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 total pore space is the sum of interconnected and noninterconnected pore space [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 correlation (Keyword) returned 209 results for the whole karstbase:
Showing 196 to 209 of 209
Hhlendunkel und Wissbegierde - Eine Kulturgeschichte der Hhlenforschung in Europa von der Antike bis zur Romantik, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Mattes, J.
On the basis of the constructivist culture theory the traditional research interests of the history of science were renewed in the 1990ies. The article bases upon an oral presentation at the Austrian Society for the History of Science. In contrast to the dominating micro historic studies in the history of speleology, the paper provides an overview of the human activity in caves from ancient world to the beginning of the 19th century. This includes not only the scientific study of caves, but also sightseeing tours, the investigation and opening of caves undertaken by scientific laymen. The focus doesnt lie on single explorers and their attainments, but concentrates on the changes in the perception and interpretation of the underground cavities as well as on the practice of the visitors and explorers. The results show an intimate correlation between the scientific and cultural discourses to the interior of the earth. The people in the antiquity and Middle Ages interpreted caves as sexualized areas, which refer to social taboos. Simultaneously caves were used for protection and as a place for religious meditations. During the Baroque period they became the location of bizarre objects, admiring promenades and aristocratic celebrations. In the Romantic period the netherworld was seen as an area of inwardness and edification. Geologists and paleontologists discovered them as archives of natural history; artists recognized caves as areas of spiritual revelation, where ancient myths were updated.

Isotopic composition of atmospheric precipitation and karstic springs of the north-west slope of the Crimean Mountains, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Dublyansky Y. V. , Klimchouk . B. , Amelichev G. N. , Tokarev S. V. , Sptl C

 

Atmospheric precipitation was sampled for isotopic analyses according to GNIP protocol at two stations in Crimea,
Ukraine: Simferopol (24 months) and Chatyrdag (15 months). In addition, several karstic springs and one well tapping deep karstic aquifer were sampled. The δD vs. δ18O relationship is only slightly differs from global Meteoric Water Line. Variable degrees of correlation with the air temperature and the precipitation amount suggest that the isotopic composition of precipitation is affected by several processes (e.g., air temperature and supply of moisture from different sources). Interestingly, drastically different makeups of precipitation were observed simultaneously at two stations located only 23 km apart. Waters in seven karstic springs discharging at Dolgorukovsky massif (2), Chatirdag (1), Baidarsky basin (3), and Mangup-kale (1) have isotopic compositions that follow local meteoric water line but are lighter than weighted annual mean values for their respective catchment areas. Isotopic composition of the underground stream in Krasnaya (Red) cave is nearly constant and thus, decoupled from changes in both the isotopic composition of atmospheric precipitation in the recharge area and the flow regime (flood or base flow). This suggests a strong buffering and homogenizing role of the soil cover and the epikarst zone, as well as the predominant role of winter recharge on these karst massifs. Still lighter isotopic composition of deep karstic water tapped by a borehole is tentatively explained by old, pre-Holocene age of this water.

Isotopic composition of atmospheric precipitation and karstic springs of the north-west slope of the Crimean Mountains, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Dublyansky Y. V. , Klimchouk . B. , Amelichev G. N. , Tokarev S. V. , Spotl, C.

Atmospheric precipitation was sampled for isotopic analyses according to GNIP protocol at two stations in Crimea, Ukraine: Simferopol (24 months) and Chatyrdag (15 months). In addition, several karstic springs and one well tapping deep karstic aquifer were sampled. The δD vs. δ18O relationship is only slightly differs from global Meteoric Water Line. Variable degrees of correlation with the air temperature and the precipitation amount suggest that the isotopic composition of precipitation is affected by several processes (e.g., air temperature and supply of moisture from different sources). Interestingly, drastically different makeups of precipitation were observed simultaneously at two stations located only 23 km apart. Waters in seven karstic springs discharging at Dolgorukovsky massif (2), Chatirdag (1), Baidarsky basin (3), and Mangup-kale (1) have isotopic compositions that follow local meteoric water line but are lighter than weighted annual mean values for their respective catchment areas. Isotopic composition of the underground stream in Krasnaya (Red) cave is nearly constant and thus, decoupled from changes in both the isotopic composition of atmospheric precipitation in the recharge area and the flow regime (flood or base flow). This suggests a strong buffering and homogenizing role of the soil cover and the epikarst zone, as well as the predominant role of winter recharge on these karst massifs. Still lighter isotopic composition of deep karstic water tapped by a borehole is tentatively explained by old, pre-Holocene age of this water


The nature and origin of the ghost-rocks at Bullslaughter Bay, South Wales, 2012,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Rowberry Matt D. , Battiauqueney Yvonne, Blazejowski Blazej, Walsh Peter

The ‘ghost-rocks’ of the British Isles have attracted very little research interest over the years despite being widely distributed. In South Wales, the ghost-rocks of the Pembroke Peninsula are usually associated with the mudrock formations immediately above and below the Carboniferous Limestone. This study focuses on their nature and origin through a detailed investigation of the cliff sections at Bullslaughter Bay. The investigated ghost-rocks are associated with a suite of breccias, collectively termed the Gash Breccias. These are an enigmatic suite of around twenty-five large breccia masses located exclusively in the eastern part of the peninsula. They comprise huge masses of coarse, chaotic, clast-supported, monomictic breccia and represent highly disturbed features in the otherwise unbroken sequences of Carboniferous Limestone. Their origin may be karstic, tectonic, or a combination of the two. They could, theoretically, have formed at any point between the end of the Carboniferous and the Pliocene. If their origin is karstic, it cannot yet be determined if the processes were attributable to per descensum or per ascensum groundwater systems. If tectonic, it is not known whether they formed during periods of compression or extension. From our own geological and geophysical fieldwork, we believe that the breccias originated as a result of subterranean karstic processes whilst retaining an open mind with regard to the role played by tectonics. The breccia and ghost-rocks are both displayed in fine cliff exposures around Bullslaughter Bay. These sections, although not extensive, are extremely instructive. The processes that generate ghost-rock result in isovolumetric weathering of the host rock and an associated loss of density and strength. They may or may not involve the removal of certain chemical constituents in the regolith through solution and hydrolysis followed by the formation of secondary minerals, frequently clay. In reality, the precise weathering process differs according to the type of rock. The process is controlled by the permeability of each rock type in banded rocks such as mudstones or shale with banded chert whereas it is controlled by fissures and faults in homogenous rocks. This control is clearly seen in the Carboniferous Limestone around Bullslaughter Bay, where ghost-rocks are present, more commonly in case of impure or dolomitic limestone. At present, it is not clear whether the groundwater movements were caused by hydrothermal or meteoric processes and this forms the basis of ongoing research. Finally, the study considers the relationship that exists between the ghost-rock and the Gash Breccia. We examine whether there is a logical correlation between the processes that came to generate the ghost-rock and the processes responsible for the generation of the breccia. It may then be possible to accurately state whether the ghost-rock formed before, during, or after, the breccia. The reasons that the ghost-rocks of the British Isles have attracted very little research interest may stem from the fact that they have no current commercial value, have seldom presented engineering problems, and are normally difficult to date. It is clear that numerous karst related sag-subsidences in the British Isles result from the large-scale decalcification of the Carboniferous Limestone (e.g. the Tortonian Brassington Formation of the southern Pennines). There is, however, an increasingly large body of evidence to suggest that these subsidences result from the same processes that generate ghost-rock rather than those that create endokarstic voids. The subsidences may preserve stratigraphical sequences several decametres thick and reach depths and widths of many hectometres. Unfortunately, the masses of decalcified limestone below the Tortonian sediments are of no commercial interest and have hardly ever been penetrated by boreholes. Therefore, we do not know exactly what underlies the karstic fills. The possibility that most of these structures are best explained as the result of per ascensum groundwater flow is discussed.


Discussion on the article Coastal and inland karst morphologies driven by sea level stands: a GIS based method for their evaluation by Canora F, Fidelibus D and Spilotro G, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
De Waele Jo, Parise Mario

Comments are presented on the article by Canora et al. (2012) dealing with karst morphologies driven by sea level stands in the Murge plateau of Apulia, southern Italy. Our comments start from cave levels, that are considered in the cited article as a proof of sea level stands. We argue that the presence of sub-horizontal passages in cave systems is not a sufficient condition for correlating them with hypothetical past sea level stands. Such a correlation must be based upon identification of speleogenetic features within the karst systems, and/or geological field data. The problems encountered when using cave surveys for scientific research, and their low reliability (especially in the case of old surveys) are then treated, since they represent a crucial point in the paper object of this discussion. Eventually, we present some final consideration on cave levels and terraces, and on the specific case study, pointing out once again to the need in including geological field data to correctly find a correspondance between flat landforms and sea level fluctuations. Our main conclusion is that field data and information on speleogenesis of the underground karst landforms cannot be disregarded in a study that claims to deal with the influence of sea-level changes on caves.


TRITIUM AND H, O AND C STABLE ISOTOPES AS A TOOL FOR TRACKING OF WATER CIRCULATION IN THE NIEDŹWIEDZIA CAVE SYSTEM (SUDETES, POLAND), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Gą, Siorowski M. Hercman H.

 

Water circulation in Niedźwiedzia Cave system is complicated. The system is fed by direct infiltration of precipitation, infiltration from the surface stream and, possibly, by rising flow from deep sources. The cave is drained by system of karst springs in the Kleśnica stream valley, but some part of water flows across border ridge and occurs in Morava stream valley, Czech Republic (Ciężkowski et al. 2009). We tried to use tritium and stable isotopes to describe hydrology of the cave system and analyzed 155 water samples for stable isotopes and 38 water samples for tritium content. The Niedźwiedzia Cave system is composed of three levels of halls and galleries. In the upper level, stable isotope composition in drip water plots close to the local meteoritic water line (LMWL) on the δ18O vs δD diagram. It varies during the year similar to stable isotope composition of precipitation (i.e. low δ18O values during winters and higher δ18O during summers). The delay between isotopic signal in precipitation and drip water is ~10–14 days and this can be interpreted as a time of infiltration from the surface to the cave upper level. The correlation between isotopic composition of precipitation and drip water is not observed in the lower level of the cave system. There isotopic composition of drip water is more stable during the year. We use tritium dating method to estimate the age of this water. It has shown that infiltration time to the lower level is 1.4±0.3 year. The “oldest” water was found in karst spring draining the cave system. The estimated transit time is 3–4 years and suggest admixture of some “old” water that was not sampled in the cave.


INCIDENCES OF THE TECTONICS IN THE KARSTIFICATION OF CHALK LIMESTONES IN THE WESTERN PARIS BASIN: EXAMPLE FROM THE PETITES DALES CAVE (SAINT MARTIN AUX BUNEAUX, FRANCE), 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Rodet J. , Ma K. , Viard J. P.

 

The classical approach to study the karstification attributes a major role to the structure in the establishment of concentrated drainage of groundwater. This structure, essentially tectonics and stratigraphy, serves to guide the water, which gradually opens up these discontinuities to build a network, from the introduction to the resurgence. This too idealistic view does not reflect the complexity of the establishment of a karst system. Indeed, experience shows that some bedrocks contain karst drains in the absence of any cracking. What’s more, some conduits can go through the structural elements without undergoing any morphological changes. In the chalk of Western Paris Basin, the Petites Dales Cave proves an excellent observatory. We have conducted a study on the relationship between the main conduit, restitution collector of the underground system, and observable fissures in the roof and walls of the conduit. Along a drain of 421 m, we counted 374 fissures, the total length of which being a little more than 867 m. Examination of the orientation of the drain and fissures reveals four types of relationship: (1) parallel (2) oblique, (3) perpendicular and (4) no joints. No correlation could be established between the development of the collector and the presence of fissures, other than very occasionally or during episodes of overflow. In fact, the relationship between fissure and karstic conduit cannot be established, therefore it is necessary to introduce other factors in the speleogenesis, such as porosity of the chalky bedrocks, and the direct effect of the hydraulic gradient.


Aquatic biota of different karst habitats in epigean and subterranean systems of Central Brazil visibility versus relevance of taxa, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Luiza Bertelli Simes, Tnia Cristina Dos Santos Ferreira, Maria Elina Bichuette

The karstic area of São Domingos, central Brazil, holds extensive drainage systems. In order to understand its biodiversity, various volumes of water were filtered with planktonic nets in stretches of subterranean and superficial rivers on five different occasions. We sampled four drips (152L), three calcite pools (368L), two subterranean rivers fed mainly by percolation water (6, 395L), two subterranean rivers fed mainly by water coming from a sinkhole (4, 175L) along different caves, one resurgence (158L), and four epigean rivers (101, 690L). Physical and chemical variables were measured at some sites. Canonical Correlation Analysis was used to verify relationships between taxa and environment. The degree of similarity of the biota was assessed by cluster analysis (Sorensen, single linkage). There were records of exclusive taxa in epigean and subterranean samples, mainly in drips, which harbour the most unique fauna. The high richness of taxa presently recorded reveals the potential of the vadose zone biota in the tropical region, which was neglected in studies on Brazilian subterranean biodiversity. According to our results, the unsaturated zone tropical fauna may have different composition compared to that from temperate habitats. The studied communities were dominated by rotifers, while crustacean are predominant in the latter. The hypothesis can be clarified with the increase of long term studies and taxa identification at species level, besides the use of complementary sampling methods.


Early results of micro-deformation measurements in Magdalena Jama (Slovenia) by a vertical static pendulum, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Kalenda Pavel, Neumann Libor, Šebela Stanka

Vertical static pendulums have been installed in mines or caves in Central Europe since 2007. Two­dimensional optical measurement of the tilt of a rock mass and continuous fully digital on­line evaluation of results makes possible the detection of a small tilt of the surroundings with a resolution of tens of nanoradians or the deformation of the surroundings in the horizontal plane with resolution of hundreds of nanometres. The paper describes the measurement device and the first results of the measurements in Magdalena Jama, which is part of the Postojna Cave System (Slovenia). The correlation of deformation between distant stations shows the existence of stress variations that are not only of local origin (high floods, local seismicity, and aseismic deformations). The stress field has a wider, and not only regional, character with effects that can be observed very far from the origin.


Temporal variability of karst aquifer response time established by the sliding-windows cross-correlation method, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Delbarta Célestine, Valdesd Danièle, Barbecotg Florent, Tognellia Antoine, Richona Patrick, Couchouxh Laurent

We study the temporal variability of water transfer through the infiltration zone of a karst aquifer by estimating the impulse response of the system using cross-correlogram analyses between rainfall and piezometric level time series. We apply a sliding-window cross-correlation method, which calculates cross-correlograms on partially superposed short time series windows. We apply this method for rainfall and piezometric level time series at six boreholes in a fractured karstic aquifer located in Burgundy, France. Based on cross-correlogram functions, we obtain a time series of response time. At most of the boreholes, the cross-correlation functions change over time, and the response times vary seasonally, being shorter during the summer. This unusual structure can be partly explained by the seasonal variability in rainfall intensity, which is higher during the summer (May–September), inducing the seasonal behaviour of the epikarst. During the summer, when rainfall intensity is higher, the epikarst is more easily and quickly saturated. This induces an increase in lateral water transfer within the epikarst and an increase in concentrated fast flows. We also show that the response time seems to tend towards a limit which represents the maximum saturation of the epikarst.


Discussion on the article ‘Coastal and inland karst morphologies driven by sea level stands: a GIS based method for their evaluation’ by Canora F, Fidelibus D and Spilotro G, 2013,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Waele J. D. , Parise M.

Comments are presented on the article by Canora et al. (2012) dealing with karst morphologies driven by sea level stands in the Murge plateau of Apulia, southern Italy. Our comments start from cave levels, that are considered in the cited article as a proof of sea level stands. We argue that the presence of sub-horizontal passages in cave systems is not a sufficient condition for correlating them with hypothetical past sea level stands. Such a correlation must be based upon identification of speleogenetic features within the karst systems, and/or geological field data. The problems encountered when using cave surveys for scientific research, and their low reliability (especially in the case of old surveys) are then treated, since they represent a crucial point in the paper object of this discussion. Eventually, we present some final consideration on cave levels and terraces, and on the specific case study, pointing out once again to the need in including geological field data to correctly find a correspondance between flat landforms and sea level fluctuations. Our main conclusion is that field data and information on speleogenesis of the underground karst landforms cannot be disregarded in a study that claims to deal with the influence of sea-level changes on caves.


Focused Groundwater Flow in a Carbonate Aquifer in a Semi-Arid Environment, 2014,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Green R. T. , Bertetti F. P. , Miller M. S.

An efficient conveyance system for groundwater is shown to have formed in a carbonate aquifer even though it is situated in a semi-arid environment. This conveyance system comprises preferential flow pathways that developed coincident with river channels. A strong correlation between high capacity wells and proximity to higher-order river channels (i.e., within 2.5 km) is used as evidence of preferential flow pathways. Factors that contributed to development of the preferential flow paths: (i) karst development in carbonate rocks, (ii) structural exhumation of a carbonate plateau, and (iii) the requirement that the groundwater regime of the watershed has adequate capacity to convey sufficient quantities of water at the required rates across the full extent of the watershed. Recognition of these preferential pathways in proximity to river channels provides a basis to locate where high capacity wells are likely (and unlikely) and indicates that groundwater flow within the watershed is relatively rapid, consistent with flow rates representative of karstic aquifers. This understanding provides a basis for better informed decisions regarding water-resource management of a carbonate aquifer in a semi-arid environment.


Caractérisation et modélisation hydrodynamique des karsts par réseaux de neurones. Application à l’hydrosystème du Lez , 2014,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943
Virgile, Taver

Improving knowledge of karst hydrodynamics represents a global challenge for water resources because karst aquifers provide approximately 25% of the world population in fresh water. Nevertheless, complexity, anisotropy, heterogeneity, non-linearity and possible non-stationarity of these aquifers make them underexploited objects due to the difficulty to characterize their morphology and hydrodynamics. In this context, the systemic paradigm proposes others methods by studying these hydrosystems through input-output (rainfall-runoff) relations.

The approach proposed in this thesis is to use information from field measurement and from systemic analyses to constrain neural network models. The goal is to make these models interpretable in terms of hydrodynamic processes by making model functioning to be similar to natural system in order to obtain a good representation and extract knowledge from model parameters.

This work covers the association of information available on the hydrosystem with correlation and spectral analyses to develop a temporal multiresolution decomposition of variables and to constrain neural network models. A new method for variable selection, adapted to represent long term hydrodynamics of the system, has been proposed. These constrained models show very good results and allow, through their parameters, to study the temporal contribution of inputs variables to the output.

Modeling nonlinear and non-stationary hydrosystems with neural network has been improved by a novel implementation of data assimilation. More precisely, when non-stationarity is attributed to the catchment, data assimilation is used to modify the model parameters. When the inputs are non-stationary, data assimilation can be used to modify the inputs.

The modification of inputs opens considerable scope to: i) fill gaps or homogenizing time series, ii) estimate effective rainfall.

Finally, these various analyses and modeling methods, mainly developed on the karst hydrosystem Lez, can improve the knowledge of the rainfall-runoff relationship at different time scales. These methodological tools thus offer perspectives of better management of the aquifer in terms of floods and resources. The advantage of these analyses and modeling tools is that they can be applicable to other systems.


Initial conditions or emergence: What determines dissolution patterns in rough fractures?, 2015,
Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/isthin5/public_html/addon-domains/speleogenesis.info/include/functions1.php on line 943

Dissolution of fractured rocks is often accompanied by the formation of highly localized flow paths. While the fluid flow follows existing fractures in the rock, these fissures do not, in general, open uniformly. Simulations and laboratory experiments have shown that distinct channels or “wormholes”develop within the fracture, from which a single highly localized flow path eventually emerges. The aim of the present work is to investigate how these emerging flow paths are influenced by the initial aperture field. We have simulated the dissolution of a single fracture starting from a spatially correlated aperture distribution. Our results indicate a surprising insensitivity of the evolving dissolution patterns and flow rates to the amplitude and correlation length characterizing the imposed aperture field. We connect the similarity in outcomes to the self-organization of the flow into a small number of wormholes, with the spacing determined of the longest wormholes. We have also investigated the effect of a localized region of increased aperture on the developing dissolution patterns. A competition was observed between the tendency of the high-permeability region to develop the dominant wormhole and the tendency of wormholes to spontaneously nucleate throughout the rest of the fracture. We consider the consequences of these results for the modeling of dissolution in fractured and porous rocks.


Results 196 to 209 of 209
You probably didn't submit anything to search for