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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. ...

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. ...

Speleology in Kazakhstan

Shakalov on 11 Jul, 2012
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 recipient is a vessel receiving liquids in volume measurements [16].?

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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
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Your search for numerical modelling (Keyword) returned 18 results for the whole karstbase:
Showing 1 to 15 of 18
Anomalous behaviour of specific electrical conductivity at a karst spring induced by variable catchment boundaries: the case of the Podstenjšek spring, Slovenia, , Ravbar, N. , Engelhardt, I. , Goldscheider, N.

Anomalous behaviour of specific electrical conductivity (SEC) was observed at a karst spring in Slovenia during 26 high-flow events in an 18-month monitoring period. A conceptual model explaining this anomalous SEC variability is presented and reproduced by numerical modelling, and the practical relevance for source protection zoning is discussed. After storm rainfall, discharge increases rapidly, which is typical for karst springs. SEC displays a first maximum during the rising limb of the spring hydrograph, followed by a minimum indicating the arrival of freshly infiltrated water, often confirmed by increased levels of total organic carbon (TOC). The anomalous behaviour starts after this SEC minimum, when SEC rises again and remains elevated during the entire high-flow period, typically 20–40 µS/cm above the baseflow value. This is explained by variable catchment boundaries: When the water level in the aquifer rises, the catchment expands, incorporating zones of groundwater with higher SEC, caused by higher unsaturated zone thickness and subtle lithologic changes. This conceptual model has been checked by numerical investigations. A generalized finite-difference model including high-conductivity cells representing the conduit network (“discrete-continuum approach”) was set up to simulate the observed behaviour of the karst system. The model reproduces the shifting groundwater divide and the nearly simultaneous increase of discharge and SEC during high-flow periods. The observed behaviour is relevant for groundwater source protection zoning, which requires reliable delineation of catchment areas. Anomalous behaviour of SEC can point to variable catchment boundaries that can be checked by tracer tests during different hydrologic conditions.


Thermal aspects of the East Midlands aquifer system, 1987, Wilson N. P. , Luheshi M. N. ,
A case study of a heat flow anomaly in the E Midlands of England is reported. The anomaly has been suggested to be an effect of water movement at depth within the E Midlands basin, with recharge to the Lower Carboniferous limestones in their outcrop, eastward movement and ascent of water up a steep faulted anticline at Eakring where the heat flow measurements were made. Numerical modelling of heat and fluid flow has been undertaken for a section running from the Peak District through Eakring to the coast. The results indicate that, although an anomaly is expected for reasonable values of hydrological parameters, its magnitude is less than that observed. The geological structure at Eakring is such that three-dimensional flow is likely to be important, and this could easily account for the discrepancy between the modelling results and the observations. The regional water flow regime has other effects on heat flow, notably the depression of heat flow above the Sherwood Sandstone aquifer

Assessments of the sensitivity to climate change of flow and natural water quality in four major carbonate aquifers of Europe, 2002, Younger P. L. , Teutsch G. , Custodio E. , Elliot T. , Manzano M. , Sauter M. ,
A numerical modelling approach has been developed to predict the vulnerability of aquifers to future climate change. This approach encompasses changes in recharge regime, dynamics of flow and storage patterns within aquifers, and natural hydrochemical changes. An application of the approach has been made to four hypothetical spring catchments representative of major carbonate aquifers in three European climatic zones. Since prolific carbonate aquifers typically combine a high transmissivity with a low specific yield, they can be expected to be more sensitive than clastic aquifers to changes in recharge patterns. Simulations of the study systems to the middle of the 21st century predict different outcomes in the three different climate zones: (1) in the northern maritime zone (UK) recharge (and therefore discharge) is predicted to increase by as much as 21 0n response to anticipated increases in precipitation; (2) in the continental zone (Germany) recharge in winter is predicted to remain approximately the same as at present, but summer recharge will decline dramatically (by as much as 32%), so that a net decrease in aquifer discharge is predicted; and (3) in the Mediterranean zone (Spain) recharge is predicted to decrease by as much as 160f the present-day values. For all three systems, increases in water hardness in response to rising CO2 are predicted, but are expected to be negligible in water resources terms

Characterisation of karst systems by simulating aquifer genesis and spring responses: model development and application to gypsum karst., 2002, Birk S.
Karst aquifers are important groundwater resources, which are highly vulnerable to contamination due to fast transport in solutionally enlarged conduits. Management and protection of karst water resources require an adequate aquifer characterisation at the catchment scale. Due to the heterogeneity and complexity of karst systems, this is not easily achieved by standard investigation techniques such as pumping tests. Therefore, a process-based numerical modelling tool is developed, designed to support the karst aquifer characterisation using two complementary approaches: Firstly, the simulation of conduit enlargement, which aims at predicting aquifer properties by forward modelling of long-term karst genesis; secondly, the simulation of heat and solute transport processes, which aims at inferring aquifer properties from short-term karst spring response after recharge events. Karst genesis modelling is applied to a conceptual setting based on field observations from the Western Ukraine, where the major part of known gypsum caves is found. Gypsum layers are typically supplied by artesian flow of aggressive water from insoluble aquifers underneath. Processes and parameters, controlling solutional enlargement of single conduits under artesian conditions, are identified in detailed sensitivity analyses. The development of conduit networks is examined in parameter studies, suggesting that the evolution of maze caves is predetermined by structural preferences such as laterally extended fissure networks beneath a horizon less prone to karstification. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The structure of the mature conduit system is found to be determined during early karstification, which is characterised by high hydraulic gradients and low flow rates in the gypsum layer. Short-term karst spring response after recharge events is firstly examined in parameter studies by forward modelling. The numerical simulations reveal that different controlling processes of heat and solute transport account for the different behaviour of water temperature and solute concentration frequently observed at karst springs. It is demonstrated that these differences may be employed to reduce the ambiguity in the aquifer characterisation. In order to test the feasibility of the corresponding inverse approach, which aims at inferring aquifer properties from the karst spring response, the model is applied to a field site in Southern Germany (Urenbrunnen spring, Vohringen). Data input is provided by both literature and own field work. Several models, which reproduce the results of a combined tracer and recharge test, are calibrated to spring discharges and solute concentrations measured after a recharge event. In order to validate the calibrated models, the measured spring water temperatures are simulated by heat transport modelling. The model application yields information on aquifer properties as well as flow and transport processes at the field site. Advection is identified as the dominant transport process, whereas the dissolution reaction of gypsum is found to be insignificant in this case. The application to gypsum aquifers demonstrates that both suggested approaches are suitable for the characterisation of karst systems. Model results, however, are highly sensitive to several input parameters, in particular in karst genesis modelling. Therefore, extensive field work is required to provide reliable data for site-specific model applications. In order to account for uncertainties, it is recommended to conduct parameter studies covering possible ranges of the most influential parameters.

Characterisation of karst systems by simulating aquifer genesis and spring responses: model development and application to gypsum karst, PhD thesis, 2002, Birk, S.

Karst aquifers are important groundwater resources, which are highly vulnerable to contamination due to fast transport in solutionally enlarged conduits. Management and protection of karst water resources require an adequate aquifer characterisation at the catchment scale. Due to the heterogeneity and complexity of karst systems, this is not easily achieved by standard investigation techniques such as pumping tests. Therefore, a process-based numerical modelling tool is developed, designed to support the karst aquifer characterisation using two complementary approaches: Firstly, the simulation of conduit enlargement, which aims at predicting aquifer properties by forward modelling of long-term karst genesis; secondly, the simulation of heat and solute transport processes, which aims at inferring aquifer properties from short-term karst spring response after recharge events.
Karst genesis modelling is applied to a conceptual setting based on field observations from the Western Ukraine, where the major part of known gypsum caves is found. Gypsum layers are typically supplied by artesian flow of aggressive water from insoluble aquifers underneath. Processes and parameters, controlling solutional enlargement of single conduits under artesian conditions, are identified in detailed sensitivity analyses. The development of conduit networks is examined in parameter studies, suggesting that the evolution of maze caves is predetermined by structural preferences such as laterally extended fissure networks beneath a horizon less prone to karstification. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The structure of the mature conduit system is found to be determined during early karstification, which is characterised by high hydraulic gradients and low flow rates in the gypsum layer.
Short-term karst spring response after recharge events is firstly examined in parameter studies by forward modelling. The numerical simulations reveal that different controlling processes of heat and solute transport account for the different behaviour of water temperature and solute concentration frequently observed at karst springs. It is demonstrated that these differences may be employed to reduce the ambiguity in the aquifer characterisation.
In order to test the feasibility of the corresponding inverse approach, which aims at inferring aquifer properties from the karst spring response, the model is applied to a field site in Southern Germany (Urenbrunnen spring, Vohringen). Data input is provided by both literature and own field work. Several models, which reproduce the results of a combined tracer and recharge test, are calibrated to spring discharges and solute concentrations measured after a recharge event. In order to validate the calibrated models, the measured spring water temperatures are simulated by heat transport modelling. The model application yields information on aquifer properties as well as flow and transport processes at the field site. Advection is identified as the dominant transport process, whereas the dissolution reaction of gypsum is found to be insignificant in this case.
The application to gypsum aquifers demonstrates that both suggested approaches are suitable for the characterisation of karst systems. Model results, however, are highly sensitive to several input parameters, in particular in karst genesis modelling. Therefore, extensive field work is required to provide reliable data for site-specific model applications. In order to account for uncertainties, it is recommended to conduct parameter studies covering possible ranges of the most influential parameters.


Karstification and Groundwater Flow, 2003, Kiraly, L.

One of the principal aims of hydrogeology is to propose a reasonably adequate reconstruction of the groundwater flow field, in space and in time, for a given aquifer. For example, interpretation of the chemical and isotopic composition of groundwater, understanding of the geothermal conditions (anomalies) or forecasting the possible effects of industrial waste disposals and of intensive exploitation nearly always would require the knowledge of the regional and/or local groundwater flow systems such as defined by Toth (1963). The problem of estimating the groundwater flow field in fractured and karstified aquifers is approached within the framework of a conceptual diagram showing the relationship between groundwater flow, hydraulic parameters (aquifer properties and boundary conditions), distribution of voids and geological factors.
Autoregulation between groundwater flow and karst aquifer properties, duality of karst, nested model of geological discontinuities, scale effect on hydraulic parameters and use of numerical finite element models to check the interpretation of the global response of karst springs are some of the subjects addressed by the author. Inferences on groundwater flow regime with respect to the stage of karst evolution can be made only if the hydraulic parameter fields and the boundary conditions are known by direct observations, or estimated by indirect methods for the different types of karst. Practical considerations on the monitoring strategies applied for karst aquifers, and on the interpretation of the global response obtained at karst springs will complete the paper, which throughout reflects the point of view of a hydrogeologist.


Chalk engineering geology - Channel Tunnel Rail Link and North Downs Tunnel, 2003, Warren C. D. , Mortimore R. N. ,
Agreat part of the Channel Tunnel Rail Link (CTRL) is constructed through the Chalk and the ground investigation for the CTRL has yielded a mass of new information on allaspects of the Chalk. A precise bed by bed lithostratigraphy obtained from cored boreholes has aided engineering description, classification, decision making on design of machines and construction methods/specifications. Correlation of Chalk marker beds between boreholes drilled for the tunnels beneath London illustrated the influence of sub-Tertiary erosion and of faulting onpreservation of different stratigraphic levels in the Chalk. These different stratigraphic levels affect materials through which the tunnels will be constructed andconsequently tunnel vertical alignment or choice of construction method. The marker bed stratigraphy in the Thames Tunnel boreholes has enabled the same stratigraphic levels to be identified in local quarries and detailed analyses to be carried out for the design of Tunnel Boring Machines. Using individual marker beds, a detailed ground profile was constructed for the North Downs Tunnel which allowed fault zones to be predicted accurately and the different rock mass character of the Chalk formations to be delimited for numerical modelling, design zones and construction monitoring. The project also provided the opportunity to evaluate the CIRIA Chalk Grading scheme

A conceptual model of flow and transport in a karst aquifer based on spatial and temporal variations of natural tracers, 2003, Perrin, Jerome

Karst aquifers represent an important groundwater resource world-wide. They are highly vulnerable to contamination due to fast transport through the system and limited attenuation of contaminants. The two main hydrogeological approaches developed for studying flow and transport are: inference of the
system structure from karst spring hydrographs and chemographs; numerical modelling of flow and transport using a theoretical distribution of flow and transport field parameters. These two approaches lack of validation by detailed field measurements and observations. The main objective of this thesis is to “fill the gap” existing between field and model data. Observations of flow and transport parameters at several locations within the system were used to develop a conceptual model. This model was then compared to the existing models.
The main field test site is the Milandre karst aquifer, located in the Swiss tabular Jura. Natural tracers (major ions, oxygen-18, specific conductance) and discharge were measured on the underground river, its main tributaries, percolation waters, and the main spring. These data were collected on a long-term basis in order to assess the spatial variability of the parameters, and on a short time scale (i.e. flood events) in order to investigate the dynamic processes. Complementary sites (Brandt and Grand Bochat) were used for more observations at the base of the epikarst.
The proposed conceptual model considers four sub-systems: the soil zone, the epikarst, the unsaturated zone, and the phreatic zone. Each has its own specificity with respect to flow and transport. The soil zone controls the actual infiltration into the system. It contributes efficiently to groundwater storage. It mixes quickly stored water with fresh infiltrated water. Its thickness determines land-use: thick soils are generally cultivated whereas thin soils are under forested areas. The solutes concentration of soil waters depends on land-use for pollution-related parameters (nitrate, chloride, sulfate, potassium, sodium). Moreover the soil zone is the main source of CO2 which controls the limestone dissolution-related parameters. The epikarst zone contributes largely to groundwater storage. It distributes groundwater into vadose flow through conduits, and base flow through low permeability volumes (LPV) in the unsaturated zone. It is the sub-system where dissolution-related parameters are mostly acquired.
The unsaturated zone is seen as a transmissive zone connecting the epikarst to the horizontal conduit network of the phreatic zone. In case of flood events, some dissolution still occurs in this sub-system.
The phreatic zone is the partly flooded conduit network draining groundwater to the spring. It collects waters issued from the unsaturated zone, mixes the tributaries, and drain the water towards the discharge area. The role of phreatic storage appears to be limited for both hydraulics and transport.
Tributary mixing is a prominent process that shapes spring chemographs during flood events. In steady-state conditions, base flow is mainly sustained by the epikarst reservoir. Tracer concentrations are stable as the chemical equilibrium is already reached in the epikarst. Waters issued from the different tributaries mix in the conduit network, and the spring chemistry is the result of this mixing.
During flood events, transient flow induces non-linear mixing of the tributaries. The respective contributions of the tributaries change throughout the flood, and the spring chemographs vary accordingly. In case of important recharge, waters issued from other sources than the epikarst participate to the flood. First, soil water reaches the phreatic zone. Its characteristics are a dampened isotopic signal, and ionic concentrations differing from those of the epikarst. Second, fresh water directly issued from rainfall, may reach the phreatic zone. Its characteristics are a varying isotopic signal, and diluted ionic concentrations. The mixing components participating to the flood are controlled by the actual infiltration volume (or height). The limestone dissolution process is effective for the fresh and soil components of flow. However mixing processes play a more important role than dissolution for shaping the spring chemographs.
From a practical point of view, the project confirmed the prominent role of the soil zone and the epikarst on the solute transport in karst systems. This was already integrated in karst vulnerability mapping methods recently developed (EPIK, PI, VULK).

http://doc.rero.ch/record/2604/files/these_PerrinJ.pdf


Concepts and models of dolomitization: a critical reappraisal, 2004, Machel Hans G. ,
Despite intensive research over more than 200 years, the origin of dolomite, the mineral and the rock, remains subject to considerable controversy. This is partly because some of the chemical and/or hydrological conditions of dolomite formation are poorly understood, and because petrographic and geochemical data commonly permit more than one genetic interpretation. This paper is a summary and critical appraisal of the state of the art in dolomite research, highlighting its major advances and controversies, especially over the last 20-25 years. The thermodynamic conditions of dolomite formation have been known quite well since the 1970s, and the latest experimental studies essentially confirm earlier results. The kinetics of dolomite formation are still relatively poorly understood, however. The role of sulphate as an inhibitor to dolomite formation has been overrated. Sulphate appears to be an inhibitor only in relatively low-sulphate aqueous solutions, and probably only indirectly. In sulphate-rich solutions it may actually promote dolomite formation. Mass-balance calculations show that large water/rock ratios are required for extensive dolomitization and the formation of massive dolostones. This constraint necessitates advection, which is why all models for the genesis of massive dolostones are essentially hydrological models. The exceptions are environments where carbonate muds or limestones can be dolomitized via diffusion of magnesium from seawater rather than by advection. Replacement of shallow-water limestones, the most common form of dolomitization, results in a series of distinctive textures that form in a sequential manner with progressive degrees of dolomitization, i.e. matrix-selective replacement, overdolomitization, formation of vugs and moulds, emplacement of up to 20 vol% calcium sulphate in the case of seawater dolomitization, formation of two dolomite populations, and -- in the case of advanced burial -- formation of saddle dolomite. In addition, dolomite dissolution, including karstification, is to be expected in cases of influx of formation waters that are dilute, acidic, or both. Many dolostones, especially at greater depths, have higher porosities than limestones, and this may be the result of several processes, i.e. mole-per-mole replacement, dissolution of unreplaced calcite as part of the dolomitization process, dissolution of dolomite due to acidification of the pore waters, fluid mixing (mischungskorrosion), and thermochemical sulphate reduction. There also are several processes that destroy porosity, most commonly dolomite and calcium sulphate cementation. These processes vary in importance from place to place. For this reason, generalizations about the porosity and permeability development of dolostones are difficult, and these parameters have to be investigated on a case-by-case basis. A wide range of geochemical methods may be used to characterize dolomites and dolostones, and to decipher their origin. The most widely used methods are the analysis and interpretation of stable isotopes (O, C), Sr isotopes, trace elements, and fluid inclusions. Under favourable circumstances some of these parameters can be used to determine the direction of fluid flow during dolomitization. The extent of recrystallization in dolomites and dolostones is much disputed, yet extremely important for geochemical interpretations. Dolomites that originally form very close to the surface and from evaporitic brines tend to recrystallize with time and during burial. Those dolomites that originally form at several hundred to a few thousand metres depth commonly show little or no evidence of recrystallization. Traditionally, dolomitization models in near-surface and shallow diagenetic settings are defined and/or based on water chemistry, but on hydrology in burial diagenetic settings. In this paper, however, the various dolomite models are placed into appropriate diagenetic settings. Penecontemporaneous dolomites form almost syndepositionally as a normal consequence of the geochemical conditions prevailing in the environment of deposition. There are many such settings, and most commonly they form only a few per cent of microcrystalline dolomite(s). Many, if not most, penecontemporaneous dolomites appear to have formed through the mediation of microbes. Virtually all volumetrically large, replacive dolostone bodies are post-depositional and formed during some degree of burial. The viability of the many models for dolomitization in such settings is variable. Massive dolomitization by freshwater-seawater mixing is a myth. Mixing zones tend to form caves without or, at best, with very small amounts of dolomite. The role of coastal mixing zones with respect to dolomitization may be that of a hydrological pump for seawater dolomitization. Reflux dolomitization, most commonly by mesohaline brines that originated from seawater evaporation, is capable of pervasively dolomitizing entire carbonate platforms. However, the extent of dolomitization varies strongly with the extent and duration of evaporation and flooding, and with the subsurface permeability distribution. Complete dolomitization of carbonate platforms appears possible only under favourable circumstances. Similarly, thermal convection in open half-cells (Kohout convection), most commonly by seawater or slightly modified seawater, can form massive dolostones under favourable circumstances, whereas thermal convection in closed cells cannot. Compaction flow cannot form massive dolostones, unless it is funnelled, which may be more common than generally recognized. Neither topography driven flow nor tectonically induced ( squeegee-type') flow is likely to form massive dolostones, except under unusual circumstances. Hydrothermal dolomitization may occur in a variety of subsurface diagenetic settings, but has been significantly overrated. It commonly forms massive dolostones that are localized around faults, but regional or basin-wide dolomitization is not hydrothermal. The regionally extensive dolostones of the Bahamas (Cenozoic), western Canada and Ireland (Palaeozoic), and Israel (Mesozoic) probably formed from seawater that was pumped' through these sequences by thermal convection, reflux, funnelled compaction, or a combination thereof. For such platform settings flushed with seawater, geochemical data and numerical modelling suggest that most dolomites form(ed) at temperatures around 50-80 {degrees}C commensurate with depths of 500 to a maximum of 2000 m. The resulting dolostones can be classified both as seawater dolomites and as burial dolomites. This ambiguity is a consequence of the historical evolution of dolomite research

Methane discharge into the Black Sea and the global ocean via fluid flow through submarine mud volcanoes, 2006, Wallmann Klaus, Drews Manuela, Aloisi Giovanni, Bohrmann Gerhard,
During the MARGASCH cruise M52/1 in 2001 with RV Meteor we sampled surface sediments from three stations in the crater of the Dvurechenskii mud volcano (DMV, located in the Sorokin Trough of the Black Sea) and one reference station situated 15[no-break space]km to the northeast of the DMV. We analysed the pore water for sulphide, methane, alkalinity, sulphate, and chloride concentrations and determined the concentrations of particulate organic carbon, carbonate and sulphur in surface sediments. Rates of anaerobic oxidation of methane (AOM) were determined using a radiotracer (14CH4) incubation method. Numerical transport-reaction models were applied to derive the velocity of upward fluid flow through the quiescently dewatering DMV, to calculate rates of AOM in surface sediments, and to determine methane fluxes into the overlying water column. According to the model, AOM consumes 79% of the average methane flux from depth (8.9 [middle dot] 10 6[no-break space]mol a- 1), such that the resulting dissolved methane emission from the volcano into the overlying bottom water can be determined as 1.9 [middle dot] 10 6[no-break space]mol a- 1. If it is assumed that all submarine mud volcanoes (SMVs) in the Black Sea are at an activity level like the DMV, the resulting seepage represents less than 0.1% of the total methane flux into this anoxic marginal sea. The new data from the DMV and previously published studies indicate that an average SMV emits about 2.0 [middle dot] 10 6[no-break space]mol a- 1 into the ocean via quiescent dewatering. The global flux of dissolved methane from SMVs into the ocean is estimated to fall into the order of 10 10[no-break space]mol a- 1. Additional methane fluxes arise during periods of active mud expulsion and gas bubbling occurring episodically at the DMV and other SMVs

Palaeoclimate Research in Villars Cave (Dordogne, SW-France)., 2008, Genty D.
Villars Cave is a typical shallow cave from South-West France (45.44N; 0.78E; 175 m asl) that has provided several speleothem palaeoclimatic records such as the millennial scale variability of the Last Glacial period and the Last Deglaciation. Monitoring the Villars cave environment over a 13-year period has helped in the understanding of the stable isotopic speleothem content and in the hydrology. For example, it was demonstrated that most of the calcite CaCO3 carbon comes from the soil CO2, which explains the sensitivity of the ?13C to any vegetation and climatic changes. Drip rate monitoring, carried out under four stalactites from the lower and upper galleries, has shown a well marked seasonality of the seepage water with high flow rates during winter and spring. A time delay of about two months is observed between the water excess (estimated from outside meteorological stations) and the drip rate in the cave. A great heterogeneity in the flow rate amplitude variations and in the annual quantity of water between two nearby stalactites is observed, confirming the complexity of the micro-fissure network system in the unsaturated zone. At a daily scale, the air pressure and drip rates are anti-correlated probably because of pressure stress on the fissure network. Cave air CO2 concentration follows soil CO2 production and is correlated with its ?13C content. Since the beginning of the monitoring, the cave air temperature, in both lower and upper galleries, displays a warming trend of ~+0.4C0.1/10yrs. This might be the consequence of the outside temperature increase that reaches the Villars Cave galleries through thermal wave conduction. Chemistry monitoring over a few years has shown that the seepage water of the lower gallery stations is significantly more concentrated in trace and minor elements (i.e. Sr, Mg, Ba, U) than the upper stations, probably due to the 10-20 m depth difference between these galleries, which implies a different seepage pathway and different water/rock interaction durations. There is also, in the elemental concentration (i.e. [Ca]), a seasonal signal which causes variation in the speleothem growth rates. Modern calcite deposit experiments conducted for several years have permitted the calculation of vertical growth rates, which are extremely high in Villars (i.e. 1.0 to 1.75 mm/ yr). Pollen filter experiments in the cave have demonstrated that most of the pollen grain found in the cave comes from the air and not from the water. The specificity of the Villars Cave records is that the climatic variations were well recorded in the calcite ?13C whereas the ?18O is usually used in such studies. Overall, these results are helpful for the interpretation of speleothem records for palaeoclimatic reconstructions, but more work is needed, especially numerical modelling of the temperature, chemistry and hydrology.

Validation of vulnerability mapping methods by field investigations and numerical modelling, 2008, Neukum Christoph, Hotzl Heinz, Himmelsbach Thomas

Vulnerability maps illustrate the potential threat of contaminants to groundwater and can be considered as important tools for land-use planning and related legislation. For karst areas with characteristic preferential infiltration conditions, vulnerability maps are also excellent tools for source and resource protection. However, the resulting qualitative maps are often inconsistent and even contradictive and thus might lead to inconclusive vulnerability assessments. The results of a validation of vulnerability maps produced using four different methods, DRASTIC, GLA, PI and EPIK, are reported for a karst area in southwest Germany. By means of measured hydraulic and transport parameters of the geological sequence, numerical simulations were used based on a conceptual model for the area under study. The mean transit time through the unsaturated zone (resource protection) was used as the validation parameter. The study demonstrates that the highest level of accuracy is achieved with the GLA- and PI methods. Both DRASTIC and EPIK are not able to incorporate highly variable distributions and thickness of cover sediments and their protective properties in the respective mapping procedure. Thus, vulnerability maps produced with DRASTIC, EPIK, and related methods should be used with care when employed in vulnerability assessments for land use planning and related decision-making.
Les cartes de vulnerabilite illustrent la menace potentielle des contaminants envers les eaux souterraines, et peuvent etre considerees comme des outils importants en matiere d'amenagement foncier et de reglementation associee. Sur les domaines karstiques, caracterises par des conditions d'infiltration preferentielle, ces cartes sont egalement d'excellents outils de protection des sources et des ressources. Cependant, les cartes qualitatives resultantes sont generalement incoherentes voire contradictoires, et peuvent par la-meme mener a des evaluations de vulnerabilite peu concluantes. La presente etude expose les resultats de validation de cartes de vulnerabilite produites selon quatre methodes differentes (DRASTIC, GLA, PI et EPIK), dans le cas d'un domaine karstique du sud-est de l'Allemagne. Par le biais des parametres de transport et hydrauliques mesures sur la sequence geologique, des simulations numeriques basees sur un modele conceptuel du secteur d'etude ont ete utilisees. Les temps de transit moyens a travers la zone non saturee (protection de la ressource) ont ete utilises comme parametres de validation. L'etude demontre que le niveau maximum de precision est obtenu par les methodes GLA et PI. Dans la phase de cartographie, les methodes EPIK et DRASTIC sont incapables d'integrer une forte variabilite dans les distributions et les epaisseurs de sediments de couverture, ainsi que dans leurs potentiels de protection. Aussi, les cartes de vulnerabilite produites par les methodes DRASTIC et EPIK doivent etre utilisees avec precaution dans le cadre des evaluations de vulnerabilite a but decisionnaire pour les amenagements fonciers.
Los mapas de vulnerabilidad ilustran la amenaza potencial de contaminantes para el agua subterranea y pueden ser considerados herramientas importantes para planeamiento del uso de la tierra y legislacion relacionada. Para areas carsticas con sus caracteristicas condiciones de infiltracion preferencial, los mapas de vulnerabilidad son tambien excelentes herramientas para proteccion de fuentes y recursos. Sin embargo, los mapas cualitativos resultantes son frecuentemente inconsistentes y hasta contradictorios y por lo tanto podrian conducir a evaluaciones de vulnerabilidad no concluyentes. Los resultados de una validacion de mapas de vulnerabilidad producidos usando cuatro metodos diferentes, DRASTIC, GLA, PI y EPIK, son presentados aqui para un area carstica en Alemania suroccidental. Se usaron simulaciones numericas usando parametros hidraulicos y de transporte medidos de la secuencia geologica y basandose en un modelo conceptual del area en estudio. El tiempo promedio de transito a traves de la zona no saturada (proteccion del recurso) fue utilizado como el parametro de validacion. El estudio demuestra que el maximo nivel de precision es alcanzado con los metodos GLA y PI. DRASTIC y EPIK no fueron capaces de incorporar distribuciones altamente variables ni espesor de sedimentos de cubierta y sus propiedades protectivas en el respectivo procedimiento de elaboracion de mapas. Por lo tanto los mapas de vulnerabilidad producidos con DRASTIC, EPIK y metodos relacionados deberian ser usados con cuidado cuando se usen en evaluaciones de vulnerabilidad para planeamiento del uso de tierra


Palaeoclimate Research in Villars Cave (Dordogne, SW-France), 2008, Genty, D.

Villars Cave is a typical shallow cave from South-West France (45.44°N; 0.78°E; 175 m asl) that has provided several speleothem palaeoclimatic records such as the millennial scale variability of the Last Glacial period and the Last Deglaciation. Monitoring the Villars cave environment over a 13-year period has helped in the understanding of the stable isotopic speleothem content and in the hydrology. For example, it was demonstrated that most of the calcite CaCO3 carbon comes from the soil CO2, which explains the sensitivity of the δ13C to any vegetation and climatic changes. Drip rate monitoring, carried out under four stalactites from the lower and upper galleries, has shown a well marked seasonality of the seepage water with high flow rates during winter and spring. A time delay of about two months is observed between the water excess (estimated from outside meteorological stations) and the drip rate in the cave. A great heterogeneity in the flow rate amplitude variations and in the annual quantity of water between two nearby stalactites is observed, confirming the complexity of the micro-fissure network system in the unsaturated zone. At a daily scale, the air pressure and drip rates are anti-correlated probably because of pressure stress on the fissure network. Cave air CO2 concentration follows soil CO2 production and is correlated with its δ13C content. Since the beginning of the monitoring, the cave air temperature, in both lower and upper galleries, displays a warming trend of ~+0.4°C±0.1/10yrs. This might be the consequence of the outside temperature increase that reaches the Villars Cave galleries through thermal wave conduction. Chemistry monitoring over a few years has shown that the seepage water of the lower gallery stations is significantly more concentrated in trace and minor elements (i.e. Sr, Mg, Ba, U) than the upper stations, probably due to the 10-20 m depth difference between these galleries, which implies a different seepage pathway and different water/rock interaction durations. There is also, in the elemental concentration (i.e. [Ca]), a seasonal signal which causes variation in the speleothem growth rates. Modern calcite deposit experiments conducted for several years have permitted the calculation of vertical growth rates, which are extremely high in Villars (i.e. 1.0 to 1.75 mm/yr). Pollen filter experiments in the cave have demonstrated that most of the pollen grain found in the cave comes from the air and not from the water. The specificity of the Villars Cave records is that the climatic variations were well recorded in the calcite δ13C whereas the δ18O is usually used in such studies. Overall, these results are helpful for the interpretation of speleothem records for palaeoclimatic reconstructions, but more work is needed, especially numerical modelling of the temperature, chemistry and hydrology.


SPELEOGENESIS OF MEDITERRANEAN KARSTS: A MODELLING APPROACH BASED ON REALISTIC FRACTURE NETWORKS, 2009, Lafare A. , Jourde H. , Leonardi V. , Pistre S. , Dorfliger N.

There are several numerical modelling approaches of speleogenesis in existence today. They take into account physical and chemical laws for flow and dissolution in fractured carbonate aquifers. Nevertheless, the initial void networks considered by these models generally do not correspond to the fracturing reality. The approach proposed here aims to simulate speleogenesis in an aquifer characterized by a fracture network, while matching field reality as closely as possible and respecting geometrical properties. Using statistical and geometrical parameters obtained by field observations and analogue experiments, it is possible to generate 3-D realistic networks in terms of the relative position of joints that control the overall network connectivity. Once the fracture networks are generated, they are adapted and incorporated in a 3-D ground water flow and transport finite element model. The flow simulations in the fracture networks allow determination of the spatial distribution of flow velocities for the initial configuration. This distribution, added to other information such as age and travel time, is used to simulate the evolution of the apertures of the different elements. This paper mainly presents the theoretical basis for the proposed method, from the fracturing model to the incorporation of the generated network in the flow model. Then, it describes the principles leading to forthcoming first benchmark simulations which will be used to develop the analogical rules concerning karst aquifer evolution, and for lead sensibility analysis.


Fluids in geological processes The present state and future outlook, 2010, Mumm Andreas Schmidt, Brugger Joel, Zhao Chongbin, Schacht Ulrike

The research of fluids in the earth's crust is greatly benefiting from methodological (analytical) and experimental advances and the rapid development of increasingly powerful numerical modelling systems. New experimental data continuously refine the accuracy of numerical models aiming to quantitatively reconstruct geological processes. Geological modelling programs have moved on from linear or 2-dimensional approaches to integrating 3 or 4D geology with geothermal aspects, fluids flow and reactive transport processes into complex, quantitative scenarios. These combinations of refinement of the data base and advances in computational capacities are the stepping stones for the development of the predictive quality of mineralising models and hydrocarbon migration and accumulation, access to geothermal energy and the sequestration of CO2.

This special issue presents a selection of contributions on “Fluids in Geological Processes” following the VIth GEOFLUIDS meeting in Adelaide in 2009, emphasizing on recent developments in the different research trends in this field.


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