Karst Network Research Articles

The karst network system of the Sierra de las Nieves (Málaga, Spain). An example of a high relief Mediterranean karst.

The aim of this work is the stochastic simulation of a network of karst conduits in a high relief karst system. The simulation completes the existing cave mapping provided by speleological exploration and connects the recharge area with the discharge at the karst springs. The Sierra de las Nieves karst system is a high relief Mediterranean karst that has allowed the development of a system of large conduits and caves. The system follows the typical pattern of an alpine karst system with two characteristic zones where the development of the caves is different. The first zone, with a mean altitude of 1750 m a.s.l., the Hoyas del Pilar and Torrecilla, is the area with highest altitude where recharge takes place and where the entrance potholes to the system are located. In this zone the cave system has a development mainly along the vertical (with 1000 m of vertical development along a few hundreds of metres of horizontal development) with large shafts and narrow and steep meanders, until the local base level is reached at 700 m a.s.l. In the second zone, the system has a quasi-horizontal development with 300 m of altitude difference for 7 km in the horizontal until the base level of the system at the Río Grande Spring (450 m a.s.l.). The transition between both zones is dominated by the presence of sumps where the conduits have vertical ondulations. The connectivity between the entrance and the resurgence has been demonstrated, in the past, by tracer tests. The system of super caves has been made possible because of the favourable conjunction of lithological, structural, geomorphological, hydrogeological and climatic factors. Geomorphic indices are introduced to describe the three-dimensional karst networks so the known network can be completed (i.e. simulated), taking into account statistical and probabilistic criteria. The simulated system can be used for the mathematical flow simulation of the karst system.

Can one identify karst conduit networks geometry and properties from hydraulic and tracer test data?

Karst aquifers are characterized by extreme heterogeneity due to the presence of karst conduits embedded in a fractured matrix having a much lower hydraulic conductivity. The resulting contrast in the physical properties of the system implies that the system reacts very rapidly to some changes in the boundary conditions and that numerical models are extremely sensitive to small modifications in properties or positions of the conduits. Furthermore, one major issue in all those models is that the location and size of the conduits is generally unknown. For all those reasons, estimating karst network geometry and their properties by solving an inverse problem is a particularly difficult problem.In this paper, two numerical experiments are described. In the first one, 18,000 flow and transport simulations have been computed and used in a systematic manner to assess statistically if one can retrieve the parameters of a model (geometry and radius of the conduits, hydraulic conductivity of the conduits) from head and tracer data. When two tracer test data sets are available, the solution of the inverse problems indicate with high certainty that there are indeed two conduits and not more. The radius of the conduits are usually well identified but not the properties of the matrix. If more conduits are present in the system, but only two tracer test data sets are available, the inverse problem is still able to identify the true solution as the most probable but it also indicates that the data are insufficient to conclude with high certainty.In the second experiment, a more complex model (including non linear flow equations in conduits) is considered. In this example, gradient-based optimization techniques are proved to be efficient for estimating the radius of the conduits and the hydraulic conductivity of the matrix in a promising and efficient manner.These results suggest that, despite the numerical difficulties, inverse methods should be used to constrain numerical models of karstic systems using flow and transport data. They also suggest that a pragmatic approach for these complex systems could be to generate a large set of karst conduit network realizations using a pseudo-genetic approach such as SKS, and for each karst realization, flow and transport parameters could be optimized using a gradient-based search such as the one implemented in PEST.

Acheulean technical behaviors in Aldène cave (Cesseras, Hérault, France)

The cave of Aldène (Cesseras, Hérault, France) is usually known for the preservation of its upper Paleolithic and Mesolithic evidence. However, older occupations are located at the entrance and the collapsed zone of this vast karst network. Unfortunately, companies looking for phosphate had earlier truncated this original filling and only nine Paleolithic stratigraphic outliers (T1 to T9) remained. Repeatedly excavated by the Museum of Prehistoric Anthropology of Monaco, from 1971 until 1998, they mainly registered Acheulean (cf. Tayacian) and Pre-mousterian activities. As interdisciplinary studies and radiometric dating (230Th/234U and ESR) were undertaken, it was possible to set up chronostratigraphic and paleoenvironnemental contexts, which mostly extend from the end of MIS 13 up to MIS 5.5. The results obtained in the different units also allowed the correlation of remote layers.Our recent study has focused on technocomplexes with the aim to update the technical behaviors of the Paleolithic knappers that lived along Cesse River, at the entrance of Aldène cave. Petroarcheology joined to technological and morphofunctional analyses have figured out technical evolution and features, even within the successive lithic Acheulean cultures. The technology and the function of the occupations incited Aldène groups to reorient their economic strategies. They abandoned the available fluviatile resources for more siliceous and remote materials (>6 km). Furthermore, percussion and pebble tools associated sometimes with rare bifacial pieces and large flake tools appear to predominate exclusively in the oldest layers (MIS 13–10). In these assemblages, debitage flakes are obtained by Elementary (unipolar or bipolar), SSDA, semi-tournant non-laminar and Discoïd (MIS 11) methods. Retouched products consist of scrapers, notched tools and points (Quinson, Tayac, bilateral).Based on a relative and comparative technological distribution, the first technical transformation emerges in MIS 9. The industries contain more handaxes, rare cleavers and include the premises of the Levallois concept. Thereafter, those technical way and needs will be confirmed (MIS 7–8) with a clear presence of handaxes, increased Levallois products, decrease of percussion and pebble tools, and absence of large flake tools. In layer B, the identification of Levallois blades production and the presence of a Mousterian point reveal the occurrence of Mousterian knappers (MIS 6). The vast archeostratigraphic sequence of Aldène gives us the opportunity to describe the main technical innovations, such as the appearance of Levallois concept throughout the evidence of old structure settlements (fireplaces, slabbed stone pavement).

Faunal analysis of the Neolithic units from the Gueldaman Cave GLD1 (Akbou, Algeria) and the shift in sheep/goat husbandry

The GDL1 cave belongs to the large karst network of the Adrar Gueldaman ridges (Northern Algeria). New excavations by the Centre National de Recherches Préhistoriques, Anthropologiques et Historiques (CNRPAH) since 2010 have yielded rich archaeological remains dated between 7002 cal BP and 1484 cal BP. The paper presents results of the zooarchaeological analysis of the macromammals from the Neolithic units in sectors S2 and S3. They reveal the presence of a restricted fauna, dominated by sheep and goat, goat being more frequent than sheep. Domestic cattle and pig may also be present. The age profiles of the goat/sheep finds suggest a shift in the management of the sheep/goat herds aiming first at the production of meat and later at the production of meat and secondary products.

Wings, mushrooms, and Christmas trees: The carbonate seismic geomorphology of Central Luconia, Miocene–present, offshore Sarawak, northwest Borneo

Central Luconia is a geological province of the Sarawak Basin, offshore northwest Borneo, characterized by extensive development of Miocene to Holocene carbonate buildups. The buildups are up to 2-km (1-mi) thick and reveal complex seismic geomorphologies including out-building, in-building, carbonate-siliciclastic intercalations, and coalescence of neighboring carbonate bodies. Intermittent carbonate and siliciclastic deposition is interpreted to have been governed by frequently oscillating sea level and variable siliciclastic input. Location of the buildups with respect to deltaic facies and the seismic expressions of marginal carbonate strata, locally known as wings, are used here to classify carbonate seismic geomorphologies. Buildups encompassed by deltaic topsets are said to reside onshelf and are flanked by marginal carbonate deposits conformable with the onlapping siliciclastics and interpreted as thin carbonate platforms deposited in situ over prominent erosional unconformities and flooding surfaces. Such marginal facies are described on the basis of their appearance as open wings. In contrast, buildups downlapped by prodelta foresets or bottomsets, or those draped by pelagic sediments, are said to reside offshelf and are characterized by high relief, steeply dipping marginal carbonate strata discordant with respect to the relatively flat-lying platform carbonates as well as the onlapping siliciclastics. These marginal strata have an appearance of closed wings and are interpreted as slope aprons composed of carbonate material derived from the productive platform tops and deposited off-platform in deeper water. Carbonate geometries range from contracting-upward pinnacles to expanding-upward platforms in onshelf settings, whereas buildups located offshelf have mostly contracting-upward or aggrading morphologies. Buildups deposited onshelf have generally maintained a similar height of depositional slopes as they evolved, reflecting rates of background siliciclastic deposition approximating those of carbonate growth. In contrast, depositional slopes of offshelf buildups have become progressively higher, owing to limited siliciclastic input. Observations presented here on carbonate geomorphology and adjacent siliciclastic stratigraphy provide important clues for the understanding of the geology of the province. Because carbonates and siliciclastics intercalate frequently, siliciclastic biostratigraphy can be used to precisely date and correlate geographically remote carbonate-reservoir intervals and intrareservoir depositional and diagenetic events such as marine transgressive or exposure surfaces or karst networks. Conversely, basin paleobathymetry can be measured by the size of carbonate clinoforms and the thickness of buildups established over flooded siliciclastic surfaces. Deposition of low-relief carbonate platforms over siliciclastic substrates indicates shallow-marine conditions, as opposed to the prevalent notion of kilometer-scale paleobathymetry. These interpretations have important implications for understanding of the sedimentology and lithology of the ambient basinal siliciclastics, with fundamental applications to hydrocarbon exploration.

Introductory editorial: thematic issue: progress in karst research

Karst landforms are developed in soluble carbonate and evaporite rocks under different climatic and hydrological conditions. The action of water has generated a great range of karstic features that often serves as cropland or as substrates for other human activity. Nevertheless, karst is highly vulnerable and exploitation of its resources or utilization of the land inappropriately provokes environmental problems (water pollution, subsidence, flooding, changes in the subterranean environment, etc.). Therefore, more investigation, specific forums and scientific discussion and publications are necessary to improve the management and protection of karst environments. During the last few decades, Karst Hydrogeology has become more consolidated into a distinct scientific field. Specific international journals and conferences have addressed this topic and international organizations have established committees to coordinate studies on the subject. One example is the Karst Commission of the International Association of Hydrogeologists (IAH, www.iah.org/karst). A recent conference on this subject is the fifth International Symposium on Karst Aquifers (ISKA5). This conference has been organized every 4 years since 1992 in Malaga, Spain, with the last one being in October 2014. This fifth Symposium in the series was organized by the Centre of Hydrogeology at the University of Malaga and the Spanish Geological Survey (IGME) in the framework of their ‘‘Advanced Hydrogeological Studies’’ partnership. Partners were UNESCO, the Nerja Cave Foundation, the Academy of Sciences of Malaga, the Spanish Groundwater Club (CAS) and the IAH Karst Commission. Utilizing the framework of ISKA5 and that of the International Conference on Limestone Hydrology (ICLH, Besancon, France and Neuchâtel, Switzerland), a new biannual conference has been created. This combined conference will be known as Eurokarst and the first meeting will be in Neuchâtel, Switzerland in September 2016. Both ISKA and ICLH have served as international forums for scientific debate on progress made in research into karst environments. At ISKA5, the main objective was to discuss and to disseminate the latest trends in research into karst aquifers and water resources. These trends are based on results obtained from application of different methodologies in various karst areas in the world in addition to results of geomorphological, engineering and karst cavity investigations. This thematic issue includes expanded versions of selected contributions from ISKA5 which have been peer reviewed by international experts under the supervision of the Editorial Board of the Environmental Earth Sciences. Three contributions concern groundwater recharge, both autogenic (in Mediterranean countries such as Italy and Spain) and allogenic (in Edwards Aquifer, USA). Several manuscripts relate to the use of hydrochemical tools to determine the functionality and karstificationi development of the aquifers and to characterize problems related to a dam. Another chapter is about the influence of a tunnel in a karst aquifer in Switzerland, along with one on the use of dye tracers to characterize the functioning of the epikarst over a cave in Belgium. In regards to protection of karst aquifers, a case study from the Balkans has been included. Modeling is another subject covered, both in karst network development and in use of neural networks for spring groundwater management in France. Last, but not the least, three chapters are dedicated to karst cavities, concerning speleological development, variations of environmental & Bartolome Andreo andreo@uma.es

Characterization of karst systems using SIc-Pco2 method coupled with PCA and frequency distribution analysis. Application to karst systems in the Vaucluse county (Southeastern France)

Estimating vulnerability of a karst system to pollution is a major current issue. However, to assess vulnerability, an understanding of the karst system functioning is necessary. The aim of this paper was to characterize the degree of karst network development used by flows (i.e. karst system functioning) to have a better knowledge on the resource and its vulnerability to any possible contamination. This characterization can be done with an analysis of water chemistry emerging from a system. Carbon dioxide partial pressure (Pco2) and saturation index with respect to calcite (SIc) are two significant parameters that can be used to study water chemistry of karst systems through calcium-carbonate equilibriums. These enable the implementation of the SIc–Pco2 method. In this article, a methodology is proposed based on the SIc–Pco2 method coupled with frequency distribution analysis and principal components analysis (PCA). This study considers three karst systems with a developed saturated zone and one epikarst spring, located near the Fontaine de Vaucluse spring (Southeast France). Results show that different water types and flowing conditions in the karst system are identified. From this acquired information, karst network development can be estimated. Finally, results can aid in the vulnerability assessment of karst systems.

The sedimentary filling in the chalk karst of the Northwestern Paris Basin (Normandy, France): Characterization, origin and hydro-sedimentary behaviour

Karst networks can be considered as zones of alteration, storage volumes of eroded material and also as zones of transit. Study of sedimentary fillings in karst allows to determine past hydrodynamic conditions as well as sediment sources. In order to better understand chalk karst genesis differents sedimentary fillings from Northwestern Paris Basin have been studied: Petites Dales, Villequier II and Orival caves. Geochemical (major elements) and grain size analysis explain the sedimentary variability both within and between sites. This can be explained by the variation of two main parameters: (i) the origin of karst sediments and (ii), the hydrodynamic conditions in the karst system. Karstic sediments can origininated (i) from allochtonous materials associated with surperficial deposits (quaternary loess, tertiary sand deposits, or a mixture of them), or (ii) from autochtonous material related to chalky residual deposit (in situ weathering). Three main deposit conditions are distinguished according to the sedimentological characteristics: flood, low flow and medium hydrodynamic conditions. A conceptual model is proposed (i) to explain hydrosedimentary conditions in undercovered chalk karst and (ii), to relate surface (plateaus) and underground (karst) geomorphological comparments in term of sediment reworking, transport and sedimentation.

A Contribution of GIS Methods to Assess the Aquifer Vulnerability to Contamination: A Case Study of the Calcareous Dorsal (Northern Rif, Morocco)

Karst groundwater constitutes the main resource for drinking water supply in Chefchaouen region, North Morocco. However, the karstic aquifers are highly vulnerable to the pollution because of the deforestation which favors the soil erosion and the landslides. Therefore, the groundwater is loaded with suspended sediment. The fertilizers disseminated for agriculture can also infiltrate and concentrate in the saturated zone of the aquifer. In this study, the geographic information system (GIS) provides an effective tool for groundwater contamination risk assessment, because it facilitates multicriteria analysis and updates the models developed. The EPIK model based on GIS uses four environmental parameters (Epikarst, Protective cover, Infiltration condition and Karst network development) to evaluate the intrinsic vulnerability of groundwater contamination potential. Each of these parameters is presented as a thematic map. After adding all data, the final result provides vulnerability map according to the protection factor relation based on which the protection zones’ map is created.

Delineating vulnerability of karst aquifers using hydrochemical tracers in Southwestern China

Karst groundwater is particularly vulnerable to contamination. Long-term hydrochemistry auto-monitoring combined with laboratory analyses has shown that the chemograph demonstrates changes in the system. In order to determine the primary groundwater vulnerability, a relationship between hydrochemical changes and the origin of vulnerability in six karst spring catchments in Southwestern China is discussed. The reason and physical meaning of the hydrochemical changes in the spring are explained based on tracer tests and physical–chemical process in the S31 spring. The results prove that the hydrochemical changes show the origin of vulnerability and also can be its expression. Generally, autogenic recharge in bare karst is concentrated in epikarst zone, forming bypass flow and shaft flow, which causes dilution of Ca2+. The chemograph reflects the percentage of concentrated and diffuse recharge. The higher the ratio of concentrated recharge, the higher the grade of groundwater vulnerability. Due to Ca2+, HCO3−, SEC, pH, and temperature in water can change for kinds of reasons during their transport, more karst systems with variable natural and human factors are discussed. Protective layer, allogenic water recharge, and transform of surface stream and subterranean river can change the origin shape of hydrochemical curve. Under this circumstance, more indicators need to be monitored, especially contaminant-related ions such as nitrate, in order to clearly understand the contribution of concentrated and diffuse recharge to water chemistry. After comparing the traditional groundwater vulnerability assessment and the methods based on hydrochemical change, rainfall, protective layer, epikarst, transient storage and karst network should be more concerned when the work is done. Auto-monitoring of karst is more and more popular in Southwestern China; therefore, it is suggested that the hydrochemical methods should be used as a primary expression of vulnerability, giving a direct reference for karst water management.

The role of condensation in the evolution of dissolutional forms in gypsum caves: Study case in the karst of Sorbas (SE Spain)

The karst of Sorbas (SE Spain) is one of the most important gypsum areas worldwide. Its underground karst network comprises over 100km of cave passages. Rounded smooth forms, condensation cupola and pendant-like features appear on the ceiling of the shallower passages as a result of gypsum dissolution by condensation water. Meanwhile, gypsum speleothems formed by capillarity, evaporation and aerosol deposition such as coralloids, gypsum crusts and rims are frequently observed closer to the passage floors. The role of condensation–dissolution mechanisms in the evolution of geomorphological features observed in the upper cave levels has been studied by means of long-term micro-erosion meter (MEM) measurements, direct collection and analysis of condensation waters, and micrometeorological monitoring. Monitoring of erosion at different heights on gypsum walls of the Cueva del Agua reveals that the gypsum surface retreated up to 0.033mmyr−1 in MEM stations located in the higher parts of the cave walls. The surface retreat was negligible at the lowest sites, suggesting higher dissolution rates close to the cave ceiling, where warmer and moister air flows. Monitoring of microclimatic parameters and direct measurements of condensation water were performed in the Covadura Cave system in order to estimate seasonal patterns of condensation. Direct measurements of condensation water dripping from a metal plate placed in the central part of the El Bosque Gallery of Covadura Cave indicate that condensation takes place mainly between July and November in coincidence with rainless periods. The estimated gypsum surface lowering due to this condensation water is 0.0026mmyr−1. Microclimatic monitoring in the same area shows differences in air temperature and humidity of the lower parts of the galleries (colder and drier) with respect to the cave ceiling (warmer and wetter). This thermal sedimentation controls the intensity of the condensation–evaporation mechanisms at different heights in the cave.

New Digital Technologies Applied to the Management of Geoheritage

During the last decade, the development of new digital technologies has strongly influenced the customs and practice of geoheritage and geotourism research. Digital tools, such as geoinformation, geovisualisation, digital monitoring and GIS systems have played an important role in the development of newmethods of assessment andmapping, as well as aiding the development of geosites for tourism and education. In September 2011, the University of Savoie and University of Lausanne co-organised an intensive course on the use of digital tools for geoheritage management activities (including geosite selection, geoheritage and geodiversity mapping, geotourism promotion and education about geoheritage) within the International Symposium on Geosite Management (ISGM) and under the auspices of the Working Group on Geomorphosites of the International Association of Geomorphologits (IAG) (Reynard and Coratza 2013). The course was held in the Chablais Geopark (Evian, France) and was financially supported by the HINT project (Heritage Interpretation through New Technologies) (Cayla 2012; Barton et al. 2014). This 2-year international project was funded by the European Leader programme and involved four partners: Geopark Shetland (Scotland), Chablais Geopark (France), North Pennines AONB (England) and Geopark de Hondsrug (The Netherlands). This special issue of the journal Geoheritage contains a selection of the papers presented during the symposium (including both on the intensive course and during the conference), as well as some additional papers dealing with this topic. The papers included focus on different digital technologies used for the assessment, monitoring and the promotion of geosites. Nathalie Cayla proposes a review of existing and emerging technologies for the depiction and interpretation of geosites. Three main topics in particular are analysed: Georeferencing and mapping of geoheritage, 3D digital imaging (including photogrammetry and laser scanning) and experiments in the promotion of geoheritage using augmented reality (a process which enriches discovery through digital media, or provides a virtual reality with which one can engage). The three following papers are case studies using new digital technologies applied to the management of geoheritage in specific geomorphological contexts. Luca Ghiraldi and colleagues present a comprehensive methodology for identifying, cataloguing, assessing, visualizing and promoting geoscientific data relevant to geological heritage, using geomatic tools, such as digital photogrammetry, GIS, GNSS, terrestrial laser scanner and web mapping. The case study was carried out in the Seguret Valley (Oulx, Turin Province) in the Italian Western Alps. This area was selected as it forms a part of the European “Cottian Alps Geopark project” which aims to develop a transboundary area between Italy and France. Fabien Hoblea and colleagues give an overview of various digital tools (including high-tech digital monitoring and 3Dmodelling technologies combining laser scanners, digital cameras and sensors) developed and used to study and promote a range of karst geosites. The paper focuses on the very high heritage value of endokarst sites (caves or karst networks) in the French Ardeche department (e.g. Chauvet Cave, Aven d’Orgnac), Chartreuse (e.g. Granier cave network), Vercors (e.g. Choranche Caves) and Bauges (e.g. Prerouge Cave) regional parks. High-alpine geomorphosites are a geoheritage which is extremely vulnerable to global warming. From the beginning of the 2000s, Ludovic Ravanel and colleagues have been N. Cayla (*) : F. Hoblea University of Savoie, Chambery, France e-mail: nathalie.cayla@univ-savoie.fr

Glaciers and rivers: Pleistocene uncoupling in a Mediterranean mountain karst

Large-scale coupling between headwater catchments and downstream depocentres is a critical influence on long-term fluvial system behaviour and on the creation of the fluvial sedimentary record. However, it is often difficult to examine this control over multiple Quaternary glacial cycles and it has not been fully explored in karst basins. By investigating the Pleistocene glacial and fluvial records on and around Mount Orjen (1894 m) in Montenegro, we show how the changing connectivity between glaciated mountain headwater source zones and downstream alluvial basins is a key feature of long-term karst system behaviour – especially in relation to the creation and preservation of the surface sedimentary record. Middle and Late Pleistocene glacial deposits are well preserved on Mount Orjen. Uranium-series dating of 27 carbonate cements in fluvial sediments shows that many alluvial depocentres were completely filled with coarse glacial outwash before 350ka during the largest recorded glaciation. This major glaciation is correlated with the Skamnellian Stage in Greece and Marine Isotope Stage 12 (MIS 12, c 480–420ka). This was a period of profound landscape change in many glaciated catchments on the Balkan Peninsula. Later glaciations were much less extensive and sediment supply to fluvial systems was much diminished. The extreme base level falls of the Late Miocene produced the world's deepest karst networks around the Mediterranean. After MIS 12, the subterranean karst of Mount Orjen formed the dominant pathway for meltwater and sediment transfer so that the depositional basins below 1000 m became disconnected (uncoupled) from the glaciated headwaters. There is little evidence of post-MIS 12 aggradation or incision in these basins. This absence of later Pleistocene and Holocene fluvial activity means these basins contain some of the thickest and best-preserved outwash deposits in the Mediterranean.

Digital Tools for Managing and Promoting Karst Geosites in Southeast France

This article provides an overview of the various digital tools we have used and developed to study and promote a range of karst geosites. Our work focused on the very high heritage value endokarst sites (caves or karst networks) in France’s Ardeche departement (Chauvet Cave, Aven d’Orgnac) and Chartreuse (Granier cave network), Vercors (Choranche Caves) and Bauges (Prerouge Cave) Regional Parks. These tools were developed using innovative, high-tech digital monitoring and 3D modelling technologies and combined laser scanners, digital cameras and sensors with specialised software. The resulting tools are now being used in the management and promotion of these sites, which are important territorial and heritage resources in areas where geotourism is increasing and being integrated into local planning strategies.

Electrical resistivity tomography to characterize a karstic Vauclusian spring: Fontaine d’Orbe (Pyrénées, France)

The study site lies on a karst system in the Pyrenees (France) that crosses the Urgonian limestones. Organic matter was dumped on the west bank of the River Vert d’Arette, which polluted a spring (the Fontaine d’Orbe) situated on the east bank. Electrical resistivity tomography was utilised in order to understand the geometry of this karst outlet. After tests with the pole-pole array, the ideal electrode spacing was found to be less than 3 m. A conduit, a little less than 10 m wide, was discovered, which proved to be the terminal conduit of the karst system. It was established that the conduit traverses both banks of the River Vert d’Arette, thus presenting a hydraulic link between the two sides. Moreover, this conduit, which is totally submerged, passes under the riverbed and goes upwards to the spring. In addition to the geophysical measurements, hydrogeological measurements and observations were made. Based on the characterisation of the geometry of the karst network’s terminal conduit, and the fact that is completely full of water and inclined, it is concluded that the Fontaine d’Orbe spring is of the Vauclusian variety.

Preliminary results from excavations at Gueldaman Cave GLD1 (Akbou, Algeria)

The limestone Adrar Gueldaman ridges of the northwestern Babors Mountains of the Tellian region (Northern Algeria) contain a large karst network with several caves. Inside one of them (GLD 1), first excavated in the 1920s, an Early Neolithic episode was identified. Since 2010, new investigations by the Centre National de Recherches Préhistoriques, Anthropologiques et Historiques, Algeria (CNRPAH), at GLD 1 and other newly discovered caves have revealed well-preserved anthropogenic deposits. The GLD1 deposits are more than 5 m deep. Four sectors (S1–S4) have been spatially defined, of which two (S2 and S3) were partially investigated. Eight samples of wood charcoal from these sectors were radiocarbon dated by AMS giving median dates ranging from 1484 cal BP to 17,031 cal BP. The main human occupation sequence at GLD1 is situated around the VI and VII millennia BP with virtually all of the archaeological deposits coming from these layers. Deeper occupation levels have not yet been investigated. Bio-archaeological remains are well preserved (mammal bones, mollusc shells and plant-remains) and linked with cultural material (ceramics, ornaments, lithic and bone tools). Multi-disciplinary analysis of this material is underway and here we report on the preliminary findings, which already bring new insights into the neolithisation process of this region. Evidence of sheep and goat domestication at more than 6 ka cal BP is particularly significant.

The comparison of hydrodynamic characteristics of karst aquifers: application on two karst formations in Zagros (Asmari and Ilam-Sarvak), southwest Iran

In order to study the function, hydrodynamic behavior, and hydraulic properties of the karst aquifers in Izeh, southwest Iran, time series analysis was applied to the precipitation, spring discharge, and piezometric head data of two representative karst systems of Zagros (Ilam-Sarvak and Asmari Formations). Time series analysis was applied to two karst aquifers, those of Asmari and Ilam-Sarvak Formations. The daily precipitations of anticlines were estimated based on the precipitation–elevation function which was applied on digital elevation model (DEM) of the area. The mean estimated daily precipitations were considered in bivariate time series analysis as input data of each karst system. The total length of time series was about 2.7 years, extending from May 2007 to December 2009. During the research, several one-parameter probe data loggers were installed, which daily measure the water surfaces in karst aquifers. Time series analysis was applied for describing Izeh karst aquifers with a focus on both univariate (autocorrelation and spectral analysis) and bivariate (cross-correlation, gain function, and coherency function) methods. The results show that Asmari karst aquifer in Kamarderaz Anticline has a large storage capacity. Because of lacking a well-organized karst network, in the Asmari karst aquifer, baseflow dominates with low contribution of quick-flow. In the Ilam-Sarvak karst aquifer (Shavish and Tanush Anticlines), the karstification occurred in fractures and small diameter conduits, which caused to quick-flow between dense limestone. The Ilam-Sarvak karst aquifer could be regarded as a transition between two extreme types of karst, e.g., highly karstified system and in the opposite, extremely diffused one. The analysis of well hydrograph in Ilam-Sarvak karst aquifer shows that the karst aquifer has a low storage capacity. Unlike Asmari karst aquifer, the fractures and small diameter conduits in Ilam-Sarvak karst aquifer are more enhanced, producing a better developed karst network. Contrary to the typical karst systems, however, diffuse flow and conduit flow coexist in the Asmari Formation.

Characterisation of hydrogeological connections in a lowland karst network using time series analysis of water levels in ephemeral groundwater-fed lakes (turloughs)

This research has used continuous water level measurements five groundwater-fed lakes (or turloughs) in a linked lowland karst network of south Galway in Ireland over a 3 year period in order to elucidate the hydrogeological controls and conduit configurations forming the flooded karstic hydraulic system beneath the ground. The main spring outflow from this network discharges below mean sea level making it difficult to determine the hydraulic nature of the network using traditional rainfall–spring flow cross analysis, as has been done in many other studies on karst systems. However, the localised groundwater–surface water interactions (the turloughs) in this flooded lowland karst system can yield information about the nature of the hydraulic connections beneath the ground. Various different analytical techniques have been applied to the fluctuating turlough water level time series data in order to determine the nature of the linkage between them as well as hydraulic pipe configurations at key points in order to improve the conceptual model of the overall karst network. Initially, simple cross correlations between the different turlough water levels were carried out applying different time lags. Frequency analysis of the signals was then carried out using Fast Fourier transform analysis and then both discrete and continuous wavelet analyses have been applied to the data sets to characterise these inherently non-stationary time-series of fluctuating water levels. The analysis has indicated which turloughs are on the main line conduit system and which are somewhat off-line, the relative size of the main conduit in the network including evidence of localised constrictions, as well as clearly showing the tidal influence on the water levels in the three lower turloughs at shallow depths ∼8 km from the main spring outfall at the sea. It has also indicated that the timing of high rainfall events coincident with maximum spring tide levels may promote more consistent, long duration flooding of the turloughs throughout the winter.

Modeling a network of turloughs in lowland karst

[1] In lowland karst areas of Ireland topographic depressions which get intermittently flooded on an annual cycle via groundwater sources are termed turloughs. These are sites of high ecological interest as they have communities and substrate characteristic of wetlands. The flooding in many turlough basins is due to insufficient capacity of the underground karst system to take increased flows following excessive precipitation events, causing the conduit-type network to surcharge. Continuous water level measurements have been taken in five linked turloughs in the lowland karst area of south Galway over a 3 year period. These water level fluctuations, in conjunction with river inputs and precipitation, were then used to elucidate the hydrogeological controls forming the hydraulic system beneath the ground. A model of the karst network has been developed using a pipe network model with the turloughs represented as ponds. The contribution to the karst network from diffuse flow through the epikarst via the matrix and fracture flow has also been modeled using a combination of an infiltration module and network of permeable pipes. The final model was calibrated against two separate hydrological years and in general provided a good simulation for all of the turloughs water levels particularly for the year with one main filling event. The model also accurately picked up the tidal response observed in these turloughs at shallow depths. The model has been used to predict the groundwater discharge to the coast via the main spring which had not heretofore been possible to measure, being below the sea level.

A method for the stochastic modeling of karstic systems accounting for geophysical data: an example of application in the region of Tulum, Yucatan Peninsula (Mexico)

The eastern coast of the Yucatan Peninsula, Mexico, contains one of the most developed karst systems in the world. This natural wonder is undergoing increasing pollution threat due to rapid economic development in the region of Tulum, together with a lack of wastewater treatment facilities. A preliminary numerical model has been developed to assess the vulnerability of the resource. Maps of explored caves have been completed using data from two airborne geophysical campaigns. These electromagnetic measurements allow for the mapping of unexplored karstic conduits. The completion of the network map is achieved through a stochastic pseudo-genetic karst simulator, previously developed but adapted as part of this study to account for the geophysical data. Together with the cave mapping by speleologists, the simulated networks are integrated into the finite-element flow-model mesh as pipe networks where turbulent flow is modeled. The calibration of the karstic network parameters (density, radius of the conduits) is conducted through a comparison with measured piezometric levels. Although the proposed model shows great uncertainty, it reproduces realistically the heterogeneous flow of the aquifer. Simulated velocities in conduits are greater than 1 cm s−1, suggesting that the reinjection of Tulum wastewater constitutes a pollution risk for the nearby ecosystems.