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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. ...

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Your search for pumping tests (Keyword) returned 17 results for the whole karstbase:
Showing 1 to 15 of 17
Selected problems of karst hydrology and hydrogeology in carbonate rocks. [in Polish], 1993, Motyka Jacek, Pulidobosch Antonio, Pulina Marian

Contribution of correlation and spectral analyses to the regional study of a large karst aquifer (Charente, France), 1998, Larocque M. , Mangin A. , Razack M. , Banton O. ,
The purpose of the study is to demonstrate that correlation and spectral analyses can contribute to the regional study of a large karst aquifer. An example is presented for the La Rochefoucauld karst aquifer (Charente, France). Different types of spatially distributed time series provide valuable spatio-temporal information for the karat aquifer. The available time series consist of the spring flow rates, the flow rates at different locations in sinking streams, the piezometric levels, the electrical conductivity and temperature of the water, the atmospheric pressure and the precipitation The analysis of the flow rates at the springs shows that the aquifer empties very slowly and has a large storage capacity. Hydrodynamic links were established between three of the four rivers flowing on the aquifer and the springs. The results also demonstrate the important spatial heterogeneity of the aquifer and indicate that the most rapid flow occurs in the northern part of the aquifer. Hourly piezometric and electrical conductivity time series indicate that the transmissivity of the aquifer varies when some conductive channels become desaturated during the low water period. The delays between the distributed recharge and the piezometric level, between the localized river input and the how rates at the springs and between the electrical conductivities in rivers and the main spring provide information on the travel times in the aquifer, The observation of earth tides and barometric effects indicate that this apparently unconfined aquifer has a confined behaviour. (C) 1998 Elsevier Science B.V. All rights reserved

Relation entre ecoulements et fractures ouvertes dans un systeme aquifere compartimente par des failles et mise en evidence d'une double porosite de fractures, 1999, Bruel T, Petit Jp, Massonnat G, Guerin R, Nolf Jl,
Hydrodynamic characterisation of real fracture systems is necessary to improve modelling of fracture reservoirs as well as nuclear waste disposal sites. This characterisation is usually considered globally and theoretically but very few studies have aimed to identify the real physical environment of flow (matrix, faults, joints etc.) before establishing hydrodynamical models. We present a case study in a fractured reservoir aiming to give an example of how and why fluids actually flow within a given fracture at the various scales of fracturation of a fracture network. This study demonstrates that the determination of type and orientation of fractures actually supporting flow is necessary for accurate interpretation of the pumping tests within a fractured reservoir. It also shows that there is no simple relationship between the fault offset and the importance of flow, probably due to the influence of in situ stress. It is shown that the combination of various methods can be used to determine the fracture-flow relationship and behaviour at subseismic scale in subsurface conditions

Transmissivity estimates from well hydrographs in karst and fractured aquifers, 2000, Powers J. G. , Shevenell L. ,
Hydrograph recessions from rainfall events have been previously analyzed for discharge at springs and streams; however, relatively little quantitative research has been conducted with regard to hydrograph analysis of recessions from monitoring wells screened in karst aquifers, In previous work, a quantitative hydrograph analysis technique has been proposed from which matrix transmissivity (i.e., transmissivity of intergranular porosity) and specific yields of matrix, fracture, and conduit components of the aquifer may be determined from well hydrographs, The technique has yielded realistic results at three sites tested by the authors (Y-12, Oak Ridge, Tennessee; Crane, Indiana; and Fort Campbell, Kentucky). Observed field data, as well as theoretical considerations, show that karst wed hydrographs are valid indicators of hydraulic properties of the associated karst aquifers, Results show matrix transmissivity (T) values to be in good agreement with values calculated using more traditional parameter estimation techniques, such as aquifer pumping tests and slug tests in matrix dominated wells. While the hydrograph analysis technique shows premise for obtaining reliable estimates of karst aquifer T with a simple, relatively inexpensive and passive method, the utility of the technique is limited in its application depending on site-specific hydrologic conditions, which include shadow submerged conduit systems located in areas with sufficient rainfall for water levels to respond to precipitation events

Karst collapse mechanism and criterion for its stability, 2001, He K. Q. , Liu C. L. , Wang S. J. ,
Karst collapse, caused by natural or artificial abstraction of groundwater, has been a focus of environmental geological problems for its ever-increasing hazardousness. The potential erosion theory and vacuum suction erosion theory, which reveal the origin of karst collapse macroscopically, are popularly accepted. However, a mathematic prediction criterion for karst collapse cannot be established only by these two theories. From a new perspective, this paper attempts to explain the microcosmic mechanism of karst collapse on the basis of these two theories. When the shear stress surpasses the shear strength of soil, a certain point or a certain plane in the unconsolidated soil covering karst caves will fail under the mechanical effects of water and air as well as its load-pressure, and with the increase of damaged points, a breaking plane appears and the soil on karst caves is completely damaged; as a result, the karst ground collapses. On the basis of the Mohr-Coulomb failure theory and previous studies, the paper presents a prediction criterion of karst collapse. Finally, by taking, for example, nine typical cases of collapse caused by pumping tests in Guizhou, the paper gives the calculation process of the model and proves its reliability

Aquifer properties of the Chalk of England, 2001, Macdonald Alan M. , Allen David J. ,
Aquifer properties data from 2100 pumping tests carried out in the Chalk aquifer have been collated as part of a joint British Geological Survey/Environment Agency project. The dataset is highly biased: most pumping tests have been undertaken in valley areas where the yield of the Chalk is highest. Transmissivity values from measured sites give the appearance of log-normality, but are not truly log-normal. The median of available data is 540 m2/d and the 25th and 75th percentiles 190 m2/d and 1500 m2/d respectively. Estimates of storage coefficient from unconfined tests have a median of 0.008 and from confined tests, 0.0006. The data indicate several trends and relationships in Chalk aquifer properties. Transmissivity is highest in the harder Chalk of Yorkshire and Lincolnshire (median 1800 m2/d). Throughout much of the Chalk aquifer a direct relation is observed between transmissivity and storage coefficient, reflecting the importance of fractures in governing both storage and transmissivity. Pumping tests undertaken in unconfined conditions give consistently higher measurements of transmissivity than in confined areas, probably as a result of increased dissolution enhancement of fractures in unconfined areas. At a catchment scale the data illustrate a relation between transmissivity and winter flowing streams

Exploration techniques for karst groundwater resources., 2001, Bakalowicz M.
Porous and fissure aquifers display statistical homogeneity of their physical and hydraulic characteristics on a scale ranging from tens to several hundreds of meters. Such homogeneity is a product of the relatively small spatial variability of these characteristics and creates conditions of general hydraulic continuity throughout the entire saturated zone. Their groundwater resources can be explored by a simple approach, i.e. defining the aquifer geometry from geological data, and determining local hydraulic parameters from pumping tests; finally, the local data are extended to characterise the entire aquifer through regionalizing techniques. However, within the infiltration and saturated zones of carbonate aquifers, karst processes create a peculiar void heterogeneity : voids may reach several meters in diameter and several kilometers in length. These voids are organized in a hierarchic network from the input surface often to a single spring: this is the conduit or drainage network. Therefore the network should be fully characterized prior to assessing the groundwater resources of a karst aquifer and its possible storage capacity, i.e. the network's transmissive or drainage function and its links with storage components (its storage function). Traditionally, speleological exploration is considered the best technique for directly characterizing a drainage network. Unfortunately, this usually gives an incorrect view of the karst aquifer because only a few parts (or none at all) are known when there is no access to the saturated zone. The classical hydrogeological approach is thus unsuitable for assessing karst aquifers. In this context, karst hydrogeologists must adopt the classical approach of physicians and biologists examining living bodies, by characterizing a karst aquifer, its resources and storage by accurate description of the void organization and an analysis of its overall behavior (or functioning) and that of its different parts or organs. With such an approach, a karst aquifer is considered as a living organism composed of different types of organs interlinked by functional relationships. Unlike physicians, hydrogeologists generally have to discover the extent of the body they wish to study (the karst system as a drainage unit, its limits and the boundary conditions). Therefore, as in the field of medicine^ techniques are used for describing the aquifer in bi- or tri-dimensional space (geology, geophysics) and for characterizing its functioning (hydrodynamics, natural tracing, hydrological balance). Moreover, data from these techniques are interpreted in order to propose a diagnosis, i.e. for building a conceptual model of the studied aquifer. In the next step, as in medicine, the conceptual model can be assessed with localized tests, such as artificial tracing and diver exploration for borehole positioning and pumping tests. Methods for interpreting tracing and pumping tests must obviously be adapted to the specific nature of karst, i.e. they cannot be based on classical models whose basic assumptions are never verified in the karstic medium. Finally, karst hydrogeologists have to set up and implement a complex set of techniques for describing the extent and limits of a karst system, exploring its drainage pattern, and analyzing its behaviour. All geoscience disciplines are ultimately required for the comprehensive exploration of groundwater resources in karst aquifers.

HJWFTAC: software for Hantush-Jacob analysis of variable-rate, multiple-extraction well pumping tests, 2002, Fleming Sw, Ruskauff Gj, Adams A,
Analytical well test solutions are a powerful approach to aquifer characterization and the parameterization of comprehensive numerical models. In addition, wellfield drawdown tests, which consist of coordinated pumping and data collection at a suite of monitoring and operating production wells, are of growing significance due to increasing pressures upon groundwater resources and the consequent management and planning requirement for superior hydrogeologic characterization of existing production wellfields. However. few pumping test analysis codes accommodate the multiple extraction wells involved, particularly for more sophisticated analytic aquifer test solutions. We present and demonstrate here a FORTRAN code for analysis of drawdown at a monitor well due to simultaneous variable-rate pumping at multiple independent production wells, which we developed in response to a need to refine an existing numerical, coupled groundwater/surface water resource management model, Spatial and temporal superposition are used to accommodate the typical operational properties of wellfield pumping tests, The software invokes the well-accepted Hantush-Jacob method for semiconfined or 'leaky' aquifers in a forward simulation procedure and effectively assumes homogeneity in applicable aquifer parameters (transmissivity, coefficient of storage, and leakance). Intended for both professionals and students, the code is widely applicable and straightforward to use as written. However, it can be modified with relative ease to use alternative well test solutions and/or formal inverse modeling techniques, or to accommodate spatial hydrogeologic variability. An application to a pumping test conducted in a karst limestone aquifer at the Cross Bar Ranch wellfield in Tampa Bay, Florida, demonstrates the utility of the software. (C) 2002 Elsevier Science Ltd. All rights reserved

The environmental hazards of locating wastewater impoundments in karst terrain, 2002, Memon B. A. , Azmeh M. M. , Pitts M. W. ,
A wastewater storage lagoon failed due to the development of a sinkhole at a site in the Lehigh River valley in Allentown, Pennsylvania (PA). The polluted wastewater from the lagoon entered into the underlying aquifer and moved within a narrow pathway controlled by cracks, fissures, and solution channels within the karstified Allentown Formation of the Cambrian Period. The Allentown Formation serves as the principal aquifer for the public water supply of the area. To develop appropriate remedial measures, a thorough understanding of the geologic setting was required. Therefore, a geologic and hydrogeologic characterization of the area was completed, aerial photography and satellite imagery interpretations were performed, stratigraphic core holes were drilled and geophysically logged, and the data correlated to define structural control and movement of ground water and pollutants. A number of wells were drilled and constructed, and water levels were monitored on a continuous basis to correlate with climatic changes and determine the direction of flow. Water samples were collected periodically and analyzed to delineate the vertical and lateral extent of migration of pollutants. Five saturated (water-bearing) zones were identified within the bedrock based on the analysis of cores and interpretation of geophysical logs. Ground water in the lower zones is polluted; the concentration of pollution increases with depth. Monitoring stations were established in the creek, south of the site, to measure flow rate several times during different seasons, and at different reaches, to determine the losing and gaining sections of the creek. Pumping tests were conducted to determine hydraulic characteristics of the aquifer. Based on the hydrogeologic model of the karstified aquifer, flow regime and structural control, a plan of action was defined and initiated to remediate the aquifer. The ground water is being remediated using a pump and treat methodology. The cleanup effort is continuous and the pollutant level is fluctuating with an overall-declining trend. The application of this technology has also created a pressure trough, thereby controlling off the site migration of pollutants. (C) 2002 Published by Elsevier Science B.V

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.


MANAGING AQUIFER RECHARGE (MAR): ASSESSMENT OF GROUNDWATER RESOURCES IN THE SAND, 2007, Kim Thoa Nguyen Thi, Giuseppe Arduino, Paolo Bono, Nguyen Van Giang, Phan Thi Kim Van, Bui Tran Vuong, Dinh Thi Bich Lieu, Brun Clarissa, Chiara Fiori, Fabrizio Gherardi, Francesca Zucco
Extensive geophysical, hydrological and isotopic investigations, including drilling campaigns, long term pumping tests and continuous monitoring of ground water levels in 4 monitoring wells, show that the sand dunes formation is characterized by the occurrence of an unconfined porous aquifer, of variable thickness (40 to 60 m), emerging at ground level in depressed morphological areas (20 to 30 m a.s.l.) where it forms intradune wetlands or natural reservoirs (lakes), and discharging directly to the sea through single springs (up to 200 l/s), linear springs and mostly by diffuse seepage along the shoreline (approximate discharge equal to 30 l/s per km). Hydrochemical and isotopic characterization of surface and groundwater in different periods, shows that the sand dunes aquifers, with electrical conductivity ranging from 50 to 500 μS/cm, are composed of different water types, characterized by complex mixing processes. The site chosen for the artificial recharge, where a 162 days pumping test has been carried out, proved that the use of the bank filtration technique has considerably improved the quality of water, originally highly contaminated by colibacteria. The well field developed within the present project is now capable of supplying 220 m3/day of good water quality to the Hong Phong community, recurrently affected by severe droughts. This project is part of UNESCO-IHP (International Hydrological Programme) and IMET (Italian Ministry for the Environment and Territory) Water Programme for Africa, Arid and Water Scarce zone - Viet Nam component funded by IMET. Funds for the Viet Nam project were also made available from the Vietnamese Government, and from ICSU, the International Council for Science and UNESCO Office Jakarta.

Interpretation of pumping tests in a mixed flow karst system, 2008, Maré, Chal J. C. Ladouche B. Dö, Rfliger N. & Lachassagne P.

A long-duration pumping test performed in the conduit of a mixed flow karst system (MFKS) is analyzed and interpreted. It constitutes a unique experiment of catchment wide response of a karst system, with drawdowns measured both in the pumped conduit and in the matrix. A modeling approach is proposed for this interpretation. The developed double continuum model consists of two reservoirs - karst conduits and the surrounding carbonate rocks - between which flow exchange is modeled using the superposition principle and the hypothesis of Darcian flow in the matrix considered as an equivalent porous media. The karst conduits are assumed to have an infinite hydraulic conductivity. Model calibration results in a very good match (relative root mean square [rRMS] = 2.3 %) with drawdown measured at the pumping well (karst conduit). It shows that the matrix hydrodynamic parameters (hydraulic conductivity and storativity) have a greater influence on the drawdown than the storage capacity of the conduit network. The accuracy of the model relies mostly on a very good knowledge of both pumping rate and natural discharge at the spring (with and without pumping). This type of approach represents an advance in double continuum modeling of karst systems. It also provides a methodology for the management of water resources from karst aquifers.


Characterization of Spatial Heterogeneity in Groundwater Applications , 2009, Trinchero, Paolo

Heterogeneity is a salient feature of every natural geological formation. In the past decades a large body of literature has focused on the effects of heterogeneity on flow and transport problems. These works have substantially improved the understanding of flow and transport phenomena but still fail to characterize many of the important features of an aquifer. Among them, preferential flows and solute paths, connectivity between two points of an aquifer, and interpretation of hydraulic and tracer tests in heterogeneous media are crucial points that need to be properly assessed to obtain accurate model predictions. In this context, the aim of this thesis is twofold:

· to improve the understanding of the effects of heterogeneity on flow and transport phenomena
· to provide new tools for characterizing aquifer heterogeneity

First, we start by theoretically and numerically examine the relationship between two indicators of flow and transport connectivity. The flow connectivity indicator used here is based on the time elapsed for hydraulic response in a pumping test (e.g., the storage coefficient estimated by the Cooper-Jacob method, Sest). Regarding transport, we select the estimated porosity from the observed breakthrough curve (Φ est) in a forced-gradient tracer test. Our results allow explaining the poor correlation between these two indicators, already observed numerically by Knudby and Carrera (2005).

Second, a geostatistical framework has been developed to delineate connectivity patterns using a limited and sparse number of measurements. The methodology allows conditioning the results to three types of data measured over different scales, namely: (a) travel times of convergent tracer tests, ta, (b) estimates of the storage coefficient from pumping tests interpreted using the Cooper-a Jacob method, S est, and (c) measurements of transmissivity point values, T. The ability of the methodology to properly delineate capture zones is assessed through estimations (i.e. ordinary cokriging) and sequential gaussian simulations based on different sets of measurements.


Third, a novel methodology for the interpretation of pumping tests in leaky aquifer systems, referred to as the double inflection point (DIP) method, is presented. The real advantage of the DIP method comes when it is applied with all the existing methods independently to a test in a heterogeneous aquifer. In this case each method yields parameter values that are weighted differently, and thus each method provides different information about the heterogeneity distribution. In particular, the combination of the DIP method and Hantush method is shown to lead to the identification of contrasts between the local transmissivity in the vicinity of the well and the equivalent transmissivity of the perturbed aquifer volume.

Fourth, the meaning of the hydraulic parameters estimated from pumping test performed in leaky aquifers is assessed numerically within a Monte Carlo framework. A synthetic pumping test is interpreted using three existing methods. The resulting estimated parameters are shown to be space dependent and vary with the interpretation method, since each method gives different emphasis to different parts of the timedrawdown data. Finally, we show that by combining the parameter estimates obtained from the different analysis procedures, information about the heterogeneity of the leaky aquifer system may be inferred.
Fifth, an unsaturated highly heterogeneous waste rock pile is modeled using a simple linear transfer function (TF) model. The calibration of the parametric model provides information on the characteristic time of the flow through the matrix and on the fraction of the water that, within each section, is channeled through the macropores. An analysis of the influence of the scale on the results is also provided showing that at large scales the behavior of the system tends to that of an equivalent matrix reservoir masking the effects of preferential flow.


DIAGNOSTIC PLOTS APPLIED TO PUMPING TESTS IN KARST SYSTEMS, 2012, MarÉ, Chal Jeanchristophe, Ladouche Bernard, Dewandel Benot, Fleury Perrine, DÖ, Rfliger Nathalie

Pumping tests conducted on wells intersecting karst heterogeneities such as the conduit network are difficult to interpret. Nevertheless, this case can be solved by assimilating the horizontal karst conduit to a finite conductivity vertical fracture. In this case, several flow patterns corresponding to the respective contributions of karst subsystems (fractured matrix, small conduits, and main karst drainage network) can be identified on the diagnostic plot of the drawdown derivative. This is illustrated on two examples from Mediterranean karst systems in southern France. A pumping test on a well intersecting the main karst drainage network of the Cent-Fonts karst system shows (i) a preliminary contribution of the karst conduit storage capacity followed by (ii) linear flows into the fractured matrix. A pumping test on a well intersecting a small karst conduit of the Corbières karst system shows the existence of (i) bi-linear flow within both the karst conduit and the fractured matrix at early times, followed by (ii) radial flows within the fractured matrix and (iii) finally the contribution of a major karst cavity. The use of diagnostic plots allows identifying the various flow regimes during pumping tests, corresponding to the response of the individual karst aquifer subsystems. This is helpful for improving the understanding of the structure of the karst aquifer and flow exchanges between subsystems.


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