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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. ...

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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 corridor is 1. long, narrow chasm enlarged by action of water and into which surface runoff or stream may flow; may be located along a fault plane, fissure, joint or between two beds. struga (slavic) refers to such a corridor along a bedding plane in a carbonate formation [20]. 2. relatively narrow passageway permitting travel between two larger areas. 3. a fairly level and straight passage that links two or more rooms or chambers in a cave. 4. intersecting linear depressions on the surface of the land, related to joints or dikes [10]. see also bogaz; struga; zanjon. related to chasm; bogaz. synonyms: (french.) gouffre absorbant; (german.) karstgasse; (greek.) apocheteftikos karstikos agogos; (italian.) dolina allongata; (russian.) coridor, hod; (spanish.) callejon; (turkish.) koridor; (yugoslavian.) struga, bogaz.?

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

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Karst environment, Culver D.C.
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Your search for aquifer evolution (Keyword) returned 28 results for the whole karstbase:
Showing 1 to 15 of 28
Relict caves as evidence of landscape and aquifer evolution in a deeply dissected carbonate terrain: south-west Edwards Plateau, Texas, U.S.A., 1983, Kastning E. H.

Karst aquifer evolution in fractured rocks., 1999, Kaufmann G. , Braun J.

Karst aquifer evolution in fractured rocks, 1999, Kaufmann G. , Braun J. ,
We study the large-scale evolution and flow in a fractured karst aquifer by means of a newly developed numerical method. A karst aquifer is discretized into a set of irregularly spaced nodal points, which are connected to their set of natural neighbors to simulate a network of interconnected conduits in two dimensions. The conduits are allowed to enlarge by solutional widening. The geometric flexibility of this method, along with a simplified model for the dissolution kinetics within the system water-carbon dioxide-calcite, enables us to study both laminar and turbulent flow in a karst aquifer during its early phase of evolution. A sensitivity analysis is conducted for parameters such as conduit diameter, hydraulic pressure differences, and recharge conditions along the surface of the aquifer and shows that passage evolution depends strongly on the recharge condition and the amount of water available. Under fixed hydraulic head boundary conditions an early single-passage system develops under laminar conditions and is transformed into a maze-like passage system after the onset of turbulence. Fixed recharge boundary conditions are more likely to result in a branchwork-like passage system, although the addition of distributed recharge may lead to a maze-like system of secondary passages

Bridging the gap between real and mathematically simulated karst aquifers, 1999, Groves C. , Meiman J. , Howard A. D.
Although several numerical codes have been developed to study the patterns of karst aquifer evolution and behavior, in the current generation of models simplifying assumptions must be made because of incomplete quantitative understanding of key processesA one-year, high-temporal-resolution study of carbonate chemistry with Mammoth Cave's Logsdon River, designed to investigate details of these processes, reveals that limestone dissolution rates vary appreciably over storm and seasonal time scales due to variations in the flux of CO2-rich waters that wash through, and flood, conduits during storm eventsThis undersaturated storm water dissolves rock within a flood zone 25-30 m thickThrough the year, waters were undersaturated only 31% of the timeTime scales of actual karst development may thus be impacted by time-varying processes different from the constant-input chemistry assumed in current published numerical codesA dual approach, coupling quantitative modeling and refinement of the models by careful measurement of processes within real karst aquifers, provides a framework for developing a comprehensive understanding of karst system behavior

Symposium Abstract: Carbon flux and aquifer evolution in the South-Central Kentucky karst [USA], 2000, Groves C. , Meiman J.

Karst aquifer evolution in fractured, porous rocks., 2000, Kaufmann G. , Braun J.

Karst aquifer evolution in fractured, porous rocks, 2000, Kaufmann G. , Braun J. ,
The evolution of flow in a fractured, porous karst aquifer is studied by means of the finite element method on a two-dimensional mesh of irregularly spaced nodal points. Flow within the karst aquifer is driven by surface recharge from the entire region, simulating a precipitation pattern, and is directed toward an entrenched river as a base level. During the early phase of karstification both the permeable rock matrix, modeled as triangular elements, and fractures within the rock matrix, modeled as linear elements, carry the now. As the fractures are enlarged with time by chemical dissolution within the system calcite-carbon dioxide-water, flow becomes more confined to the fractures. This selective enlargement of fractures increases the fracture conductivity by several orders of magnitude during the early phase of karstification. Thus flow characteristics change from more homogeneous, pore-controlled flow to strongly heterogeneous, fracture-controlled flow. We study several scenarios for pure limestone aquifers, mixed sandstone-limestone aquifers, and various surface recharge conditions as well as the effect of faulting on the aquifer evolution. Our results are sensitive to initial fracture width, faulting of the region, and recharge rate

Modelling karst denudation on a synthetic landscape, 2001, Kaufmann G. , Braun J. ,
This contribution presents the results of a numerical study of karst denudation on limestone plateaux. The landscape evolution model used incorporates not only long-range fluvial and short-range hill-slope processes, but also large-scale chemical dissolution of limestone surfaces. The relative efficiencies of fluvial and chemical processes are of equal importance to the landscape evolution of a plateau dropping to sea level along an escarpment. While fluvial processes have an impact confined mostly to river channels, the karst denudation process is more uniform, removing material also from the plateau surface. The combined effect of both processes results in a landscape evolution almost twice as effective as the purely erosional evolution of an insoluble landscape

Inorganic carbon flux and aquifer evolution in the south central Kentucky karst, 2001, Groves C. , Meiman J.

Karst aquifer evolution in a changing water table environment - art. no. 1090, 2002, Kaufmann G. ,
[1] A vertical cross section through a karst aquifer is modeled by means of the finite element method to study the evolution of fractures and flow in the aquifer. The karst aquifer receives a constant recharge along the top boundary by precipitation and drains toward a resurgence assumed to be the base level in a valley. Flow is allowed both in the permeable rock matrix and the fracture network, and the fractures are enlarged with time by chemical dissolution. Hence during the early evolution of the karst aquifer the conductivity increases over several orders of magnitude, and the initially high water table drops to a steady state base level niveau. As a consequence, fractures above the final water table change from phreatic to vadose flow conditions. A systematic parameter study is carried out to investigate the aquifer evolution over a wide range of parameters, such as recharge rate, initial fracture width and density, and initial calcium concentration. The numerical models cover a wide range of drainage patterns, from phreatic water table caves to deep bathyphreatic caves to vadose river caves. The models suggest that a single theoretical approach is capable of explaining most common cave passage patterns

Concurrent tectonism and aquifer evolution > 100,000 years recorded in cave sediments, Dinaric karst, Slovenia, 2003, Sasowsky I. D. , Sebela S. , Harbert W. ,
A natural conduit that had formed along a fault was exposed in Upper Cretaceous limestones during construction of a tunnel near Postojna,. Slovenia. The conduit is filled with poorly indurated clastic sediments. Slickensides found on the margin of the sediment deposit show sinistral fault motion that is consistent with regional tectonism. Analysis of the sediments revealed reversed magnetic polarity. The minimum age for latest movement on the fault, origin of the cave, and deposition of these sediments is 780 ka. Present-day tectonic stresses are concordant with the fault movement, and it is likely that the fault has been continuously active throughout growth, infilling, and hydrologic abandonment of the conduit. Based upon known and modeled growth rates for conduits, this system is recording a period of growth and abandonment that exceeds 100,000 years. The role that rock discontinuities play in groundwater flow may vary over these timescales, and it may be important to account for tectonism when evaluating the long-term evolution of aquifers

A model comparison of karst aquifer evolution for different matrix-flow formulations, 2003, Kaufmann G. ,
The evolution of permeability and flow in a karst aquifer is studied by numerical simulations. The aquifer considered consists of a large central fracture, a network of finer fissures, and a porous rock matrix. Enlargement of both the central fracture and the fissures by chemical dissolution is possible, hence the conductivities in the fracture and the fissure system can increase with time. No dissolution is allowed in the porous rock matrix, which has a constant conductivity. How is driven by a simple fixed head boundary condition representative for the initial phase of karstification. A systematic parameter study is carried out by varying the initial width of the fissure network and the conductivity of the rock matrix, while keeping the initial width of the central fracture fixed. Key parameters such as flowrates, breakthrough times, and conductivities for the different models are compared. If either the conductivity of the rock matrix is high enough or the initial width of the fissures is large enough to carry flow, breakthrough times of the aquifer are significantly reduced, when compared to a model with low matrix conductivity and small fissures. However, due to the dissolutional widening of fissures the evolution of the aquifer is distinctively different for models with rock matrix simulated by a porous medium or a fissure network. (C) 2003 Elsevier B.V. All rights reserved

Modeling of karst aquifer genesis: Influence of exchange flow, 2003, Bauer S, Liedl R, Sauter M,
[1] This paper presents a numerical model study simulating the early karstification of a single conduit embedded in a fissured system. A hybrid continuum-discrete pipe flow model (CAVE) is used for the modeling. The effects of coupling of the two flow systems on type and duration of early karstification are studied for different boundary conditions. Assuming fixed head boundaries at both ends of the conduit, coupling of the two flow systems via exchange flow between the conduit and the fissured system leads to an enhanced evolution of the conduit. This effect is valid over a wide range of initial conduit diameters, and karstification is accelerated by a factor of about 100 as compared to the case of no exchange flow. Parameter studies reveal the influence of the exchange coefficient and of the hydraulic conductivity of the fissured system on the development time for the conduit. In a second scenario the upstream fixed head boundary is switched to a fixed flow boundary at a specified flow rate during the evolution, limiting the amount of water draining toward the evolving conduit. Depending on the flow rate specified, conduit evolution may be slowed down or greatly impaired if exchange flow is considered

Numerical models for mixing corrosion in natural and artificial karst environments, 2003, Kaufmann G. ,
[1] The enlargement of initially small fractures in a karst aquifer by chemical dissolution is studied. Flow in the aquifer is driven by head differences between sinks and resurgences, and flow depends on the permeability of small fissures and fractures in the aquifer. Enlargement of fractures is controlled by the chemical composition of the recharge, as water undersaturated with respect to calcite is able to dissolve material from the fracture walls. As fractures are enlarged with time, permeability within the aquifer increases significantly, and flow becomes very heterogeneous. Two different processes are considered: enlargement due to normal corrosion, where water is undersaturated with respect to calcite, and enlargement due to mixing corrosion, where two solutions saturated with respect to calcite but with different carbon dioxide concentrations mix and the resulting solution becomes undersaturated again. The importance of mixing corrosion is discussed for two boundary conditions: A natural karst aquifer is modeled with fixed recharge boundary conditions representing sinking streams, and an artificial karst aquifer is simulated with fixed head boundary conditions representing a reservoir. In both cases, mixing corrosion is important, especially if recharge is characterized by an almost saturated chemistry. Mixing corrosion significantly changes the evolving passage pattern, as dissolution due to mixing of solutions is possible deep in the aquifer. Mixing corrosion also reduces breakthrough times of the aquifer and can result in dramatic leakage underneath dam sites, even if the impounded water is almost saturated with respect to calcite

Simulation of the development of karst aquifers using a coupled continuum pipe flow model - art. no. 1057, 2003, Liedl R. , Sauter M. , Huckinghaus D. , Clemens T. , Teutsch G. ,
[1] This paper is intended to provide insight into the controlling mechanisms of karst genesis based on an advanced modeling approach covering the characteristic hydraulics in karst systems, the dissolution kinetics, and the associated temporal decrease in flow resistance. Karst water hydraulics is strongly governed by the interaction between a highly conductive low storage conduit network and a low-conductive high-storage rock matrix under variable boundary conditions. Only if this coupling of flow mechanisms is considered can an appropriate representation of other relevant processes be achieved, e.g., carbonate dissolution, transport of dissolved solids, and limited groundwater recharge. Here a parameter study performed with the numerical model Carbonate Aquifer Void Evolution (CAVE) is presented, which allows the simulation of the genesis of karst aquifers during geologic time periods. CAVE integrates several important features relevant for different scenarios of karst evolution: (1) the complex hydraulic interplay between flow in the karst conduits and in the small fissures of the rock matrix, (2) laminar as well as turbulent flow conditions, (3) time-dependent and nonuniform recharge to both flow systems, (4) the widening of the conduits accounting for appropriate physicochemical relationships governing calcite dissolution kinetics. This is achieved by predefining an initial network of karst conduits ('protoconduits'') which are allowed to grow according to the amount of aggressive water available due to hydraulic boundary conditions. The increase in conduit transmissivity is associated with an increase in conduit diameters while the conductivity of the fissured system is assumed to be constant in time. The importance of various parameters controlling karst genesis is demonstrated in a parameter study covering the recharge distribution, the upgradient boundary conditions for the conduit system, and the hydraulic coupling between the conduit network and the rock matrix. In particular, it is shown that conduit diameters increase in downgradient or upgradient direction depending on the spatial distribution (local versus uniform) of the recharge component which directly enters the conduit system

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