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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 glacial deposit is sedimentary deposits due to transport by glaciers [16].?

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

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What is Karstbase?



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.
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;
See all featured articles from other geoscience journals

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Your search for surface-water (Keyword) returned 60 results for the whole karstbase:
Showing 31 to 45 of 60
Results from the Big Spring basin water quality monitoring and demonstration projects, Iowa, USA, 2001,
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Rowden R. D. , Liu H. B. , Libra R. D. ,
Agricultural practices, hydrology, and water quality of the 267-km(2) Big Spring groundwater drainage basin in Clayton County, Iowa, have been monitored since 1981. Land use is agricultural; nitrate-nitrogen (-N) and herbicides are the resulting contaminants in groundwater and surface water. Ordovician Galena Group carbonate rocks comprise the main aquifer in the basin. Recharge to this karstic aquifer is by infiltration, augmented by sinkhole-captured runoff. Groundwater is discharged at Big Spring, where quantity and quality of the discharge are monitored. Monitoring has shown a threefold increase in groundwater nitrate-N concentrations from the 1960s to the early 1980s. The nitrate-N discharged from the basin typically is equivalent to over one-third of the nitrogen fertilizer applied, with larger losses during wetter years. Atrazine is present in groundwater all year; however, contaminant concentrations in the groundwater respond directly to recharge events, and unique chemical signatures of infiltration versus runoff recharge are detectable in the discharge from Big Spring. Education and demonstration efforts have reduced nitrogen fertilizer application rates by one-third since 1981. Relating declines in nitrate and pesticide concentrations to inputs of nitrogen fertilizer and pesticides at Big Spring is problematic. Annual recharge has varied five-fold during monitoring, overshadowing any water-quality improvements resulting from incrementally decreased inputs

Water budget and vertical conductance for Lowry (Sand Hill) Lake in north-central Florida, USA, 2001,
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Motz L. H. , Sousa G. D. , Annable M. D. ,
Water-budget components and the vertical conductance were determined for Lowry (Sand Hill) Lake in north-central Florida, USA. In this type of lake, which interacts with both the surface-water and groundwater systems, the inflow components are precipitation, surface-water inflow, groundwater inflow, and direct runoff (i.e. overland flow), and the outflow components are evaporation, groundwater outflow, and surface-water outflow. In a lake and groundwater system that is typical of many karst lakes in Florida, a large part of the groundwater outflow occurs by means of vertical leakage through an underlying confining unit to a deeper, highly transmissive aquifer called the upper Floridan aquifer. The water-budget component that represents vertical leakage to the upper Floridan aquifer was calculated as a residual using the water-budget equation. For the 13 month period from August 1994 to August 1995, relative to the surface area of the lake, rainfall at Lowry Lake was 1.55 m yr(-1), surficial aquifer inflow was 0.79 m yr(-1), surface-water inflow was 1.92 m yr(-1), and direct runoff was 0.01 m yr(-1). Lake evaporation was 1.11 m yr(-1), and surface-water outflow was 1.61 m yr(-1). The lake stage increased 0.07 m yr(-1), and the vertical leakage to the upper Floridan aquifer was 1.48 m yr(-1). Surficial aquifer outflow from the lake was negligible. At Lowry Lake, vertical leakage is a major component of the water budget, comprising about 35% of the outflow during the study period. The vertical conductance (K-V/b), a coefficient that represents the average of the vertical conductances of the hydrogeologic units between the bottom of a lake and the top of he upper Floridan aquifer, was determined to be 2.51 x 10(-4) day(-1) for Lowry Lake. (C) 2001 Elsevier Science B.V. All rights. reserved

Geostatistical and geochemical analysis of surface water leakage into groundwater on a regional scale: a case study in the Liulin karst system, northwestern China, 2001,
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Wang Y. , Ma T. , Luo Z. ,
The Liulin karst system is typical of hydrogeological systems in northern China, with a group of springs as the dominant way of regional groundwater discharge. Surface water leakage into groundwater has been observed in six sections of the rivers in the study area. To extract hydrogeological information from hydrochemical data, 29 water samples were collected from the system. On a trilinear diagram, most of the groundwater samples are clustered around the surface waters, indicating the effect of leakage on their chemistry. R-mode factor analysis was made on seven variables (Na, Ca, Mg, SO4, Cl, HCO3, and NO3) of the samples and three principal factors were obtained: the F-1 factor is composed of Ca, Mg and SO4, the F-2 of HCO3 and NO3, and the F-3 of Na and Cl. These factors are then used as regionalized variables in ordinary Kriging for unbiased estimates of the spatial variations of their scores. Considering regional hydrogeological conditions, the hydrogeological implications of the spatial distribution of the factor scores as related to the effects of the surface leakage are discussed. To evaluate the geochemical processes, the geochemical modeling code NETPATH was employed. The modeling results: show that mixing commonly occurs in the system and dolomite dissolution is more important than calcite dissolution. Dedolomitization (calcite precipitation and dolomite dissolution driven by anhydrite dissolution) is locally important, in the western flank of the system where the surface water leakage has the least effect.

Determining the source of stream contamination in a karst water system, southwest Virginia, USA, 2001,
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Younos T. , Kaurish F. W. , Brown T. , De Leon R. ,
Karst terrane provides a linkage between surface water and ground water regimes by means of caves, sinkholes and swallets, and sinking streams, and facilitates the inter-watershed transfer of water and contaminants through these subsurface systems. The goal of this study was to develop procedures to identify the sources of degradation of a creek situated in a complex karst-water system. The study approach consisted of using dye tracing technique to determine subsurface flow paths through the karst system, a water-sampling network to identify and characterize pollution sources within the surface watershed and subsurface flow regime, and evaluation of analytical data for several water quality parameters. The results of this study provide an interesting perspective of water and contaminant movement in karst-water systems and pinpoint the sources of stream contamination for a case study site in southwest Virginia where two springs supply water to a contaminated freshwater stream

Application of morphometric relationships to active flow networks within the Mammouth Cave Watershed, MSc Thesis., 2001,
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Glennon, A.

Numerous quantitative relationships have been formulated to describe the nature of surface-drainage networks. These parameters have been used in various studies of geomorphology and surface-water hydrology, such as flood characteristics, sediment yield, and evolution of basin morphology. Little progress has been made in applying these quantitative descriptors to karst flow systems due to the lack of sufficiently complete data and inadequate technology for processing the large, complex data sets. However, as a result of four decades of investigation, an abundance of data now exists for the Mammoth Cave Watershed providing the opportunity for broader quantitative research in the organization of a large, highly-developed, karst-drainage network. Developing Geographic Information System (GIS) technology has provided tools to 1) book-keep the karst system's large, complex spatial data sets, 2) analyze and quantitatively model karst processes, and 3) visualize spatially and temporally complex data. []Karst aquifers display drainage characteristics that in many ways appear similar to surface networks. The purpose of my research was to explore techniques by which quantitative methods of drainage-network analysis can be applied to the organization and flow patterns in the Turnhole Bend Groundwater Basin of the Mammoth Cave Watershed. []Morphometric analysis of mapped active base-flow, stream-drainage density within the Turnhole Bend Groundwater Basin resulted in values ranging from 0.24 km/km2 to 1.13 km/km2. A nearby, climatologically similar, nonkarst surface drainage system yielded a drainage density value of 1.36 km/km2. Since the mapped cave streams necessarily represent only a fraction of the total of underground streams within the study area, the actual subsurface values are likely to be much higher. A potential upper limit on perennial drainage density for the Turnhole Bend Groundwater Basin was calculated by making the assumption that each sinkhole drains at least one first-order stream. Using Anhert and Williams’ (1998) average of 74 sinkholes per km2 for the Turnhole Bend Groundwater Basin, the minimum flow-length draining one km2 is 6.25-7.22 km (stated as drainage density, 6.25-7.22 km/km2). []Stream ordering of cave streams and their catchments generally follow Hortonian relationships observed for surface-stream networks. Subsurface streams within the Mammoth Cave Watershed generally exhibit a converging, dendritic pattern and possess drainage basins proportionately large for their order. However, even at base-flow conditions, the Turnhole Bend drainage system continues to possess confounding characteristics. These include at least one leakage to an adjacent groundwater basin (Meiman et al., 2001), diverging streams sharing the same surface catchment (Glennon and Groves, 1997), and highly complex, three-dimensional basin boundaries (Meiman et al., 2001). In spite of the incomplete data set available for the Mammoth Cave Watershed, study of initial values suggests an orderly subsurface flow network with numerical results that allow for comparison of the karst-flow network to surface fluvial systems.

Coastal karst springs in the Mediterranean basin : study of the mechanisms of saline pollution at the Almyros spring (Crete), observations and modelling, 2002,
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Arfib B, De Marsily G, Ganoulis J,
Variations in salinity and flow rate in the aerial, naturally salty spring of Almyros of Heraklion on Crete were monitored during two hydrological cycles. We describe the functioning of the coastal karstic system of the Almyros and show the influence of the duality of the flow in the karst (conduits and fractured matrix) on the quality of the water resource in the coastal area. A mechanism of saltwater intrusion into this highly heterogeneous system is proposed and validated with a hydraulic mathematical model, which describes the observations remarkably well. Introduction. - Fresh groundwater is a precious resource in many coastal regions, for drinking water supply, either to complement surface water resources, or when such resources are polluted or unavailable in the dry season. But coastal groundwater is fragile, and its exploitation must be made with care to prevent saltwater intrusion as a result of withdrawal, for any aquifer type, porous, fractured or karstic. In karstic zones, the problem is very complex because of the heterogeneous nature of the karst, which makes it difficult to use the concept of representative elementary volume developed for porous or densely fractured systems. The karstic conduits focus the major part of the flow in preferential paths, where the water velocity is high. In coastal systems, these conduits have also an effect on the distribution of the saline intrusion. As was shown e.g. by Moore et al. [1992] and Howard and Mullings [1996], both freshwater and salt-water flow along the fractures and conduits to reach the mixing zone, or the zone where these fluids are superposed in a dynamic equilibrium because of their differences in density ; but the dynamics of such a saltwater intrusion are generally unknown and not represented in models. Such coastal karstic systems are intensely studied at this moment in the Mediterranean region [Gilli, 1999], both as above sea-level or underwater springs, for potential use in areas where this resource would be of great value for economic development. This article discusses the freshwater-saltwater exchange mechanisms in the karstic aquifer of the Almyros of Heraklion aquifer (Crete) and explains the salinity variations observed in the spring. First, the general hydrogeology of the study site is described, then the functioning of the spring : a main conduit drains the freshwater over several kilometres and passes at depth through a zone where seawater is naturally present. The matrix-conduit exchanges are the result of pressure differences between the two media. These processes are represented in a mathematical model that confirms their relevance. General hydrogeology of the studied site. - The karstic coastal system of the Almyros of Heraklion (Crete) covers 300 km2 in the Ida massif whose borders are a main detachment fault, and the Sea of Crete in the north, the Psiloritis massif (highest summit at 2,456 m) in the south and west, and the collapsed basin of Heraklion filled in by mainly neo-geneous marl sediments in the east. The watershed basin consists of the two lower units of characteristic overthrust formations of Crete (fig. 1) : the Cretaceous Plattenkalk and the Cretaceous Tripolitza limestones. The two limestone formations are locally separated by interbedded flysch or phyllade units that form an impervious layer [Bonneau et al., 1977 ; Fassoulas, 1999] and may lead to different flow behaviour within the two karstic formations. Neo-tectonic activity has dissected these formations with large faults and fractures. The present-day climate in Crete is of Mediterranean mountain type, with heavy rain storms and snow on the summits in winter. Rainfall is unevenly distributed over the year, with 80 % of the annual total between October and March and a year-to-year average of 1,370 mm. The flow rate of the spring is high during the whole hydrologic cycle, with a minimum in summer on the order of 3 m3.s-1 and peak flow in winter reaching up to 40 m3.s -1. The water is brackish during low flow, up to a chloride content of 6 g.l-1, i.e. 23 % of seawater, but it is fresh during floods, when the flow rate exceeds 15 m3.s-1. During the 1999-2000 and 2000-2001 hydrologic cycles, the water was fresh during 14 and 31 days, respectively. The water temperature is high and varies very little during the year (see table I). In the areas of Keri and Tilissos (fig. 1), immediately south of the spring, the city of Heraklion extracts water from the karstic system through a series of 15 wells with depth reaching 50 to 100 m below sea level. Initially, when the wells were drilled, the water was fresh, but nowadays the salinity rises progressively, but unequally from well to well (fig. 2). The relatively constant temperatures and salinities of the wells, during the hydrological cycle, contrast with the large salinity variations at the spring (fig. 2 and table I). They show that the karstic system is complex and comprises different compartments, where each aquifer unit reacts to its individual pressures (pumping, rainfall) according to its own hydrodynamic characteristics [Arfib et al., 2000]. The Almyros spring seems disconnected from the surrounding aquifer and behaves differently from that which feeds the wells (upper Tripolitza limestone). It is recharged by fresh water from the mountains, which descends to depths where it probably acquires its salinity. The spring would thus be the largest resource of the area, if it was possible to prevent its pollution by seawater. A general functioning sketch is proposed (fig. 3), which includes the different geological units of interest. Identification of the functioning of the Almyros spring through monitoring of physical and chemical parameters. - The functioning of the aquifer system of the Almyros spring was analysed by monitoring, over two hydrological cycles, the level of the spring, the discharge, the electric conductivity and the temperature recorded at a 30 min time interval. In the centre of the watershed basin, a meteorological station at an altitude of 800 m measures and records at a 30 min time interval the air temperature, rainfall, relative humidity, wind velocity and direction ; moreover, an automatic rain gauge is installed in the northern part of the basin at an altitude of 500 m. The winter floods follow the rhythm of the rainfall with strong flow-rate variations. In contrast, the summer and autumn are long periods of drought (fig. 7). The flow rate increases a few hours after each rainfall event ; the water salinity decreases in inverse proportion to the flow rate a few hours to a few days later. Observations showed that the water volume discharged at the Almyros spring between the beginning of the flow rate increase and the beginning of the salinity decrease is quite constant, around 770,000 m3 (fig. 4) for any value of the flow rate, of the salinity and also of the initial or final rainfall rates. To determine this constant volume was of the upmost importance when analyzing the functioning of the Almyros spring. The lag illustrates the differences between the pressure wave that moves almost instantaneously through the karst conduit and causes an immediate flow rate increase after rainfall and the movement of the water molecules (transfer of matter) that arrives with a time lag proportionate to the length of the travel distance. The variation of the salinity with the flow rate acts as a tracer and gives a direct indication of the distance between the outlet and the seawater entrance point into the conduit. In the case of the Almyros, the constant volume of expelled water indicates that sea-water intrusion occurs in a portion of the conduit situated several kilometres away from the spring (table II), probably inland, with no subsequent sideways exchange in the part of the gallery leading up to the spring. As the lag between the flow rate and the salinity recorded at the spring is constant, one can correct the salinity value by taking, at each time step, with a given flow rate, the salinity value measured after the expulsion of 770,000 m3 at the spring, which transforms the output of the system so as to put the pressure waves and the matter transfer in phase [Arfib, 2001]. After this correction, the saline flux at the spring, equal to the flow rate multiplied by the corrected salinity, indicates the amount of sea-water in the total flow. This flux varies in inverse proportion to the total flow rate in the high-flow period and the beginning of the low-flow period, thereby demonstrating that the salinity decrease in the spring is not simply a dilution effect (fig. 5). The relationship that exists between flow rate and corrected salinity provides the additional information needed to build the conceptual model of the functioning of the part of the Almyros of Heraklion aquifer that communicates with the spring. Freshwater from the Psiloritis mountains feeds the Almyros spring. It circulates through a main karst conduit that descends deep into the aquifer and crosses a zone naturally invaded by seawater several kilometers from the spring. The seawater enters the conduit and the resulting brackish water is then transported to the spring without any further change in salinity. The conduit-matrix and matrix-conduit exchanges are governed by the head differences in the two media. Mathematical modelling of seawater intrusion into a karst conduit Method. - The functioning pattern exposed above shows that such a system cannot be treated as an equivalent porous medium and highlights the influence of heterogeneous structures such as karst conduits on the quantity and quality of water resources. Our model is called SWIKAC (Salt Water Intrusion in Karst Conduits), written in Matlab(R). It is a 1 D mixing-cell type model with an explicit finite-difference calculation. This numerical method has already been used to simulate flow and transport in porous [e.g. Bajracharya and Barry, 1994 ; Van Ommen, 1985] and karst media [e.g. Bauer et al., 1999 ; Liedl and Sauter, 1998 ; Tezcan, 1998]. It reduces the aquifer to a single circular conduit surrounded by a matrix equivalent to a homogeneous porous medium where pressure and salinity conditions are in relation with sea-water. The conduit is fed by freshwater at its upstream end and seawater penetrates through its walls over the length L (fig. 6) at a rate given by an equation based on the Dupuit-Forchheimer solution and the method of images. The model calculates, in each mesh of the conduit and at each time step, the head in conditions of turbulent flow with the Darcy-Weisbach equation. The head loss coefficient {lambda} is calculated by Louis' formula for turbulent flow of non-parallel liquid streams [Jeannin, 2001 ; Jeannin and Marechal, 1995]. The fitting of the model is intended to simulate the chloride concentration at the spring for a given matrix permeability (K), depth (P) and conduit diameter (D) while varying its length (L) and its relative roughness (kr). The spring flow rates are the measured ones ; at present, the model is not meant to predict the flow rate of the spring but only to explain its salinity variations. Results and discussion. - The simulations of chloride concentrations were made in the period from September 1999 to May 2001. The depth of the horizontal conduit where matrix-conduit exchanges occur was tested down to 800 m below sea level. The diameter of the conduit varied between 10 and 20 m, which is larger than that observed by divers close to the spring but plausible for the seawater intrusion zone. The average hydraulic conductivity of the equivalent continuous matrix was estimated at 10-4 m/s. A higher value (10-3 m/s) was tested and found to be possible since the fractured limestone in the intrusion zone may locally be more permeable but a smaller value (10-5 m/s) produces an unrealistic length (L) of the saline intrusion zone (over 15 km). For each combination of hydraulic conductivity, diameter and depth there is one set of L (length) and kr (relative roughness) calibration parameters. All combinations for a depth of 400 m or more produce practically equivalent results, close to the measured values. When the depth of the conduit is less than 400 m, the simulated salinity is always too high. Figure 7 shows results for a depth of 500 m, a diameter of 15 m and a hydraulic conductivity of 10-4 m/s. The length of the saltwater intrusion zone is then 1,320 m, 4,350 m away from the spring and the relative roughness coefficient is 1.1. All the simulations (table II) need a very high relative roughness coefficient which may be interpreted as an equivalent coefficient that takes into account the heavy head losses by friction and the variations of the conduit dimensions which, locally, cause great head losses. The model simulates very well the general shape of the salinity curve and the succession of high water levels in the Almyros spring but two periods are poorly described due to the simplicity of the model. They are (1) the period following strong freshwater floods, where the model does not account for the expulsion of freshwater outside the conduit and the return of this freshwater which dilutes the tail of the flood and (2) the end of the low-water period when the measured flux of chlorides falls unexpectedly (fig. 5), which might be explained by density stratification phenomena of freshwater-saltwater in the conduit (as observed in the karst gallery of Port-Miou near Cassis, France [Potie and Ricour, 1974]), an aspect that the model does not take into account. Conclusions. - The good results produced by the model confirm the proposed functioning pattern of the spring. The regulation of the saline intrusion occurs over a limited area at depth, through the action of the pressure differences between the fractured limestone continuous matrix with its natural saline intrusion and a karst conduit carrying water that is first fresh then brackish up to the Almyros spring. The depth of the horizontal conduit is more than 400 m. An attempt at raising the water level at the spring, with a concrete dam, made in 1987, which was also modelled, indicates that the real depth is around 500 m but the poor quality of these data requires new tests to be made before any firm conclusions on the exact depth of the conduit can be drawn. The Almyros spring is a particularly favorable for observing the exchanges in the conduit network for which it is the direct outlet but it is not representative of the surrounding area. To sustainably manage the water in this region, it is essential to change the present working of the wells in order to limit the irreversible saline intrusion into the terrain of the upper aquifers. It seems possible to exploit the spring directly if the level of its outlet is raised. This would reduce the salinity in the spring to almost zero in all seasons by increasing the head in the conduit. In its present state of calibration, the model calculates a height on the order of 15 m for obtaining freshwater at the spring throughout the year, but real tests with the existing dam are needed to quantify any flow-rate losses or functional changes when there is continual overpressure in the system. The cause of the development of this karstic conduit at such a great depth could be the lowering of the sea level during the Messinian [Clauzon et al., 1996], or recent tectonic movements

Evaporite karst and resultant geohazards in China, 2002,
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Lu Y. R. , Zhang F. E. , Qi J. X. , Xu J. M. , Guo X. H. ,
The main kinds of evaporite karst, both sulphate karst and halide karst, are widely distributed in China. Gypsum karst is especially widespread, because China contains the largest gypsum resources in the world. These gypsum deposits range in age from Precambrian to Quaternary, and they were deposited in many environments, including marine, lacustrine, thermal process, metamorphic, and also as secondary deposits. Halide karst is developed in rock salt and salt-water lakes, the latter related to more than 300 salt-water lakes distributed in the Qinghai Plateau of Xizang (Tibet) province. Gypsum and halite are easily dissolved; therefore, development of evaporite karst is somewhat different when compared with carbonate karst, which has developed many typical features in China. This paper discusses the mechanism and development of evaporite karst in sulphate rocks and in halides, and makes comparisons between evaporite karst and carbonate karst based upon field investigations and new tests in the laboratory. The geohazards of evaporite karst usually are triggered by natural karst processes, but often they are exaggerated by artificial (human) actions and engineering impacts that cause flesh groundwater or surface water to come in contact with the evaporite rocks. Some examples of evaporite-karst geohazards are described in this paper; they are present in Shandong, Sichuan, and Guizhou Provinces, and in the Qinghai Plateau of China

Conditioning factors in flooding of karstic poljes - the case of the Zafarraya polje (South Spain), 2002,
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Lopezchicano A. , Calvache M. L. , Martinrosales W. , Gisbert J. ,
The Zafarraya polje undergoes periodical flooding, of which the last episode (1996-1997) was analysed in detail on this paper. On the basis of the retention curves of the two lakes that formed in the northwestern and southwestern sectors, we calculated the total infiltration capacity of the polje to have a maximum value of 3 - 3.5 m(3)/s and so we infer that when the flow of the Arroyo de la Madre exceeds this figure, there will be a risk of flooding in the polje. We also propose a model for the 1996 flood that can be extended to other similar occurrences in this and other poljes where we can establish the role played by groundwater and surface water during this flood. In response to the heavy precipitation, the flow of the Arroyo de la Madre rose abruptly, exceeding the infiltration capacity of the main swallow holes on the polje, causing first the northern lake and then the southern lake to form with only surface water supply. The water table of the karst aquifer rose sharply, reaching a situation of equilibrium between the level in the lakes and the water table in this sector of the karst aquifer that prevented infiltration through the swallow holes. In the case of the southern lake, there were even cases of swallow holes that began to operate as estavelles. During this phase of maximum flooding, one single lake was present, which was divided into two once more when the water table of the karst aquifer in the polje sector began to fall and surface supply also began to decrease. (C) 2002 Elsevier Science B.V. All rights reserved

Deep karst conduits, flooding, and sinkholes: lessons for the aggregates industry, 2002,
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Lolcama J. L. , Cohen H. A. , Tonkin M. J. ,
Limestone aggregate quarries in deeply penetrating karst terrain are often at considerable risk of artesian inflow from groundwater or surface water channeled through the karstic aquifer. The inflow occurs through what are likely to be complex conduits that penetrate hundreds of feet into bedrock. Rates of inflow can exceed the operation's pumping capabilities proving to be uneconomic to manage over the long term. Over time, inflow rates can increase dramatically as turbulent flow through the conduit erodes its soft residual clay-rich fill. One recent investigation observed an inflow rate of more than 40,000 gpm from a surface water source. Floodwater persistently laden with sediment is an indicator of conduit washout and implies increasing inflow rates over time. Conduits carrying floodwater can exist in a variety of forms: along deeply penetrating geologic faults, joints, or following the path of preferentially eroded bedding. Preferential structural deformation along faults or bedding can enhance dissolution during subsequent interaction with groundwater. The resulting conduit may be a complex combination of many geological features, making the exploration and remediation of the pathway difficult. Sinkholes at the site can occur within several contexts. Pre-existing subsidence structures can reactivate and subside further, forming new collapse sinkholes within soil directly overlying the conduit. Cover-collapse sinkhole development can be a direct result of increasing downward groundwater velocities and subsurface erosion associated with the enlargement of a conduit. Normal operation events such as a quarry blast can also provide a significant new linkage between the groundwater and the quarry, allowing rapid drainage of the groundwater reservoir. With such drainage and erosion of karst-fill, sinkholes will develop over localized water table depressions, most significantly over enhanced permeability zones associated with fractures. Paradoxically, although the rise in quarry water level will lead to regional reduction in the hydraulic gradients, on local scales, drainage of the groundwater reservoir increases gradients and leads to the development of cover-collapse sinkholes. Recommended methods for preliminary site investigation can include a detailed review of geological literature and drilling logs to compile a conceptual model of the site. A fracture trace analysis with EM geophysics can confirm the locations of major faults and fractures. Fingerprinting of the various water sources to the quarry and the water in the quarry is an inexpensive and effective means of identifying the source and likely direction of the groundwater and surface water flow. Automated geophysical equipment on the market for performing rapid resistivity and microgravity surveys speeds up the site screening process during reconnaissance exploration for deep structure. It is recommended that mine planning fully incorporate this information so that quarry operators can take proactive measures to avoid catastrophic and costly flooding events. (C) 2002 Elsevier Science B.V. All rights reserved

Efficient hydrologic tracer-test design for tracer-mass estimation and sample-collection frequency, 2. Experimental results, 2002,
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Field Ms,
Effective tracer-test design requires that the likely results be predicted in advance of test initiation to ensure tracer-test success. EHTD-predicted breakthrough curves (BTCs) for various hydrological conditions were compared with measured BTCs obtained from actual tracer tests. The hydrological conditions for the tracer tests ranged from flowing streams to porous-media systems. Tracer tests evaluated included flowing streams tracer tests conducted in small and large surface-water streams, a karst solution conduit, and a glacial-meltwater stream and porous-media systems conducted as natural-gradient, forced-gradient, injection-withdrawal, and recirculation tracer tests. Comparisons between the actual tracer tests and the predicted results showed that tracer breakthrough, hydraulic characteristics, and sample-collection frequency may be forecasted sufficiently well in most instances as to facilitate good tracer-test design. Comparisons were generally improved by including tracer decay and/or retardation in the simulations. Inclusion of tracer decay in the simulations also tended to require an increase in set average tracer concentration to facilitate matching peak concentrations in the measured BTCs, however. Both nonreactive tracer and reactive tracer predictions produced recommended sample-collection frequencies that would adequately define the actual BTCs, but estimated tracer-mass estimates were less precise

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

Using stable isotope analysis (delta D-delta O-18) to characterise the regional hydrology of the Sierra de Gador, south east Spain, 2002,
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Vandenschrick G. , Van Wesemael B. , Frot E. , Pulidobosch A. , Molina L. , Stievenard M. , Souchez R. ,
Water stress is rapidly increasing in many Mediterranean coastal zones mainly due to expansion in agriculture and tourism. In this paper, we focus on the Sierra de Gador-Campo de Dalias aquifer system (southeastern Spain) in order to assess the capability of water stable isotope analysis (deltaD-delta(18)O) to refine the understanding on recharge of this karstic aquifer system. Different types of surface and groundwater were sampled along an altitudinal gradient from the recharge zone in the mountains to the coastal plain. Surface water is restricted to local runoff, collected in closed reservoirs. Runoff amounts, collected in three of these reservoirs were monitored together with the precipitation in their catchments. Meteorological maps were used to detect the origin of the precipitation generating the majority of the runoff. The results were compared to literature data on local and regional precipitation. The use of oxygen and hydrogen isotopic composition has proved to be a useful tool to explain the origin of groundwater in a Mediterranean karstic system. Such studies are, however, not numerous and are often limited to local scale recharge for fast-reacting systems. This paper focuses on the delta(18)O-deltaD relationships of local precipitation to explain the isotopic variability of a large karstic aquifer system. The isotopic compositions of groundwater sampled along an altitudinal gradient from the recharge zone to the coastal plain are well displayed, in a deltaD-delta(18)O diagram, on a mixing line connecting a pole of Mediterranean waters to a pole of Atlantic waters. The Atlantic signature predominates in the shallow groundwater of natural springs, reflecting the rainfall which produced the local runoff sampled. The Mediterranean signature is mainly restricted to deep groundwater from boreholes in the coastal plain. The existence of a degree of spatial separation of groundwater types demonstrates that groundwater flow in a complex karstic system is not always continuous. The Mediterranean signature of deep groundwater could be due to past extreme rainfall events during which connectivity between recharge and reservoir exists, while at the same time the Atlantic signature of recent winter rains dominates in shallow groundwater. The assumption that an equilibrium in isotopic composition is established within a continuous aquifer and that therefore a slope lower than 8 in a deltaD-delta(18)O diagram indicates evaporation is not necessarily valid.

Last glacial-Holocene paleoceanography of the Black Sea and Marmara Sea: stable isotopic, foraminiferal and coccolith evidence, 2002,
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Aksu Ae, Hiscott Rn, Kaminski Ma, Mudie Pj, Gillespie H, Abrajano T, Yasar D,
Multi-proxy data and radiocarbon dates from several key cores from the Black Sea and Marmara Sea document a complex paleoceanographic history for the last ~30[punctuation space]000 yr. The Marmara Sea was isolated from both the Black Sea and the Aegean Sea during glacial periods when global sea-level lowering subaerially exposed the shallow sills at the Straits of Bosphorus and Dardanelles (i.e. lake stage), and reconnected through both straits during interglacial periods, when rise of global sea level breached the shallow sills (i.e. gateway stage). Micropaleontological data show that during the `lake stage' the surface-water masses in both the Marmara Sea and Black Sea became notably brackish; however, during the `gateway stages' there was a low-salinity surface layer and normal marine water mass beneath. Two sapropel layers are identified in the Marmara Sea cores: sapropels M2 and M1 were deposited between ~29.5 and 23.5 ka, and ~10.5 and 6.0 ka, respectively. Micropaleontological and stable isotopic data show that the surface-water salinities were reduced considerably during the deposition of both sapropel layers M2 and M1, and calculation using planktonic foraminiferal transfer functions shows that sea-surface temperatures were notably lower during these intervals. The presence of fauna and flora with Black Sea affinities and the absence of Mediterranean fauna and flora in sapropels M1 and M2 strongly suggest that communication existed with the Black Sea during these times. A benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the Marmara Sea rapidly followed the establishment of fully marine conditions at ~11-10.5 ka, and are attributed to Black Sea outflow into the Marmara Sea since 10.5 ka. These suboxic conditions have persisted to the present. The data discussed in this paper are completely at odds with the `Flood Hypothesis' of Ryan et al. (1997), and Ryan and Pitman (1999)

Origin and Significance of Postore Dissolution Collapse Breccias Cemented with Calcite and Barite at the Meikle Gold Deposit, Northern Carlin Trend, Nevada, 2003,
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Emsbo P, Hofstra Ah,
The final event in a complicated hydrothermal history at the Meikle gold deposit was gold deficient but caused extensive postore dissolution of carbonate, collapse brecciation, and precipitation of calcite and barite crystals in the resulting cavities. Although previously interpreted to be part of the Carlin-type hydrothermal system, crosscutting relationships and U-Th-Pb geochronology constrain this hydrothermal event to late Pliocene time (ca. 2 Ma), nearly 36 Ma after ore formation. Mineralogic, fluid inclusion, and stable isotope data indicate that postore hydrothermal fluids were reduced, H2S-rich, unevolved meteoric waters ({delta}18O = -17{per thousand}) of low temperature (ca. 65{degrees}C). The{delta} 18O values of barite and calcite indicate that these minerals were in isotopic equilibrium, requiring that barite SO4 was derived from the oxidation of reduced sulfur; however, preexisting sulfides in breccia cavities were not oxidized. The{delta} 34S (15{per thousand}) values of barite are higher than those of local bulk sulfide and supergene alunite indicating that SO4 was not derived from supergene oxidation of local sulfide minerals. The 15 per mil {delta}34S value suggests that the H2S in the fluids may have been leached from sulfur-rich organic matter in the local carbonaceous sedimentary rocks. A reduced H2S-rich fluid is also supported by the bright cathodoluminescence of calcite which indicates that it is Mn rich and Fe poor. Calcite has a narrow range of {delta}13C values (0.3-1.8{per thousand}) that are indistinguishable from those of the host Bootstrap limestone, indicating that CO2 in the fluid was from dissolution of the local limestone. These data suggest that dissolution and brecciation of the Bootstrap limestone occurred where H2S-rich fluids encountered more oxidizing fluids and formed sulfuric acid (H2SO4). Intense fracturing in the mine area by previous structural and hydrothermal events probably provided conduits for the descent of oxidized surface water which mixed with the underlying H2S-rich waters to form the dissolving acid. The surface-derived fluid apparently contained sufficient oxygen to produce H2SO4 from H2S but not enough to alter pyrite to Fe oxide. Although H2S is an important gold-transporting ligand, the temperature was too low to transport a significant amount of gold. The presence of analogous calcite- and barite-lined cavities in other Carlin-type deposits suggests that the generation (and oxidation) of H2S-rich meteoric waters was a common phenomenon in north-central Nevada. Previous sulfur isotope studies have also shown that the Paleozoic sedimentary rocks were the principal source of H2S in Devonian sedimentary exhalative-type, Jurassic intrusion-related, Eocene Carlin-type, and Miocene low-sulfidation gold deposits in the region. The similar sulfur source in all of these systems suggests that basin brines, magmatic fluids, and meteoric waters all evolved to be H2S-rich ore fluids by circulation through Paleozoic sedimentary rocks. Thus, although not directly related to gold mineralization, the recent hydrologic history of the deposit provides important clues to earlier ore-forming processes that were responsible for gold mineralization

Evaluation of a peat filtration system for treating highway runoff in a karst setting, 2003,
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Zhou W. F. , Beck B. F. , Green T. S. ,
The deleterious character of highway runoff, especially following long periods without precipitation, has been well documented in the literature. It transports hydrocarbons, heavy metals, and other contaminants from highways, contributing to the pollution of surface water and groundwater. Groundwater is particularly vulnerable in karst areas where highway runoff is transferred quickly into subsurface conduit networks through open sinkholes and/or sinking streams. The difficulties in remediating contaminated karst aquifers make it crucial for karst aquifers to receive only uncontaminated water. A peat filtration system was constructed at the I-40/I-640 interchange in eastern Knoxville, Tennessee, USA, to remove highway runoff contaminants prior to being transported into karst aquifers.- Recent field tests indicate that the system can significantly decrease the concentrations of analyzed constituents including PAHs (polyaromatic hydrocarbons), popper, and zinc. However, the removal efficiency depends on the concentration of the contaminants in the runoff. Long-term monitoring is required to determine the true effectiveness of the designed filtration system and its reliability

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