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2014 | Buch

H2Karst Research in Limestone Hydrogeology

herausgegeben von: Jacques Mudry, François Zwahlen, Catherine Bertrand, James W. LaMoreaux

Verlag: Springer International Publishing

Buchreihe : Environmental Earth Sciences

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SUCHEN

Über dieses Buch

Chapters in this book are contributions from the 9th Conference on limestone hydrogeology, organized in Besançon in September 2011 selected by the scientific committee of H2Karst.The book presents latest results on in the field of groundwater flow and storage within the different subsystems of karst aquifers; insights into the complex interaction between groundwater and surface water in karst areas by a multidisciplinary approach; current knowledge on contamination problems and contaminant transport in karst aquifers as well as an overview of karst hydrogeology in different contexts around the world.

Inhaltsverzeichnis

Frontmatter
Expect the Unexpected! Groundwater Flow in Karstified Carbonate Aquifers
Abstract
Aquifers in carbonate rocks characteristically display triple porosity, the most complex type of groundwater flow system. The complexity arises from antecedent geological conditions, from local geomorphology and climate, and from the patterns of solutional conduits (including accessible caves) and their relationships with any matrix or fracture flow. Much is being learned from study of calcite and other precipitates in such caves. Where not directly accessible, karst aquifers are best approached by study of natural springs, recharge sink points and dye tracing; wells and boreholes are secondary sources. Double continuum and triple porosity designs are most suitable for computer predictive modeling.
Derek Ford
Hydraulic Properties of Karst Groundwater and Its Impacts on Large Structures
Abstract
A karst environment is a particularly sensitive and risky geological formation for the infrastructure construction from the micro to the mega scale. The hydraulic properties and specific regime of groundwater in karst are, in many cases, the source of catastrophic failures. The most common destructive influence of groundwater is the consequence of: massive turbulent flows; the fast erosion of unconsolidated deposits in caverns and joints; the great kinetic energy of underground flows; propagation of hydraulic pressure at large distances (piston effect); and the enormous hydraulic pressures created in periods of full aquifer saturation, including water-hammer and air-hammer effects due to rapid fluctuation of the water levels. Despite extensive investigations, the destructive impacts are mostly unpredictable in space and time. In many cases these destructive processes take time to become established but final effects appear abruptly, causing considerable damages or failures. The most common consequences of these impacts are subsidence at the urban areas, along the roads and railways, as well as at the bottom of reservoirs; water seepage from reservoirs; break-in of groundwater under high pressure during underground excavation; destruction of surface remediation structures; destruction of tunnel lining; degradation of grout curtains, induced seismicity; decreasing of downstream spring discharges; endangerment of underground species; and the creation of many other unpredictable and unexpected problems. Some dam failures (empty reservoirs) or collapses (entire buildings and factories sinks) were catastrophic. Successful remediation solutions require serious and comprehensive investigations including long period monitoring of groundwater regimes and (in many cases) remedial works during the lifetime of the structure. During construction modifications and adaptations of structures are very common in karst. Persistent, time-consuming and expensive remedial works during the lifetime of the structure are no exception, but, rather, they are the rule.
Petar Milanović
Inferred Conduit Network Geometry from Geological Evidences and Water-Head in a Fluvio-Karstic System (Val D’Orleans, France)
Abstract
Flow modeling is a useful tool to investigate sustainable scenarios of water use for groundwater resources managers. However, the applications of this approach in karstic aquifers are still limited due to the difficulties of locating and describing the position and geometry of conduits. In the karstic aquifer of the ‘Val d’Orléans’ (France), the location of the conduits was identified by the presence of land-surface collapses and voids in the boreholes. In this dataset, 103 logs showed voids >0.1 m and a highly porous zone around 80 m.a.s.l. In this chapter, a methodology is proposed to interpolate the dataset to build a karstic network at the regional scale. Here, four scenarios of the conduit network geometry are tested, related to the morphology of the network and its complexity. The scenarios are included in a 3D coupled continuum-conduit flow model (Feflow®). The flows in the conduits and in the host rock are respectively described by the Manning-Strickler equation and Darcy’s law. Constant boundary conditions and hydrodynamic properties are assumed to test the model sensitivity to different network geometry scenarios. The most relevant scenario is selected by comparing calculated and observed water-heads in the boreholes. It aims to calculate a water balance at the regional scale, results suggest that accurate models (correlation coefficient r2 > 0.9) can be obtained with an average hydraulic diameter approach and with highly simplified conduit network geometries. This confirms the interest of discrete continuum approaches, even if the actual conduit geometry will never be known.
Chrystelle Auterives, Stéphane Binet, Patrick Albéric
Contribution of Isotopes of the Water Molecule to Determine Recharge Altitude of the Main Springs Welling Up in the Middle Atlas Limestone (Morocco)
Abstract
The present study contributes to characterize the Middle Atlas limestone karst aquifers by implementing water stable isotope techniques, to determine the recharge altitudes of major springs issuing from the Liassic dolomitic limestone, and helping to delineate protection zones of the springs. Chemical analyses of spring water show a composition that reflects both reservoir lithology and chemical evolution over the flow transit through the reservoir. Analysis of the evolution of deuterium as a function of oxygen-18 suggests a local water line similar to that derived for rainwater at the Fez weather station, indicating that the concerned aquifers are recharged through rapid infiltration, without appreciable evaporation of rainwater. Application of the established −0.27 ‰ per 100 m altimetry gradient for oxygen-18 to the isotopic signatures of other analyzed springs enables the backtracking of recharge altitudes of these springs. Comparison of these results with local and regional hydrogeological data shows a notable agreement among springs for which the drainage basin is known, and allows for more precise localization of recharge area of springs for which the drainage basin is poorly known, with recharge altitudes up to 1,090 m higher than their emergence zones. To a certain extent, these results help to determine recharge zones for Middle Atlas springs and thus help in strategizing protection for this resource.
Abdelhadi El Ouali, Soumaya Sefrioui, Jacques Mudry, Omar Fassi Fihri, Ali Essahlaoui, Hamid Marah
Detection of Underground Cavities by Combining Electrical Resistivity Imaging and Ground Penetrating Radar Surveys: A Case Study from Draa Douamis Area (North East of Algeria)
Abstract
A geophysical survey routine is proposed to detect underground cavities and dolines, based on the sequential application of ground penetrating radar (GPR) and electrical resistivity imaging or tomography (RESTOM). A case study near Cherea area (NE Algeria) demonstrates the applicability of these methods. Nine GPR profiles and two-dimensional RESTOM have been applied, with relative success, to locate paleo-collapses and cavities, and to detect and characterize karst at two sinkhole sites near Cheria city where limestone is covered by about 10 m of clayey soils. The survey results suggest that GPR and RESTOM are ideal geophysical tools to aid in the detection and monitoring of sinkholes and other subsurface cavities.
C. Fehdi, I. Nouioua, D. Belfar, L. Djabri, E. Salameh
Using Hybrid Genetic Algorithms in Assembling Master Recession Curves of Karst Springs
Abstract
Computation methods, using the evolution algorithm concept—mainly group of optimization methods known as genetic algorithms—provide an interesting methodical approach, applicable for a construction (not interpretation) of assembled recession curves. Assemblage of the master recession curve from various hydrograph segments by the help of the hybridized genetic algorithm approach can avoid obstacles such as limited time-series datasets, incomplete recessions or too many segments in many recession curves, complicated hydrograph shape in the case of karstic springs (caused by combined laminar and turbulent discharge sub-regimes due to karst network settings), different time intervals of observations (daily or weekly frequencies), short time-series intervals, imprecise measurements, different types of datasets (averaged or directly measured data) or even rough (inaccurate) measurements of discharges. The only type of discharge curve without practical output solution of the method presented is the constant outflow. In practice, assembling of recession curves is necessary for hydrogeological phenomena, especially in moderate climate regions, where recessional periods are frequently interrupted by partial recharge events. The presented algorithm was already implemented to a programme solution, so that the applicability of the hybrid genetic algorithms method for master recession curve creation is at hand without requirements on programming skills of hydrologists involved, which can be considered as an immediate advantage of the method described.
Miloš Gregor, Peter Malík
Well Hydrograph Analysis for the Estimation of Hydraulic and Geometric Parameters of Karst and Connected Water Systems
Abstract
Well hydrographs contain crucial information about the hydraulic parameters and geometric characteristics of karst aquifers and connected water systems. This chapter provides quantitative tools for the estimation of hydraulic and geometric parameters by means of well hydrograph analysis. The analytical formulae provided in this chapter establish links between aquifer properties and hydrograph recession coefficients, and describe the spatial and temporal variations of the water table. A first set of equations describe the recession limb of hydrograph peaks, while another formula provides a quantitative characterization of the entire hydrograph peaks as a response to diffuse recharge. While existing spring hydrograph analytical techniques provide information on the overall characteristics of a karst catchment, well hydrograph analysis provides information on the hydraulic and geometric characteristics of individual matrix blocks. The combination of the spring and well hydrograph analytical techniques provides a powerful tool for the characterization of the structure and hydraulic behaviour of karst and connected water systems. A new approach to well hydrograph decomposition is presented, which makes the estimation of exact block geometry possible. In most cases, well hydrograph peaks can be decomposed into three exponential segments. These segments, however, do not represent different types of storage as suggested by previous studies. The asymmetric analytical solution presented in this study represents a powerful tool for parameter estimation in both karst and connected water systems. The symmetric and 1D solutions can be applied for order of magnitude parameter estimation. The proposed investigation method provides useful information for water resource assessment, flood prediction, vulnerability assessment, contamination risk assessment, geotechnical and speleological studies.
Attila Kovács, Pierre Perrochet
Distributed Hydrological Modeling and Model Adaption in High Alpine Karst at Regional Scale (Berchtesgaden Alps, Germany)
Abstract
Distributed hydrological modeling in karst dominated catchments is challenging as various unknown underground flow conditions and flow directions lead to unknown storage quantities. Missing parameterization in karst catchments at regional scale prevents reliable hydrological modeling of subsurface (unsaturated and saturated) water fluxes; and consequently, climate impact modeling in karst dominated catchments is until today insufficient. The deterministic hydrological model WaSiM-ETH by Schulla and Jasper was applied in the Alpine catchment of the river Berchtesgadener Ache to describe the water balance and to determine and quantify karst impact on hydrological processes at different time and space scales in the watershed. The study area is situated in the northern limestone Alps, characterized by a huge carbonate stratum, which is exposed to karstfication processes since Alpine lift. It is assumed, that subsurface flow channels and heterogeneous storage effects lead to groundwater redistribution through mountain ranges and influence hydrological processes of neighboring valleys. In a first step, former karst research in the area is evaluated to draw the main subsurface flow directions within or in between sub-basins. Based on this, the water balance of the sub-basins is examined to obtain further information on the regional hydrology. This is done by analyzing model results of the hydrological model. A systematic mismatch between modeled and measured runoff (over and underestimation) was detected in three high Alpine karst dominated sub-basins, indicating hydrological subsurface processes at sub-basin scale. The comparison of monthly sums of modeled and measured water storage indicates subsurface water inflow, outflow or redistribution in sub-basins and enables quantification of those processes. Based on these outcomes, a method to predict future water storage in the Berchtesgaden karst is developed and groundwater modeling is adapted in WaSiM-ETH, which was developed to improve the hydrological model for karst-dominated catchments.
Gabriele Kraller, Michael Warscher, Ulrich Strasser, Harald Kunstmann, Helmut Franz
Diagnostic Plots Applied to Well-Tests in Karst Systems
Abstract
Pumping tests conducted on wells intersecting karst heterogeneities, such as the conduit network, are difficult to interpret. Nevertheless, this case can be solved by assimilating the horizontal karst conduit to a finite-conductivity vertical fracture. In this case, several flow patterns corresponding to the respective contributions of karst subsystems (fractured matrix, small conduits and main karst drainage network) can be identified on the diagnostic plot of drawdown derivative. This is illustrated on two examples from Mediterranean karst systems. A pumping test on a well crossing the main karst drainage network of the Cent-Fonts karst system shows: (1) a preliminary contribution of the karst conduit storage capacity followed by (2) linear flows into the fractured matrix. A pumping test on a well intersecting a small karst conduit of the Bas-Agly karst system shows the existence of (1) bi-linear flows within both the karst conduit an the fractured matrix at early times, followed by (2) radial flows within the fractured matrix and (3) finally the contribution of a major karst cavity. The use of diagnostic plots allows the identification of the various flow regimes during pumping tests, corresponding to the response of the individual karst aquifer subsystems. This is helpful in order to understand the structure of the karst aquifer and flow exchanges between subsystems.
Jean-Christophe Maréchal, Bernard Ladouche, Benoît Dewandel, Perrine Fleury, Nathalie Dörfliger
Application of Methods for Resource and Source Vulnerability Mapping in the Orehek Karst Aquifer, SW Slovenia
Abstract
In a shallow karst aquifer in SW Slovenia assessment of groundwater and drinking water source vulnerability has been performed using different methods. The small, but well defined, Orehek karst is mainly drained by the no longer exploited Korentan spring. The recharge area of the spring is well karstified, densely wooded, and covered by thin soils. Besides precipitation, the spring is additionally recharged by temporally active sinking streams. To assess the vulnerability, two methods, COP+K and Slovene approach, have been applied. Both methods provide tools for assessing vulnerability in carbonate rocks. They both rank among very sophisticated methods that require vast amounts of data, time, and financial and technical resources. Both methods share the same methodological procedure and consider the same type of information, categorized by the same factors. On the other hand, the scoring, classification and weighting of individual parameters between the methods are different. Consequently, the resulting maps differ significantly. Major differences between the results are identified and discussed. In addition, sensitivity analysis of individual factors have been performed and compared to cross-correlation, autocorrelation and water budget calculations. The results show high dependence of the COP+K method to the parameters characterizing the infiltration conditions (the so-called C factor) and distance to water source. The Slovene approach vulnerability classes are mainly influenced by thickness of the soil cover, presence of morphological features and the temporal hydrological variability that is justified by the performed statistical analysis.
Ana Isabel Marín, Nataša Ravbar, Gregor Kovačič, Bartolomé Andreo, Metka Petrič
Study of Subterranean Floods in Oceanic Subpolar Karst of Madre de Dios Archipelago (Patagonia, Chile)
Abstract
Madre de Dios archipelago is located, at 50°30′ S, on the Pacific front. The karst areas in the reef limestone of Upper Paleozoic of Chilean Patagonia have long remained unexplored because of their remoteness, difficult access and very inhospitable cold, wet and windy climate. The annual rainfall is 7–8 m/year and the average wind speed reaches 70 km/h almost unidirectional (W to NW), and involve strong floods at a high rate. To study the flood dynamics, several underground sites have been instrumented in 2008 and recovered in 2010.
Laurent Morel, Stéphane Jaillet, Richard Maire, Members of Ultima Patagonia
Characterizing the Hydrogeology of Bell Harbour Catchment, a Coastal Karstic Aquifer Influenced by the Tide and Affected by a Saltwater Intrusion
Abstract
A hydrogeological study focused on a karstic aquifer of a small catchment (~50 km2) located on the south coast of Galway Bay is described. The key aim of the study is to better understand the freshwater/seawater interaction in this coastal region west of Ireland. Discharge from the catchment is entirely through intertidal diffuse springs and submarine groundwater discharges (SGD). Logging of temperature, conductivity and water levels at coastal springs, turloughs and boreholes in the catchment is underway; water samples have been recovered for chemical analysis and water tracing has been undertaken. Initial results clearly show a tidal influence up to 2.5 km inland and an intrusion of seawater at least up to 1 km inland. This saltwater intrusion varies, depending on the balance between the tidal periods (spring/neap) and the groundwater level.
M. Perriquet, T. Henry
Contaminant Attenuation in Karst Aquifers: A Paradigm Shift
Abstract
Significant advances have been made in the characterization of transport and storage in karst aquifers over recent decades. This improved understanding permits further integration of the behaviour of individual contaminants and their specific transport, enabling comparisons to be made. This has been particularly challenging as it is necessary to consider different flow components encountered in karst aquifers, including fast conduit flow and storage in less permeable rock volumes. Comparative tracing experiments using contaminant surrogates have proved to be an appropriate method for estimating the specific attenuation of selected substances at the field scale. Several attenuation processes may be involved and could be identified. Examples from Swiss karst aquifers highlight the in situ effectiveness of such attenuation processes, some of which can be described using first-order kinetics. It could be shown that solute and colloid tracers are able to interact with aquifer material despite the dominance of preferential and conduit flow components. Consequently, if reactive and/or non-persistent contaminants are involved, the arrival at karst springs is determined by contaminant-specific properties and hydrochemical characteristics rather than by the intrinsic vulnerability of the aquifer. This demands more refined conceptual transport models and also represents a paradigm shift in the assessment of karst groundwater vulnerability and contaminant attenuation.
M. Sinreich
Metadaten
Titel
H2Karst Research in Limestone Hydrogeology
herausgegeben von
Jacques Mudry
François Zwahlen
Catherine Bertrand
James W. LaMoreaux
Copyright-Jahr
2014
Electronic ISBN
978-3-319-06139-9
Print ISBN
978-3-319-06138-2
DOI
https://doi.org/10.1007/978-3-319-06139-9