risk for geothermal energy projects in the Molasse Basin. More importantly, this study serves as a reference for the comparison and understanding of the interplay of high permeability aquifers, gravity-driven groundwater flow and paleoclimate in other orogenic foreland basins worldwide.

scholarly journals Effects of Baekje Weir Operation on the Stream–Aquifer Interaction in the Geum River Basin, South Korea

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2984
Author(s):  
Hyeonju Lee ◽  
Min-Ho Koo ◽  
Byong Wook Cho ◽  
Yong Hwa Oh ◽  
Yongje Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Flow ◽  
Groundwater Quality ◽  
Flow System ◽  
Natural Ecosystem ◽  
Visual Modflow ◽  
Ecosystem Recovery ◽  
Groundwater Use ◽  
Groundwater Flow System ◽  
The Impact

Hydraulic structures have a significant impact on riverine environment, leading to changes in stream–aquifer interactions. In South Korea, 16 weirs were constructed in four major rivers, in 2012, to secure sufficient water resources, and some weirs operated periodically for natural ecosystem recovery from 2017. The changed groundwater flow system due to weir operation affected the groundwater level and quality, which also affected groundwater use. In this study, we analyzed the changes in the groundwater flow system near the Geum River during the Baekje weir operation using Visual MODFLOW Classic. Groundwater data from 34 observational wells were evaluated to analyze the impact of weir operation on stream–aquifer interactions. Accordingly, the groundwater discharge rates increased from 0.23 to 0.45 cm/day following the decrease in river levels owing to weir opening, while the hydrological condition changed from gaining to losing streams following weir closure. The variation in groundwater flow affected the groundwater quality during weir operation, changing the groundwater temperature and electrical conductivity (EC). Our results suggest that stream–aquifer interactions are significantly affected by weir operation, consequently, these repeated phenomena could influence the groundwater quality and groundwater use.

scholarly journals Groundwater flow below construction pits and erosion of temporary horizontal layers of silicate grouting

2020 ◽  
Vol 28 (8) ◽  
pp. 2821-2832
Author(s):  
Joris M. Dekker ◽  
Thomas Sweijen ◽  
Alraune Zech
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Flow ◽  
Analytical Solutions ◽  
Mass Flux ◽  
Approximate Solutions ◽  
Sensitivity Study ◽  
Advective Transport ◽  
Dilution Ratio ◽  
The Impact ◽  
Horizontal Layers

AbstractInjection of silicate grouting materials is widely used to create temporary horizontal layers for reducing inflow of groundwater at construction sites, in regions with shallow water tables. The erosion of a grouting layer was investigated by means of analytical solutions for groundwater flow and transport within a pit after construction finished. Erosion is assumed to occur by dissolution of the temporary injection layer and subsequent advective transport. Thereby, the hydraulic conductivity changes with time. This paper presents novel analytical solutions and approximate solutions for the major fluxes in the construction pit as a function of the domain settings, aquifer gradient and hydraulic conductivity. In addition, the mass flux and the dilution ratio of erosion-related components leaving the construction pit and entering the aquifer are quantified. Derived solutions are verified against numerical simulations. A sensitivity study shows the impact of domain settings on fluxes and dilution ratio. The results confirm that mass flux of grout components increases with ongoing erosion. Thus, its effect on groundwater quality increases with time after construction ceased.

scholarly journals Influence of aquifer and streambed heterogeneity on the distribution of groundwater discharge

2009 ◽  
Vol 13 (1) ◽  
pp. 69-77 ◽  
Author(s):  
E. Kalbus ◽  
C. Schmidt ◽  
J. W. Molson ◽  
F. Reinstorf ◽  
M. Schirmer
Keyword(s):  
Groundwater Flow ◽  
Transport Model ◽  
Regional Scale ◽  
Base Case ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Heterogeneous Distribution ◽  
Heterogeneous Aquifer ◽  
The Impact ◽  
Low K

Abstract. The spatial distribution of groundwater fluxes through a streambed can be highly variable, most often resulting from a heterogeneous distribution of aquifer and streambed permeabilities along the flow pathways. Using a groundwater flow and heat transport model, we defined four scenarios of aquifer and streambed permeability distributions to simulate and assess the impact of subsurface heterogeneity on the distribution of groundwater fluxes through the streambed: (a) a homogeneous low-K streambed within a heterogeneous aquifer; (b) a heterogeneous streambed within a homogeneous aquifer; (c) a well connected heterogeneous low-K streambed within a heterogeneous aquifer; and (d) a poorly connected heterogeneous low-K streambed within a heterogeneous aquifer. The simulation results were compared with a base case scenario, in which the streambed had the same properties as the aquifer, and with observed data. The results indicated that the aquifer has a stronger influence on the distribution of groundwater fluxes through the streambed than the streambed itself. However, a homogeneous low-K streambed, a case often implemented in regional-scale groundwater flow models, resulted in a strong homogenization of fluxes, which may have important implications for the estimation of peak mass flows. The flux distributions simulated with heterogeneous low-K streambeds were similar to the flux distributions of the base case scenario, despite the lower permeability. The representation of heterogeneous distributions of aquifer and streambed properties in the model has been proven to be beneficial for the accuracy of flow simulations.

scholarly journals Assessing the impact of Syrian refugees on earthquake casualty estimations in southeast Turkey

2017 ◽  
Author(s):  
Bradley Wilson ◽  
Thomas Paradise
Keyword(s):  
Population Distribution ◽  
Dead Sea ◽  
Fault Zones ◽  
Earthquake Risk ◽  
Syrian Refugees ◽  
Displaced Populations ◽  
Geographically Distributed ◽  
Earthquake Casualty ◽  
Semi Empirical ◽  
The Impact

Abstract. The influx of millions of Syrian refugees into Turkey has rapidly changed the population distribution along the Dead Sea Rift and East Anatolian fault zones. In contrast to other countries in the Middle East where refugees are accommodated in camp environments, the majority of displaced individuals in Turkey are integrated into local cities, towns, and villages – placing stress on urban settings and increasing potential exposure to strong earthquake shaking. Yet, displaced populations are often unaccounted for in the census based population models used in earthquake casualty estimations. Accordingly, this study constructs a refugee inclusive gridded population model and analyzes its impact on semi-empirical casualty estimations across southeast Turkey. Daytime and nighttime fatality estimates were calculated for five geographically distributed fault zones at earthquake magnitudes 5.8, 6.4, and 7.0. Total casualty estimates ranged from 28–7723 individuals, with the contribution of refugees varying from 1 %–26 % of total estimated casualties. On average, these percentages correspond to casualty underestimations of tens to hundreds of individuals. These findings communicate the necessity of incorporating refugee statistics into earthquake risk analyses in southeast Turkey and the ongoing importance of placing environmental hazards in their appropriate regional and temporal context.

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