Influence of initial aperture variability on conduit development in hypogene settings

Rehrl, C.

doi:10.1127/0372-8854/2010/0054s2-0013

Cited by 7 publications

(5 citation statements)

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“…The resulting bimodal aperture distribution is dynamically stable and evolves both in the low and high heterogeneous settings. Similar findings were reported by Bloomfield et al (2005) and Rehrl et al (2008Rehrl et al ( , 2010 considering a generic dissolution rate law and gypsum dissolution kinetics, respectively.…”

Section: Aperture Distributionssupporting

confidence: 89%

“…In contrast, confined flow in artesian basins is expected to be more restricted than flow in unconfined settings. Simulations by Rehrl et al (2008Rehrl et al ( , 2010 addressing the evolution of conduits in artesian gypsum settings of the Western Ukraine indeed suggest that the flow rates may be sufficiently low to cause the development of unimodal aperture distributions. Because of the high solubility of gypsum, a few hundred thousand years were found to be sufficient to create maximum aperture sizes in the range of metres, whereas the maximum apertures occurring in the carbonate setting considered here are in the centimetre range even after 3 Ma (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…The number of large-aperture conduits was found to be controlled by the chosen exponent of the generic rate law used for describing dissolutional widening and also by intial aperture heterogeneity. Rehrl et al (2008Rehrl et al ( , 2010 used cumulative aperture distributions to analyse conduit evolution in artesian gypsum karst settings of the Western Ukraine. Bimodality was found to depend on the chemical saturation of the inflow but the effect of the hydraulic conductivity of the rock formation incorporating the conduit network was even more pronounced.…”

Section: Introductionmentioning

confidence: 99%

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Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

Hubinger

Birk

2011

Hydrol. Earth Syst. Sci.

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Karst aquifers evolve where the dissolution of soluble rocks causes the enlargement of discrete pathways along fractures or bedding planes, thus creating highly conductive solution conduits. To identify general interrelations between hydrogeological conditions and the properties of the evolving conduit systems the aperture-size frequency distributions resulting from generic models of conduit evolution are analysed. For this purpose, a process-based numerical model coupling flow and rock dissolution is employed. Initial protoconduits are represented by tubes with log-normally distributed aperture sizes with a mean μ<sub>0</sub> = 0.5 mm for the logarithm of the diameters. Apertures are spatially uncorrelated and widen up to the metre range due to dissolution by chemically aggressive waters. Several examples of conduit development are examined focussing on influences of the initial heterogeneity and the available amount of recharge. If the available recharge is sufficiently high the evolving conduits compete for flow and those with large apertures and high hydraulic gradients attract more and more water. As a consequence, the positive feedback between increasing flow and dissolution causes the breakthrough of a conduit pathway connecting the recharge and discharge sides of the modelling domain. Under these competitive flow conditions dynamically stable bimodal aperture distributions are found to evolve, i.e. a certain percentage of tubes continues to be enlarged while the remaining tubes stay small-sized. The percentage of strongly widened tubes is found to be independent of the breakthrough time and decreases with increasing heterogeneity of the initial apertures and decreasing amount of available water. If the competition for flow is suppressed because the availability of water is strongly limited breakthrough of a conduit pathway is inhibited and the conduit pathways widen very slowly. The resulting aperture distributions are found to be unimodal covering some orders of magnitudes in size. Under these suppressed flow conditions the entire range of apertures continues to be enlarged. Hence, the number of tubes reaching aperture sizes in the order of centimetres or decimetres continues to increase with time and in the long term may exceed the number of large-sized tubes evolving under competitive flow conditions. This suggests that conduit development under suppressed flow conditions may significantly enhance the permeability of the formation, e.g. in deep-seated carbonate settings

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Section: Aperture Distributionssupporting

confidence: 89%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

Hubinger

Birk

2011

Hydrol. Earth Syst. Sci.

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“…This switch to the external conservative control over discharge in hypogene speleogenesis subdues the positive feedback loop and the speleogenetic competitiveness and allows adjacent flow pathways to continue their growth, favoring formation of pervasive, maze-like patterns (Klimchouk 2000). This effect has been confirmed by numerical modeling of hypogene speleogenesis in a stratified aquifer system with dispersed basal recharge to the soluble bed (Birk 2002;Birk et al 2003;Rehrl et al 2008Rehrl et al , 2010. Modeling of conduit development by hydrothermal dissolution along localized cross-formational fractures (Andre & Rajaram 2005;Rajaram et al 2009) revealed that the thermal coupling between the fluid and rock also causes the suppression of the flow-growth feedback and speleogenetic competition soon after breakthrough.…”

Section: The Author Defines Hypogene Speleogenesis As the Formation Omentioning

confidence: 64%

The Karst Paradigm: Changes, Trends and Perspectives

Klimchouk

2016

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UDC 551.435.8 Alexander Klimchouk: The karst paradigm: changes, trends and perspectives The paper examines representative definitions of karst (21), and discusses some concepts that influenced the modern understanding of the phenomenon. Several trends are discussed that took karst science beyond the limits of the traditional paradigm of karst. Dramatic progress in studies of speleogenesis plays the most significant role in changes taking place in the general understanding of karst. Also important is an adoption of the broad perspective to karst evolution which goes beyond the contemporary geomorphologic epoch and encompasses the entire life of a geological formation. Speleogenesis is viewed as a dynamic hydrogeological process of self-organization of the permeability structure in soluble rocks, a mechanism of the specific evolution of the groundwater flow system. The result is that these systems acquire a new, "karstic", quality and more complex organization. Since almost all essential attributes of karst owe their origin to speleogenesis, the latter is considered as the primary mechanism of the formation of karst. Two fundamental types of speleogenesis, hypogene and epigene, differentiate mainly due to distinct hydrodynamic characteristics of the respective groundwater flow systems: (1) of layered aquifer systems and fracture-vein flow systems of varying depths and degrees of confinement, and (2) of hydrodynamically open, near-surface unconfined systems. Accordingly, two major genetic types of karst are distinguished: hypogene and epigene. They differ in many characteristics, notably in relationships with the surface, hydrogeological behaviour, groundwater quality, and the areas of practical importance and approaches to solving karst-related issues. Although views on essential attributes of karst have been clearly changing, this was not reflected in definitions of the notion which are in broad use in the earth-science literature. A refined approach is suggested to the notion of karst in which it is viewed as a groundwater (fluid) flow system of a specific kind, which has acquired its peculiar properties in the course of speleogenesis. Keywords: karst, definition of karst, speleogenesis, karst geosystem, karst evolution. IzvlečekUDK 551.435.8 Alexander Klimchouk: Kraška paradigma: spremembe, tre ndi in perspektive Dokument obravnava reprezentativne definicije krasa (21) in obravnava nekatere koncepte, ki so vplivali na sodobno razumevanje tega pojava. Razpravlja o več trendih, ki so popeljali krasoslovje preko meja tradicionalne paradigme krasa. Dramatični napredek v speleogenetskih raziskavah je igral najpomembnejšo vlogo pri spremembah, ki so se zgodile pri splošnem razumevanju krasa. Prav tako je za razvoj krasoslovja pomembno sprejetje široke perspektive, ki presega sodobno geomorfološko epoho in zajema celoten geološki razvoj. Speleogeneza je predstavljena kot dinamični hidrogeološki proces samoorganizacije stopnje prepustnosti posameznih struktur v topnih kamninah, to je kot mehanizem specifičnega ...

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“…Этими исследованиями был выявлен особый механизм спелеогенеза восходящими потоками в относительно закрытых условиях напорных водоносных комплексов, включающий «внешний» гидродинамический контроль над расходом в формирующихся карстовых каналах и скоростью их роста, осуществляемый наименее проницаемыми слоями нерастворимых пород покрова. Он был подтвержден и детально изучен работами по численному моделированию [Birk et al, 2005;Klimchouk et al, 2006;Rehrl et al, 2008Rehrl et al, , 2010 в рамках международных проектов Европейской комиссии (ROSES -Risk of Subsidence due to Evaporite Solution, 1998-2001) и немецкого фонда исследований (Void evolution in soluble rocks: Development and validation of numerical models by field evidence, [2004][2005][2006], а также работами по моделированию карстообразования в сквозьформационных гидротермальных системах [Rajaram et al, 2005;Chaudhuri et al, 2013].…”

Section: карстолого-спелеологические исследования изучение гипогенноunclassified

Development of Hydrogeology in the World and Hydrogeological Research in the Institute of Geological Sciences of the Nas of Ukraine

Шестопалов¹,

Klimchouk²,

Onyshchenko³

2018

Geological Journal

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Кандидат геолого-минералогических наук, старший научный сотрудник отдела гидрогеологических проблем. Представлен обзор развития гидрогеологии в мире и гидрогеологических исследований в Институте геологических наук НАН Украины. Рассмотрены проблемы и достижения в некоторых ключевых направлениях гидрогеологии в общемировом контексте, охарактеризованы история и содержание этих исследований в институте. С учетом имеющихся достижений и мировых трендов намечены перспективные направления гидрогеологических исследований. Ключевые слова: гидрогеология; история гидрогеологии; ключевые проблемы и тренды гидрогеологии; перспективные направления гидрогеологии; гидрогеология в Институте геологических наук НАН Украины.

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Influence of initial aperture variability on conduit development in hypogene settings

Cited by 7 publications

References 0 publications

Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

The Karst Paradigm: Changes, Trends and Perspectives

Development of Hydrogeology in the World and Hydrogeological Research in the Institute of Geological Sciences of the Nas of Ukraine

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