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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 dissociation is a chemical process that causes a molecule to split into simpler groups of atoms, or ions. for example, the water molecule (h2o) breaks down spontaneously into h+ and oh- ions [6].?

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KarstBase a bibliography database in karst and cave science.

Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Journal of Hydrology, 2001, Vol 241, Issue 0, p. 177-193
Dispersion, retardation and scale effect in tracer breakthrough curves in karst conduits
Abstract:
Characteristics of tracer breakthrough curves in karst conduits are examined and compared to results generated using well known equations applied to porous media. The equations of the turbulent dispersion lead to a transport equation similar to the classical advection-dispersion equation for porous media with a slightly different meaning for the dispersion and advection terms. For investigations at the meter length scale, we used a three-dimensional (3-D) computational fluid dynamics (CFD) code to simulate tracer transport in several conduit geometries. The simulations show that turbulent dispersion can be considered as Fickian at a meter length scale of observation and that turbulent dispersivity depends linearly on the average flow velocity in the range of observed velocities. The simulations show that pools induce retardation (tailing of the breakthrough curve) due to flow reversal in eddies. Retardation has a complex relationship with the pool dimensions. Irregularity of the conduit cross-section along the investigated section clearly produces retardation. This is obvious at the meter length scale but may still be visible 10(3) m downstream from the injection point. A transfer function ('black box') approach is used for upscaling from a meter to a 10(3) m length scale. Before applying it to natural examples, the transfer function approach is tested by using the 3-D CFD code and appears to perform well. Several tests, based on numerical, laboratory and held experiments, of conduit segments which includes various dispersive features indicate that retardation tends to be transformed to symmetrical dispersion with distance. At large scale it appears that the dominant dispersion factor is the irregularity of the conduit geometry, which produces an increase in dispersivity with distance ('scale effect'), similar to that observed in porous media. In conclusion this suggests that retardation and high dispersion provide evidence of an irregular conduit, including either numerous dispersive features or large-scale ones (pools for example). Conversely no retardation and moderate dispersion (close to 0.012 m) must result from turbulent Row through a smooth conduit. (C) 2001 Elsevier Science B.V. All rights reserved