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Enviroscan Ukrainian Institute of Speleology and Karstology

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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. ...

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 transition zone is 1. portion of bedrock in the vadose zone that is between the epikarst zone and the phreatic zone, is relatively waterless and unfractured, but is locally breached by discrete percolation points (vadose shafts.) 2. the zone in which the properties of two adjacent units change gradually (freshwater/saltwater). see also epikarst zone; subcutaneous drain; subcutaneous flow; subcutaneous zone; vadose caves; vadose shafts.?

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

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KarstBase a bibliography database in karst and cave science.

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 parameters (Keyword) returned 351 results for the whole karstbase:
Showing 31 to 45 of 351
Alpine karsts. Genesis of large subterranean networks. Examples : the Tennengebirge (Austria) - the Ile de Crémieu, the Chartreuse and the Vercors (France), PhD Thesis, 1993,
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Audra, Philippe

This work, based on the study of several underground alpine networks, aims to propose some milestone in the history of these karstic regions.

The first part of the work is made up of three regional studies.

The Tennengebirge mountains are a massif of the limestone High Alps in the region of Salzburg in Austria. A cone karst close to the base level developed in the Neogene. Streams from the Alps fed the karst, resulting in the huge horizontal networks of which the Eisriesenwelt provides evidence. During the successive phases of upthrust, the levels of karstification, whether on the surface or deeper down, settled into a tier pattern, thus descending in stages from the base level. From the Pliocene era onwards, thanks to an increase in potential, alpine shafts replace the horizontal networks. The formation of these shafts is more pronounced during glaciation. The study of the Cosa Nostra - Bergerhöhle system developing 30 km of conduits on a gradient reaching almost 1 500 m provides a fairly full view of the karstification of this massif. It includes the horizontal levels developed in the Miocene and the Plio-Pleistocene, joined together by vertical sections. The most noteworthy features of the Tennengebirge, as in the neighboring massifs, lie first and foremost in the extreme thickness of the limestone which has recorded and immunized the differents steps of karstification. Secondly, the size of the networks can be, for the most part, accounted for by the contribution of allogenous waters from the streams of the Neogene and the glaciers of the Pleistocene. Generally sudden and unexpected, these flows of water engendered heavy loads (up to 600 m), simultaneously flooding several levels. To a lesser extent, the situation is similar today.

The Ile de Cremieu is a low limestone plateau on the western edge of the Jura. Due to its location in the foothills, the lobes of the Rhône glacier have covered it up, obliterating the surface karst. However, widespread evidence of anteglacial morphologies remains : paleokarst, cone karst, polygenic surface. Because of glacial plugging, access to the underground karst is limited. The main cavity is the cave of La Balme. Its initial development dates back to an early period. The morphological study has permitted the identification of several phases which go back to the Pleistocene and which are related to the Rhône glacier. The latter brought about modifications in the base level by supplying its merging waters as well as moraine material. These variations in the base level shaped the drainage structure. The underground glacial polishes are one of the noteworthy aspects recorded.

The massives of the Moucherotte and dent de Crolles belong to the northern French Prealps. They conceal large networks, respectively the Vallier cave and the Dent de Crolles. They were formed in the early Pliocene after the final orogenic phase and are in the form of horizontal conduits. The upthrust, which brought about the embanking of the Isère valley, left them in a perched position by taking away the basin which fed them. They were later, however, able to take advantage of waters from the Isère glacier during a part of the Pleistocene. The Vallier cave contains particularly glacio-karstic sediments of the lower Pleistocene, representing unique evidence of glaciation during this period. The vertical networks were put in place at the end of the Pliocene with the increase in karstification potential ; they underwent changes in the Pleistocene due to the effect of autochton and allogenous glaciers.

The second part of the work deals in general with the various forms and processes of karstification, sometimes going beyond the Alps. The study of cave deposits is a privileged tool in the understanding and reconstruction not only of the history of the networks but also the regional environment. The dating of speleothems by the U / Th method has very ofen given an age of over 350 000 years. The age of the networks is confirmed by the use of paleomagnetism which has yielded evidence of speleothems and glacio-karstic sediments anterior to 780 000 years. Anisotropic measurements of magnetic susceptibility have been used to distinguish the putting into place of glacio-karstic deposits by decantation.

Measurements of calcite rates lead to a typology of sediments based on their nature and carbonate content (rehandled weathered rocks, fluvial sands, carbonated varves, decantation clays). Granulometry confirms this differenciation by supplying precise details of transport and sedimentation modes : suspension and abrupt precipitation of clay, suspension and slow decantation of carbonated varves, suspension and rolling together with a variable sorting of sand and gravel. Mineralogical analyses oppose two types of detrital deposits. On the one hand, the rehandling of antequaternary weathered rocks extracted by the karst as a result of scouring during environmental destabilization and on the other hand, sediments characteristic of the ice age of the Pleistocene. The latter are not highly developed and their arrival in the karst is always later. Examination of heavy minerals, the morphoscopy of quartz grains and study of micromorphologies on thin blades provide precise details of conditions of evolution. The use of these methods of investigation allows for an accurate definition of the features of the evolution of the differents types of fillings, particularly speleothems, rehandled weathered rocks as well as carbonated varves. This wealth and complexity are emphasized by a detailed study of the sedimentary sequences of the Vallier cave and of the Bergerhöhle.
Speleogenesis is approached last of all in the light of above study. Emphasis is placed on the major part played by corrosion in the temporarily phreatic zone and on its many consequences (multi-level concept, simultaneous evolution of levels, origin of deep waterlogged karsts…).
Varia tions in the base level have induced karstification in contexts in which the potential was weak. These were followed by periods of increased potential to which were added the effects of glaciation. Perched horizontal levels belong to the first stages which ended in the early Pliocene, whereas alpine shafts developed in the second context. The role of structure and the parameters governing the shape of conduits (pits, meanders, canyons) are also dealt with. The different parts of the karst are borne in mind when dealing with the strength of karstic erosion during the ice age. It notably appears that it is weak on the crests and more or less non-existent in the deep parts of the karst which are liable to flooding. Finally, a preliminary analysis of an observation of neotectonic traces is presented.

Activity od the scientific commission of ''Grotta Grande del Vento'' (Genga, Ancona, Central Italy)., 1994,
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Bertolani Mario, Cigna Arrigo A.
The Grotta Grande del Vento (the Great Wind Cave) was discovered in 1971. An administrative body (the "Consorzio Frasassi") under the control of some local authorities took care of its development and the cave was opened to tourists in 1974. A Scientific Commission formed by some experts (choosen by the Consorzio Frasassi) of different disciplines was established in 1975. During these 15 years the Commission acted as an advisory committee for the Consorzio in order to guarantee the protection of the cave environment. In particular the Commission set up a monitoring network of the most important environmental parameters (air and water temperature. air currents, relative humidity and CO2 concentration) in some suitable locations and studied the best solutions to avoid algae and other plants proliferation in the vicinity of light sources. The Commission promoted and directed researches in the karst system under a strict co-operation with the Consorzio Frasassi which funded most of them. Some scientific papers resulted from these researches.

Middle Holocene environmental change determined from the salt caves of Mount Sedom, Israel, 1994,
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Frumkin, A. , Carmi, I. , Zak, I. And Magaritz, M. , 1994
Paleoclimatic sequence for the Middle Holocene was constructed, based on Mount Sedom salt caves, and other evidence. Mount Sedom is a salt diapir, on the southwestern shore of the Dead Sea, which has been rising above the local base level throughout the Holocene. Allogenic karst development has kept pace with the rising, forming vadose caves. Wood fragments found embedded in flood sediments that were deposited in sub-horizontal cave passages yielded 14C ages from 7090 to 200 YBP. The paleoclimatic sequence is based on parameters that include: relative abundance of plant types or floral communities, the elevations of the corresponding relict cave passages and the ratio of their width to present passage width. Moister climatic stages are indicated by relatively abundant wood remains, by wide cave passages and by higher-level outlets, indicating high Dead Sea levels. Arid periods are marked by a scarcity of wood remains, by narrow cave passages and by low-level outlets. The results were correlated to other middle-Holocene evidence and temporal settlement changes. The Early Bronze period in Israel was the moistest period during the last 6000 years and as such it encouraged cultural development. It was followed by a considerable desiccation that caused a cultural deterioration.

Recent flowstone growth rates: field measurements and comparison to theoretical results, 1995,
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Baker A. , Smart Pl. ,
The model of calcite precipitation kinetics of D. Buhmann and W. Dreybrodt, based on the rate laws of L.N. Plummer et al., is used to predict cave flowstone growth rates. These theoretically modelled growth rates are compared to actual growth rates of recent samples found in cave and mine sites in southwest England. A good agreement is found between modelled and actual growth rates within the 95% confidence level of the determinations, although in general modelled growth rates overestimate actual growth rate by between 2.4 and 4.7 times. Several reasons for this overestimation are discussed, including uncertainties arising from the experimental data of L.N. Plummer et al., seasonal shut-off of water flow onto the flowstones and significant variations in the growth rate determining parameters during the period of flowstone growth. For one flowstone an underestimation of growth rate is observed and is explained by the presence of rimstone pools which pond water on the sample surface

Paleoclimate implications of mass spectrometric dating of a British flowstone, 1995,
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Baker A, Smart Pl, Edwards Rl,
The timing of growth phases in a cave flowstone from Yorkshire, England, has been precisely dated by thermal ionization mass spectrometric 238 U- 234 U- 230 Th dating. Six growth periods of both short duration and fast growth rate are separated by nondepositional hiatuses. The ages of these phases were determined to be 128.8 or -2.7, 103.1 or -1.8, 84.7 or -1.2, 57.9 or -1.5, 49.6 or -1.3, and 36.9 or -0.8 ka. There is a remarkably good correlation between the periods of active speleothem growth and the timing of solar insolation maxima, derived from orbital parameters, which has not previously been reported. Speleothem growth theory and evidence from other terrestrial paleoclimate records suggest that episodic, rapid growth phases at the insolation maxima are most likely to be caused by changes in either precipitation intensity or volume, which caused switching in the routing of water flow in the unsaturated zone above the cave. Such a result provides new evidence of the importance of variations in solar insolation for terrestrial paleoclimate and offers the potential for derivation of a paleowetness index from speleothem growth

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Stoessell R. K. ,
A range of hydrodynamic dispersion coefficients was estimated for fracture-fluid and combined fracture and pore-fluid now within the halocline of the limestone aquifer forming the surface of the northern Yucatan Peninsula. The coefficients are fit parameters in a model reproducing observed halocline profiles in a sinkhole and in a borehole near the northeastern coast. Fitted coefficients range from 10(-7) to 10(-4) cm(2)/sec, of which molecular diffusion, without transverse (vertical) dispersion, can account for 10(-7) to 10(-5) cm(2)/sec. The mechanical stability of the vertical density gradient in the halocline dampens transverse dispersion in pore fluids and in fracture fluids that are transitional between laminar and turbulent flow. The dampening is proportional to the ratio of the energy needed for the fluid to rise and displace a less dense fluid to the vertical component of the kinetic energy of the fluid. The ratio of these two energies is at a maximum during the initial stage of development of a halocline and decreases as the halocline widens

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Jones B. , Kahle C. F. ,
Cavities in the dolostones of the Cayman Formation (Miocene) on Grand Cayman and Cayman Brac commonly contain spar calcite cements and/or a variety of exogenetic (derived from sources external to the bedrock) and endogenetic (derived from sources in the bedrock) internal sediments. Micrite is a common component in many of these internal sediments. The exogenetic micrite, which is typically laminated and commonly contains fragments of marine biota, originated from the nearby shallow lagoons. The endogenetic micrite formed as a residue from the breakdown of spar calcite crystals by etching, as constructive and destructive envelopes developed around spar calcite crystals, by calcification of microbes, by breakdown of calcified filamentous microbes, and by precipitation from pore waters. Once produced, the endogenetic micrite may be transported from its place of origin by water flowing through the cavities. Endogenetic micrite can become mixed with the exogenetic micrite. Subsequently, it is impossible to recognize the origin of individual particles because the particles in endogenetic micrite are morphologically like the particles in exogenetic micrite. Formation of endogenetic micrite is controlled by numerous extrinsic and intrinsic parameters. In the Cayman Formation, for example, most endogenetic micrite is produced by etching of meteoric calcite crystals that formed as a cement in the cavities or by microbial calcification. As a result, the distribution of the endogenetic micrite is ultimately controlled by the distribution of the calcite cement and/or the microbes-factors controlled by numerous other extrinsic variables. Irrespective of the factors involved in its formation, it is apparent that endogenetic micrite can be produced by a variety of processes that are operating in the confines of cavities in karst terrains

The last glacial/interglacial record of rodent remains from the Gigny karst sequence in the French Jura used for palaeoclimatic and palaeoecological reconstructions, 1995,
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Chaline J, Brunetlecomte P, Campy M,
A multidisciplinary approach has produced an exceptional chronological log of climatic patterns for the Upper Pleistocene sequence of Gigny Cave (Jura, France) covering the Pre-Eemian, Eemian Interglacial, Middle Glacial and Upper Pleniglacial, as well as a part of the Holocene. Multivariate analysis (correspondence and component analysis) of rodent associations from the sequence is used here to characterize the different climatic stages in terms of relative temperature, plant cover and moisture. Faunal analysis establishes: (1) positive and negative correlations among the variations of the different species; (2) the significance of axis 1 (component analysis) which, in terms of temperature, opposes cold environments with contrasted continental biotopes; (3a) the significance of axis 2 (component analysis), which reflects vegetation patterns ranging from open to closed habitats; (3b) the significance of axis 3 (component analysis), which expresses trends in moisture; (4) various correlations between faunal and climatic parameters (temperature, plant cover and moisture); (5) evaluation of faunal diversity (Shannon index ranging from 0.74 to 2.27) showing that diversity increases with temperature and the complexity of vegetation, but is not sensitive to moisture. Lastly, the comparison of multivariate methods with the weighted semi-quantitative Hokr method shows the complementarity of the two approaches, the first methods quantifying climatic parameters while the second seems to provide more precise evaluations of the main seasons of rainfall

Un aquifre gypseux de haute montagne : mesures physico-chimiques et traage dans la valle de Gbroulaz (Vanoise, France), 1996,
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Dzikowski M. , Nicoud G. , Arfib B. , Paillet A. , Rovera G.
During the high flow period of summer 1995, conductivity and temperature were periodically measured in two losses and five springs along a gypsum and anhydrite outcrop in the Gbroulaz valley. These experiments together with a water chemical analysis and an artificial tracer test have highlighted two kinds of flows through the evaporitic formations. The springs are characterised by a rapid flow directly influenced by the infiltration of melt water in a surficial karst. A slower flow shows a deeper circulation through a saturated and fissured milieu. So, in a high mountainous area, the gypsum layer shows a surficial karst over a fissured aquifer. This interpretation allows us to explain the stability of the physico-chemical parameters for the springs, which are not influenced by karstic flow conditions.

Le Luirographe : tude de la crue du 22 avril 1995 (rseau de la Luire, Vercors), 1996,
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Morel, L.
The Luirographe can record automatically parameters such as the water height in a karstic network. Placed at the beginning of April 1995, at -200 m, it recorded for the first time the Luire swelling, which lasted two days. The cave of the Luire is situated in the massif of Vercors, with an hydrogeological basin of 230 km2. The Vercors is a forest of middle mountain within the French Pre-Alps of the North. The Luire swelling only exits when there are very big nival spate accentued by important rainfalls and by a southern wind. Such event arrives only every other year on average. The difference between the high and low level of karst flood can reach the impressive height of 475 m, the most important known in the world. It is the difference between altitude of saturated zone where there is the continuous spring of Arbois and the temporary emergence of the Luire, known up to -451 m and are 20 km apart.

The governing factors of the physicochemical characteristics of Sheshpeer karst springs, Iran, 1996,
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Raeisi E. , Karami G. ,
The physical and chemical characteristics of karst springs are not a sole function of flow path in the carbonatic rock mass. A number of other parameters, including the type of precipitation, soil cover morphology of the exposed area, and the hydrochemistry of the infiltrating water into the karst system also have their own contribution. In the present study, the Car and Barm-Firooz mountains me chosen to determine some of the governing factors of the physical and hydrochemical characteristics of karst springs. The following measurements were carried out: 1. Concentration of major ions and electrical conductivity of the fresh snow and snowpack. 2. Variation of discharge as a function of time at six sicking streams. 3. Time Variation of discharge, electrical conductivity, and air and water temperature of sinking streams at seven sinkholes. 4. Electrical conductivity and temperature of water at the surface and 40 cm beneath the soil cover. 5. Discharge, major ions, temperature and electrical conductivity of the Sheshpeer spring water were measured every twenty days for a period of three years. The results indicate that if the physical and chemical characteristics of a karst spring are going to be used to determine the characteristics of corresponding aquifer, first the effect of external factors on the outflow should be accounted for, and then the characteristics of the karst aquifer be determined

Agricultural chemicals at the outlet of a shallow carbonate aquifer, 1996,
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Felton Gk,
A groundwater catchment, located in Woodford and Jessamine Counties in the Inner Bluegrass of Kentucky, was instrumented to develop long-term flow and water quality data. The land uses on this 1 620-ha catchment consist of approximately 59% in grasses consisting of beef farms, horse farms, and a golf course; 16% row crops; 6% orchard; 13% forest; and 6% residential. Water samples were analyzed twice a week for, Ca, Mg, Na, Cl-, HCO3-, SO4=, NO3-, total solids, suspended solids, fecal coliforms, fecal streptococci, and triazines. Flow rate and average ambient temperature were also recorded. No strong linear relationship was developed between chemical concentrations and other parameters. The transient nature of the system was emphasized by one event that drastically deviated from others. Pesticide data were summarized and the ''flushing'' phenomena accredited to karst systems was discussed. The total solids content in the spring was consistent at approximately 2.06 mg/L. Fecal bacteria contamination was well above drinking water limits (fecal coliform and fecal streptococci averages were 1 700 and 4 300 colony-forming-units/100 mL, respectively) and the temporal variation in bacterial contamination was not linked to any other variable

Principles of early development of karst conduits under natural and man-made conditions revealed by mathematical analysis of numerical models, 1996,
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Dreybrodt W,
Numerical models of the enlargement of primary fissures in limestone by calcite aggressive water show a complex behavior. If the lengths of the fractures are large and hydraulic heads are low, as is the case in nature, dissolution rates at the exit of the channel determine its development by causing a slow increase of water flow, which after a long gestation time by positive feedback accelerates dramatically within a short time span. Mathematical analysis of simplified approximations yields an analytical expression for the breakthrough time, when this happens, in excellent agreement with the results of a numerical model. This expression quantifies the geometrical, hydraulic, and chemical parameters determining such karat processes. If the lengths of the enlarging channels are small, but hydraulic heads are high, as is the case for artificial hydraulic structures such as darns, it is the widening at the entrance of the flow path which determines the enlargement of the conduit. Within the lifetime of the dam this can cause serious water losses, This can also be explained by mathematical analysis of simplified approximations which yield an analytical threshold condition from which the safety of a dam can be judged. Thus in both cases the dynamic processes of karstification are revealed to gain a deeper understanding of the early development of karst systems. As a further important result, one finds that minimum conditions, below which karstification cannot develop, do not exist

Theoretical model of surface karstic processes, 1996,
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Veress M. , Pentek K. ,
Our study improves theories of denudation of karst surfaces. We examine a debris zone developed mostly by solutional fragmentation of the fissured rock. Denudation of karsts is attributed to the downward movement of the debris zone. The different rates of this movement in a karst region cause different denudation rates and so wight result in the development of dolinas. Therefore our model might be suitable for the explanation and description of the development of solution dolines. According to the differential equation of solution, the migration rate of the karstic relief is determined by the CO2 production, the soaking time and the average diameter of the fragments of the debris zone. According to the above - supposing constant parameters of karstification - the time of denudation at any point of a karstic area can be also calculated when knowing the original thickness of the rock exposed to karstic denudation. The age of a solution doline can be determined by the formula obtained

Structure et comportement hydraulique des aquifers karstiques, DSc thesis, 1996,
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Jeannin, P. Y.

This thesis aims to provide a better knowledge of karst flow systems, from a functional point of view (behaviour with time), as well as from a structural one (behaviour in space). The first part of the thesis deals with the hydrodynamic behaviour of karst systems, and the second part with the geometry of karstic networks, which is a strong conditioning factor for the hydrodynamic behaviour.
Many models have been developed in the past for describing the hydrodynamic behaviour of karst hydrogeological systems. They usually aim to provide a tool to extrapolate, in time and/or space, some characteristics of the flow fields, which can only be measured at a few points. Such models often provide a new understanding of the systems, beyond what can be observed directly in the field. Only special field measurements can verify such hypotheses based on numerical models. This is an significant part of this work. For this purpose, two experimental sites have been equipped and measured: Bure site or Milandrine, Ajoie, Switzerland, and Holloch site, Muotathal, Schwyz, Switzerland. These sites gave us this opportunity of simultaneously observe hydrodynamic parameters within the conduit network and, in drillholes, the "low permeability volumes" (LPV) surrounding the conduits.
These observations clearly show the existence of a flow circulation across the low permeability volumes. This flow may represent about 50% of the infiltrated water in the Bure test-field. The epikarst appears to play an important role into the allotment of the infiltrated waters: Part of the infiltrated water is stored at the bottom of the epikarst and slowly flows through the low permeability volumes (LPV) contributing to base flow. When infiltration is significant enough the other part of the water exceeds the storage capacity and flows quickly into the conduit network (quick flow).
For the phreatic zone, observations and models show that the following scheme is adequate to describe the flow behaviour: a network of high permeability conduits, of tow volume, leading to the spring, is surrounded by a large volume of low permeability fissured rock (LPV), which is hydraulically connected to the conduits. Due to the strong difference in hydraulic conductivity between conduits and LPV, hydraulic heads and their variations in time and space are strongly heterogeneous. This makes the use of piezometric maps in karst very questionable.
Flow in LPV can be considered as similar to flow in fractured rocks (laminar flow within joints and joints intersections). At a catchment scale, they can be effectively considered as an equivalent porous media with a hydraulic conductivity of about 10-6 to 10-7 m/s.
Flow in conduits is turbulent and loss of head has to be calculated with appropriate formulas, if wanting any quantitative results. Our observations permitted us to determine the turbulent hydraulic conductivity of some simple karst conduits (k', turbulent flow), which ranges from 0.2 to 11 m/s. Examples also show that the structure of the conduit network plays a significant role on the spatial distribution of hydraulic heads. Particularity hydraulic transmissivity of the aquifer varies with respect to hydrological conditions, because of the presence of overflow conduits located within the epiphreatic zone. This makes the relation between head and discharge not quadratic as would be expected from a (too) simple model (with only one single conduit). The model applied to the downstream part of Holloch is a good illustration of this phenomena.
The flow velocity strongly varies along the length of karst conduits, as shown by tracer experiments. Also, changes in the conduit cross-section produce changes in the (tow velocity profile. Such heterogeneous flow-field plays a significant role in the shape of the breakthrough curves of tracer experiments. It is empirically demonstrated that conduit enlargements induce retardation of the breakthrough curve. If there are several enlargements one after the other, an increase of the apparent dispersivity will result, although no diffusion with the rock matrix or immobile water is present. This produces a scale effect (increase of the apparent dispersivity with observation scale). Such observations can easily be simulated by deterministic and/or black box models.
The structure of karst conduit networks, especially within the phreatic zone, plays an important role not only on the spatial distribution of the hydraulic heads in the conduits themselves, but in the LPV as well. Study of the network geometry is therefore useful for assessing the shape of the flow systems. We further suggest that any hydrogeological study aiming to assess the major characteristics of a flow system should start with a preliminary estimation of the conduit network geometry. Theories and examples presented show that the geometry of karst conduits mainly depends on boundary conditions and the permeability field at the initial stage of the karst genesis. The most significant boundary conditions are: the geometry of the impervious boundaries, infiltration and exfiltration conditions (spring). The initial permeability field is mainly determined by discontinuities (fractures and bedding planes). Today's knowledge allows us to approximate the geometry of a karst network by studying these parameters (impervious boundaries, infiltration, exfiltration, discontinuity field). Analogs and recently developed numerical models help to qualitatively evaluate the sensitivity of the geometry to these parameters. Within the near future, new numerical tools will be developed and will help more closely to address this difficult problem. This development will only be possible if speleological networks can be sufficiently explored and used to calibrate models. Images provided by speleologists to date are and will for a long time be the only data which can adequately portray the conduit networks in karst systems. This is helpful to hydrogeologists. The reason that we present the example of the Lake Thun karst system is that it illustrates the geometry of such conduits networks. Unfortunately, these networks are three-dimensional and their visualisation on paper (2 dimensions) is very restrictive, when compared to more effective 3-D views we can create with computers. As an alternative to deterministic models of speleogenesis, fractal and/or random walk models could be employed.

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