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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 ridge is an elongated narrow elevation [16].?

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

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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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;
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Your search for cover-collapse (Keyword) returned 15 results for the whole karstbase:
Showing 1 to 15 of 15
Sinkholes, soils, fractures, and drainage: Interstate 70 near Frederick, Maryland, 1997,
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Boyer Bw,
Numerous sinkholes have recently formed on both sides of Interstate 70 south of Frederick, Maryland, All the sinkholes are cover-collapse types, which form when soil cavities grow upward from the bedrock surface until their roofs become unstable, Areas at greatest risk for sinkhole development lie within a network of dry swales, The roughly dendritic map pattern and presence of allochthonous siliciclastic alluvium suggest that these swales are the vestiges of a vanished surface drainage system. Sinkholes occur mainly along bedrock escarpments underlying the swales, which are located along an easterly-trending transverse fracture and a series of strike-parallel fractures which intersect with it. Although the surface drainage appears to have Bowed east and north in the past, surface runoff in large quantities is infiltrating the ground or directly entering some of the sinkholes, then following subsurface conduits which convey it southward under the highway. Compaction grouting has been employed to prevent collapse or further subsidence of the most threatened portions of the highway. Soil Survey maps can be useful in locating cryptic intermittent or relict drainage pathways which may be at high risk for sinkhole formation when subjected to anthropogenic concentrations of perched storm water

Cover-collapse sinkholes in the 'Tournaisis' area, southern Belgium., 1999,
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Kaufmann O. , Quinif Y.

Cover-collapse sinkhole formation and piezometric surface drawdown, 2001,
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Tharp T. M.

Geohazard map of cover-collapse sinkholes in the 'Tournaisis' area, southern Belgium, 2002,
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Kaufmann O. , Quinif Y. ,
This paper reports the methodology developed to draw up a geohazard map of cover-collapse sinkhole occurrences in the 'Toumaisis' area. In this area, Carboniferous limestones are overlain by a Mesocenozoic cover, mainly consisting of marls, sand and clay. The thickness of this cover ranges from a few meters to more than 100 m. The surficial morphology of the area does not show any karstic evidence except for the occurrence of these collapses. From a paleogeographical point of view, a developed quaternary karst is not conceivable in the area. Recent works suggested that the collapses are set off from reactivated paleokarsts. The paleokarsts studied in the area proved to be the result of a particular weathering of the limestone. The organization of these paleokarsts seems very low and mainly guided by the limestone fracturing. As for most induced sinkholes, the reactivation of these paleokarsts is linked to the lowering of piezometric heads. In most of the area, a thick cover and intensive land use mask potential surface hints of the buried paleokarsts and of the fracturing of the bedrock. Aerial photographs and remote sensing techniques have therefore shown little results in delineating collapse hazard zones up to now. The study of the surficial morphology is also of little help. In order to draw up the geohazard map in such a difficult context, hydrogeological data and geological mapping information could only be used. These informations are based on a limited number of boreholes and piezometers and are thus, only valid on a regional scale. Records of former collapses were also available. These records were of great interest since sinkhole distribution is obviously clustered in the area. Bedrock roof and cover formation floor altitudes were digitized and adapted to produce digital thematic maps. Piezometric heads were imported from a calibrated groundwater model of the aquifer. These data and a digital elevation model of the area were integrated into a geographical information system (GIs) to produce a coherent 3-D description of the area on a regional scale. Parameters such as the dewatering of the limestone and the thickness of the cover formation where sinkholes occurred were then estimated. Density of former collapses was also computed. This showed that zones of high sinkhole occurrence coincide with zones of heavy lowering of piezometric heads. Combining the density of former collapses with the dewatering of the limestone enabled us to delineate zones of low, moderate and high collapse hazard. (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

Geological and geotechnical context of cover collapse and subsidence in mid-continent US clay-mantled karst, 2002,
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Cooley T,
This paper presents a synthesis of geologic and geotechnical concepts to present a unified model of conditions controlling The development of cover-collapse sinkholes and associated ground subsidence. Appropriate engineering response to the hazards associated with collapse and subsidence requires a full understanding of the underlying mechanisms that produce such effects. The geotechnical characteristics of the overlying clay mantle and occurrence of the associated cover-collapse features are not random, but rather are directly tied to the underlying water flow routes and their development through time. The clay mantle and underlying epikarst are two components of a single system, each of the components influencing the other. This paper brings together these two aspects in terms of the author's personal experience and observations as a geologist, geotechnical engineer, hydrogeologist, and caver. A summary of the basic model follows. Much of the clay mantle and pinnacled upper surface of the epikarst form while surface drainage still prevails. At this stage, the karst underdrains are insufficiently developed to transport soils, although some subsidence into cutters occurs because of dissolutional rock removal. Soil arches and macropore flow routes associated with cutters have developed by this stage. As competent deep conduits extend into the area by headward linking, the cutters with the most favorable drains are linked to the conduits first and act as attractors for the development of a tributary, laterally integrated drainage system in the epikarst. Once the most efficient cutter drains become competent to transport soils, the depressed top-of-rock and ground surfaces characteristic of dolines develop. A given doline underdrain is likely to have multiple tributary drains from adjacent cutters, which vary in soil transport competence. Soil stiffness in the clay mantle over the limestone varies as a result of the pattern of stresses imposed as the underlying rock surface is lowered by dissolution and later as soil piping locally removes soils. In the absence of karst, these soils would have developed a laterally uniform, stiff to very stiff consistency. Where soil near the soil-bedrock interface is locally removed, however, the weight of the materials overlying this void is transferred to abutment zones on the pinnacles by soil arches. Local soil loading in the abutment areas of these arches would increase at least on the-order of 50% in the case of an isolated cavity. In some cases, multiple closely spaced cutters whose soil arches have narrow, laterally constrained abutment zones bearing on the intervening pinnacles may produce substantially higher soil abutment stresses. If the clays in the abutment zones do not fail, they would respond to this increase in stress by consolidating: stiffening and decreasing in volume. The cutters spanned by the soil arches accumulate raveled soils that are 'under-consolidated', the soft zones noted between pinnacles by Sowers. A simple integral of stresses analysis makes it obvious, however that no continuous soft zone exists. It is the transfer of load to the pinnacles through the stiffened abutment soils that allows these locally soft areas to exist. Soil stiffness profiles from borings substantiate this pattern. Cover-collapse features develop where soil transport through cutter drains is sufficient to remove the soils from beneath these arched areas. Two types of collapse have been observed: type I collapses have an upward-stoping open void whose rubble pile is removed by transport as fast as it is generated, producing a deep, steep-sided final collapses. In some cases, multiple voids in clusters can form with narrow abutments separating them. Large collapses may involve a progressive failure of several members of a cluster, including intervening pillars. Type 2 features are soil-filled voids limited in their rate of upward growth by the rate of soil removal, have little open void space, and migrate to the ground surface as a column of soft soils, finally producing a shallow depression. The type 2 features have geotechnical significance because of their effect on settlement under imposed loads. A single underdrain system may service both types of features, the behavior of particular voids being dependent on the relative efficiencies of their drains. This behavior can also change with time because backfilling of the underdrains with soil or flushing out of the soil filling can occur with changes in hydrologic or erosional regimes

Poroelastic analysis of cover-collapse sinkhole formation by piezometric surface drawdown, 2002,
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Tharp T. M. ,
Where the water table is above the soil-rock contact in karst regions, cover-collapse sinkholes in the soil and soft sediment above the rock commonly occur as a result of drawdown of the piezometric surface in the karst aquifer. Transient stresses and pore pressures around soil voids at the soil-rock contact can cause hydraulic fracturing of the soil near the wall of the void. After the first such fracture, successive sloughing of soil propagates the soil void rapidly to the surface, resulting in a cover-collapse sinkhole. Sinkhole formation by this mechanism should be strongly a function of rate and magnitude of piezometric surface drawdown, permeability and tensile strength of the soil, and the size, depth, and geometry of the initial soil void. Large soil voids and those with walls that are partly planar or of low curvature are most susceptible to hydraulic fracture and the resulting progression to sinkhole formation

Development of collapse sinkholes in areas of groundwater discharge, 2002,
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Salvati R. , Sasowsky I. D. ,
Collapse sinkholes are found in groundwater recharge zones throughout the world. They cause substantial loss of property each year, and occasional fatalities. In such settings, the formation of these features occurs through the downward migration of regolith into karst voids. The presence of a void in the bedrock. and sufficient seepage pressure or gravitative force in the regolith, is required for their creation. We investigated the development of cover collapse sinkholes in an unusual setting, areas of groundwater discharge rather than recharge. Upward hydraulic gradients and the likelihood of groundwater saturated with respect to calcite are difficult to reconcile with standard models for collapse development. Short flowpaths or renewed groundwater aggressivity towards calcite (via mischungskorrosion, thermally driven circulation, or deep-seated gaseous sources) are hypothetical mechanisms that could generate the subsurface voids that are needed to allow cover collapse development in discharge areas. For the two field sites in central Italy that we investigated, calculated carbon dioxide partial pressures in springs ranged from 7.38 X 10(-2) to 7.29 X 10(-1) atm. This indicates that deep-seated gaseous sources are most likely the mechanism allowing the development of the sinkholes. Groundwater is recharged in surrounding limestone massifs. The water moves through the carbonates and becomes saturated with calcite. As it circulates deeply in to the adjacent valleys, it mixes with deep-seated waters and gaseous fluxes from major fault systems, acquiring renewed aggressivity towards calcite. Finally, the water ascends into confined aquifers in the valley fill, and dissolves carbonate material present within, leading to surface collapse. (C) 2002 Elsevier Science B.V. All rights reserved

Occurrence of cover-collapse sinkholes [cover-collapse dolines] in the May Dam reservoir area (Konya, Turkey), 2003,
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Cicek Ihsan, Dogan Ugur

Occurrence of cover-collapse sinkholes [cover-collapse dolines] in the May Dam reservoir area (Konya, Turkey), 2003,
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Cicek Ihsan, Dogan Ugur

Sinkhole genesis and evolution in Apulia, and their interrelations with the anthropogenic environment, 2004,
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Le Rose M. , Federico A. , Parise M. ,
Sinkhole development occurs in many areas of the world where soluble rocks crop out. Sinkholes are generally the surface expression of the presence of caves and other groundwater flow conduits in carbonate rocks, which are solutionally enlarged secondary permeability features. Their formation may be either natural or caused by man's activities. In both cases, heavy consequences have to be registered on the anthropogenic environment and related infrastructures. Knowledge of the mechanism of formation of this subtle geohazard is therefore necessary to planners and decision makers for performing the most appropriate and suitable programs of land use and development. The Apulia region of southern Italy is characterized for most of its extension by carbonate rocks, which makes it one of the most remarkable example of karst in the Mediterranean Basin. Based on analysis of literature and in situ surveys, including caving explorations, we have identified in Apulia three main types of possible mechanisms for sinkhole formation: 1) collapse of a chamber in a natural cave or in man-made cavities; 2) slow and gradual enlargement of doline through dissolution; 3) settlement and internal erosion of filling deposits of pre-existing dolines. Since sinkhole formation very often affects directly the human settlements in Apulia, and have recently produced severe damage, some considerations are eventually presented as regards the interrelationships between sinkholes and the anthropogenic environment

Groundwater fluxes into a submerged sinkhole area, Central Italy, using radon and water chemistry, 2005,
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Tuccimei P. , Salvati R. , Capelli G. , Delitala M. C. , Primavera P. ,
The groundwater contribution into Green Lake and Black Lake (Vescovo Lakes Group), two cover collapse sinkholes in Pontina Plain (Central Italy), was estimated using water chemistry and a Rn-222 budget. These data can constrain the interactions between sinkholes and deep seated fluid circulation, with a special focus on the possibility of the bedrock karst aquifer feeding the lake. The Rn budget accounted for all quantifiable surface and subsurface input and output fluxes including the flux across the sediment-water interface. The total value of groundwater discharge into Green Lake and Black Lake (similar to 540 160 L s(-1)) obtained from the Rn budget is lower than, but comparable with historical data on the springs group discharge estimated in the same period of the year (800 90 L s(-1)). Besides being an indirect test for the reliability of the Rn-budget 'tool', it confirms that both Green and Black Lake are effectively springs and not simply 'water filled' sinkholes. New data on the water chemistry and the groundwater fluxes into the sinkhole area of Vescovo Lakes allows the assessment of the mechanism responsible for sinkhole formation in Pontina Plain and suggests the necessity of monitoring the changes of physical and chemical parameters of groundwater below the plain in order to mitigate the associated risk. (c) 2005 Elsevier Ltd. All rights reserved

Preliminary screening of residual soil stability in karst terrain, 2005,
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Drumm Ec, Yang Mz,
The stability of the residual soils that overlie cavitose limestone is often a concern during the siting, construction, and maintenance of facilities in karst terrain. Voids or domes often form in the residual soil above the rock cavities, and unless the thickness of the residual soil is sufficient for the development of arching, the soil may collapse and sinkholes may form. A preliminary screening method is proposed to estimate the thickness of residual soil required to provide stability for a given range of potential soil-void diameters. The method considers two modes of instability for sites with shallow (less than 25 m) overburden. Stability with respect to the first mode (cover collapse) depends on the development of arching in the residual soil and suggests a minimum allowable cover thickness for stability. Stability with respect to the second mode (cover subsidence) corresponds to the yielding and plastic flow of the soils into the soil and/or rock void and suggests a maximum cover thickness above which subsidence should be evaluated. Sites with very thick overburden (more than 25 m) are generally not considered problematic. The limiting conditions for the first stability mode are compared with estimated sinkhole dimensions reported in the literature and the application of the stability chart is demonstrated by an example

Assessment of cover-collapse sinkholes in SW Sardinia (Italy), 2007,
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Ardau F, Balia R, Bianco M, De Waele J,
The SW part of Sardinia has been afflicted, in recent years, by several cover-collapse sinkholes mostly occurring in low-density population areas. The study area, that lies in the Iglesiente-Sulcis region, is characterized by the cropping out of the Palaeozoic basement related to the South European Hercynian chain, covered with Tertiary-Quaternary sediments. The main rock types that crop out are Palaeozoic metasandstones, metadolostones, metalimestones, shales and metaconglomerates, and Tertiary-Quaternary fluvial-lacustrine continental sediments. The combined application of several geophysical techniques, integrated with boreholes and geotechnical as well as hydrogeological measurements, proved to be very useful and promising in defining in detail the geological context in which each sinkhole has formed. Moreover, the gravity method, even when used alone, proved to be very effective in detecting the regional geological structures to which sinkholes are related. Eventually, the historical analysis of phenomena, the geological knowledge of the Iglesiente-Sulcis area and the results of properly designed geophysical surveys allows the most probable areas for cover-collapse sinkholes to occur in the future to be determined. In fact, this research pointed out that the depth of the sediment-covered Palaeozoic bedrock is one of the major constraints in delimiting hazardous areas, leading to the construction of a preliminary hazard map. This map shows a belt of high risk, and also suggests the areas in which further geophysical and geotechnical investigations should be carried out to estimate the depth of the bedrock

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Hunt B. B. , Smith B. A. , Adams M. T. , Hiers S. E. , Brown N.

Sudden cover-collapse sinkhole (doline) development is uncommon in the karstic Cretaceous-age Edwards limestone of central Texas. This paper presents a case-study of a sinkhole that formed within a stormwater retention pond (SWRP) in southwest Austin. Results presented include hydrogeologic characterizations, fate of stormwater, and mitigation of the sinkhole. On January 24, 2012, a 11 cm (4.5 in) rainfall filled the SWRP with about 3 m (10 ft) of stormwater. Subsequently, a sinkhole formed within the floor of a SWRP measuring about 9 m (30 ft) in diameter and 4 m (12 ft) deep. About 26.5 million liters (7 million gallons) of stormwater drained into the aquifer through this opening. To determine the path, velocity, and destination of stormwater entering the sinkhole a dye trace was conducted. Phloxine B was injected into the sinkhole on February 3, 2012. The dye was detected at one well and arrived at Barton Springs in less than 4 days for a minimum velocity of 2 km/day (1.3 mi/day).Review of pre-development 2-foot topographic contour and geologic maps reveals that the SWRP was built within a broad (5,200 m2; 6 acre), shallow depression bounded by two inferred NE-trending fault zones. Photographs taken during SWRP construction showed steep west-dipping bedrock in the northern SWRP wall. Following collapse of the sinkhole, additional hydrogeologic characterization included excavation to a depth of 6.4 m (21 ft), surface geophysics (resistivity), and rock coring. Geologic materials consisted mostly 89of friable, highly altered, clayey limestone consistent with epikarst in-filled with terra rosa providing a cover of the feature. Dipping beds, and fractured bedrock support proximity to the mapped fault zone. Geophysics and surface observations suggested a lateral pathway for stormwater flow at the junction between the wet pond’s impermeable geomembrane and compacted clay liner for the retention pond. The collapse appears to have been caused by stormwater down-washing poorly consolidated sediments from beneath the SWRP and into a pre-existing karst conduit system.

Mitigation of the sinkhole included backfill ranging from boulders to gravel, a geomembrane cover, and reinforced concrete cap. Additional improvements to the SWRP included a new compacted clay liner overlain by a geomembrane liner on the side slopes of the retention pond.

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