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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 lineation is the parallel orientation of structural features that are lines rather than planes. some examples are parallel orientation of the long dimensions of minerals, long axes of pebbles, striae on slickensides, and cleavage-bedding plane intersections.?

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 domain (Keyword) returned 77 results for the whole karstbase:
Showing 16 to 30 of 77
Unusual flooding in the Calernakm shaft (Alpes-maritimes, France) Origin and consequences of the phenomen on the deep drainage organisation, 1998,
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Audra Ph.
The Calernakm shaft is located in the Southern french Alps, near Nice It contains large galleries reaching -478 m deep During unusual high waters, the lower part floods over 100 m height The flooding is linked to a semi-dammed karst structure The galleries organisation proves that the karstification privileges subhorizontal conduits in the epiphreatic zone, without favouring any deep phreatic passages The origin of deep phreatic karsts is discussed

Les stalagmites : archives environnementales et climatiques haute rsolution, prsentation des protocoles dtudes et premiers rsultats sur des splothmes du Vercors, 1999,
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Perrette, Yves
Since the late 80's, the detailed study of speleothem has deve_loped from the crossing of two main approachs; one comes from the ques_tions of speleologists confronted with magnificent cave scenery, the other comes from citizen questions about climatic and environmental changes. The aim of this paper is to show the diversity and the relevance of the data collected by such studies on stalagmitic samples from the Vercors -France. The knowledge of the chemical processes of the H20 - CaCO3 - C02 system in the perspective of the karst infiltration leads to ques_tions about the role of the "supstrat". This word has been used to describe the "roofrock" rather than the bedrock. So, to better unders_tand the different modes of drainage in karst, a global hydrologic study of the Choranche cave vadose zone has been realised, e.g. seepage water rates have been monitoring. These recent studies allow us to model the structural and functional hydrologic network of such a well developed karst system. Actually we demonstrated the hierar_chisation of the drainage and the relation between a transmissive system and a capacitive one. They have been used to propose a graphical typology leading to a better appreciation of the various environmental interests of speleothems. Understanding the processes of speleothem environmental and climatic archiving, needs to know the processes of calcite crystal growth. They are briefly presented through some usual fabrics like columnar, palissadic or dendritic ones and through the optical relation between macroscopic colours and crys_talline porosity. It is the evolution of these crystalline features, which creates the laminae. To explain what are laminae, the diffe_rent type of emission by a solid after a laser irradiation are shown. It justifies the choice of two kinds of laminae measurement i.e. reflectance and fluorescence. Then, results of spectroscopic studies which show a covariation between Mn2+ concentration, the maximum intensity wave length of fluorescence spectra and the reflec_tance trend, allow us to consider reflectance measurement as a water excess proxy. This experimental approach is confirmed by the infra annual laminae. The hydrological interest of "visible" laminae (i.e. reflectance one) is increased by the fluorescence "invisible" lami_nae. In fact, the presence of a wide diversity of organic molecule in the calcite lead us to consider the fluorescence lamina as a temporal proxy controlled by the annual leaf fall and biopedological degradation. To measure these two proxies, an original experimental set has been developed in collaboration with the PhLAM laboratory (Lille, France). Particularly, this experimental set up permits to realise simultaneously a reflectance and a fluorescence image. The data collected are processed and are analysed in the frequency domain. All these data allow us to extract different proxies from speleothems. These proxies have been studied for some Vercors samples. We present the global environmental and climatic data archiving of the post_wurmian (isotopic stage 1) warming. At a higher resolution, the Vercors climate forcing is shown through the spectral analysis of the reflectance of a well laminated sample. The solar (T=22y) and atmospheric (NAO, T=17y) forcings are clearly distinguished. The climate analysis of this sample is limited by an anthropic mask. We show the similarity of the crystal facies evolution of two samples located around the Alps but far from more than 100 km. We would like to interpret this changes as an archiving of the post Little Ice Age warming but here too, Man interfere with climate to induce environmental changes. We show an example of the possibility for distinguishing climate from anthropic changes in environmental evolutions. The wealth of data of the speleothem allows us to appreciate the environ_ment stability of the Vercors which is confirmed in the spectral analysis of the growth rates of a Gouffre Berger sample. The diversity of the data collected in speleothems is directly linked to the diversity of the way of archiving in a karst system. It is why only a global approach seems to be relevant for answering environmental hydrological or morphological karst questions.

Environmental vulnerability and agriculture in the karstic domain: landscape indicators and cases in the Atlas Highlands, Morocco, 1999,
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Akdim Brahim, Amyay Mohammed
After the brief presentation of the major karstic areas in Morocco, the article focused essentially on the Atlas mountains to investigate the impact of the agriculture on the natural systems equilibrium. Socio-economic changes (demographic pressure, escalation of the landscape use, utilisation of new techniques in water harvesting, etc...) have sometimes fathered mechanisms of degradation. Many indicators seem to reflect these mechanisms. The pedologic indicators, soil erosion, the hydrologic and geomorphic indicators, are apprehended to demonstrate existent correlation between different variables and the often negative impacts of land over-use in the karstic domain of the Middle Atlas.

The role of western Mediterranea tectonic evolution in the geometry of a karstic domain in the Betic Cordilleras (Sierra Gorda, Spain): importance of a tardy extensional regime, 1999,
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Pistre S. , Lopezchicano M. , Pulidobosch A. , Drogue C. ,
Located in the central part of the Betic Cordilleras, the large carbonate Sierra Gorda Massif provides an example of a west-Mediterranean karstic aquifer. In spite of a complex polyphased tectonic history, the fracturing presents, from aerial views and at outcrop scale a quite organised geometry. Four fracture directions are found over the massif: N000-010, N050-070, N090-100 and N140-170. The statistical and geostatistical approach allows the characteristics (lengths, orientations) and the spatial structure for each fracture set to be determined. The N000-010 and N140-170 sets are grouped in packers whereas the two other sets are grouped in bands. The microtectonic study describes the evolution of the massif in the geodynamic context of this part of Mediterranea, distinguishing three recent stages of brittle tectonic activity in the gu massif: a WNW-ESE Middle Miocene compression, then a NNW-SSE to NW-SE compression with a poorly wrenching regime, and finally a probably pre-Quaternary N-S radial distension. This last stage is essential for the karstification of the massif and groundwater circulation. From the combined analysis of fracture network geometry and palaeostresses a multiple porosity model in agreement with hydrological observations made inside the massif can be proposed: in particular, the hectometric N090-100 land N050-070) fractures which are essential for the network connectivity, and have a major drainage role at aquifer scale, while the N000-010 and N140-170 ones have a more local drainage role. This extensive tardy regime, which is for the first time described separately from the internal zones of the Cordilleras, must be considered as a significant phenomenon on a regional scale, and henceforth integrated in future geodynamic schemes of this part of Mediterranea. (C) Elsevier, Paris

Volcanic gaps and subaerial records of palaeo-sea-levels on Flores Island (Azores): tectonic and morphological implications, 1999,
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Azevedo Jmm, Ferreira Mrp,
The morphological evolution of Flores Island, as commonly observed for volcanic islands, suggests (1) the balance between constructive processes (effusive and moderately explosive volcanic activities and tectonic uplifting movements) and destructive processes (marine abrasion, stream erosion, crater-forming volcanic explosions, caldera collapses and tectonic subsidence) and (2) the recurrent fluctuations of the sea-level. Records of (a) gaps in the volcanic activity and (b) erosional and depositional marine activity are shown as: - epiclastic deposits of marine origin - erosional morphologies, such as abrasion platforms, terraces, cliffs and caves - intensive palagonitization of the volcanic rocks - vertical changes of the structures in the hydroclastic submarine formations. Taking into account (1) the vertical crustal movements (uplift and subsidence) which may occur in volcanic domains and (2) the sequence of regressive-transgressive trends in the relative sea-level as expressed by indicators of pale-sea-levels, it is assumed that the morphological evolution of Flores Island comprehends three main stages, The existence of important differences between the present-day altitudes of correlated marine records noted in Flores, in Santa Marie Island (Azores Archipelago) and Porto Santo Island (Madeira Archipelago) is related with their crustal behaviour and different volcanic and tectonic evolution.

Linear systems analysis in a karst aquifer, 1999,
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Long A. J. , Derickson R. G. ,
A linear systems analysis applied to ground-water flow is presented as an alternative modeling technique to traditional discretized ground-water models (i.e. finite-difference and finite-element), which require elaborate parameters and boundary conditions. Linear systems analysis has been used extensively for surface-water modeling and to 3 lesser extent for groundwater applications. We present a method for the analysis of an aquifer's response in hydraulic head to recharge that comprises two major components. The first component is to predict the drop in hydraulic head over time if recharge is eliminated. By fitting logarithmic curves to selected short-term hydraulic head recession periods, a long-term recession or 'base head' can be established. The estimation of base head is necessary for the second component of the method, which is the derivation of an impulse response function or transfer function. The transfer function H-as derived by deconvolution of two time series data sets - estimated recharge and the measured response in hydraulic head. An aquifer's response to recharge can be characterized and modeled by using the transfer function. which also establishes the time to peak response. the response time distribution, and the total memory length of the system. The method requires fitting smooth curves to the oscillatory transfer function derived by deconvolution in the Fourier transform domain. The smooth curve is considered to be the physically valid transfer function. In this analysis, curve fitting was more effective than other smoothing techniques commonly used. We applied the method to the karstic Madison aquifer and found that thr time to peak response is less than one month, the system's total memory is about six years, and a logarithmic curve best fits the system response. This method has potential to be useful as 3 predictive tool in aquifer management. (C) 1999 Elsevier Science B.V. All rights reserved

Vertical zonation of the speleogenetic space, 1999,
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Š, Uš, Terš, Ič, France

The point of this paper is to demonstrate that not only the spatial domain where underground karst phenomena are being systematically transformed exist but also that this knowledge makes the role of caves within the geospeleological space/time more consistent. A true cave is any underground karst feature resulting from mass removal, regardless of its dimensions provided that the trajectory of the formative water passes through the cave and that the mass is removed in liquid phase (solution). Speleogenetic space is defined as that portion of the Earth's crust within which karst caverns may be formed. Thus, a karstified rock mass is defined as activated speleogenetic space. Due to the effects of denudation and watertable lowering, as the time passes a single cave seems to move upwards through speleogentic space, until it reaches the surface. The denudational logic of the karst surface is vertical, and the rock suffers disintegration throughout the thickness of its outermost layers. The same argument applies also to in-rock features. Consequently, the idea of the speleothanatic zone is introduced. Within it all of the rock is attacked, on any possible surface, and the final result is its complete annihilation. It may be expected that all structures, of any origin, that expose the rock surface to contact with aggressive water, will evolve via some "speleothanatic" progression. It is demonstrated that three vertical zones of specific formative/de-formative processes exist within speleogenetic space.


The stratigraphical record and activity of evaporite dissolution subsidence in Spain, 2001,
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Gutierrez F. , Orti F. , Gutierrez M. , Perezgonzalez A. , Benito G. , Prieto J. G. , Valsero J. J. D. ,
The evaporite formations tin outcrop and at shallow depth) cover an extensive area of the Spanish territory. These soluble sediments are found in diverse geological domains and record a wide time span from the Triassic up to the present day. Broadly, the Mesozoic and Paleogene formations (Alpine cycle) are affected by compressional structures, whereas the Neogene (post-orogenic) sediments remain undeformed. The subsidence caused by subsurface dissolution of the evaporites (subjacent karst) takes place in three main types of stratigraphical settings: a) Subsidence affecting evaporite-bearing Mesozoic and Tertiary successions (interstratal karst); b) Subsidence in Quaternary alluvial deposits related to the exorheic evolution of the present-day fluvial systems (alluvial or mantled karst); c) Subsidence in exposed evaporites (uncovered karst). These types may be represented by paleosubsidence phenomena (synsedimentary and/or postsedimentary) recognizable in the stratigraphical record, or by equivalent currently active or modem examples with surface expression. The interstratal karstification of the Mesozoic marine evaporites and the consequent subsidence of the topstrata is revealed by stratiform collapse breccias and wedge-outs in the evaporites grading into unsoluble residues. In several Tertiary basins, the sediments overlying evaporites locally show synsedimentary and/or postsedimentary subsidence structures. The dissolution-induced subsidence coeval to sedimentation gives place to local thickenings in basin-like structures with convergent dips and cumulative wedge out systems. This sinking process controls the generation of depositional environments and lithofacies distribution. The postsedimentary subsidence produces a great variety of gravitational deformations in the Tertiary supra-evaporitic units including both ductile and brittle structures (flexures, synforms, fractures, collapse and brecciation). The Quaternary fluvial terrace deposits on evaporite sediments show anomalous thickenings (> 150 m) caused by a dissolution-induced subsidence process in the alluvial plain which is balanced by alluvial aggradation. The complex space and time evolution pattern of the paleosubsidence gives place to intricate and anarchical structures in the alluvium which may be erroneously interpreted as pure tectonic deformations. The current subsidence and generation of sinkholes due to suballuvial karstification constitutes a geohazard which affects to large densely populated areas endangering human safety and posing limitations to the development. An outstanding example corresponds to Calatayud historical city, where subsidence severely damages highly valuable monuments. The subsidence resulting from the underground karstification of evaporites has determined or influenced the generation of some important modem lacustrine basins like Gallocanta, Fuente de Piedra and Banyoles lakes. The sudden formation of sinkholes due to the collapse of cave roofs is relatively frequent in some evaporite outcrops. Very harmful and spectacular subsidence activity is currently occurring in the Cardona salt diapir where subsidence has been dramatically exacerbated by mining practices

Speleogenesis of Sandstone Caves: some considerations applied to the Serra de Itaqueri Speleological Province, São Paulo State, BRAZIL, 2001,
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Rubens Caldeira Monteiro 1, Luiz Felipe Brandini Ribeiro 2
The origin and evolution of sandstone caves are a function of structural patterns, geomorphology, stratigraphy and climate of the region. In this paper is presented a new speleogenetic model for the endocarstic features of the center-western portion of the ?Depressão Periférica Paulista? transitioning to the ?Cuestas Basálticas? domain, in the region named Serra de Itaqueri, a model assumed to others near sandstone caves, like the ones at Serra do Padre and Serra de São Pedro. This paper emphasizes the importance of the tectonic regime as main condition to its evolution model and innovate relating the blocks falling and arenisation process to the fault type associated, according the Riedel?s model.

Public Datasets Integrated with GIS and 3-D Visualization Help Expand Subsurface Conceptual Model, 2002,
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Phelan, T. L.
Public domain water well drilling logs were used to construct a 3-D visualization of the subsurface in a karst terrain. Subsurface displacements seen in the 3-D visualization model were shown to correlate with surface topography in the Digital Elevation Model (DEM). This methodology could improve the effectiveness of limited funding by using public datasets to contribute to conceptual hydrogeologic models. It could also identify areas that merit additional investigation which might have gone unnoticed otherwise

Role of an extension of pre-Quaternary age for the evolution of the carbonate massifs in the occidental Betic Cordillera: The case of the Yunquera-Nieves massif (southern Spain), 2002,
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Pistre Severin, Linan Cristina, Andreo Bartolome, Carrasco Francisco, Drogue Claude, Martinalgarra Agustin,
A simultaneous analysis of the fracture geometry and paleo-stress fields of the karstic Yunquera-Nieves massif i n southern Spain (Malaga Province) has been carried out with microtectonic stations. It reveals polyphased t ec -tonics linked to the structural position of this carbonate domain in the western Betic Cordillera. Among the tectonic regimes described in this domain appears a distensive stage with a radial trend probably of post-Tortonian to Quaternary age. Todate, it has seldom been described and is absent from geodynamic models though it seems to have had a regional importance. Furthermore, it played a major role for the acquisition of the hydrodynamic properties of t he aquifer and its karstogenesis. This stage opened all fractures and allowed t he development of karstic drains with NW-SE and N-S directions. Finally, the karstic network was shaped by more recent climatic and tectonic events

Paleosubsidence and active subsidence due to evaporite dissolution in Spain, 2002,
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Gutierrez F. , Orti F. , Gutierrez M. , Perezgonzalez A. , Benito G. , Gracia F. J. , Duran J. J. ,
Evaporite formations crop out or are at shallow depth present in an extensive area of Spain. These soluble sediments occur in diverse geological domains and were deposited over a long time span, from the Triassic up to the present day. Broadly, the Mesozoic and Paleogene formations (Alpine cycle) are affected by compressional structures, whereas the Neogene (post-orogenic) sediments remain undeformed. Subsidence caused by subsurface dissolution of evaporites (subjacent karst) takes place in three main types of stratigraphic settings: a) subsidence affecting evaporite-bearing Mesozoic and Tertiary successions (interstratal karst); b) subsidence in Quaternary alluvial deposits related to the exorheic evolution of present-day fluvial systems (alluvial or mantled karst); and c) subsidence in exposed evaporites (uncovered karst). These types may be represented by paleosubsidence phenomena (synsedimentary and/or postsedimentary) recognizable in the stratigraphic record, or by equivalent, currently active or modem examples which have a surface expression. Interstratal karstification of Mesozoic marine evaporites, and the consequent subsidence of overlying strata, is revealed by stratiform collapse breccias and wedge outs of the evaporites grading into unsoluble residues. In several Tertiary basins, the sediments overlying evaporites locally show synsedimentary and/or postsedimentary subsidence structures. Dissolution-induced subsidence coeval with sedimentation is accompanied by local thickening of strata in basin-like structures with convergent dips and cumulative wedge-out systems. This sinking process controls the generation of depositional environments and lithofacies distribution. Postsedimentary subsidence produces a great variety of gravitational deformations in Tertiary supra-evaporitic units, including both ductile and brittle structures (flexures, synforms, fractures, collapse, and brecciation). Quaternary fluvial terrace deposits overlying evaporites show anomalous thickenings (>150 m) caused by a dissolution-induced subsidence process in the alluvial plain, which is balanced by alluvial aggradation. The complex evolution (in time and space) of paleosubsidence leads to intricate and chaotic structures in the alluvium, which may be erroneously interpreted as pure tectonic deformations. The current subsidence and generation of sinkholes due to suballuvial karstification constitutes a geohazard which affects large, densely populated areas, and thus endangers human safety and poses limitations on development. An outstanding example can be seen in Calatayud, an important historical city where subsidence has severely damaged highly valuable monuments. Subsidence resulting from the underground karstification of evaporites has caused or influenced the generation of some important modem lacustrine basins, such as Gallocanta, Fuente de Piedra, and Banyoles Lakes. The sudden formation of sinkholes due to collapse of cave roofs is fairly frequent in some evaporite outcrops. Very harmful and spectacular subsidence activity is currently occurring in the Cardona salt diapir, where subsidence has been dramatically exacerbated by mining practices

Toward a better understanding of fissure growth in karst formations: Investigations from genesis to maturation and the influence of fracture-matrix interactions., 2002,
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Cheung, Wendy Wai Wan

There has been interest in quantitative modeling of early karstification with the objectives of estimating time-scales of conduit growth and understanding the nature of cave patterns. In particular, the initiation phase has been studied in great detail because it is the slowest phase in the development of caverns. In this study aperture variability in a two-dimensional framework and fracture matrix interaction are studied to better understand their role in time estimations of aperture growth. The initial phase of karst development is studied from its nascent stage as a fissure into the early stages of turbulence. In uniform fissures in rapidly dissolving minerals, the concentration reaches the solubility limit within a short distance along the flow path. However, the variability in the aperture field inherently provides instabilities to the system and growth is propagated along these perturbations. Flow is focused into preferential channels which are enlarged at a faster rate than surrounding regions of slow flow. As a result, a positive feedback mechanism takes place and creates growth in a highly selective manner. Only in large domains (>25 correlation lengths), can the instabilities create competition for flow at the solution front as well and lead to significant branching. It is this branching which creates the non-monotonic behavior in breakthrough times (defined as the point in which turbulent flow is first encountered). It has been observed that the non-monotonic behavior is scale dependent. Smaller domains do not exhibit this behavior because there are only a few correlation lengths between
the fingertip and the lateral domain boundaries. Aperture variability significantly impacts dissolution patterns in a two-dimensional framework. While aperture variability speeds up growth, the inclusion of the porous bedrock can inhibit growth. The porous matrix serving as a large low - conductive reservoir can significantly influence the development of the fracture by slowing down dissolution growth through matrix diffusion. In a one dimensional model, this issue is further explored. Although the focus of the study is on modeling of early karstification, there are many common themes between this problem and other reactive transport problems that this model can be made suitable for exploring.


Interaction of Fracture and Conduit Flow in the Evolution of Karst Aquifers, 2003,
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Romanov D. , Dreybrodt W. , Gabrovsek F.

Karst aquifers in their initial state consist of a net of fractures with largely differing aperture widths. As a most simple example we investigate the evolution of a karst aquifer where a wide fracture with aperture width A0 = 0.03 cm is embedded into a dense net of narrow fractures of aperture widths a0 < A0. The aim of this work is to investigate the influence of the hydraulic coupling between these fractures to the evolution of the karst aquifer. The modelling domain consists of a confined aquifer, which is divided into a square network consisting of narrow fractures. In its center a straight wide fracture leads from the input at hydraulic head h to the output at head zero. We have computed the breakthrough times of this aquifer as a function of a0. For a0 = 0 the breakthrough time is that of an isolated one-dimensional fracture. As a0 is increased the breakthrough times drop until at about a0 > 0.02 cm they are reduced significantly by almost one order of magnitude. This is caused by the following mechanism. As the central tube gets enlarged into a funnel like shape from its entrance water from its tip is injected into the fine net of fractures. Therefore more aggressive solution enters into the central fracture and enhances dissolutional widening there. By this way aquifers with wide fractures embedded into a continuum of fine fractures experience accelerated karstification.


Hydrogeological overview of the Bure plateau, Ajoie, Switzerland, 2003,
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Kovacs A. , Jeannin P. Y. ,
This study presents a hydrogeological synthesis of the most recent data from the Bure plateau in Ajoie, canton Jura, NW Switzerland. Included is a complete reappraisal of aquifer geometry and aquifer boundaries, the delineation of catchment areas based on tracing experiments, and the evaluation of the hydraulic role of different hydrostratigraphic units. Furthermore, it presents GIS-based calculations on the mean piezometric surface, the thickness of the unsaturated zone and on the thickness of the minimum and mean saturated zones. The spatial extension of the shallow karst zone is also evaluated. A coherent conceptual model and the two-dimensional steady-state combined discrete channel and continuum type numerical model of the aquifer has been constructed. The research site is 83 km(2) in area and is underlain by slightly folded layers of Mesozoic limestones and marls. The Bure plateau is dissected by normal faults, which form a succession of elongated horst and graben structures. The main aquifer consists of Maim limestones, with thicknesses varying between zero (eastern border) and 320 m (south-eastern regions). The aquifer is bounded from below by the Oxfordian Marls. The underlying sediments of Middle Jurassic age are considered to be hydraulically independent. The surface topography of the Oxfordian Marls reveals the periclinal termination of a wide anticline over the plateau and a syncline in the southern parts. The aquifer contains three marly intercalations. Tracing experiments prove that marl layers do not act as regional aquicludes. These experiments also allow for the division of the aquifer surface into several water catchments. Based on tracing tests and piezometric data a NW-SE oriented groundwater divide seems to extend in the regions of Porrentruy-Bure-Croix. Calculations of the average (matrix flow) and minimum (conduit flow) water tables indicate an extended shallow karst zone in the region of Boncourt-Buix-St-Dizier. The thickness of the saturated zone increases towards the extremities of the research site, being thickest in the South. The thickness of the unsaturated zone shows a large variation, reaching its maximum in the central areas. Numerical model calculations roughly reproduce the observed hydraulic heads and mean spring discharges, they confirm current ideas about hydraulic parameters and suggest the existence of extended karst subsystems throughout the model domain

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