MWH Global

Enviroscan Ukrainian Institute of Speleology and Karstology


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_left.php on line 5
Community news

Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That cement grout is cement slurry of pumpable consistency [16].?

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


Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/template/toolbar_right.php on line 7
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.
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

Search in KarstBase

Your search for storage (Keyword) returned 166 results for the whole karstbase:
Showing 151 to 165 of 166
Hydrogeology of the Gokpinar karst springs, Sivas, Turkey, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Kacaroğ, Lu F.

Gökpınar karst springs are located 8 km to the south of the Gürün district centre, Sivas, Turkey. The springs have two main outlets (Gökpınar-1 and Gökpınar-2) and outflow from Jurassic-Cretaceous Yüceyurt formation (limestone). The total discharge of the springs ranges between 4.5 and 7.8 m3/s.The study area is formed of allocthonous and autocthonous lithological units whose ages range from Upper Devonian to Quaternary. These lithologies are mostly formed of limestones. Yüceyurt formation (limestone), from which Gökpınar karst springs outflow, constitute the main aquifer in the study area and is karstified. The unit has a well developed karst system comprising karren, dolines, ponors, underground channels and caves. The recession (discharge) analysis of the Gökpınar springs was carried out and the storage capacitiesand discharge (recession) coefficients of the Gökpınar-1 and Gökpınar-2 springs were calculated as 141×10^6 m3 and 98×10^6 m3, and 2.71×10^-3 day-1 and 2.98×10^-3 day-1, respectively. The storage capacities and discharge (recession) coefficients obtained suggest that the karst aquifer (Yüceyurt limestone) has large storage capacity, and drainage occurs very slow. The major cations in the study area waters are Ca2+ and Mg2+, and anion is HCO3-. The waters are calcium bicarbonate type. Some of the water chemistry parameters of the Gökpınar springs range as follows: T=10.8–11.1°C, pH=7.65–7.95,EC=270–310 μS/cm, TDS=170–200 mg/L, Ca2+=40.0–54.0 mg/L,Mg2+=4.5–10.0 mg/L, HCO3-=144.0–158.0 mg/L. Temperature, EC, TDS, and Ca2+ and HCO3- concentrations of the Gökpınar springs did not show significant variations during the study period.


Effective porosity of a carbonate aquifer with bacterial contamination: Walkerton, Ontario, Canada, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Worthington S. R. H. , Smart C. C. , Ruland W.

Preferential flow through solutionally enlarged fractures can be a significant influence on travel times and source area definition in carbonate aquifers. However, it has proven challenging to step beyond a conceptual model to implementing, parameterizing and testing an appropriate numerical model of preferential flow. Here both porous medium and preferential flow models are developed with respect to a deadly contamination of the municipal groundwater supply at Walkerton, Ontario, Canada. The preferential flow model is based on simple orthogonal fracture aperture and spacing. The models are parameterized from bore hole, gamma, flow and video logs resulting in a two order of magnitude lower effective porosity for the preferential flow model. The observed hydraulic conductivity and effective porosity are used to predict groundwater travel times using a porous medium model. These model predictions are compared to a number of independent estimates of effective porosity, including three forced gradient tracer tests. The results show that the effective porosity and hydraulic conductivity values closely match the preferential flow predictions for an equivalent fracture network of _10 m spacing of 1 mm fractures. Three tracer tests resulted in groundwater velocities of hundreds of meters per day, as predicted when an effective porosity of 0.05% was used in the groundwater model. These velocities are consistent with a compilation of 185 tracer test velocities from regional Paleozoic carbonate aquifers. The implication is that carbonate aquifers in southern Ontario are characterized by relatively low-volume dissolutionally enlarged fracture networks that dominate flow and transport. The porous matrix has large storage capacity, but contributes little to transport. Numerical models based on much higher porosities risk significantly underestimating capture zones in such aquifers. The hydraulic conductivity – effective porosity prediction framework provides a general analytical frame work for a preferential flow carbonate aquifer. Not only is the framework readily parameterized from borehole observations, but also it can be implemented in a conventional porous medium model, and critically tested using simple tracer tests.


Hydrogeology of the Gokpinar karst springs, Sivas, Turkey , 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Kaaroğ, Lu Fikret

Gökpınar karst springs are located 8 km to the south of the Gürün district centre, Sivas, Turkey. The springs have two main outlets (Gökpınar-1 and Gökpınar-2) and outflow from Jurassic-Cretaceous Yüceyurt formation (limestone). The total discharge of the springs ranges between 4.5 and 7.8 m3/s.The study area is formed of allocthonous and autocthonous lithological units whose ages range from Upper Devonian to Quaternary. These lithologies are mostly formed of limestones. Yüceyurt formation (limestone), from which Gökpınar karst springs outflow, constitute the main aquifer in the study area and is karstified. The unit has a well developed karst system comprising karren, dolines, ponors, underground channels and caves. The recession (discharge) analysis of the Gökpınar springs was carried out and the storage capacitiesand discharge (recession) coefficients of the Gökpınar-1 and Gökpınar-2 springs were calculated as 141×10^6 m3 and 98×10^6 m3, and 2.71×10^-3 day-1 and 2.98×10^-3 day-1, respectively. The storage capacities and discharge (recession) coefficients obtained suggest that the karst aquifer (Yüceyurt limestone) has large storage capacity, and drainage occurs very slow. The major cations in the study area waters are Ca2+ and Mg2+, and anion is HCO3-. The waters are calcium bicarbonate type. Some of the water chemistry parameters of the Gökpınar springs range as follows: T=10.8–11.1°C, pH=7.65–7.95,EC=270–310 μS/cm, TDS=170–200 mg/L, Ca2+=40.0–54.0 mg/L,Mg2+=4.5–10.0 mg/L, HCO3-=144.0–158.0 mg/L. Temperature, EC, TDS, and Ca2+ and HCO3- concentrations of the Gökpınar springs did not show significant variations during the study period.


Wet season hydrochemistry of Bribin Cave in Gunung Sewu Karst, Indonesia, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Tjahyo Nugroho Adji

This research was conducted on the Bribin River, the most important underground river in the Gunung Sewu Karst, Gunung Kidul, Java, Indonesia. The main purpose of this study was to define the wet-season hydrochemistry of this river. This research also focuses on identifying the relationship between hydrochemical parameters to provide better aquifer characterization.Water-level monitoring and discharge measurements were conducted over a 1-year period to define the discharge hydrograph. Furthermore, baseflow-separation analysis is conducted to determine the diffuse-flow percentage throughout the year. Water sampling for hydrogeochemical analysis is taken every month in the wet season and every 2 hours for two selected flood events. To describe the hydrogeochemical processes, a bivariate plot analysis of certain hydrochemical parameters is conducted. The results show that the diffuse-flow percentage significantly controls the river hydrochemistry. The domination of diffuse flow occurs during non-flooding and flood recession periods, which are typified by a high value of calcium and bicarbonate and low CO2 gas content in water. Conversely, the hydrochemistry of flood events is characterized by the domination of conduit flow and CO2 gas with low calcium and bicarbonate content. According to the wet-season hydrochemistry, it seems that the small- and medium-sized fractures in the Bribin aquifer still provide storage for the diffuse and fissure flows, although the conduit fracture is already developed.


Cave ventilation is influenced by variations in the CO2-dependent virtual temperature, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Snchezcaete E. P. , Serranoortiz P. , Domingo F. , Kowalski A. S.

Dynamics and drivers of ventilation in caves are of growing interest for different fields of science. Accumulated CO2 in caves can be exchanged with the atmosphere, modifying the internal CO2 content, affecting stalagmite growth rates, deteriorating rupestrian paintings, or creating new minerals. Current estimates of cave ventilation neglect the role of high CO2 concentrations in determining air density – approximated via the virtual temperature (Tv) –, affecting buoyancy and therefore the release or storage of CO2. Here we try to improve knowledge and understanding of cave ventilation through the use of Tv in CO2-rich air to explain buoyancy for different values of temperature (T) and CO2 content. Also, we show differences between T and Tv for 14 different experimental sites in the vadose zone, demonstrating the importance of using the correct definition of Tv to determine air buoyancy in caves. The calculation of Tv (including CO2 effects) is currently available via internet using an excel template, requiring the input of CO2 (%), air temperature (oC) and relative humidity (%).


Poljes, Ponors and Their Catchments, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Bonacci, O.

Poljes can be defined as depressions in limestone karst. They commonly occur as large-scale landforms in tectonically active karst areas. Their origin is generally polygenetic. A distinctive subtype of polje, the ‘turlough’, occurs in many formerly glaciated or glacial-margin terrains. Poljes exhibit complex hydrological and hydrogeological features and characteristics, such as permanent and temporary springs and rivers, losing and sinking rivers, and swallow holes and estavelles. From the hydrologic–hydrogeologic perspective, a polje is to be considered as part of a wider system. It cannot be treated as an independent system, but only as a subsystem in the process of surface and groundwater flow through the karst massif. Poljes are regularly flooded in the cold and wet periods of the year. Ponors or swallow holes represent fissures in the karst massif through which the water sinks underground. The determination of the catchment area for a karst polje is an unreliable procedure due to unknown morphology of underground karst features. Anthropogenic influences on the hydrological–hydrogeological regime of the poljes can be considered under the following four categories: (1) water storage; (2) increase in the capacity of outlet structures; (3) surface hydrotechnical aspects; and (4) other works. 


COMPLEX EPIKARST HYDROLOGEOLOGY AND CONTAMINANT TRANSPORT IN A SOUTH-CENTRAL KENTUCKY KARST LANDSCAPE, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Polk J. S. , Vanderhoff S. , Groves C. , Miller B. , Bolster C.

 

The movement of autogenic recharge through the shallow epikarstic zone in soil-mantled karst aquifers is important in understanding recharge areas and rates, storage, and contaminant transport processes. The groundwater in agricultural karst areas, such as Kentucky’s Pennyroyal Plateau, which is characterized by shallow epikarst and deeper conduits flow, is susceptible to contamination from organic soil amendments and pesticides. To understand the storage and flow of autogenic recharge and its effects on contaminant transport on water flowing to a single epikarst drain in Crump’s Cave on Kentucky’s Mississippian Plateau, we employed several techniques to characterize the nature and hydrogeology of the system. During 2010–2012, water samples and geochemical data were collected every four hours before, during, and between storm events from a waterfall in Crumps Cave to track the transport and residence time of epikarst water and organic soil amendments during variable flow conditions. Geochemical data consisting of pH, specific conductivity, temperature, and discharge were collected continuously at 10-minute intervals, along with rainfall amounts. In addition, stable isotope data from rainfall, soil water, and epikarst water were collected weekly and during storm events to examine storage and recharge behavior of the system. The changes in geochemistry indicate simultaneous storage and transport of meteoric water through epikarst pathways into the cave, with rapid transport of bacteria occurring through the conduits that bypass storage. The isotopic data indicate that recharge is rapidly homogenized in the epikarst, with storage varying throughout the year based on meteorological conditions. Results indicate current best management practices in agricultural karst areas need to be revisited to incorporate areas that do not have surface runoff, but where contaminants are transported by seepage into local aquifers.


Characterization and conceptualization of a relict karst aquifer (Bilecik, Turkey), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Aydin H. , Ekmekci M. , Soylu M. E.

The carbonate rocks in Turkey have different hydrogeological properties as a result of controlling karstification factors, such as lithostratigraphy, source of energy gradient, tectonic activity, type of erosion base, fluctuation in sea level, and climate change in their extended areas. This study was undertaken for the characterization and conceptualization of the hydrogeological behavior of a unique example of the dissected relict karst aquifer, which is known as the Harmanköy-Beyyayla Karst System (HBKS) in Central Turkey. In order to obtain the conceptualization of the HBKS, properties of recharge, flow, storage, and discharge was analyzed. The contribution of allogenic-point recharge to the Beyyayla and Döşkaya aquifers occurs from the Beyyayla and Tozman sinkhole with approximately 85% of total recharge. The rest of the recharge takes place as autogenic-diffuse/point type from the limestone rock-mass. The recharge on the Nardın aquifer originates from direct precipitation onto the limestone area mainly as autogenic-diffuse and, to lesser extent, as autogenic-point. Groundwater flow occurs as conduit flow at the Beyyayla and Döşkaya aquifers and as dispersed flow at the Nardın aquifer. The evaluation of all parameters shows that the HBKS can be divided into three distinct sub-catchments, namely, the Beyyayla, Döşkaya, and Nardın, while it has two different hydrogeological system so Beyyayla and Döşkaya have similar characteristics.


DELINEATION AND CLASSIFICATION OF KARST DEPRESSIONS USING LIDAR: FORT HOOD MILITARY INSTALLATION, TEXAS, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Shaw Faulkner M. G. , Stafford K. W. , Bryant A. W.

The Fort Hood Military Installation is a karst landscape characterized by Cretaceous-age limestone plateaus and canyons in Bell and Coryell Counties, Texas. The area is located in the Lampasas Cut Plain region of the Edwards Plateau and is stratigraphically defined by exposures of the Fredericksburg Group. Spatial interpolation of 105 km2 of the Fort Hood Military Installation provided depression data that were delineated and classified using geoanalytical methods. Most of the karst features within the study area are predominantly surficial expressions of collapse features, creating windows into karst conduits with surficial exposures of epikarst spatially limited.The increasing capabilities of GIS (Geographic Information Systems) and accuracy of geographically referenced data has provided the basis for more detailed terrain analysis and modeling. Research on terrain-related surface features is highly dependent on terrain data collection and the generation of digital models. Traditional methods such as field surveying can yield accurate results; however, they are limited by time and physical constraints. Within the study area, dense vegetation and military land use preclude extensive traditional karst survey inventories. Airborne Light Detection and Ranging (LiDAR) provides an alternative for high-density and high-accuracy three-dimensional terrain point data collection. The availability of high density data makes it possible to represent terrain in great detail; however, high density data significantly increases data volume, which can impose challenges with respect to data storage, processing, and manipulation. Although LiDAR analysis can be a powerful tool, filter mechanisms must be employed to remove major natural and anthropogenic terrain modifications resulting from military use, road building and maintenance, and the natural influence of water bodies throughout the study area.


Interpretation of hydrogeological functioning of a high karst plateau using the KARSYS approach: the case of Trnovsko-Banjška planota (Slovenia), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Turk Janez, Malard Arnauld, Jeannin Pierreyves, Vouillamoz Jonathan, Masini Jean, Petrič Metka, Gabrovšek Franci, Ravbar Nataša, Slabe Tadej

The high karst plateau of Trnovsko­Banjška planota is one of the most important reservoirs of karst water in Slovenia. Almost all important karst springs in this area are captured for water supply. A sustainable management of this source of groundwater is of strategic importance, not only as drinking water supply but also for the economy. For these reasons, many hydrogeological monitoring studies have been carried out over the last decades. However, no consistent regional overview of the hydrogeological functioning of Trnovsko­Banjška planota was available and we decided to study this area with more direct approach based on 3D geological and hydrogeological models. The so called KARSyS approach was developed in Switzerland and applied primarily to characterize groundwater reserves within a karst massif, and to sketch the main flow­paths carrying groundwater from recharge areas to the respective springs. The delineation of spring catchment areas in karst regions was better defined and interactions between catchments were interpreted. These results can be used to improve the management of karst waters in the studied area.


Karst aquifer average catchment area assessment through monthly water balance equation with limited meteorological data set: Application to Grza spring in Eastern Serbia, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Vakanjac Vesna Ristić, Prohaska Stevan, Dušan Polomčić, Blagojević Borislava, Vakanjac Boris

In the absence of detailed exploration of karstic catchments, the calculation of available reserves and elements of the water balance equation frequently reflect the topographic size of the catchment area, and not the actual, active (underground) size. The two differ largely where karst is concerned. The paper deals with the problem of average catchment area size estimation in the situation when meteorological data are limited to precipitation and temperature, but discharge records are available for long period. Proposed methodology was applied to, calibrated, and validated on 15 karst springs in Serbia. Results obtained with the model differ up to 20% from hydrogeological exploration results. One of investigated springs is Grza karst spring, which belongs to the karstic formation of Kučaj and Beljanica (the Carpatho­Balkanide Arch of Eastern Serbia). In this paper, we used the Grza Spring to show model application and necessary improvements to progress from graphoanalytical to analytical model. The average catchment area is linked to the model parameter that reduces potential to real evapotranspiration on monthly bases. The model potential lies in the possibility to determine not only catchment area, but real evapotranspiration and dynamic volume of the porous ­ karst groundwater storage as well.


Carbon fluxes in Karst aquifers: Sources, sinks, and the effect of storm flow, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
White William B.

An effective carbon loading can be calculated from measured alkalinity and pH of karst waters. The carbon loading is independent of the degree of saturation of the water and does not depend on the water being in equilibrium with the carbonate wall rock. A substantial data base of spring water analyses accumulated by students over the past 40 years has been used to probe the CO2 generation, transport, and storage in a variety of drainage basins that feed karst springs. Carbon loading in the water exiting karst drainage basins depends on the rate of CO2 generation in the soils of the catchment areas and on the partitioning between CO2 dissolved in infiltration water and CO2 lost by diffusion upward to the atmosphere. For any given drainage basin there are also influences due to vegetative cover, soil type, and the fraction of the water provided by sinking stream recharge. Losses of CO2 back to the atmosphere occur by speleothem deposition in air-filled caves, by degassing of CO2 in spring runs, and by tufa deposition in spring runs. There are seasonal cycles of CO2 generation that relate growing season and contrasts in winter/summer rates of CO2 generation. Overall, it appears that karst aquifers are a net, but leaky, sink for atmospheric CO2


A framework for assessing the role of karst conduit morphology, hydrology, and evolution in the transport and storage of carbon and associated sediments, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Veni George

Karst aquifers and conduits form by dissolution of carbonate minerals and the slow release of inorganic carbon to the surface environment. As conduits evolve in size, morphology, and position within the aquifer, their function and capacity change relative to the storage and transport of inorganic and organic carbon as sediment. Conduits serve mostly as transport mechanisms in relation to sediments. quantified data are sparse, but for conduits to function effectively there must be at least equilibrium in the amount of sediment entering and exiting the aquifer. If sediment discharge exceeds input, little sediment will remain underground. when natural declines in base level cease removing sediments and only deposit calcite speleothems, these materials are stored until the rock mass is denuded. while sediment storage is mostly transient in hydrologically active conduits, relative differences occur. Aquifers with conduits developed at multiple levels or as floodwater mazes store proportionately greater volumes of sediment. Hypogenic systems should store greater volumes of sediment than epigenic aquifers because they mostly discharge a dissolved load as opposed to both dissolved and suspended clastic loads. However, some hypogenic aquifers are diffusely recharged and receive and store little sediment from the surface. The global volume of sediment and organic carbon stored in karst aquifers is estimated in this study to be on the order of 2x104 km3 and 2x102 km3, respectively. The amount of organic carbon stored in paleokarst is not estimated, but available data indicate it is substantially greater than that stored in modern karst aquifers. Development of such data may suggest that paleokarst petroleum reservoirs might serve as efficient carbon sinks for global carbon sequestration. Hydrocarbon-depleted paleokarst reservoirs should provide substantially more storage per injection well than sequestration in non-paleokarstic rocks.


Using hydrogeochemical and ecohydrologic responses to understand epikarst process in semi-arid systems, Edwards plateau, Texas, USA, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Schwartz Benjamin F. , Schwinning Susanne, Gerrard Brett, Kukowski Kelly R. , Stinson Chasity L. , Dammeyer Heather C.

The epikarst is a permeable boundary between surface and subsurface environments and can be conceptualized as the vadose critical zone of epigenic karst systems which have not developed under insoluble cover. From a hydrologic perspective, this boundary is often thought of as being permeable in one direction only (down), but connectivity between the flow paths of water through the epikarst and the root systems of woody plants means that water moves both up and down across the epikarst. However, the dynamics of these flows are complex and highly dependent on variability in the spatial structure of the epikarst, vegetation characteristics, as well as temporal variability in precipitation and evaporative demand. Here we summarize insights gained from working at several sites on the Edwards Plateau of Central Texas, combining isotopic, hydrogeochemical, and ecophysiological methodologies. 1) Dense woodland vegetation at sites with thin to absent soils (0-30 cm) is in part supported by water uptake from the epikarst. 2) However, tree transpiration typically becomes water-limited in dry summers, suggesting that the plant-available fraction of stored water in the epikarst depletes quickly, even when sustained cave drip rates indicate that water is still present in the epikarst. 3) Flow paths for water that feeds cave drips become rapidly disconnected from the evaporation zone of the epikarst and out of reach for plant roots. 4) Deep infiltration and recharge does not occur in these systems without heavy or continuous precipitation that exceeds some threshold value. Thresholds are strongly correlated with antecedent potential evapotranspiration and rainfall, suggesting control by the moisture status of the epikarst evapotranspiration zone. The epikarst and unsaturated zone in this region can be conceptualized as a variably saturated system with storage in fractures, matrix porosity, and in shallow perched aquifers, most of which is inaccessible to the root systems of trees, although woody vegetation may control recharge thresholds.


Physical Structure of the Epikarst, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Jones, William K.

Epikarst is a weathered zone of enhanced porosity on or near the surface or at the soil/bedrock contact of many karst landscapes. The epikarst is essentially the upper boundary of a karst system but is also a reaction chamber where many organics accumulate and react with the percolating water. The epikarst stores and directs percolating recharge waters to the underlying karst aquifers. Epikarst permeability decreases with depth below the surface. The epikarst may function as a perched aquifer with a saturated zone that transmits water laterally for some distance until it drains slowly through fractures or rapidly at shaft drains or dolines. Stress-release and physical weathering as well as chemical dissolution play a role in epikarst development. Epikarst may be found on freshly exposed carbonates although epikarst that develops below a soil cover should form at a faster rate due to increased carbon dioxide produced by vegetation. The accumulation of soil within the fractures may create plugs that retard the downward movement of percolating water and creates a reservoir rich in organic material. The thickness of the epikarst zone typically ranges from a few meters to 15 meters, but vertical weathering of joints may be much deeper and lead to a “stone forest” type of landscape. Some dolines are hydrologically connected directly to the epikarst while other dolines may drain more directly to the deeper conduit aquifer and represent a “hole” in the epikarst. water stored in the epikarst may be lost to evapotranspiration, move rapidly down vertical shafts or larger joints, or drain out slowly through the soil infillings and small fractures. Much of the water pushed from the epikarst during storms is older water from storage that is displaced by the new event water.


Results 151 to 165 of 166
You probably didn't submit anything to search for