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Enviroscan Ukrainian Institute of Speleology and Karstology


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Community news

Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That water content is the amount of water lost from the soil after drying it to constant weight at 105oc, expressed either as the weight of water per unit weight of dry soil or as the volume of water per unit bulk volume of soil [22]. see moisture content.?

Checkout all 2699 terms in the KarstBase Glossary of Karst and Cave Terms


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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
See all featured articles
Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for heterogeneity (Keyword) returned 84 results for the whole karstbase:
Showing 16 to 30 of 84
Structural effects on carbonate aquifers, 1999,
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Sasowsky I. D
Structural geology affects the behavior of karst aquifers by controlling the overall placement and orientation of the limestone and through fracturesThe placement and orientation affect the position of recharge and discharge boundaries to the system, while the fractures serve as pathways for water movementWhen creating a conceptual or numerical model of a karst site, it is useful and cost-efficient to consider all of these effects, as well as the geologic and geomorphic history of the areaBy understanding structural controls on the genesis of the aquifer, predictions can be made regarding current-day behavior in terms of heterogeneity and anisotropy of flowBecause conduits and fissures mainly form along structurally created discontinuities, structural data can be very useful for understanding aquifer behavior, and determining specific high-conductivity flowpaths

Investigation of flow in water-saturated rock fractures using nuclear magnetic resonance imaging (NMRI), 1999,
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Dijk P. , Berkowitz B. , Bendel P.

The application of nuclear magnetic resonance imaging (NMRI) to the direct three-dimensional measurement of flow in rough-walled water-saturated rock fractures is presented for the first time. The study demonstrates the abilities of NMRI to noninvasively measure rock-water interfaces and water flow velocities in these fractures and investigates the effects of wall morphology on flow patterns inside a typical rock fracture. Two- and three-dimensional flow-encoded spin-echo pulse sequences were applied. The stability and reproducibility of the water flow patterns were confirmed by analyzing two-dimensional velocity images. A variety of geometrical and hydraulic features were determined from three-dimensional velocity images, including the rock-water interfaces, the fracture aperture distribution, and the critical aperture path; velocity profiles and volumetric flow rates; flow and stagnant regions; and the critical velocity path. In particular, the effects of a sharp step discontinuity of the fracture walls and the applicability of the cubic law were examined. As a result of the complex three-dimensional geometry, velocity profiles are generally parabolic but often highly asymmetric, with respect to the fracture walls. These asymmetric velocity profiles are clustered together, with significant correlations; they are not just local random phenomena. However, theoretical considerations indicate that the effects of the measured asymmetry on volumetric flow rates and hydraulic conductivities are insignificant, in that the overall flow inside rough fractures still obeys the cubic law. The features discussed in this study emphasize the strong heterogeneity and the highly three-dimensional nature of the flow patterns in natural rock fractures and consequently the need for three-dimensional flow analysis.


Modeling of the complex karstic system in Saint-Chaptes (Gard, France): A tool for the synthesis of geological and hydrogeological data, 2000,
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Josnin J. Y. , Pistre S. , Drogue C. ,
Numerous software packages allow the efficient modeling of the hydrodynamic behaviour of aquifers in continuous media. To study pressure transfer in discontinuous media like karsts, the black-box models are restrictive and the models that consider discrete conduit networks are unsuitable for reservoir scale. We show that the utilization of a continuous media model can lead to useful results, even in the case of complex systems, but needs to be adapted to karst specificity. The problem is approached by studying a hydrogeological system located in the Mediterranean Languedoc region: the S-t-Chaptes basin. This system consists of three superposed aquifers included in four different stratigraphic series. The main aquifer is a karst formation in contact with two other karst formations that belong to different hydrogeologic systems. Considering geological data in addition to hydrological data and with the hypothesis of a relative homogenization of the karst's hydraulic behaviour on a large spatial scale for daily to monthly increments, the model that takes into account the relations with the other aquifers allows (i) a preliminary identification of the main heterogeneities inside the reservoir; (ii) the location of barriers and low-permeability zones that isolate some parts of the aquifer; (iii) the observation of a curious behaviour of the piezometric levels in the confined zones of the aquifer; and (iv) the characterization of the exchanges with the other low-volume but existing aquifers

Genesis of a large cave system: the case study of the North of Lake Thun system (Canton Bern, Switzerland), 2000,
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Jeannin Py. , Bitterli T. , Hauselmann P.
The genesis of the cave system in the region Hohgant-Sieben Hengste-Lake of Thun (more than 250 km of surveyed passage) has been reconstructed based on speleomorphological observations (mainly by observing where the morphology changes from vadose to phreatic). Eight flow systems (phases) and their respective conduit networks have been distinguished so far. The oldest had a phreatic level at an altitude of 1950 m a.s.l. The last corresponds to today's phreatic zone located at 658 m a.s.l. Between each system, the water table dropped several hundred meters. This appears to be a consequence of changes in boundary conditions, mainly the springis position, which moved down as a tectonic uplift and deepening of the nearby valleys occured. Observations demonstrate that phreatic conduits are sometimes developed close to the ancient water table, but often much deeper, down to 200 to 400 m below this level. The change from one phase to the next seems to have been quick. This stepwise evolution is compatible with the results of computer models which give durations of 10'000 to 30i000 years for conduits systems to develop. Analysis of the conduit networks of each flow system shows that their geometry is mainly influenced by the hydraulic gradients and the overall geometry of the aquifer. The orientation of discontinuity surfaces (fractures and bedding planes) and/or their intersections, play a subordinate role. This is also supported by numerical models found in the literature. As, despite a high fracture density, we observe deep rather than shallow phreatic loops, we assume that the heterogeneity of the discontinuity openings plays a more important role in the depth of karstification than the frequency of the discontinuities.

Lithological and structural controls of cave development, 2000,
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Klimchouk A. , Ford D.
This Chapter summarizes the important general controls that lithology and geologic structure impose on most cave genesis: rock purity, the presence of interbedded clastic rocks and adjacent or interbedded sequences of sulfates and carbonates, and various kinds of initial porosity, fissures in particular. Lithological and structural conditions for speleogenesis evolve throughout sedimentation, eogenesis, mesogenesis and telogenesis and change drastically between these stages. Inheritance in the evolution of different kinds of pre-speleogenetic porosity causes increasing heterogeneity in their distribution and parameters, which reaches the highest degree at the stage of rock emergence to the shallow subsurface and the surface after burial. The importance of fabric-selective porosity and stratigraphical elements diminishes with time in favor of fissure network porosity. Fissures evolve at different stages of the rock evolution. Networks are composed of complex planar and curvilinear surfaces interconnecting in three dimensions, constructed from fissures of various origins, generations and ages. The initial structural conditions for speleogenesis thus can be very varied depending on which particular stage speleogenesis commences. Conditions in deep-seated settings favor uniform speleogenetic development, while in shallow settings increased heterogeneity in fissure parameters can favor selective development. Modeling of conduit initiation and early development needs to take into account a great variability of initial permeability structures between common geological environments and evolutionary stages, especially rather dynamic non-dissolutional changes of these structures in shallow settings.

Pollution by seawater intrusion into a karst system: new research in the case of the Almyros source (Heraklio, Crete, Greece), 2000,
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Arfib Bruno, De Marsily Ghislain, Ganoulis Jacques

Saline intrusion in karstic coastal aquifers is a common phenomenon which affects the quantity and quality of the freshwater resource. This paper examines the case of the Almyros system at Heraklio in Crete (Greece), characterized by a vast recharge area (300 km2) and a single brackish spring. Data from the Almyros spring and the surrounding wells are analyzed and a specific configuration of the karstic system is proposed. The evolution in time and space of the water temperature and chloride content is shown to be conditioned by the complex structure of this system and the heterogeneity of the karstic formations. These two parameters are analyzed and two storage zones are identified which generate different types of saline pollution. The water in the Almyros spring is not directly connected to the surrounding water-table aquifer. An inland reservoir far from the coast stores the cold, freshwater recharged in the mountains and supplies the Almyros spring. The pollution occurs during the transfer of the water toward the spring, through karstic conduits. Moreover, the local coastal aquifer is polluted by a generalized saline intrusion into the fractured matrix of the limestone, increased by withdrawals. Furthermore, the wells are contaminated by preferential saltwater flow through karstic channels reaching the seawater intrusion zone. The case of the Almyros system shows: (a) that a karstic coastal spring is not necessarily indicative of saline intrusion into the system; (b) that in optimal groundwater resource management, the whole hydrogeological system should be taken into account.


Inverse modeling of the hydrological and the hydrochemical behavior of hydrosystems: Characterization of karst system functioning, 2001,
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Pinault J. L. , Plagnes V. , Aquilina L. , Bakalowicz M. ,
Inverse modeling of mass transfer characterizes the dynamic processes affecting the function of karst systems and can be used to identify karst properties. An inverse model is proposed to calculate unit hydrographs as well as impulse response of fluxes from rainfall-runoff or rainfall-flux data, the purpose of which is hydrograph separation. Contrary to what hydrologists have been doing for years, hydrograph separation is carried out by using transfer functions in their entirety, which enables accurate separation of fluxes, as was explained in the companion paper [Pinault et al., this issue]. The unit hydrograph as well as impulse response of fluxes is decomposed into a quick and a slow component, and, consequently, the effective rainfall is decomposed into two parts, one contributing to the quick flow (or flux) and the other contributing to the slow flow generation. This approach is applied to seven French karstic aquifers located on the Larzac plateau in the Grands Causses area (in the south of France). Both hydrodynamical and hydrogeochemical data have been recorded from these springs over several hydrological cycles. For modeling purposes, karst properties can be represented by the impulse responses of flow and flux of dissolved species. The heterogeneity of aquifers is translated to time-modulated flow and transport at the outlet. Monitoring these fluxes enables the evaluation of slow and quick components in the hydrograph. The quick component refers to the 'flush flow' effect and results from fast infiltration in the karst conduit network when connection is established between the infiltration and phreatic zones, inducing an increase in water head. This component reflects flood events where flow behavior is nonlinear and is described by a very short transfer function, which increases and decreases according to water head. The slow component consists of slow and fast infiltration, underground runoff, storage in annex-to-drain systems, and discharge from the saturated zone. These components can be further subdivided by measuring chemical responses at the karst outlet. Using Such natural tracers enables the slow component of the unit hydrograph to be separated into preevent water, i.e., water of the reservoir and event water, i.e., water whose origin can be related to a particular rainfall event. These measurements can be used to determine the rate of water renewal. Since the preevent water hydrograph is produced by stored water when pushed by a rainfall event and the event water hydrograph reflects rainwater transfer, separating the two components can yield insights into the characteristics of karst aquifers, the modes of infiltration, and the mechanisms involved in karstification, as well as the degree of organization of the aquifer

Exploration techniques for karst groundwater resources., 2001,
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Bakalowicz M.
Porous and fissure aquifers display statistical homogeneity of their physical and hydraulic characteristics on a scale ranging from tens to several hundreds of meters. Such homogeneity is a product of the relatively small spatial variability of these characteristics and creates conditions of general hydraulic continuity throughout the entire saturated zone. Their groundwater resources can be explored by a simple approach, i.e. defining the aquifer geometry from geological data, and determining local hydraulic parameters from pumping tests; finally, the local data are extended to characterise the entire aquifer through regionalizing techniques. However, within the infiltration and saturated zones of carbonate aquifers, karst processes create a peculiar void heterogeneity : voids may reach several meters in diameter and several kilometers in length. These voids are organized in a hierarchic network from the input surface often to a single spring: this is the conduit or drainage network. Therefore the network should be fully characterized prior to assessing the groundwater resources of a karst aquifer and its possible storage capacity, i.e. the network's transmissive or drainage function and its links with storage components (its storage function). Traditionally, speleological exploration is considered the best technique for directly characterizing a drainage network. Unfortunately, this usually gives an incorrect view of the karst aquifer because only a few parts (or none at all) are known when there is no access to the saturated zone. The classical hydrogeological approach is thus unsuitable for assessing karst aquifers. In this context, karst hydrogeologists must adopt the classical approach of physicians and biologists examining living bodies, by characterizing a karst aquifer, its resources and storage by accurate description of the void organization and an analysis of its overall behavior (or functioning) and that of its different parts or organs. With such an approach, a karst aquifer is considered as a living organism composed of different types of organs interlinked by functional relationships. Unlike physicians, hydrogeologists generally have to discover the extent of the body they wish to study (the karst system as a drainage unit, its limits and the boundary conditions). Therefore, as in the field of medicine^ techniques are used for describing the aquifer in bi- or tri-dimensional space (geology, geophysics) and for characterizing its functioning (hydrodynamics, natural tracing, hydrological balance). Moreover, data from these techniques are interpreted in order to propose a diagnosis, i.e. for building a conceptual model of the studied aquifer. In the next step, as in medicine, the conceptual model can be assessed with localized tests, such as artificial tracing and diver exploration for borehole positioning and pumping tests. Methods for interpreting tracing and pumping tests must obviously be adapted to the specific nature of karst, i.e. they cannot be based on classical models whose basic assumptions are never verified in the karstic medium. Finally, karst hydrogeologists have to set up and implement a complex set of techniques for describing the extent and limits of a karst system, exploring its drainage pattern, and analyzing its behaviour. All geoscience disciplines are ultimately required for the comprehensive exploration of groundwater resources in karst aquifers.

Geochemical methods for distinguishing surface water from groundwater in the Knox Aquifer System, 2002,
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Redwine J. C. , Howell J. R. ,
The Knox Group, a thick package of Cambro-Ordovician rocks, occurs over a wide geographic area in the southeastern US. Characteristics of the Knox Group include strong structural control on porosity and permeability, deep near-vertical solution features, great depth of water circulation, dolomite, as well as limestone, hosting the karstic features, and extreme anistropy and heterogeneity. In this study, geochemical methods were used to distinguish ambient groundwater, in the Knox aquifer from surface water, specifically, water leaking from the Logan Martin resevoir in east-central Alabama. Major cations and anions, as well as stable isotopes of hydrogen and oxygen, were used to distinguish lake water from groundwater, and to determine mixed waters. Lake water and groundwater components for mixed waters were calculated, and mapped in plan view. A relatively narrow zone of mixing occurs in the vicinity of Logan Martin dam in map view, which is consistent with the hydrogological conceptual model of deep near-vertical solution-widened fractures (fissures), oriented east-norteast and to a lesser extent north-west, in a much less permeable dolomite matrix

Particle transport in a karst aquifer: natural and artificial tracer experiments with bacteria, bacteriophages and microspheres, 2002,
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Auckenthaler A, Raso G, Huggenberger P,
Fast changes in spring water quality in karst areas are a major concern for production of drinking water and require detailed knowledge of the complex interaction between karst aquifer, transport behavior of microorganisms and water treatment We have conducted artificial and natural particle transport experiments at a karst spring with bacteria, bacteriophages, microspheres, and pathogens Transport of the investigated microorganisms, turbid matter and chemical pullutants as well as increase in discharge are strongly related to precipitation and the heterogeneity of the aquifer The indicator bacteria E cob revealed a significant correlation to verotoxin-producing E cob and Cryptosporidium spp We conclude that artificial particle tracers can help identify 'hot spots' for microbial recharge and that system parameters in spring water such as turbidity, UV-extinction and increase in discharge can be key parameters for efficient raw water management

Characterisation of karst systems by simulating aquifer genesis and spring responses: model development and application to gypsum karst., 2002,
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Birk S.
Karst aquifers are important groundwater resources, which are highly vulnerable to contamination due to fast transport in solutionally enlarged conduits. Management and protection of karst water resources require an adequate aquifer characterisation at the catchment scale. Due to the heterogeneity and complexity of karst systems, this is not easily achieved by standard investigation techniques such as pumping tests. Therefore, a process-based numerical modelling tool is developed, designed to support the karst aquifer characterisation using two complementary approaches: Firstly, the simulation of conduit enlargement, which aims at predicting aquifer properties by forward modelling of long-term karst genesis; secondly, the simulation of heat and solute transport processes, which aims at inferring aquifer properties from short-term karst spring response after recharge events. Karst genesis modelling is applied to a conceptual setting based on field observations from the Western Ukraine, where the major part of known gypsum caves is found. Gypsum layers are typically supplied by artesian flow of aggressive water from insoluble aquifers underneath. Processes and parameters, controlling solutional enlargement of single conduits under artesian conditions, are identified in detailed sensitivity analyses. The development of conduit networks is examined in parameter studies, suggesting that the evolution of maze caves is predetermined by structural preferences such as laterally extended fissure networks beneath a horizon less prone to karstification. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The structure of the mature conduit system is found to be determined during early karstification, which is characterised by high hydraulic gradients and low flow rates in the gypsum layer. Short-term karst spring response after recharge events is firstly examined in parameter studies by forward modelling. The numerical simulations reveal that different controlling processes of heat and solute transport account for the different behaviour of water temperature and solute concentration frequently observed at karst springs. It is demonstrated that these differences may be employed to reduce the ambiguity in the aquifer characterisation. In order to test the feasibility of the corresponding inverse approach, which aims at inferring aquifer properties from the karst spring response, the model is applied to a field site in Southern Germany (Urenbrunnen spring, Vohringen). Data input is provided by both literature and own field work. Several models, which reproduce the results of a combined tracer and recharge test, are calibrated to spring discharges and solute concentrations measured after a recharge event. In order to validate the calibrated models, the measured spring water temperatures are simulated by heat transport modelling. The model application yields information on aquifer properties as well as flow and transport processes at the field site. Advection is identified as the dominant transport process, whereas the dissolution reaction of gypsum is found to be insignificant in this case. The application to gypsum aquifers demonstrates that both suggested approaches are suitable for the characterisation of karst systems. Model results, however, are highly sensitive to several input parameters, in particular in karst genesis modelling. Therefore, extensive field work is required to provide reliable data for site-specific model applications. In order to account for uncertainties, it is recommended to conduct parameter studies covering possible ranges of the most influential parameters.

Characterisation of karst systems by simulating aquifer genesis and spring responses: model development and application to gypsum karst, PhD thesis, 2002,
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Birk, S.

Karst aquifers are important groundwater resources, which are highly vulnerable to contamination due to fast transport in solutionally enlarged conduits. Management and protection of karst water resources require an adequate aquifer characterisation at the catchment scale. Due to the heterogeneity and complexity of karst systems, this is not easily achieved by standard investigation techniques such as pumping tests. Therefore, a process-based numerical modelling tool is developed, designed to support the karst aquifer characterisation using two complementary approaches: Firstly, the simulation of conduit enlargement, which aims at predicting aquifer properties by forward modelling of long-term karst genesis; secondly, the simulation of heat and solute transport processes, which aims at inferring aquifer properties from short-term karst spring response after recharge events.
Karst genesis modelling is applied to a conceptual setting based on field observations from the Western Ukraine, where the major part of known gypsum caves is found. Gypsum layers are typically supplied by artesian flow of aggressive water from insoluble aquifers underneath. Processes and parameters, controlling solutional enlargement of single conduits under artesian conditions, are identified in detailed sensitivity analyses. The development of conduit networks is examined in parameter studies, suggesting that the evolution of maze caves is predetermined by structural preferences such as laterally extended fissure networks beneath a horizon less prone to karstification. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The structure of the mature conduit system is found to be determined during early karstification, which is characterised by high hydraulic gradients and low flow rates in the gypsum layer.
Short-term karst spring response after recharge events is firstly examined in parameter studies by forward modelling. The numerical simulations reveal that different controlling processes of heat and solute transport account for the different behaviour of water temperature and solute concentration frequently observed at karst springs. It is demonstrated that these differences may be employed to reduce the ambiguity in the aquifer characterisation.
In order to test the feasibility of the corresponding inverse approach, which aims at inferring aquifer properties from the karst spring response, the model is applied to a field site in Southern Germany (Urenbrunnen spring, Vohringen). Data input is provided by both literature and own field work. Several models, which reproduce the results of a combined tracer and recharge test, are calibrated to spring discharges and solute concentrations measured after a recharge event. In order to validate the calibrated models, the measured spring water temperatures are simulated by heat transport modelling. The model application yields information on aquifer properties as well as flow and transport processes at the field site. Advection is identified as the dominant transport process, whereas the dissolution reaction of gypsum is found to be insignificant in this case.
The application to gypsum aquifers demonstrates that both suggested approaches are suitable for the characterisation of karst systems. Model results, however, are highly sensitive to several input parameters, in particular in karst genesis modelling. Therefore, extensive field work is required to provide reliable data for site-specific model applications. In order to account for uncertainties, it is recommended to conduct parameter studies covering possible ranges of the most influential parameters.


Apports des mthodes hydrologiques dans la comprhension des coulements en pays calcaire : exemple des bas plateaux jurassiques du haut bassin de la Marne (France), 2004,
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Lejeune Olivier, Devos Alain
Hydrological methods for the study of river flows in limestone areas: the Marne basin in the Jurassic low plateaux (NE France) - We investigated the geographical heterogeneity of river flows in limestone areas in the upper Marne valley (interfluves of Marne-Aube and Marne-Meuse) by using the low water profiles, the modelling of discharges and the study of physicochemical parameters. We studied five basin-slopes belonging to the Marne-basin (4500 km2) and the measures were realised between 2001 and 2003 at the time of low water periods. We used an instrument (perche intgration type Pire) in order to measure the stream flows of river water. We also measured temperature and electrical conductivity in order to identify the origin of the water. The measures allowed us to identify low water profiles of the river and we also can map the discharge in low water periods. The methods show the water flow inside a basin-slope and also hydrogeological connections to the adjacent basin-slopes. Thus, they revealed that the divergence or the concentration of discharges depends on the limits of the aquifers sections related to their morphological structure and on the differential incision of the valleys. We obtained a hydrogeological pattern of interfluves and we can distinguish between areas of water lost and areas with an increasing of water volume. We confirmed this process of water transfers, called the active stream piracy, which is often approved by hydrogeologic tracers. This active stream piracy revealed by these methods in warm or interglacial period, prepare future stream piracy of surface, collectively recognised in the beginning of cold phase.

Heterogeneity of parent rocks and its constraints on geochemical criteria in weathering crusts of carbonate rocks, 2004,
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Wang S. J. , Feng Z. G. ,
Owing to the low contents of their acid-insoluble components, carbonate rocks tend to decrease sharply in volume in association with the formation of weathering crust. The formation of a 1 m-thick weathering crust would usually consume more than ten meters to several tens of meters of thickness of parent rocks. The knowledge of how to identify the homogeneity of parent rocks is essential to understand the formation mechanism of weathering crust in karst regions. especially that of thick-layered red weathering crust. In this work the grain-size analyses have demonstrated that the three profiles studied are the residual weathering crust of carbonate rocks and further showed that there objectively exists the, heterogeneity of parent rocks in the three studied weathering crusts. The heterogeneity of parent rocks can also be. reflected in geochemical parameters of major elements, just as the characteristics of frequency plot of pain-size distribution. Conservative trace element ratios Zr/Hf and Nb/Ta are proven to be unsuitable for tracing the heterogeneity of parent rocks of weathering crust, but its geochemical mechanism is unclear. The authors strongly suggest in this paper that the identification of the homogeneity of parent rocks of weathering crust in karst regions is of prime necessity

Stochastic discrete model of karstic networks, 2004,
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Jaquet O. , Siegel P. , Klubertanz G. , Benabderrhamane H. ,
Karst aquifers are characterised by an extreme spatial heterogeneity that strongly influences their hydraulic behaviour and the transport of pollutants. These aquifers are particularly vulnerable to contamination because of their highly permeable networks of conduits. A stochastic model is proposed for the simulation of the geometry of karstic networks at a regional scale. The model integrates the relevant physical processes governing the formation of karstic networks. The discrete simulation of karstic networks is performed with a modified lattice-gas cellular automaton for a representative description of the karstic aquifer geometry. Consequently, more reliable modelling results can be obtained for the management and the protection of karst aquifers. The stochastic model was applied jointly with groundwater modelling techniques to a regional karst aquifer in France for the purpose of resolving surface pollution issues. (C) 2004 Elsevier Ltd. All rights reserved

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