Hydrogeological and Environmental Investigations in Karst Systems

This paper presents preliminary results from two karst systems belonging to the “Jurassic Karst” observatory in the French Jura Mountains. The sites are characterized by localized and diffuse recharge. Physicochemical monitoring was performed at the karst outlet (springs), as well as in the unsaturated zone (cave and epikarstic spring). During two contrasting flood events, water level, temperature, electrical conductivity, dissolved organic carbon, turbidity, and dissolved oxygen were recorded at high frequency and compared. These preliminary results allow to propose a conceptual model for both sites. It was possible to distinguish specific autogenic and allogenic recharge mechanisms and to characterize the respective contribution of the saturated and unsaturated zones.

The hydrodynamical response at 45 flow points in the gallery of the Low Noise Underground Laboratory—carbonate aquifer (Rustrel, southern France) was monitored in order to determine the relationship between the hydrodynamical functioning of each flow component—slow, intermediate and quick, the depth and the fracturing density. Analysis of the relationship between the distribution of each flow component in function of depth and fracturing density in the karst vadose zone revealed the importance of (1) the variation of flow activation conditions with the depth, (2) the evolution of the flow component distribution with the depth and the fracturing density, and (3) the variability of the vadose zone role in supplying baseflow discharge, in function of carbonate thickness and fracturing state of the study area.

This paper aims at characterizing the functionality of karstic systems. In order to do so, an extend of a method based on the saturated index with respect to calcite (SI

c

) and CO

2

partial pressure (Pco

2

) is used. The initial method already applied by Peyraube et al. (

2012

) uses the Pco

2

of water at equilibrium with atmosphere (Pco

2_eq

) and the Pco

2

of water for a SI

c

equal to zero (Pco

2_sat

). The Pco

2_sat

variation gives information on flows conditions within the karstic system. It describes the degree of karstification of the system. Systems with developed saturated zone are characterized by under-saturated waters as well as saturated ones with variable Pco

2_sat

. At last, fissured system has Pco

2_sat

which vary only slightly. Moreover, variations of Pco

2_sat

show homogenization capacities of a karst.

Characterising the hydrodynamic processes in the unsaturated zone is a prerequisite to efficiently protect and manage the karst water resource. In this study, we use rainfall-discharge cross-correlation analysis to improving the understanding of the hydrodynamic functioning of the karst unsaturated zone. This analysis is based on sparse discharge measurements from five flow points located within the artificial LSBB gallery. Our results are consistent with hydrochemical analyses, and they evidence the influence of inter-annual rainfall variability on the hydrological functioning of the unsaturated zone. They also show that cross-correlation may prove an efficient tool for sparse data analyses.

The hydrogeological behavior of the unsaturated zone in karst limestones is far to be completely understood. However, this part of aquifer systems is the most important for the vulnerability of drinking water resources. In Wallonia, the majority of tap water is provided by Devonian and Carboniferous limestones, which consist of highly karstified and fractured formations. The purpose of this research was to apply an experimental approach in order to assess the functioning of the unsaturated part of karst systems. We choose to follow two drip sites within the Han-sur-Lesse cave system (Rochefort, Belgium), the actual dataset covers the 2008–2013 period and the recording device is still active. We also conduct dye tracer experiment (uranin) from the surface with a fluorometer into the cave coupled with a drip collector. In this paper, we present the contextualization of the study site, the experimental methodology, and the first results.

The common hydrogeological concepts assume that water enters in karst media by preferential pathways. But it is difficult to identify these pathways, particularly if soil or scree covers the karst features. When and where does water enter in the hydrosystem? How fast? A unique large-scale Electrical Resistivity Tomography (ERT) surface-based time-lapse experiment was carried out during a typical Mediterranean autumn rainy episode (230 mm of rain over 17 days). A total of 120 ERT time-lapse sections were measured over the same profile during and after this event (30 days). The main goal was to evaluate efficiency and limits of the ERT to monitor water infiltration, under natural conditions. Apparent (directly measured) and inverted resistivity’s variation during the rainy event highlights some interesting zones. They could be interpreted as preferential pathways, where water dynamic seems quicker in term of moistening and drainage. Nevertheless, these results have to be interpreted reasonably because ERT does not provide enough precision to determine exact pathways geometry and functioning. In addition, forward modeling provided relevant data treatment limitations mainly for the deeper parts of the sections.

Temporal evolutions of discharge, water chemistry (electrical conductivity, temperature, alkalinity, Cl

−

, SO

4

2−

, Ca

2+

, Na

+

, Mg

2+

) and carbonate controlling variables (PCO

2

and SI

calcite

), together with natural tracers of infiltration (TOC and NO

3

−

), monitored in two karst springs of the Sierra Gorda de Villanueva del Trabuco aquifer (Southern Spain), reflect the greater relative importance of the soil-epikarst-unsaturated zone in the hydrogeological functioning of this aquifer. Each recharge event provoked an increase of discharge rates and water mineralization, the latter being due to an increase of alkalinity, and Ca

2+

, Cl

−

and SO

4

2−

contents, while Mg

2+

content decreased. Moreover, these variations were mostly accompanied by the rise of TOC content, while concentration of NO

3

−

only rose during the first flood episodes (normally in autumn), and progressively fell during winter and spring times. Water temperature varied annually in a similar way to changes in air temperature.

Researchers have been troubled with finding a reliable technique for estimating groundwater recharge in carbonate aquifers. Many studies have recognized the importance of preferential flow in karst systems. Despite this evidence, preferential infiltration has no effect on estimating recharge with a classical soil water budget. The present research aims to determine the significance of the correct location of preferential infiltration areas in estimating recharge with the APLIS method. The study was carried out in Sierra de las Nieves aquifer (Southern Spain). The effect of correctly estimating the preferential infiltration areas is studied through different levels of complexity in the geomorphological information: (i) a classical geomorphologic map with pothole databases available, (ii) a reviewed geomorphologic map, and (iii) fracture density and epikarst cartography obtained with field work and remote sensing interpretation. The obtained results provided a mean difference of more than 10 % of recharge in the whole aquifer, and up to 20 % when the pixel scale is considered at.

Karst depressions of decametric scale (dolines, uvalas, poljes, and other endorheic basins) play an important role in the hydrogeology of karst aquifers. They are traps of sediment and when their detritic filling has an important thickness they can retain a large amount of water delaying their percolation towards the water table or towards the networks of conduits. Many times the delineation of the depressions may be difficult because the study area may be very large, or inaccessible or hidden by vegetation. In those circumstances, it is of great help to have an automatic method of depression detection and delineation. The proposed procedure uses the digital elevation model, a geographical information system, an algorithm of pit removal and basic operations of map algebra. The method provides the depth of each detected depression measured from its rim. This fact can be used to detect the center of maximum depth as well as for calculating morphometric parameters using depth. The final map of depressions can be characterized by altitude in order to have morphometric parameters related with elevation. The algorithm has been extended for detection and delineation of karst hills. The methodology is illustrated with the Sierra de las Nieves karst aquifer in the province of Malaga, Southern Spain, where the depressions and hills show a strong structural control.

Estimates of groundwater recharge were made for a karst aquifer in the Amazonas Region of northern Peru based on two methods: the APLIS method, and the modified-APLIS method. The study area is a 9.6 km

2

section of the upper La Florida Catchment, located on the eastern slope of the Andes mountain range at an elevation of approximately 2500 m. Annual precipitation is over 1,500 mm/year, with high intensity storms during the rainy season (November–April). The study area is characterized by high relief, including deep canyons, and is underlain by limestone-dolomite of the Upper Triassic Pucara Group, which contains karst and epikarst features. These conditions make it difficult to accurately estimate the magnitude and distribution of runoff, infiltration and groundwater recharge. The APLIS and the modified-APLIS methods were applied to estimate the spatial distribution and the annual rate of groundwater recharge in the study area. These methods were developed for carbonate aquifers under Mediterranean conditions, and some modifications were required to apply them to the study area in Peru. The average annual recharge rate estimated with the APLIS method is 48 % of the total rainfall, with high recharge areas occurring in canyons where porous dolomite outcrops. The average recharge with the modified-APLIS method is 24 %. The difference in the recharge rate by these methods is considerable, while the areas of greatest recharge are similar mainly due to the application of aquifer and non-aquifer designations common to both methods. The recharge distributions estimated with these methods were introduced into a numerical groundwater flow model for the study area. The calibration process indicates that the modified-APLIS method provides a more reasonable representation of the recharge rates for the study area.

This paper presents a synthesis of the results and the evaluation methods of recharge in 51 carbonate aquifers of the Betic Cordillera. The average infiltration coefficient is 38 %, with a standard deviation of 12 %. The method of evaluation of recharge most applied is soil water balance, which served to take the first steps in groundwater management in Spain. Other widely used methods are water balance of the aquifer, chloride mass balance, and empirical methods such as APLIS. In eastern areas of the Cordillera, where the semiarid conditions are more overt, distributed models are used to assess recharge and calibrate it with data from the piezometric level evolution. In general, the annual recharge rates obtained appear higher when correlated with the annual rainfall. Thus, the data presented in this work contribute to a correct evaluation of renewable resources associated with the carbonate aquifers of the region. The high capacity of recharge and good quality of water for different uses, and especially to supply the population, makes these aquifers essential in the face of strong demand. Moreover, the data presented should be of special interest for future comparisons involving recharge assessments and different scenarios of climate change and changes in land use.

Recharge of karst aquifers occurs when rainfall (or snowmelt) infiltration crosses the soil mantle and percolates through the vadose zone. In karst environments, the infiltration can occur in both concentrated and diffuse forms. In several areas of the Mediterranean, karst massifs are important sources of drinking water. In southern Italy, karst massifs are generally characterized by wide endorheic basins with seasonal lakes, which constitute large parts of the spring catchments. The origin of these endorheic basins is related to tectonism during the upper Pliocene-Pleistocene epochs and subsequent erosion and karstification. These endorheic basins constitute the most important recharge areas of karst massifs in central-southern Italy, and have been designated as groundwater protection areas. This study focuses on the karst massifs of the Picentini Mountains, which is characterized by rugged, steep landscape, and comprised of mainly dolostone and limestone. These karst massifs feed many basal karst springs with discharges up to thousands of liters for second, and constitute the main water resource in the region of Campania. The hydrological processes in these basins are simulated using a Geographic Information System (GIS)-based model on an annual scale. The results of the annual scale model have been used to successfully calibrate a daily time step model of infiltration and run off.

The impact of the variations of multiple environmental parameters on the response of karstic systems was investigated after a campaign of tracing tests acquired in very different hydrologic conditions. Principal components analysis and hierarchical clustering were applied on both environmental variables and karstic system response variables (parameters of the RTD curves). Equations between the RTD parameters and the most relevant variables were established using a symbolic regression algorithm. This model giving RTDs parameters in function of boundary conditions is more accurate than the PCA analysis since it takes into account the nonlinearity of the relations between variables. It appeared that the variations of the RTD parameters depend mainly on the piezometric level downstream of the aquifer, the cumulated rainfall preceding the injection, and on the tide coefficient (suggesting sensitivity to the annual variations of tide, in this case of a karstic system under marine influence). So the RTDS parameters are controlled by the hydraulic conditions downstream of the system, including tide. The dispersivity was found to be very sensitive to the precipitation and tides variations at a daily scale.

Tracer tests are an irreplaceable tool for hydrogeologists. They are used to determine the paths of water flow between two spots in a catchment below the surface of the earth. Usually, hydrogeologists carry out tracer tests with only one tracer at a time, but sometimes two or more fluorescent substances are simultaneously injected into different spots and collected in a spring. Then, the resulting cocktail is analyzed by optical methods (fluorescence spectrometer) to separate the tracers and calculate their concentrations. Molecules with sufficiently different excitation spectra are easily separated. But two among the most frequently used tracers, uranine (Na fluoresceine) and eosine, are very close in this respect. Their separation is well-known to be difficult. Other examples are sodium naphthionate and amino G acid, two very useful tracers since they are colorless and therefore unnoticed in surface waters. The eluent of charcoal bags (fluocapteurs) is another example. Beside the released tracer, there is a very high fluorescence background of dissolved organic matter (DOM) from which it must be optically separated. The shape of the excitation spectrum of a fluorescent tracer can be approximated by a Gaussian curve. This curve is completely described by three parameters: peak wavelength, height, and width. The spectrum of a cocktail of two tracers is the sum of two such Gaussian curves. To separate these two curves, we use an algorithm based on the steepest descent in the parameter space to find the best set of 2 × 3 = 6 parameters of the model that best fits the measured curve. We achieve good separation even with a concentration ratio smaller than 1:10.

An approach for conducting tracer tests in karst systems is proposed in order to assess differing degrees of groundwater vulnerability. It consists of (i) a standardized artificial recharge scenario, (ii) the selection of conservative tracers, and (iii) application to contrasting vulnerability situations within a catchment. Results from multi-tracer testing at a karst site in Switzerland provided breakthrough curves that were significantly different in terms of mass recovery, which is considered the key parameter for defining a quantitative protection effect. The presented approach may provide a better basis for both punctual validation of vulnerability maps and refinement of associated assessment methods.

Brazilian economy has experienced substantial growth in the last decade. Balancing economic development and the associated increase of water consumption with environmental sustainability is a challenge for both society and government. Karst aquifers are important freshwater resources for the growing population in some regions of Brazil. The west region of the state of Bahia is known for its abundant water resources. Corrente River (basin surface: 42,732 km

2

), provides ca. 30 % of the total water flow of the Sao Francisco River (basin surface 631,133 km

2

). During recent years, Bahia’s state has undergone a marked process of economic growth driven by agricultural modernization. Important transformations of soil occupation can be observed, and water resource exploitation is often disorganised and predatory. The karst aquifers on the San Franciscan depression are located downstream of an intensively exploited region, the Urucuia sandstone aquifer. Karst aquifers are characterised by high vulnerability to contamination and low capacity of self-purification. This study aims to: (i) perform a preliminary characterization of the hydrogeological behaviour of the karst system in relation with the whole basin context by characterising water hydrochemistry, and (ii) to verify the existence of anthropogenic pollution in order to delineate the aquifer vulnerability. The first results showed a great heterogeneity of aquifer waters, denoted by water chemistry. This heterogeneity was not only related to a large basin surface and different recharge conditions, but also to aquifer compartmentalisation in depth. Results denoted the possible existence of redox processes associated to organic deposits in depth.

Plotting multiyear chemographs in a karst river may display evolutional trends in water quality. In recent decades, different factors could explain for instance phosphate decrease and nitrate increase. In the Jura karst area, different springs and rivers not only exhibit variation of anthropogenic molecule concentrations, but also evolution of major element concentrations, that results in a change in electrical conductivity. Over a 30-year period, average electrical conductivity of the Loue River, which is totally supplied by karst springs, has increased from 260 to 470 µS/cm. Such an 81 % variation is only explainable by increases in major components, i.e. calcium and hydrogenocarbonate ions, which are the almost exclusive by-products of karstification processes in the Jurassic limestones of the Jura Mountains. Indeed, no direct anthropogenic cause may be invoked for such an evolution. An increase of dissolution throughout the system is necessarily correlated to an increase in the carbon dioxide transfer, resulting from an increase in dissolution and/or production rate.

The Blanco River of central Texas provides an important hydrologic link between surface and groundwater as it traverses two major karst aquifer systems—the Trinity and Edwards Aquifers. The Blanco River is characterized by alternating gaining and losing stretches due to the presence of springs that discharge water into the river and swallets that drain water from the river. The region consists primarily of Lower Cretaceous limestone, dolomite, and marls. One of the more significant springs along the Blanco River is Pleasant Valley Spring. During below-average flow conditions, Pleasant Valley Spring becomes the headwaters of the Blanco River even though the headwaters, under wet conditions, are about 50 km upstream. Water that enters the Edwards Aquifer from the Blanco River can eventually discharge at both San Marcos Springs to the south and Barton Springs to the north. During periods of extreme drought, when other recharging streams are dry, the Blanco River can provide enough water to the Edwards Aquifer that will help maintain flow at Barton Springs where endangered species of salamanders need sufficient flow of high-quality groundwater. In the western part of the study area, increasing rates of pumping from the Trinity Aquifer, combined with impact from drought, are reducing heads in the aquifer and are subsequently reducing springflows (such as from Pleasant Valley Spring) that sustain the Blanco River. Decreasing flow in the Blanco River can lead to less recharge to the Edwards Aquifer and less discharge from San Marcos and Barton Springs. A better understanding of these aquifer systems and how they are influenced by the Blanco River is important for management of groundwater in an area undergoing significant population growth.

Time analysis of the chemical, thermal and isotopic characteristics of spring waters was conducted to infer the different flow types feeding the Torrox spring (Teba-Peñarrubia carbonate aquifer, southern Spain). The results suggest that the relatively high mineralized and thermal groundwater drained by the outlet is conditioned by the mixing among recently infiltrated waters through the carbonate outcrops, runoff infiltration in La Venta river and (not yet proved) deep groundwater coming from neighbouring aquifers. This example comprises a hydrogeological characterization of the groundwater discharge in karst aquifers from the analysis of the spring natural responses, which is crucial to understand its functioning and, consequently, to plan a suitable management and protection of karst waters.

Hydrodynamic and hydrochemical monitoring of springs has been largely used to study carbonate aquifers and to determine their hydrogeological functioning. In this work, temporal evolutions regarding flow discharge, major components, and natural soil tracers (Total Organic Carbon and NO

3

−

) of four springs draining karst aquifers located in Sierra de Grazalema Natural Park (Southern Spain) have been analyzed. Results show the existence of aquifers with a high degree of karstification in which recharge water rapidly infiltrates and causes sharp water dilutions and steep flow increases. These aquifers coexist with others characterized by a lower development of karstification processes, but higher natural attenuation capacities.

Leakage detection and prediction of fractured rocks is an important question in hydropower engineering. Some of large water reservoirs are built in karstic carbonate areas. In order to understand underground circulations in the limestone/dolomite foundation of Vouglans dam (Jura, France), analysis of groundwater chemistry, according to geological conditions, is used. Statistical analyses (PCA and DFA) are used (i) to characterise more precisely the low contrast in chemical composition resulting from the interaction between surface water, groundwater and carbonate environment, and (ii) to reclassify individuals in homogeneous groups with respect to the variables studied. Three hydrodynamic behaviours were determined in the sector. The area of influence of the rapid transit of the lake water varies with the seasons, and particularly in response to changes of the water level of the lake. The hydrostatic pressure of the water column has an influence on the opening and closing of cracks at the bottom of the dam.

Long-term monitoring of soil CO

2

dynamic was applied under different weather conditions and land uses to investigate the influences of weather and LUCC on soil CO

2

variations as well as its potential carbon sink. Observation results demonstrate that seasonal variations of soil CO

2

are mainly controlled by temperature-water combined effect, rising to the peak in wet–hot season and declining to the valley during dry–cold time. In spatial scale, soil CO

2

concentration is largely regulated by LUCC and follows the descending order of forest, shrubbery, dry land, and paddy land except for rice growing season, but with an ascending sequence for coefficient of variations (C.V.s), among which the highest C.V. and the abrupt changes of CO

2

in paddy land are mainly due to the alternate cultivation, flooding irrigation, and draining mechanism. Furthermore, by means of modeling calculations, wet–hot weather conditions and land uses as forests are provided with higher dissolved inorganic carbon (DIC) equilibrium concentration than the other sites, reflecting stronger karst process as well as larger potential carbon sink.

Hydrogeological studies were performed on two karst springs located in a mining area of soil-covered karst in the Lagoa Santa region, in subtropical southeastern Brazil. Although they are located close together, the Tadinho and Cafundó springs exhibit distinct hydrogeological behaviors. Groundwater flow routes were determined through quantitative and qualitative rhodamine tracer tests through artificial injection in swallow holes. A 2-year discharge monitoring demonstrated that there is a 4-month delay between pluvial and discharge peaks at Tadinho spring due to the presence of a constriction, which causes the retention of the dye and a delay in the discharge response. Tadinho spring also displays an average discharge that is smaller than the total injection flow feeding the spring, as indicated by an only 20 % dye recovery. Conversely, Cafundó Spring displays a closer response to pluvial peaks because it is located within a much larger groundwater system, which major outlet is Tadinho Spring. Tadinho is characterized as an underflow karst spring (sensu Worthington

1991

) because its discharge displays a constant depletion coefficient. Cafundó spring is interpreted as an overflow spring, situated in a higher topographic position, being constrained by the geometry and porosity of the aquifer system. A 4-year hydrochemical monitoring program showed sharp variations in calcite saturation indexes for Tadinho spring, with a negative correlation between rainfall and aggressiveness. The denudation rates for Tadinho spring are, on average, 22.5 mm/ka, in agreement with other studies in the Brazilian karst. Water budget calculations and spring hydrograph analysis indicate that the catchment area of the springs is much larger than determined by surface divides, with the Tadinho catchment area comprising significant areas of mantled karst.

The Mt. Canin massif, from a hydrogeological and geomorphological point of view, is a unique structure, being an independent part of the Italian Julian Alps (north east Italy) bounded on all sides by impressive karst springs. Extensive outcropping limestones go from the top (2587 m a.s.l.) to the bottom of the valleys (about 500 m a.s.l.) creating an hydrostructure subdivided between two countries originating two transboundary watersheds: the Mediterranean one to the South and the Black Sea to the North. The aim of this paper is to define the dynamic and the characteristics of the groundwaters and to identify the superficial and deep watersheds in order to elaborate the aquifer vulnerability.

Temperature is the easiest water quality parameter to measure and a variety of robust, waterproof and relatively inexpensive temperature loggers are available that enable high-resolution data to be collected from remote locations. It has long been known that in regions where there is a seasonal variation in surface air temperature the water temperature at karst springs can be used to distinguish between those systems that are fed partly by sinking streams (wider annual temperature range) and those fed only by autogenic percolation water (narrower annual temperature range). However, there has been little analysis of short-term temperature changes within open and flooded conduit systems as well as at springs, which can provide significant additional information. The potential utility of water temperature logging is demonstrated in the Peak-Speedwell cave system, Derbyshire, England where high temporal resolution (2-min) water temperature data have provided information on internal geometry, residence times and velocities.

In the period of September 10–21, 2002, 317 km

2

of Muránska planina karstic plateau (Slovakia) was mapped for springs in great detail. Within this short time interval, 295 springs were documented and also sampled for δ

18

O. Although only freshwater of apparently similar origin was sampled, δ

18

O was in a range between −10.90 and −7.32 ‰. Plateau is moderately vertically exaggerated (~400 to ~1400 m a.s.l.), but altitudinal differences do not explain this wide oxygen isotope span. Patterns of δ

18

O distribution were examined for the possible influence of documented springs’ parameters (temperature, discharge, electric conductivity, geology, aquifer circulation type, morphology around spring’s orifice) without finding any significant dependency. The main reason for very different δ

18

O values in nearby groundwater sources was identified in individual groundwater circulation regimes. According to IAEA GNIP stations’ records, a significant contrast in precipitation δ

18

O values was found within 14 months previous to the sampling. Heavier oxygen isotopes in the sampled set (around −8 ‰) probably reflect quick circulation influenced by enriched July–August 2002 precipitation (−5.28 ‰). Depleted δ

18

O in springs (around −10 ‰), corresponding to the impact of winter 2001/2002 precipitation (−18.4 to −14.7 ‰), suggests longer residence times.

The Ordesa and Monte Perdido National Park constitutes the largest calcareous mountain range of Western Europe, where the highest altitude karst of Europe is found. No previous studies regarding groundwater isotopic characterization in this area are known. This work presents the results of two preliminary campaigns carried out during July 2007 and April 2012. The water stable isotopes (δ

18

O, δ

2

H) show that the oceanic fronts from the Atlantic are responsible for the high levels of precipitation. In autumn, winter, and spring time, a deuterium excess is found in recharge water, which could be related to snow sublimation and its later condensation on the snow surface. The recharge zones are between 2,500 m and 3,200 m asl. The water tritium content points to short groundwater transit times.

A methodological procedure is proposed for evaluating the groundwater reserves in carbonate aquifers. It is applied to the Solana-Onteniente-Volcadores aquifer (Alicante, SE Spain), subjected to groundwater mining exploitation. The large amount of geological and geophysical information available (361 km

2

of geological mapping, 84 lithological columns of boreholes, 47 km of seismic reflection profiles, 68 vertical electrical soundings [VES], 22 MT soundings and 1,600 gravity measurements) was integrated using two different 3D geological modelling codes: 3D Geomodeller and GOCAD. In addition, a petrophysical study of the rock matrix was accomplished with 39 rock samples, aiming to determine their storage capacity and calculate the total groundwater reserves. Information provided by the 3D model stands as a great advance in our hydrogeological knowledge of the region.

The geological structure of Los Chotos-Sazadilla-Los Nacimientos carbonate aquifer (S of Jaén) and its hydraulic connection with the La Serreta-Gante-Cabeza Montosa carbonate aquifer have been established through geophysical prospecting–gravity and magnetics–structural measurements and study of piezometric levels. The scarce hydrogeological data, the complexity of the tectonic structure, and the presence of Plio-Quaternary rocks covering the permeable carbonate rocks make it difficult to establish a robust conceptual hydrogeological model. This study focuses on an area where hydraulic disconnection between the two aquifers was traditionally assumed, given the diapiric emplacement of low-permeable rocks between them. A connection between aquifers implies greater groundwater reserves than supposed up to present. These results are valuable for efficient and sustainable groundwater management.

The three-dimensional distribution of karst conduits in a karst aquifer is the main source of its heterogeneity and anisotropy. It also has a strong effect on peak spring discharge, and in the form of the karstic hydrograph, chemograph, and thermograph. The direct access to the conduits is only possible by speleological exploration and cave mapping, which provides a very valuable information for karst modeling. However, this information is biased because the speleologists can only explore a limited part of the conduit network: they can only map conduits of a minimum diameter, the speleological exploration can take many years in order to explore all the leads that appear in a network system and parts of the network are not accessible. In order to estimate conduit porosity we can take advantage of the fractal character of nature. The volume of conduits larger than a given diameter can be estimated in a particular volume of rock. This is done by extrapolating a power law that has been fitted to experimental data. The power law distribution of the volume of conduit voids larger than a particular diameter is related with the fractal behavior of a network of karst conduits. This fact was also used for simulating a three-dimensional network of karst conduits by a stochastic process of diffusion limited aggregation. The procedure is illustrated in the Sierra de las Nieves karst aquifer in the province of Malaga, Southern Spain. Karst conduit porosity can be used for generation of numerical models of karst systems, and for the mathematical modeling of flow in karst aquifers.

Karst aquifers are very complex and heterogeneous systems because of the presence of three kinds of porosity (matrix rock porosity, fracture porosity, and conduit porosity) that generally have a large spatial variability. In order to have realistic karst models the three kinds of porosity and their spatial variability must be taken into account. A quantitative model of a karst aquifer is proposed by integration of the three kinds of porosity in a three dimensional numeric model. Nevertheless, the main task of this work is restricted to the proposal of methods for their evaluation. Matrix rock porosity has been measured in the laboratory from samples collected in the field. Matrix rock porosity is well correlated with the lithology and with the structural position of the rock. Fracture porosity has been estimated from fracture mapping and field measurements. A geostatistical method is used to obtain a continuous field of fracture porosity. Conduit porosity has been calculated from a power model fitted to speleologic cave mapping data. However, because of the scarcity of conduit data, probabilistic models must be conjectured. The integration of the three kinds of porosity gives a three dimensional numerical model that can be used in vulnerability mapping, recharge estimation, and mathematical modeling of flow and transport in karst systems. The approach is illustrated with the Sierra de las Nieves karst aquifer in the province of Málaga in Southern Spain.

The mathematical modeling of karst aquifers has been limited to black box models many times where the input (recharge) is related to the output (spring discharge) by using a transfer function from system theory and the spectral analysis of time series. These so-called black box models have a limited use because they do not provide information on the local spatial characteristics of the karst aquifer. In order to have a mathematical spatio-temporal model of the karst hydrogeology, several issues must be addressed, including a three-dimensional numeric model of the karst system, a spatial evaluation of recharge, and a consideration of the epikarst, karst depressions, fracture zones, thick vadose zones, and the simulation of conduit flow and karst spring discharge. All these characteristics have been taken into account in the Sierra de las Nieves karst aquifer in the Malaga province, Southern Spain. Furthermore, this aquifer has three hydrogeologic basins, with three main discharge points. It is concluded that spatially distributed karst models have following requirements: the integration of all the available information, the availability of speleologic cave mapping, the development of numerical karst system simulation methods and karst models of flow in the karst system. The problems encountered are discussed and the proposed solutions are described.

This paper investigates the role of karst aquifers on flood generation and propagation using the Hayami Diffusive Wave (DW) model accounting for uniformly distributed lateral flows. The inverse model was applied on the main channel reaches of the Tarn basin at Millau (2,400 km

2

) in southern France to assess lateral inflows from karstic springs as well as lateral outflows from river losses. Results show that the DW model, which is simple, parsimonious, and easy-to-use, is able to quantify lateral flows avoiding difficult parameterisation. Surface/groundwater exchanges were characterised on several reaches along the stream, showing a highly variable attenuation/amplification influence of flood peak by karst units during a single flood event. We showed that the upstream part of the karst area have a dominant attenuation role by re-infiltrating part of runoff from the head-water basin in hard-rock areas, while the downstream part have a dominant amplification role due to high contributions of karst groundwater. These results improved the conceptual hydrogeological model of the Grands Causses region.

The Almyros spring is the outlet of the largest karst coastal aquifer in Crete Island, Greece. The spring is important for drinking water supply of Heraklion, the capital city of Crete. However, because of sea water intrusion, most of the time and especially during the dry season, the water is brackish. Since the 1960s, despite repeated efforts to collect the freshwater resources of the aquifer, only few practical results have been obtained. In order to investigate alternative measures for collecting the aquifer’s freshwater a mathematical model was developed for simulating the saturated groundwater flow in the karst porous medium. Although the local use of the Darcy’s law for flow simulation in discontinuous porous media such as karst aquifers is problematic, it can give useful results when applied in larger scales. For studying the hydrodynamic characteristics of the Almyros/Heraklion aquifer, the numerical model MODFLOW was used and after calibration, it is shown that useful results can be obtained in practice.

Freshwater resources in coastal aquifers are restricted by seawater intrusion. Studying brackish spring can be an appropriate approach to assess this saline intrusion and to elaborate a conceptual model of the karst aquifer. The aim of this study is to model the hydrogeological flows and the salinity of a brackish spring using a lumped numerical model (Rainfall-Discharge-Salinity), and to quantify the freshwater discharge available. The model is based on a classical karst model composed of connected reservoirs representing the main storage elements of the karst aquifer, which can be deduced from the analysis of discharge and salinity recorded time series. The model was successfully applied on the Port-Miou spring (400 km

2

), in SE France, which is one of the main submarine springs around the Mediterranean Sea. Four reservoirs were used to model spring discharge and salinity: a SOIL reservoir feeding a DEEP brackish reservoir impacted by seawater intrusion, and two FAST and SLOW reservoirs representing the shallower freshwater resource. We showed that the spring water is always brackish more or less diluted by freshwater during flood events. These results improved the conceptual hydrogeological model of the Port-Miou spring and showed the effectiveness of lumped models to simulate discharge and salinity in coastal karst aquifers.

Karst aquifers typically have complex flow patterns as a result of the depositional heterogeneities and large conduits from dissolution features. Various field measurements were carried out to build a hydrogeological conceptual model of the Jurassic aquifer close to Blaubeuren (Germany), including drilling data, well tests, and geophysical surveys. These data were assembled to simulate the groundwater flow at a site where a possible new pumped-storage plant is in planning approval. The favorable layout of the lower reservoir is designed without sealing to the connected karst aquifer underneath. Approving this construction concept, various measures and strategies have to be formulated by using numerical modeling to limit possible adverse impacts on the construction site and its environment, considering that the Blau Valley requires high level of protection. Based on the conceptual model, the aquifer system is represented by a three-dimensional finite element model using the FEFLOW numerical code. The model is calibrated for steady-state and transient conditions by matching computed and measured piezometric levels (November 2012—March 2013) from over 30 observation wells to estimate the best-fitted spatial distribution of both hydraulic conductivity and storage coefficient in the aquifer. The model is used to analyze quantitatively the flow regime, the groundwater mass balance, and the aquifer hydraulic properties of this karst area. The results of the study provide necessary information regarding the hydraulic behavior of the aquifer in order to plan the construction phase and the subsequent operation of the pumped-storage plant.

The present study focuses on the hydrodynamic characterization of the Lez karst aquifer (Southern France) on the basis of hydraulic field tests performed at different scales of space and under distinct hydrological conditions. Depending on the water level conditions, the organization of the flow paths linked to the geological structure of the reservoir changes and a compartmentalization of the system due the hierarchization of hydraulic connections to the main flow paths was assessed. For the same parameter characterized at borehole scale and at regional scale, a difference of 10–10

5

has been quantified. This quantification of hydrodynamic parameters provides important constraints on multiscale modeling and the characterization of main flow paths in such a karst system.

On the basis of the characterization of the different karst subsystems (Soil/Epikarst—Unsaturated Zone—Saturated Zone) and mathematical models developed on specific sites, we propose an adjustable modeling platform of karst for both the simulation of spring discharge at outlets and the analysis of the hydrodynamics of the compartments considered in the model. This platform was developed within the framework of the KARST observatory network initiative from the INSU/CNRS, which aims to strengthen knowledge-sharing and promote cross-disciplinary research on karst systems at the national scale.

GIS-based methods are often used to assess the spatial distribution of mean annual recharge rates of karstic aquifers, but they typically do not provide temporal information about the dynamics of recharge. Numerical models are able to assess the temporal dynamics of recharge but they often provide only a single time series of recharge without any information on spatial distributions of recharge. In this study, we compare a process-based numerical karst model—in which the spatial variability of karst properties is considered statistically using analytical distribution functions—with an independently applied GIS-based recharge estimation method. We find that both methods produce similar spatial distributions of recharge rates. We further demonstrate that similarity between the two methods can only be achieved if the numerical model is calibrated with discharge and hydrochemical data. Using this similarity, we explore the value of the relations between the spatial input information of the GIS-based method and the analytical distributions of the process-based karst model for combined application of the two methods at sites without calibration data.

Karst catchments frequently exhibit complex exchanges between surface and subterranean flow. While the swing between surface flood and underground flood is complex, the ability to predict such behavior would be of great interest for flood forecasting and water recharge assessment. To this end an innovative methodology is proposed to visualize internal variables of a neural network model. It proves to be efficient to extract internal variables highly correlated to measured signals previously identified as proxy of the karst-river exchanges. The study focuses on a small Mediterranean catchment where karst/river interactions control the dynamic and genesis of surface floods. But the methodology is generic and can be applied to any catchment provided the availability of a sufficient database.

Karst hydrosystems constitute important water resource but their recharge and emptying process are poorly known and quantified. Water resource management is thus difficult. Nevertheless, it is a major issue when rainfall is not uniformly distributed during the year, as in Mediterranean climate. This study proposes a method based on neural networks permitting to simulate karst emptying as a function of the pumping volume during the dry period. Applied to the

Lez

karst system, the model provides excellent simulations of the water level at the main outlet of the system by using mean pumping discharge and zero rainfall hypothesis during dry period. An arbitrary extreme scenario is also provided by introducing a mean pumping volume.

Fuenmayor is a modest karst spring that tapes a small limestone aquifer near Huesca, Spain. A previous paper proposes a transfer function between effective rainfall and discharge concluding that Fuenmayor has an acceptable linear response. However, the linear model does not estimate adequately the response to some events where the nonlinearities are evidenced. To deal with the nonlinear characteristics of Fuenmayor, it is proposed a black-box model based on the Hammerstein-Wiener block-oriented structure. It is composed by a linear dynamic system surrounded by two static nonlinearities at its input and output. Seven different configurations of blocks are presented. Their efficiency has been evaluated by the Nash–Sutcliffe model efficiency coefficient. A good result is obtained with a configuration where the linear block is a second-order transfer function, with a zero and seven unit delays. The first nonlinear block is a piecewise polynomial and the second block has been suppressed. The running test draws out a maximum Nash-Sutcliffe efficiency of

E

= 0.9383.

Flow and water discharge in karst aquifers are controlled by the conduit network. Therefore, understanding karst conduit formation is important to conjecture the aquifer topology, i.e., conduit density and size, and to predict the aquifer dynamics. Conduits are generated by preferential pathways to flow known as wormholes that grow competing with each other. The success of a wormhole is determined by its ability to drive water away from its neighbors. Once a wormhole forms, water tends to flow along this preferential path thus reducing the availability of water for the enlargement of less developed wormholes. Wormhole growth is then controlled by the flow rate, the dissolution mechanisms and the heterogeneity of the hydraulic conductivity field. In this work, we propose two conceptual models to describe the geometry of the wormhole capture zone and its effect on the surrounding wormholes. First, we consider a cross-section intersecting the wormhole longitudinally. Second, we consider a radial model centered in the wormhole. These models are representative of field (fracture) and laboratory (tube), respectively. We perform a series of steady state simulations to obtain the dependence of the capture zone on the wormhole’s geometry. This naturally leads to a relation between the wormhole’s geometry and the density of wormholes because only one wormhole grows within a capture zone.

The paper presents the method and results of an assessment and delineation of the catchment area of the karstic spring “Perućac,” which is the main drainage area of Tara Mt. in western Serbia. It is the northeastern, inner zone of the classic Dinaric karst characterized by a dominant extension of highly karstified Triassic limestones, a poorly developed hydrographic network with many ponors, and dense forests. Tara Mt. is one of five national parks in Serbia. The goal of the project was to identify a high-priority protection zone within the preserved natural area. Based on data on the discharge regime of the Perućac Spring, and by applying the multiple nonlinear correlation method, the size of the direct catchment area was assumed to be 79.3 km

2

, which was 5–18 % larger than that estimated by previous surveys.

The groundwater vulnerability assessment is based on the evaluation of physical, chemical, and biological properties of the environment which can provide a certain degree of protection to the groundwater from contamination. In this paper are presented results of application four different methods (SINTACS, EPIK, PI, and COP) for groundwater vulnerability assessment in karstic aquifer in Croatia. The main objectives of the study were to apply the methods on test site where, so far, groundwater vulnerability was never assessed, then to modify the methods in order to improve adaptation to the research field and available data. After comparing vulnerability maps obtained by all four presented methods, it was determined that the most appropriate method is COP + K, which was additionally modified. Although presented methodology is not new, it can be used as a background for land-use planning, because it identifies parts of the catchment area that are, due to its natural features, more vulnerable to human impact. It can be also applied as an additional tool in groundwater protection for delineation of protection zones, and provides very useful data in various fields of water management, especially for karst area in Croatia.

In this study, we consider the dynamical aspect of groundwater vulnerability in fissured medium. This aquifer is considered as intermediary between porous and karst media. For these two media, there are several vulnerability assessment methods as DRASTIC for porous media and EPIK for karst ones. For fissured media, we used in this study the F-DRASTIC method adapted by introducing a new parameter, F, reflecting the fissures effects on the vulnerability. The dynamical aspect of vulnerability is proofed through two vulnerability maps realized, for the Angad region, Morocco, for two different years. These years are chosen according to their significant level of regional climate variations. These maps were made using a geographic information system, GIS. The results analysis has shown, first, the dynamical aspect of vulnerability, but also the effect of the fissure parameter on vulnerability and its variations.

In the shallow Orehek karst aquifer in southwest Slovenia, the use of hydrological data analysis for the purpose of validating the assessment of water source vulnerability was tested. The appropriate criteria for the aquifer and groundwater flow characterization were identified and major drawbacks highlighted. Results of water budget calculations were used to determine the extent of the catchment of the Korentan spring, which is the main outflow from the aquifer. The vulnerability assessment was verified by autocorrelation and cross-correlation analyses of available daily hydrological time series data. The small variability of the Korentan spring water temperature and electric conductivity time series points to the dominance of autogenic recharge and that sinking streams in the catchment contribute to the spring to a minor degree. The analysis indicated relatively small storage capacity of the aquifer and its high degree of karstification and rapid groundwater flow. The results justify the small proportion of highly vulnerable areas and lower vulnerability for marginal parts of the aquifer. Time series analyses proved to be time- and cost-effective, but have limited applicability for vulnerability validation purposes, as they do not provide direct and clear spatially resolved information on the vulnerability of the catchment.

Carbonate aquifers constitute a water reserve of essential importance for human supply. Accordingly, suitable protection measures should be established in order to meet the requirements of the Water Framework Directive (WFD). The objective of this paper is to discuss a methodology for defining protection zones for carbonate bodies containing groundwater intended for human consumption, these zones being determined by mapping the activities permitted within them. This approach constitutes an effective tool for land-use planning, enabling the appropriate location of human activities to ensure no adverse effects are produced on the quality of drinking water, in accordance with WFD criteria. The results obtained in a karst groundwater body in southern Spain show the percentage of land that must be protected to preserve the quality of water intended for human consumption, and its territorial distribution, demonstrating the value of this method in land-use planning.

The objective of this study was to assess the pollution of groundwater in Yucatan aquifer. The study area is centered on the city of Merida, the main city of the Yucatán state and its surroundings. This aquifer supplies groundwater to urban, agricultural, and industrial activities. Due to its high degree of karstification, it is a very vulnerable area because water and any substance within infiltrates rapidly and could affect the quality of groundwater. Therefore, a groundwater sampling campaign was done to study different pollutants, such as NO

3

−

, Cl

−

, fecal coliforms, and organophosphorus compounds. Data were treated with geostatistical tools and different maps were obtained by kriging. The main sources of pollution are located close to the city of Merida, in addition to isolated points of rural or industrial areas. Pollution plume moves toward North or Northwest area. NO

3

−

, Cl

−

, organophosphorus compounds, and fecal coliforms are an issue of concern for groundwater quality.

This paper deals with the occurrence of pollution in two important karst springs, supplying the aqueduct of the city of Ragusa, which happened in September 2010 and it is still taking place. Both springs show higher values of ammonia and the presence of salmonella, elements ascribable to wastewater of animal origin. According to this, investigations identified a number of farms present within the springs-protected areas as likely to have caused the pollution. These were imposed by ordinances to build adequate storage tanks for the animal wastewater. Paradoxically, the construction of these tanks led to a further worsening of the state of pollution, as the latter from episodic, linked to rainfall, became continuous due to the overflowing of wastewater from the tanks never emptied, as it was ascertained. A geological and geochemical study, preparatory to the execution of tracer tests, conducted by the Water Department of Genio Civile of Ragusa and ARPA (Regional Agency for the Environmental Protection), allowed a hydrogeological characterization of the recharge area and the definition of the hydrologic regime of the springs, that in this case, resulted as interconnected. Follow-up tests with fluorescent tracers, carried out on a few farms, were then interrupted because of the opposition of one of the owners. From that moment on, everything stops as for the research of the origin of the pollutant, while at the same time the situation gets worse, both in terms of environment, for the devastating effect on the ecosystem of the Ciaramite stream due to the spill in the riverbed of the polluted water springs, and for the resulting pollution of two municipal drinking water wells placed at the confluence of the Ciaramite stream with the Irminio river. The lack of further drinkable water determined the starting of the crisis of the city water distribution system having to turn to a supply of chance with tank trucks and shifts that created situations of considerable discomfort to major part of the citizens. At present, after 3 years from the start of the polluting event, despite the ordinances issued by the City Hall toward a number of livestock farms who do not comply with the collection of waste and its disposal, as a result we assist to the loss of a spring and the ecological degradation of the Ciaramite stream valley.

Karstic groundwater, because of its unique hydrological characteristics, is extremely sensitive to contamination by pathogens. For this reason more attention has recently been paid to the relationship between pathogens and the hydrogeological and geological characteristics of karst aquifer. This paper presents causes of contamination of three large sources located in the karst aquifers in the Carpathian-Balkanides in eastern Serbia. The bacteriological analyses and their correlation with physical and chemical characteristics in seasonal intervals provide an insight into the functioning of studied karst aquifers. It has been confirmed that ascending springs which drain deeper siphonal systems or the presence of adjacent porous aquifers as an additional purifier barrier mitigate bacterial waves and have much better water quality than gravity springs with an unstable discharge regime. For the latter, typical fast draining does not allow the activation of the attenuation capacity of the aquifer system.

Tunnel drilling in karst regions often leads to major disturbances in the hydrogeological functioning of aquifers and flow-systems. Numerous examples are documented in Switzerland and induced significant costs, which were not or rarely anticipated (e.g.: Flims, Jeannin et al.

2009

). The Ligerztunnel is one of these example. The tunnel was built a few hundreds of meters upstream from the Brunnmühle spring, which contributes to the drinking water supply of communities of Twann and Ligerz. During the construction, a major karst conduit with a huge discharge rate was intersected in a side exploration tunnel. Overflowing water was diverted into the Twannbach canyon. In the main section, smaller conduits were found and drained outside by pipe leading water close to the Brunnmühle spring. Actually, authorities want to add a safety tunnel parallel to the main tunnel. In this view, SISKA is in charge of evaluating the hydrological disturbances on the spring regime. The paper presents the approach applied to assess the potential effect of the drilling of a new tunnel near to a group of karst springs and pumping wells. The approach combines available spatial information and a hydraulic model. The KARSYS approach is first applied on this system in order to set up a 3D geological and hydrogeological model of the karst aquifer and the related systems. The spatial distribution of karst conduits within the massif is assessed based on a speleogenetical and inception horizons model (KarstALEA method). Inferring from these models, a karst conduits network is generated. The hydraulic model of the downstream part of the conduits network, which concerns the close vicinity of the safety tunnel project, is precisely calibrated using head and discharge data. Flow in this conduits network is then simulated using SWMM 5.0 in order to reproduce the hydrological responses of the different outlets (permanent springs, drainage devices, overflow springs, etc.).

Managing mine waste is one of the greatest challenges facing mining companies globally. Over the next 20 years, more than 10 billion of tons of waste will be generated in Peru based on the projected mining rates from existing mines and new projects. Most of Peru’s metal ore deposits are located at high elevations within a narrow, tectonized carbonate-rock belt extending over 2,000 km in length. Many of the limestone formations are karstified and characterized by high recharge and percolation rates, well-developed subsurface drainage and complex flow patterns. Mine tailings and waste rock facilities are preferably located close to the mine and processing operations and are often underlain, at least partially, by karstic limestone. Mining companies prefer to place mine waste in unlined basins when it can be shown that “natural hydraulic containment” will limit seepage to environmentally acceptable levels. Such a demonstration relies on detailed geological and hydrogeological investigations and the development of sound conceptual groundwater flow models. The depth of epigenetic karstification is greatly influenced by carbonate purity, bedding dip, faulting intensity, and oxidation of sulfide minerals (ARD). In addition, hypogenic karstification is common, particularly in areas with recent volcanism and hydrothermal activity. Detailed three-dimensional geological and numerical seepage models are used to predict seepage and environmental risk although simulating the effect of the channel network is often challenging.

Karstic landforms abound in the vicinity of the Uchucchacua mine (4,500–5,000 m a.s.l.). These help infiltration and the rapid inflow of water, which penetrates even the deepest working levels of the mine. These inflows affect mining operations and the mine has to be drained. In wet months, high volumes of mine water must be pumped, and these volumes are drastically reduced in dry months. Mine water is collected and drains by gravity along the Patón Tunnel. The mine dewatering has created drawdown cones, so modifying natural groundwater flow patterns. Surface water and groundwater are interconnected because of the karst, and this influences the volume of mine water that must be pumped from the mine. Direct infiltration occurs via dolines and sinkholes, and along the main interconnected open faults and mineral veins, leading to very high infiltration rates overall. The current study aims to evaluate the impact of meteoric water on mining operations.

The exploitation of mineral reserves in Brazil, especially limestone and iron ore, is currently restricted due to the existence of caves. The vast majority of caves documented in the country over the last 4 years (approximately 3,000) have been identified through environmental studies conducted for mining operations. To determine whether a cave should be protected or not, a series of criteria were formally established by recent (2008/2009) federal laws. Four classes of cave relevance were formally designated, based primarily on geological and biospeleological criteria.

Maximum Relevance

caves must be protected, together with a 250 m buffer zone.

High Relevance

caves may be removed, provided that two other high relevance caves, preferably within the same geological unit and containing similar characteristics, are permanently protected. However, the acquisition of areas containing caves, especially within iron ore regions, has become extremely difficult due to the high price of iron ore.

Medium Relevance

caves may be subject to removal, but speleological compensation must be applied.

Low Relevance

caves may be mined with no need for environmental compensation. Although these laws occasionally permit cave destruction, their ambiguous specifications and numerous criteria produce a highly restrictive scenario in which approximately 85 % of all caves are categorized as Maximum or High Relevance. The situation is further exacerbated by the very low minimum length of 5 m for any void to be classified a cave, producing a high number of caves regardless of lithology. Conducting a full cave environmental study, besides being financially costly, takes approximately 1.5 years to complete, primarily due to the requirement to perform two biospeleological sampling events during dry and wet seasons. The protection of several caves within mining areas has significantly decreased access to exploitable reserves, causing caves to remain under severe economic pressure. While Brazilian law emphasizes cave preservation, it provides no specific provisions for the protection of other karst features or karst aquifers.

Rull Cave (Alicante, SE Spain) is a shallow karstic cavity located in metre-thick beds of Miocene limestone conglomerate and overlain by soil with little profile development. A microenvironmental monitoring system was installed in order to record the exchange between the cave and the external atmosphere. Data were collected every 15 min over a period of 14 months (from 22/11/2012 to 13/01/2014). Both radon and CO

2

concentration values changed over the course of the annual cycle and were strongly controlled by the difference in air temperature between the exterior and the cave atmosphere. Wavelet transform was applied to the data to determine the influence of visitors on the environmental parameters controlling the cave’s microclimate.

In the Nerja Cave, there is a natural convective airflow which follows a seasonal model common in caves known as “chimney” characterized by, at least, two entrances at different altitudes. To explain this model, contradictory to the known entrances of the Nerja Cave, located at the same height, some research has been done in a surrounding cavity, known as the Pintada Cave. The obtained results confirm the existence of a physical connection between the Nerja Cave and the Pintada Cave, inaccessible to humans, and describe a very simplified, general model of airflow circulation between them, which allows for the removal of anthropogenic impact in the Nerja Cave during the most visited season in the year.

Las Herrerías Cave (Llanes, North Spain) is a relevant cave due to its cave palaeolithic paintings. It was declared of Good Object of Cultural Interest by the Asturias Regional Government. It is located in a karst Carboniferous aquifer which surface involves farming, livestock and tourist use, as well as a discrete mining activity and an old quarry converted into a waste area above the karst massif. A hydrogeological research was carried out from 2007 to 2010 focusing on the impact of land use on the cave. The aim of this work is to highlight the importance of using hydrochemistry monitoring to determinate the impact of the land use on cave waters. Several sampling campaigns of rainfall, the waters inside and outside the cave and El Boláu spring were carried out. A sampling device was installed inside the cave to collect discrete samples of dripwater each 48 h in 1.5 l bottles. The array contains 24 bottles and was deployed for 48 days intervals. Results evidence that calcium bicarbonate is the dominant chemical component in all the sampled water. Some of them, collected under the waste area, show high values in NO

3

−

, Ba

2+

, TOC, K

+

, SO

4

2−

, Silicium, Fe, Si, PO

4

3−

and Sr

2+

, being indicative of an adverse effect on the quality of drip water.

A comprehensive environmental monitoring programme has been recently launched in Ojo Guareña cave system (Burgos, Spain), one of the longest caves in Europe, aimed to assess the magnitude of the spatiotemporal changes of CO

2

(g), on daily and synoptic timescales in the cave–soil–atmosphere profile. CO

2

concentration of cave air is usually close to atmospheric background but huge daily oscillations of CO

2

levels, ranging 680–1,900 ppm/day on average, have registered during periods when exterior air temperature oscillates every day around cave air temperature. These daily variations of CO

2

content are hidden once the air temperature outside is continuously below cave temperature and a prevailing advective-renewal of cave air is established, so that daily-averaged concentrations of CO

2

reach minimum values close to 500 ppm. The spatiotemporal pattern of CO

2

(g) provides evidence that the amounts of carbon that might be sequestered and then emitted (CO

2

) from subsurface air located in the uppermost part of the vadose zone could be noticeable at local or regional scale by considering long subterranean systems as Ojo Guareña karst.

We present new data that illustrate the hydrochemical evolution of groundwater along a flow line in the Triassic marbles around the Nerja Cave, South Spain. Water dissolves calcite and dolomite, and then CaSO

4

. The environment is locally rich in CO

2

(up to near 60,000 ppmv) and consequently the water increases significantly its content in Ca

2+

, Mg

2+

, HCO

3

−

and SO

4

2−

along the flow, with EC values between 500 and 900 μS/cm. The pH values are typically in the 7–8 range, and the equilibrium PCO

2

of the water varies between 10

−1.5

and 10

−2.5

atm. In the considered flow line there is a relatively deep borehole (S2: 380 m; 280 m saturated) that shows pH values around 10 and equilibrium PCO

2

of 10

−6

atm, with EC values generally in the 150–200 μS/cm range. Most of its solutes derive from rainwater concentration, together with the dissolution of carbonate minerals in a system closed to CO

2

. For this reason we consider S2 to be a field analog of such conditions. The nearly stagnant water of this well also shows evidence of sulphate reduction. Unlike its solute contents, isotopically (δ

2

H and δ

18

O) the water of S2 does not show any modification with respect to the other points along the flow line.

Recent developments in laser scanning techniques and digital modelling provide powerful tools for the knowledge, management and preservation of the underground. A Terrestrial Laser Scanner (TLS) survey was performed to create a 3D virtual model of the Santa Croce cave (Apulia, Southern Italy); this is well known for its Palaeolithic and Neolithic finds (a Neanderthal thigh-bone among all) and used as a showcave both for its natural and historic heritage. The survey included chimneys, passages and also the surface over the cave to acquire a model of the entire system. Data were acquired by processing the resulting points cloud to pursue three main purposes: karst hazard management, education and geoheritage preservation. Thanks to the virtual model, the opportunity to visit the site through a virtual tour, also showing hardly accessible details, is an exciting way to discover the underground environment. Therefore, interactive virtual image can be utilised to promote the site as an important tool to disseminate knowledge and to increase interest in the Earth sciences in society at large.

For the acquisition of 3D-geometry data of groundwater conduits in the coastal Karst plain of Yucatan near the town of Tulum a novel laser scanning device was developed and applied. The method is derived from similar industrial systems and for the first time adapted to the specific measurement conditions in underwater cave systems. The device projects a laser line over the whole cave perimeter at a certain position. This line represents the intersection of a plane with the caves wall. Through proper design and calibration of an imaging system it is possible to derive the true scale geometry of the perimeter by special image processing techniques. Through caption of regularly spaced images it is possible to reconstruct the true scale 3D-shape of a tunnel if position and attitude data is incorporated. The method provides easily operable acquisition of the 3D-data of caves in clear water with superior resolution and speed and facilitates the measurement in underwater tunnels as well as in dry tunnels significantly. The data gathered represent crucial input to the study of state, dynamics and genesis of a complex karst water regime.

Paleoclimatic reconstruction in southern Spain has been investigated in this study using stable isotope analyses from Órganos Cave (Southern Spain). A combination of δ

18

O and δ

13

C analyses with uranium-series dating and δD values of the water extracted from stalagmite fluid inclusions makes it possible to obtain an isotopic record during 340–370 ky BP (MIS10). The profile shows the climatic evolution in the area and we can see a colder early stage with small fluctuations that change to warmer conditions at the end, coinciding with the start of the interglacial stage MIS9.

A stalagmite that grew during the Holocene (between 4.9 and 0.9 ka BP) in Kaite Cave (Ojo Guareña Karst Complex, Burgos, N Spain) has been analyzed by Laser-Induced Breakdown Spectroscopy (LIBS) with the aim of reconstructing secular variations in the hydrochemistry of the karst system, in turn related to changes in the environment outside the cave. LIBS analyses yield significant changes in Mg/Ca and Sr/Ca intensity ratios through the stalagmite, which reveal consistent trends and patterns at decadal to centennial scales. The origin of the observed changes in Mg/Ca and Sr/Ca ratios is discussed in the framework of the cave system and the regional climatic variability, particularly the changes in precipitation.

Drip-water chemistry in karstic caves can vary at seasonal to inter-annual scales in response to climatic factors such as temperature, rainfall, and seasonality, which determine changes in the hydrological and hydrochemical processes of the percolating waters in their paths from the atmosphere to the cave. In this paper the characterization of stalagmite forming drip-waters based on long-term (years) time-series data is presented as a key task for understanding the geochemical behavior of a specific system, the Kaite Cave (N Spain). The work focuses on the relationships between rainfall, drip rates, drip-water calcium concentration, and drip-water trace elements amount (e.g., Mg and Sr); as indicators of hydrologic processes defining the karst system and controlling speleothem growth and composition patterns.

Unique striped karren give a special landscape stamp to the extensive top of Snake Mountain above Kunming. Lithomorphogenetic research reveals the manner of the formation and development of this karren on vertical rock strata in transition from limestone to dolomite and their formation from subsoil karren to karren shaped by exposure to rainwater.

The influence of rivers on speleogenesis is studied analyzing the cave levels located in the underground drainage areas related to two fluvial basins. Cave levels are analyzed through their vertical distribution profiles. The underground limits of the fluvial basins are defined using a 3D geometric model of the karst aquifer established according to the KARSYS approach. The aim of this work is to analyze the influence of the rivers on cave evolution using cave morphology. The study area corresponds to the Western and Central massifs of Picos de Europa (Northern Spain), with 214 km of cave conduits up to 1.6 km vertical range. As a result, we established two sequences of development of the cave levels related to the differences of the incision rate of the Cares and Dobra Rivers, and the partial capture of the Western Massif by the Cares River.

The Yucatan Peninsula in south-eastern Mexico is the largest karstic area of the country; however, there are very few studies on the geodiversity of the region. The objective of this study is the identification and qualification of the diversity of elements of the relief, considering geomorphology, geology, hydrology and soil properties as components of geodiversity. To calculate the geodiversity, a simple additive model of thematic diversity was used, following Jačková and Romportl (

2008

). The geodiversity in the east of the Yucatan Peninsula manifests as a north to south banding. The geodiversity of coastal portion presents values ranging from medium to very high, in the central portion it ranges from medium to very low and in the western portion, where are the oldest geological formations, have high and very high values.

The endokarst presents a spectacular Geoheritage involving many singular features with thousands to millions years in age. The Picos de Europa National Park has one of the most important karst landscapes in the world. The endokarst of Picos de Europa shows high natural, scientific, and cultural values mainly related to cave features, with a spectacular vertical development (14 % of known world caves deeper than 1 km), the presence of geomorphological and sedimentary records related to the Quaternary evolution of the Cantabrian Mountain Range, and the traditional and sport uses of the cavities. The aim of this work is to inventory and to evaluate the Geoheritage and Geodiversity of the endokarst of Picos de Europa National Park combining speleological data, field work, and geomorphological mapping from nine selected caves. As a result, the Picos de Europa Geodiverstiy features show a high variability: 75 different natural features have been recognized with a density ranging from 0.3 to 1.1 different features per cm

2

of cave area.

The study area is located in the Marginal Pyrenean Sierras, which include the Hydrogeological Unit Estopiñán Syncline, consisting of two permeable levels: Upper Cretaceous and Eocene, and Hydrogeological Unit Estaña where endorheic and karstic Estaña Lakes are located. This work introduces the first results obtained from the hydrogeochemical and isotopic (δO

18

, δH

2

and H

3

) precipitacion and groundwater description, made to determine the general hydrological and hydrogeological of Estaña Lakes. This description allowed to differentiate the groundwater main chemical groups and to deduce qualitatively the dominating chemical processes. A large regional chemical variability is observed, mainly attributed to the different permeable levels as well as to mixing processes. The Estaña’s Big Lake presents a marked calcium sulphate composition, constant either in depth and time. Multiparametric profiles have been done (EC, T, pH, DO, δ

18

O) confirming its monomictic character, sufering a process of stratification in the water between March and October and with a termocline about 6 m of depth.