Karst and Cave RSS news feed Like us on Facebook! follow us on Twitter!
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. ...

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 suffosion is undermining through removal of sediment by mechanical and corrosional action of underground water [20]. synonyms: (french.) soutirage karstique; (german.) anzapfung; (greek.) ypoghion thiavrosis; (russian.) suffozija; (spanish.) sufosion; (turkish.) karstik yeraltisuyu kazimasi; (yugoslavian.) sufozija.?

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

What is Karstbase?

Search KARSTBASE:

keyword
author

Browse Speleogenesis Issues:

KarstBase a bibliography database in karst and cave science.

Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
Engineering challenges in Karst, Stevanović, Zoran; Milanović, Petar
See all featured articles
Featured articles from other Geoscience Journals
Geochemical and mineralogical fingerprints to distinguish the exploited ferruginous mineralisations of Grotta della Monaca (Calabria, Italy), Dimuccio, L.A.; Rodrigues, N.; Larocca, F.; Pratas, J.; Amado, A.M.; Batista de Carvalho, L.A.
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
See all featured articles from other geoscience journals

Search in KarstBase

Your search for scenario (Keyword) returned 76 results for the whole karstbase:
Showing 1 to 15 of 76
Controversy over the great flood hypotheses in the Black Sea in light of geological, paleontological, and archaeological evidence, , Yankohombach Valentina, Gilbert Allan S. , Dolukhanov Pavel,
Legends describing a Great Flood are found in the narratives of several world religions, and the biblical account of Noah's Flood is the surviving heir to several versions of the ancient Mesopotamian Flood Myth. Recently, the story of the biblical deluge was connected to the Black Sea, together with the suggestion that the story's pre-Mesopotamian origins might be found in the Pontic basin [Ryan, W.B.F., Pitman, III, W.C., 1998. Noah's Flood: The New Scientific Discoveries About the Event That Changed History. Simon and Schuster, New York]. Based on the significance of this flood epic in the Judeo-Christian tradition, popular interest surged following publication of the idea.Currently, two Great Flood scenarios have been proposed for the Black Sea: (1) an Early Holocene event caused by catastrophic Mediterranean inflow at 7.2 ky BP (initial hypothesis of [Ryan et al., 1997. An abrupt drowning of the Black Sea shelf. Marine Geology 138, 119-126]) or 8.4 ky BP (modified hypothesis of [Ryan et al., 2003. Catastrophic flooding of the Black Sea. Annual Review of Earth and Planetary Science 31, 525-554.); and (2) a Late Pleistocene event brought on by Caspian influx between 16 and 13 ky BP [Chepalyga, A.L., 2003. Late glacial Great Flood in the Black Sea and Caspian Sea. GSA Annual Meeting and Exposition, 2-5 November 2003, Seattle, USA, p. 460]. Both hypotheses claim that the massive inundations of the Black Sea basin and ensuing large-scale environmental changes had a profound impact on prehistoric human societies of the surrounding areas, and both propose that the event formed the basis for the biblical Great Flood legend.This paper attempts to determine whether the preponderance of existing evidence sustains support for these Great Floods in the evolution of the Black Sea. Based upon established geological and paleontological data, it finds that the Late Pleistocene inundation was intense and substantial whereas the Early Holocene sea-level rise was not. Between 16 and 13 ky BP, the Late Neoeuxinian lake (the Late Pleistocene water body in the Pontic basin pre-dating the Black Sea) increased rapidly from ~-14 to -50 m (below the present level of the Black Sea), then rose gradually to ~-20 m by about 11 ky BP. At 11-10 ky BP (the Younger Dryas), it dropped to ~-50 m. When the Black Sea re-connected with the Sea of Marmara at about 9.5 ky BP, inflowing Mediterranean water increased the Black Sea level very gradually up to ~-20 m, and in so doing, it raised the salinity of the basin and brought in the first wave of Mediterranean immigrants. These data indicate no major drawdown of the Black Sea after the Younger Dryas, and they do not provide evidence for any catastrophic flooding of the Black Sea in the Early Holocene.In addition, available archaeological and paleoenvironmental evidence from the Pontic region reveal no recognizable changes in population dynamics between 14 and 6 ky BP that could be linked to an inundation of large magnitude [Dolukhanov, P., Shilik, K., 2006. Environment, sea-level changes, and human migrations in the northern Pontic area during late Pleistocene and Holocene times. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 297-318; Stanko, V.N., 2006. Fluctuations in the level of the Black Sea and Mesolithic settlement of the northern Pontic area. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 371-385]. More specifically, Mesolithic and early Neolithic archaeological data in southeastern Europe and Ukraine give no indications of shifts in human subsistence or other behavior at the time of the proposed catastrophic flood in the Early Holocene [Anthony, D., 2006. Pontic-Caspian Mesolithic and Early Neolithic societies at the time of the Black Sea Flood: A small audience and small effects. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 345-370; Dergachev and Dolukhanov, 2006. The Neolithization of the North Pontic area and the Balkans in the context of the Black Sea Floods. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 489-514]

A New Equation Solver for Modeling Turbulent Flow in Coupled Matrix‐Conduit Flow Models, ,

Karst aquifers represent dual flow systems consisting of a highly conductive conduit system embedded in a less permeable rock matrix. Hybrid models iteratively coupling both flow systems generally consume much time, especially because of the nonlinearity of turbulent conduit flow. To reduce calculation times compared to those of existing approaches, a new iterative equation solver for the conduit system is developed based on an approximated Newton–Raphson expression and a Gauß–Seidel or successive over-relaxation scheme with a single iteration step at the innermost level. It is implemented and tested in the research code CAVE but should be easily adaptable to similar models such as the Conduit Flow Process for MODFLOW-2005. It substantially reduces the computational effort as demonstrated by steady-state benchmark scenarios as well as by transient karst genesis simulations. Water balance errors are found to be acceptable in most of the test cases. However, the performance and accuracy may deteriorate under unfavorable conditions such as sudden, strong changes of the flow field at some stages of the karst genesis simulations.

Do you want to read the rest of this publication?

 


Sport and Scout Caving - The Present Dilemma, 1987, Crabb, Evalt

This paper traces the evolution of organised caving as a post World War 2 phenomenon, and the changes in practice and attitude that have occurred. These practices are contrasted against stated behavioural codes. Parallel to this, the development of caving as a scouting activity is discussed, with reference to the general principles and practices of scouting. The author has been working toward evolving policies and practices within scouting which are consistent with the needs of conservation and the underlying philosophies of scouting. Implementation of these attitudes in one area is fully detailed, with some comment on the success and acceptability of the program. This training program is contrasted against the foreshadowed N.S.W. Branch Policy on Rock-Related Activities. The sequential discussion highlights some weaknesses within clubs and A.S.F., particularly in our methods of communication. There are no firm proposals, but possible directions for future discussions are indicated. It is the intention of this paper to give a historical perspective to some of the present perceived conflicts; in reality, the only conflict is between our oft-expressed aim of conservation of caves (i.e. safeguard the karst heritage of Australia), and our visible activity - use of caves for recreational activity. Both the intensity of expression of our concern, and lessening of self-constraint on recreational activity have greatly magnified with time; we are fast approaching a 'crossroads' scenario where our credibility is at great risk.


Paleoenvironment and speciation in the cave beetle complex Speonomus delarouzeei (Coleoptera, Bathysciinae), 1988, Juberthie Christian
In the eastern part of the Pyrenees (France) the author describes a scenario of speciation in the cave species complex Speonomus delarouzeei (Coleoptera Bathysciinae); the speciation processes have been initiated by a breakdown of the ecological equilibrium induced during three glacial-interglacial episodes. The scenario is the following: during the first glaciation (2.3-2.1 MY), psychrophilic populations ancestral to S. brucki were selected over the highest elevation of the range, by means of cold effect which produced an adaptive demographic advantage; adaptive characters of troglobitic species (K strategy) take place presumably in relation to colonization of caves and M.S.S.; during the second glaciation (1.7-1.3 MY) and a more recent, S. charlottae, latter S. emiliae, diverged from troglobite ancestors of S. brucki without further adaptive characters, as result from stochastic and historical events. M.S.S. generated during erosional period of glacial event provided ways for migration and new niches for colonization. Bottleneck effect in size population of ancestors, founder effect, and colonization by local population which present genetic and behavioural geographical polymorphism, argue for a rapid speciation, presumably 100,000 years long and 50,000 generations in the case of S. emiliae.

The origin and development of Brucker Breakdown and the adjacent area, Mammoth Cave System, Kentucky. Masters Thesis, 1989, Blackeagle, Cory W.

The appearance and relationships of Brucker Breakdown and adjacent area, a portion ofthe Mammoth Cave System,implythatcomplex structural and hydrogeological factors affectected and/or controlled passage development. Detailed surveys include geographic, cartographic, lithologic, morphologic, stratigraphic, and paleoflow indicators. The five proposed scenarios were the following. Case 1: All (or most) of the passages were once continuous across the Brucker Breakdown void, which is a subsequent feature. Case Ia: The Brucker Breakdown void is a subsequentfeature whose development caused morphological changes in the pre-existing passages adjacent to it (traditional hypothesis). Case II: The passages converge toward or diverge from the Brucker Breakdown void, which acted as either a source or target of flow and is a primary feature. Case Ila: Several passages converge on the Brucker Breakdown void and fewer components depart from it, indicating that the Brucker Breakdown void is a primary feature and represented a local potentiometric low. Case lIb: Several passages diverge from the Brucker Breakdown void, and fewer components converge on it, indicating that the Brucker Breakdown void is a primary feature and represented a local potentiometric high. Of these, Case lib was found to most closely represent the situation presented by the data.

To perform this study, a detailed procedure was developed that, until this time, had not been established nor outlined in the literature. Once the area of study was chosen and defined, an extremely detailed cartographic and morphologic survey was performed that established both horizontal and vertical data points throughout the area. These data points were tied to existing transit surveys of the surface that linked the subsurface area to U.S. Geological Survey bench marks. The cartographic, geographic, and morphologic data were converted with computer aid to map form. The maps were then field-checked for accuracy. Comprehensive geological mapping surveys were executed. Multiple stratigraphic sections were described and measured in each passage segment, and these were tied to the vertical data points. Correlations were made between sections and were physically traced whenever conditions permitted. Speleothem dating information from prior research was obtained and correlated throughout the study area. Finally, important features and passage morphologies were documented photographically.


LATE TO POSTHERCYNIAN HYDROTHERMAL ACTIVITY AND MINERALIZATION IN SOUTHWEST SARDINIA (ITALY), 1992, Boni M, Iannace A, Koppel V, Fruhgreen G, Hansmann W,
Several kinds of base metal deposits occur in the lower Paleozoic of southwest Sardinia (Iglesiente-Sulcis mineral district). This paper deals with those deposits which are generally referred to as Permo-Triassic, because they accompany and postdate the Hercynian orogeny and are related to magmatic activity. A large number of previously published geochemical data, integrated with additional new data (Sr, Pb, O, C, and S isotopes), are reviewed and discussed in the frame of the late to post-Hercynian geologic evolution of southwest Sardinia. According to geological and mineralogical characteristics, three types of deposits can be distinguished: (1) skarn ores related to late Hercynian leucogranitic intrusions, (2) high-temperature veins, and (3) low-temperature veins and karst filling. Pervasive epigenetic dolomitization phenomena are geochemically related to the low-temperature deposits. Sr and Pb isotopes of the first and second types (0.7097-0.7140 Sr-87/Sr-86; 17.97-18.29 Pb-206/Pb-204; 38.11-38.45 Pb-208/Pb-204) are distinctly more radiogenic than those of the third type (0.7094-0.7115 Sr-87/Sr-86; 17.86-18.05 Pb-206/Pb-204; 37.95-38.19 Pb-208/Pb-204) which, in turn, are closer to Paleozoic ores and carbonates. Fluid inclusion data indicate that the fluids responsible for mineralization of the first and second types of deposits were hot and dilute (T(h)= 370-degrees-140-degrees-C; <5 wt % NaCl equiv). In contrast, relatively colder and very saline fluids (T(h)= 140-degrees-70-degrees-C; >20 wt % NaCl equiv) were responsible for the third type of mineralization, as well for epigenetic dolomitization of the Cambrian host rocks. O isotopes measured in minerals from the first two types (deltaO-18SMOW = 12.8-18.9 parts per thousand) are O-18 depleted with respect to the third type (deltaO-18SMOW = 15.9-22.1 parts per thousand). These data, coupled with fluid inclusion formation temperatures, indicate that the fluids responsible for the first two types of mineralization were O-18 enriched with respect to those of the third type and related hydrothermal phenomena. The deltaS-34CDT in sulfides of the first two types vary between 3.7 and 10.73 per mil, whereas the values of the third type range from 12.0 to 17.9 per mil. Late to post-Hercynian mineralization is thus explained as the result of three distinct, though partly superimposed, hydrothermal systems. System 1 developed closer to the late Hercynian leucogranitic intrusions and led to the formation of the first and subsequently the second type of mineralization. The relatively hot and diluted fluids had a heated meteoric, or even partly magmatic, origin. Metals were leached from an external, radiogenic source, represented either by Hercynian leucogranites or by Paleozoic metasediments. Sulfur had a partly magmatic signature. System 2 was characterized by very saline, colder fluids which promoted dolomitization, silicification, and vein and karst mineralization. These fluids share the typical characteristics of formation waters, even though their origins remain highly speculative. The hydrothermal system was mainly rock dominated, with only a minor participation of the external radiogenic source of metals. Sulfur was derived by recirculation of pre-Hercynian strata-bound ores. System 3 records the invasion of fresh and cold meteoric waters which precipitated only minor ore and calcite gangue. It may represent the further evolution of system 2, possibly spanning a time well after the Permo-Triassic. The timing of all these phenomena is still questionable, due to the poor geologic record of the Permo-Triassic in southwest Sardinia. Nevertheless, the hypothesized scenario bears many similarities with hydrothermal processes documented throughout the Hercynian in Europe and spanning the same time interval. A comparison with the latter mineralization and hydrothermal activities leads to the hypothesis that the first two types of mineralization are linked to late Hercynian magmatic activity, whereas the third type may be related to either strike-slip or tensional tectonics which, throughout Europe mark the transition from the Hercynian orogeny to the Alpine cycle

Some remarks on the genus Microcharon Karaman in Greece, and description of M. agripensis n. sp. (Crustacea, Isopoda, Microparasellidae), 1994, De Laurentiis Paola, Galassi Diana M. P. , Pesce Giuseppe L.
Several samples of microparasellid isopods of the genus Microcharon Karaman were obtained in groundwater habitats of Greece. Four species are identified, and taxonomical and zoogeographical remarks on some rare or poorly known taxa are made. One species, herein described as Microcharon agripensis n. sp., is new to Science. M. latus prespensis Karaman, 1954, on account of the different morphology of the first and second male pleopods, and its partially overlapping distribution, in respect to M. latus Karaman, 1934, is definitively raised at specific rank. Supplementary descriptions and illustrations are reported for incompletely described species such as M. latus, M. prespensis stat. nov., M. major Karaman, 1954 and M. othrys Argano & Pesce, 1979. For some species, such as M. latus, M. othrys and M. antonellae Galassi, 1991, SEM preparations of the mouthparts, not well detailed with the optical microscopy, were carried out. According to data from the present study, a paleogeographical scenario of the Balkan Peninsula is briefly depicted in order to sketch the most significative events which led to the colonization and speciation of the Microcharon species in this area.

Genetic divergence and evolutionary times: calibrating a protein clock for South-European Stenasellus species (Crustacea, Isopoda), 1997, Argano Roberto, Sbordoni Marina Cobolli, Matthaeis Elvira De, Ketmaier Valerio
We studied genetic divergence in a group of exclusively stygobiont isopods of the family Stenasellidae. In particular, we assessed evolutionary relationships among several populations of Stenasellus racovitzai and Stenasellus virei. To place this study in a phylogenetic context. we used another species of Stenasellus, S. assorgiai, as an outgroup. S. racovitzai occurs in Corsica, Sardinia and in the fossil islands of the Tuscan Archipelago, while S. virei is a polytypic species widely distributed in the central France and Pyrenean area. This vicariant distribution is believed to be the result of the disjunction of the Sardinia-Corsica microplate from the Pyrenean region and its subsequent rotation. Since geological data provide time estimates for these events, we can use the genetic distance data to calibrate a molecular clock for this group of stygobiont isopods. The calibration of the molecular clock reveals a roughly linear relationship (r = 0.753) between the genetic distances and absolute divergence times, with a mean divergence rate (19.269 Myr/DNei,) different from those previously reported in the literature and provides an opportunity to shed some light on the evolutionary scenarios of other Stenasellus species.

A simple scenario for stygobitization in Stenobermuda Schultz, 1978 (Isopoda Asellota Stenetriidae), with description of a new species from Andros Island, Bahamas, 1997, Botosaneanu Lazare, Iliffe Thomas M.
Description of a new stygobitic and troglomorphic species of Stenobermuda from a Blue Hole in the Bahamas, is an opportunity for speculation about hypogean colonization by this and by another cave-dwelling species from Bermuda, starting from populations of a widely distributed Western Atlantic shallow water marine species.

Determining karst transmissivities with inverse modeling and an equivalent porous media, 1999, Larocque M. , Banton O. , Ackerer P. , Razack M. ,
Flow simulation is difficult to implement in heterogeneous media such as karst aquifers, primarily because the structure of the rock is extremely complex and usually unknown. The aim of this study was to verify the possibility of using inverse modeling and an equivalent porous media to identify transmissivities in a slightly karstified aquifer, the La Rochefoucauld karst (Charente, France), Different simulation scenarios were tested: using two spatial discretizations with different finite-element cell sizes and using measured or interpolated heads. The inverse modeling was performed with the downscaling parameterization procedure, using a finite-element representation of bidimensional ground water flow. The inverse modeling converged satisfactorily with all scenarios: head residuals were small and spring flow rates and the river/aquifer exchanges were adequately stimulated. The scenario using small cells and measured heads generated a highly heterogeneous transmissivity field, indicating an overparameterization of the problem. The calibrated transmissivities and simulated heads of this scenario proved less reliable overall than those of the other scenarios. The use of interpolated heads generated more uniform transmissivities as a result of the head smoothing. A rotation of the initial parameter mesh showed that the scenarios using interpolated heads generate the most stable and reliable results. The scenarios with interpolated heads could therefore be used when head measurements are limited or are unevenly distributed over the aquifer. Overall, the calibrated transmissivities reproduced the entire range of transmissivities measured in the field using different methods. The results indicate that inverse modeling and an equivalent porous media can be used to determine transmissivities in a moderately karstified aquifer

Solutionally enhanced leakage rates of dams in karst regions, 1999, Bauer S. , Birk S. , Liedl R. , Sauter M.
This paper presents numerical model studies regarding the development of leakage rates of dams in karst regions due to solutional enlargement of conduits in the rock beneath the reservoirA hybrid continuum-discrete flow model (CAVE) is used for the modelingThe fractured carbonate rock beneath the reservoir is represented by a network of initial conduitsThe effects of a preferential flowpath and a grout curtain on leakage rates are studied in different scenariosFor the parameters considered in this paper, the simulation results suggest that dissolutional widening of the network leads in all scenarios to leakage rates endangering the reservoir within 100 years

A model of early evolution of karst conduits affected by subterranean CO2 sources, 2000, Gabrovsek F, Menne B, Dreybrodt W,
In investigating early karstification of one-dimensional conduits by computer models, so far one has assumed that the CO2 content of the calcite aggressive water stems entirely from the surface. Subterranean sources of CO2, however, can rejuvenate the solutional power of water already close to equilibrium with respect to calcite, and boast dissolution rates. In a first scenario we have investigated the influence of a punctual source of CO2 as the most simple case of release of CO2 into a karstifiable fracture at some position KL from its entrance of the widening joint with length L, (K < 1). The results show that only a small increase of the p(CO2) in the solution to about 0.01 atm is sufficient to reduce the breakthrough times to about 0.3 with respect to the case, where no CO2 is delivered. Other sources of CO2 are due to the metabolic activity of microorganisms. The existence of such diverse subterraneous microbial life in karst systems demonstrated. Whether situated on the fissure surfaces or free floating in the karst water, one basic product of their metabolism is CO2. This contributes over the whole flow path to the p(CO2) of the karst water. Therefore in a second scenario we assumed a constant rate of CO2-input along parts of the fracture, as could be delivered by the activity of aerobic bacteria dwelling at its walls. Such a scenario also applies to an extended diffuse CO2 migration from volcanic activity deep underground. In this case drastic reductions of the breakthrough time by about one order of magnitude are observed. These reductions are enhanced when the fracture aperature width of the initial fracture decreases. The physicochemical mechanisms of enhancement of karstification are discussed in detail by considering the evolution of the fracture aperature width and of the dissolution rates in space and time

Climate-change impacts in a regional karst aquifer, Texas, USA, 2000, Loaiciga H. A. , Maidment D. R. , Valdes J. B. ,
Climate-change scenarios were created from scaling factors derived from several general circulation models to assess the likely impacts of aquifer pumping on the water resources of the Edwards Balcones Fault Zone (BFZ) aquifer, Texas, one of the largest aquifer systems in the United States. Historical climatic time series in periods of extreme water shortage (1947-1959), near-average recharge (1978-1989), and above-average recharge (1975-1990) were scaled to 2 x CO2 conditions to create aquifer recharge scenarios in a wanner climate. Several pumping scenarios were combined with 2 x CO2 climate scenarios to assess the sensitivity of water resources impacts to human-induced stresses on the Edwards BFZ aquifer. The 2 x CO2 climate change scenarios were linked to surface hydrology and used to drive aquifer dynamics with alternative numerical simulation models calibrated to the Edwards BFZ aquifer, Aquifer simulations indicate that, given the predicted growth and water demand in the Edwards BFZ aquifer region, the aquifer's ground water resources appear threatened under 2 x CO2 climate scenarios. Our simulations indicate that 2 x CO2 climatic conditions could exacerbate negative impacts and water shortages in the Edwards BFZ aquifer even if pumping does not increase above its present average level. The historical evidence and the results of this article indicate that without proper consideration to variations in aquifer recharge and sound pumping strategies, the water resources of the Edwards BFZ aquifer could be severely impacted under a warmer climate. (C) 2000 Elsevier Science B.V. All rights reserved

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 aquifer genesis using a coupled continuum-pipe flow model, 2000, Sauter M. , Liedl R.
This contribution presents a modeling approach for the simulation of karst aquifer genesis during geologic time periods. The approach used here is based upon a hydraulic coupling of a pipe network to a continuum in order to represent the well-known duality of karst aquifer flow systems. In addition, the growth of the karst conduits due to carbonate dissolution can be simulated so that a feedback mechanism with respect to the hydraulic properties of the pipe network is established. The model is applied to some typical scenarios of karst aquifer genesis, i. e. the evolution of a dendritic tube system and of a maze cave network. It is found that the model results can successfully reproduce the basic features of karst development, e. g. the development of maze caves in a carbonate aquifer which is covered by a sandstone caprock.

Results 1 to 15 of 76
You probably didn't submit anything to search for