Development challenges in karst regions: sustainable ...

Development challenges in karst regions: sustainable land use planning in the karst of Slovenia Franci Gabrovšek, Martin Knez, Janja Kogovšek, Andrej Mihevc, Janez Mulec, Matija Perne, Metka Petrič, Tanja Pipan, Mitja Prelovšek, et al. Carbonates and Evaporites ISSN 0891-2556 Volume 26 Number 4 Carbonates Evaporites (2011) 26:365-380 DOI 10.1007/s13146-011-0072-3

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Author's personal copy Carbonates Evaporites (2011) 26:365–380 DOI 10.1007/s13146-011-0072-3

ORIGINAL ARTICLE

Development challenges in karst regions: sustainable land use planning in the karst of Slovenia Franci Gabrovsˇek • Martin Knez • Janja Kogovsˇek • Andrej Mihevc • Janez Mulec • Matija Perne • Metka Petricˇ • Tanja Pipan • Mitja Prelovsˇek Tadej Slabe • Stanka Sˇebela • Natasˇa Ravbar

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Accepted: 31 October 2011 / Published online: 12 November 2011 Ó Springer-Verlag 2011

Abstract The comprehensive knowledge of karst surface, caves, waters and biodiversity were examined with special emphasis on planning for environmental management and land use in karst regions using examples of projects performed by the staff from the Karst Research Institute ZRC SAZU. Based on the knowledge of karst, karst phenomena, karst waters and karst biodiversity, karstological monitoring was developed throughout the construction of expressways and planning for railways on karst terrain. Newly revealed karst phenomena were properly preserved. Regular climatic and biological monitoring were developed and implemented, as well as karstology consultation with an emphasis on the impact of the use of caves as natural assets. To understand karst, its evolution dynamics and processes, models were developed with which the study of the risk posed by dam site construction in karst areas was possible. Karst aquifers and their protection were studied using tracer tests and different methods of the transfer of contaminants through the vadose zone and underground flow connections. In assessing the vulnerability and contamination risk of groundwater, a comprehensive method was elaborated. Microorganisms and fauna of dripping water in caves were used as monitors of cave ecosystem health. By applying high-quality karstological research results from individual spheres of karstology and interdisciplinary studies, a foundation for sustainable planning of life in karst regions that will consider the natural and

F. Gabrovsˇek M. Knez J. Kogovsˇek A. Mihevc J. Mulec M. Perne (&) M. Petricˇ T. Pipan M. Prelovsˇek T. Slabe S. Sˇebela N. Ravbar Karst Research Institute at Scientific Research Centre of the Slovenian Academy of Sciences and Arts, Titov trg 2, Postojna, Slovenia e-mail: [email protected]

cultural characteristics and vulnerability of karst landscapes has been established. Keywords Caves Karst Karstological assessment Protection Slovenia Sustainable planning

Introduction A good knowledge of the natural and cultural heritage of karst regions is a precondition for the rational planning of life in them. It is possible to know and understand karst primarily through comprehensive studies of its surface, caves, waters and ecological characteristics. By deepening this basic knowledge, the Karst Research Institute of the Scientific Research Centre of the Slovenian Academy of Sciences and Arts has been developing and linking the most important fields of karstology for more than 60 years in an interdisciplinary fashion and upgrading them into a comprehensive science of karstology. The institute aims at making the scientific results applicable and available for those planning life in karst regions. In view of the rapid development and increasing investment in the karst regions, there is a lack of consistent consideration of karstological finds and knowledge of the karst and its peculiar potentials in regional planning (local communities, municipalities). The Classical Karst plateau rises above a narrow coastal belt that is home to Koper, Slovenia’s largest port, which requires a major space for warehousing. The karst today is also attractive for settlement. A great deal of money has been invested in the construction of modern new apartments and houses that have begun to change the appearance of the karst landscape; however, to a large extent, this new housing remains unoccupied since the

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majority of buyers, including the ever-increasing number of owners of karst holiday homes from across Slovenia, are looking for more traditional karst architectural and lifestyle features. A large part of the local population is trying to insure harmonious development by following the principle of preserving regional karst characteristics and limiting the direction taken by outside investors and municipalities driven by profit alone. These aspirations have led to the formation of a strong civil initiative that continually draws attention to important development challenges. Despite local environmental protection legislation, planning without a good knowledge of the environment is simply not enough. The Karst Research Institute is trying to overcome this problem by participating in major projects and contributing to the public planning process. Five years ago, the institute signed an agreement with the Minister for the Environment and Spatial Planning on its continuous and comprehensive participation in planning development in karst regions. However, the changing of ministers sometimes causes the revision of such agreements; therefore, regular participation is most often focused on selected fields, such as the protection of Slovenia’s caves. The Scientific Research Centre of the Slovenian Academy of Sciences and Arts, which includes the Karst Research Institute, was a leading partner in a EU-funded project for Regional Development ‘‘Center of Excellence’’ and through the interdisciplinary Karst Project has focused on the sustainable development of Slovenia’s karst regions (Luthar et al. 2008) and helped prepare starting points for planning life in the karst. Ten years ago, the institute established a postgraduate course in karstology, and karstology courses are provided as part of the university geography curriculum. Together with geographers, the institute is establishing a course on spatial planning in various types of regions. These developments are promising in the long run, but the question remains on how to address current developmental problems. The Scientific Research Center of the Slovenian Academy of Sciences and Arts is establishing a Center for Planning in Karst Regions that will integrate knowledge from a variety of disciplines and offer it for use by local communities and the government. The institute has founded the International Academy of Karstology, which will even more efficiently integrate international knowledge and experience and find the best approaches for rationally planning life in various karst regions in Slovenia and around the world. The Karst Research Institute is currently engaged in specific projects involving regional planning and the protection of karst, the protection and development of the natural and cultural heritage, karst water supplies, closing

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dump sites and landfills in karst areas, gathering information on karst caves and their conservation, and the planning and exploitation of karst phenomena for tourist purposes.

Karstological monitoring of planning and construction of expressways on karst Over the last 20 years, the construction of modern expressways in Slovenia has been one of the major construction projects aimed at connecting important parts of the country and opening them to Europe. A large proportion of the expressways run across karst. Almost half of Slovenia is karst and more than half of the water supply for its population comes from karst aquifers. The Karst Research Institute actively participates in the planning and construction of expressways (Knez and Slabe 2007). In selecting routes, the entire karst landscape is considered to avoid important surface karst phenomena and already known caves. Before construction work starts, the perforation of the karst is described as accurately as possible. Good comprehensive knowledge of the karst and its typical cave features helps anticipate the shape, type and incidence of caves in the area of the route. Data on all Slovenian caves are collected in the cadastre of caves. Special attention is devoted to the impact of the construction and use of expressways on karst waters and the preservation of karst aquifers. Expressways are impermeable and runoff water from the road is gathered in oil collectors and then released clean onto the karst surface. Karstological monitoring is conducted throughout the construction of expressways. Newly revealed karst phenomena are studied as an important part of the natural heritage and advice is given on how to preserve them if the construction work allows it. The institute’s new findings are of great help to the construction companies. Based on continuous studies of newly discovered caves, their extent can be estimated so that construction companies can plan accordingly. Numerous new findings on the formation and development of the karst surface, the epikarst, the vadose zone and the perforation of the aquifer have been documented. More than 350 caves were opened on the 70-km expressway route across the Classical Karst region. Relative to the development of the aquifer, it is possible to distinguish between old caves through which watercourses flowed when the karst was surrounded and covered by flysch, and shafts through which water vertically percolates from the permeable karst surface to the underground water (Fig. 1). Excavations have revealed that roofless caves, the consequence of the development and denudation of karst, are a special and frequent feature on the karst surface. Determining the age of sediments in the

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Fig. 1 Different types of caves according to karst development, opened during motorway construction

newly discovered caves helps understand the oldest periods of karstification and thus develop a new conception of the age of caves. Unique challenges arose during construction on covered karst dissected by subsoil forests in southern Slovenia and on slope breccia below the high karst plateau. The aim of monitoring during construction was to preserve as many karst caves as possible. Shafts were easiest to preserve. Smaller entrances to shafts were simply closed with concrete plates. It was also possible to preserve old caves with solid walls and ceilings; however, caves in crushed rock or caves opened due to blasting had to be filled in. Rock walls were used to close caves with entrances on embankments that were damaged by road cuts. Their circumferences were fractured to such an extent that they were unsuitable for continued exploration, and water could wash clay from caves filled with alluvia and deposit it on the roads. Caves important for further exploration or natural heritage were preserved and made accessible for visiting. The access to these caves was enabled through concrete culverts or through a door from the tunnel. Georadar studies of older expressways that have been in use for decades proved useful as well. They clearly

revealed the geological bedrock and perforation below the roads and demonstrated the need for similar studies on a regular basis. The participation of karstologists in the construction of expressways on karst is extremely important and useful.

Routing and karstological planning for a new railroad line A proposed railway between the northern Adriatic ports of Koper (Slovenia) and Trieste (Italy) and the interior of Slovenia on the 5th European Railway Corridor (VeniceKiev) required extensive karstological planning for the route. Relative to the strategic goal of establishing a transportation connection between Slovenia and Europe and the fact that the 5th European Railway Corridor also represents a high-speed rail connection between European countries, the Karst Research Institute has undertaken a study on the routing of the railway line from Trieste (Italy) and Koper (Slovenia) toward Austria and Croatia (Fig. 2). Spatial and other consequences of the project at the local, regional, national and international levels are being evaluated.

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The section of the railroad that climbs from the Port of Koper to an altitude of 450 m at the top of the Classical Karst plateau is a primary branch of the public railway infrastructure in Slovenia. The existing line no longer meets modern transportation demands and relative to capacity is a bottleneck in Slovenia’s railway network and simultaneously in the 5th European Railway Corridor. Modernization is therefore a necessity. In addition to increasing capacity and safety, the new line will shorten rail transport times. The length of railway sections running from the sea (Port of Koper or Port of Trieste) to the top of the Classical Karst plateau is about 30 km. The new railway is planned to allow speeds up to 160 km/h with a maximum grade of 17%. According to the latest plans, the route will not run across the existing relief but rather almost entirely through longer tunnels and over viaducts (Fig. 2). The development of the transportation infrastructure in Slovenia must support the development of a polycentric network of cities and other settlements, the balanced development of areas with common spatial development characteristics, the reciprocal upgrading of the functions of


rural and urban areas and their integration into European transportation systems. At the same time, in developing transportation networks, the goal is to safeguard sustainable living and working conditions, reduce negative impacts on the natural environment, preserve natural resources, biodiversity, and natural assets and preserve the cultural heritage. The envisaged railway line will cross the karst area near Slovenia’s southwestern border with Italy. For this reason, the study focused on finding a route whose construction will have the least impact on karst phenomena and the flow of underground waters. The study was conducted in several consecutive work phases to find the most appropriate route. The selection of a route is a very demanding task due to an extensive system of karst caves (more than 100 caves are located in the wider area) and a network of underground waters that is very vulnerable to pollution. Further phases in the route selection process will therefore require additional analyses, optimizations and the highest quality project solutions, particularly due to the amount and quality of karst waters along the route. In this area, the karst aquifer is the main water source for Slovenia’s entire

Fig. 2 Variants of railway line between Trieste, Koper and the interior of Slovenia

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coastal area. The envisaged route runs across the water protection area, which imposes a very high level of limitations in planning and routing it. The flysch in the southern section of the future railway line is less permeable. The limestone in the northern section, however, is fissured and karstified and comprises the main aquifer in this karst region. The tunnels run partly through the vadose zone, largely through an area with an extensive oscillation of the water table that can span up to 100 m. The karstification of the area means that locally additional measures will have to be taken in the construction of the tunnels. One of the most critical points of the project is the risk of cutting through karst caves that are empty, filled with a variety of sediments or filled with water. Encroaching on underground caves may bring problems in the realization of the construction and, from the ecological viewpoint, can have a potentially harmful impact on underground habitats. For the karstological assessment of the routing of the envisaged railway in this unique and vulnerable region, research has been divided into three independent but related spheres: the surface, the underground and karst hydrology. The future railway will run across a karst area known for a great number of karst cavities and the segments of old or recent drainage courses through the karst. The denudation of the karst surface has exposed many roofless caves that are now visible on the karst surface. The thematic maps used to show the known entrances to underground caves will be augmented with newly discovered entrances. Working in the field, karstologists have been assessing important rock segments and, on the basis of surface mapping and genetic interpretation, identifying morphologically expressed roofless caves in the relief. During construction, it is reasonable to anticipate encountering underground caves and parts of cave systems several meters to several dozen meters in diameter. Interpolating from known surface and underground phenomena allows prediction of the shape and type of caves. Caves in the corresponding belt along the axis of the route are being studied in detail. The type of caves, their position and role in the aquifer, shape, rock relief, sediments and flowstone are used to verify the known data in the field and supplement them with new measurements and genetic interpretations, to present previous knowledge of the perforation of the aquifer, and to anticipate the type and distribution of caves on the envisaged route. Due to the specific properties of carbonate rock, the karst rivers and streams that sink in the studied area easily find direct routes into the underground karst aquifer. From the hydrological viewpoint, a state of the environment inventory is being performed and an assessment of the impact of the railway on the underground water is being conducted.

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Correct decisions regarding temporary and permanent dump sites and landfills are of key importance in such important construction projects in the karst region. Around 3.5 million cubic meters of material will be excavated on the route of the future railway line. The volume of landfills for permanent surpluses of limestone and flysch could total around 1.5 million cubic meters.

Process-based modeling in karst systems Karst is a complex dynamic system governed by many interacting processes, such as dissolution of soluble rocks and transport of mass, heat and dissolved species. Understanding karst also requires understanding of these processes and their role in the development and functioning of karst systems. The physics and chemistry of these processes are well understood, as they have been studied in other fields of science. However, quantitative understanding of karst processes has been evolving for only the last few decades; therefore, there are still wide fields waiting to be explored. Analytical and computational methods employing basic physical and chemical processes have been developed to study some of the features and processes in karst. While models which simulate flow and transport in porous aquifers have been employed for decades, models which ‘‘accurately’’ simulate karst aquifers have only appeared recently. However, all ‘‘karst models’’ require sound characterization of karst aquifers, which is one of the key problems: namely, the geometry of the network of solution conduits, which carry most of the flow in karst aquifers, is rarely known. To understand the genesis of such network, a set of generic models has been developed during recent decades (Dreybrodt et al. 2005). These models couple flow, transport and dissolution processes to simulate growth of solution conduits in various settings, from the evolution of a single fracture (Dreybrodt and Gabrovsek 2000) to the evolution of a complex network in a three-dimensional block of fractured-porous limestone (Kaufmann et al. 2010). The rate equations that define the retreat of rock in a unit of time for different conditions of flow and chemical composition of groundwater are based on the work of Plummer et al. (1978) and Dreybrodt and his colleagues (Eisenlohr et al. 1999; Kaufmann et al. 2010). Although there are still open questions related to dissolution rates in various settings, these are currently not a subject of intense research. As the reliability of the above-mentioned models crucially depends on well-defined dissolution kinetics, further research is needed. Nevertheless, genetic models have enabled more profound understanding of karst aquifer genesis.

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Apart from basic understanding of evolution dynamics of karst conduit networks, the models were applied to study the risk posed by dam site construction in karst areas. In nature, extreme hydraulic gradients, which drive fast evolution of conduits, are rare. In man-made situations, such as at dam sites, high gradients are common. There are many reports about increased leakage at dam sites built in karst areas. Adoption of genetic models to such scenarios is relatively easy (Fig. 3). The models revealed that leakage that leads to a non-operative dam can happen in the lifetime of the dam even if there has been no prior karstification. The use of such models in a real situation has been demonstrated on a dam site by Epting et al. (2009). Current models cannot characterize the advanced stages of karst evolution, when fully flooded conduits become vadose and when mechanical transport of sediments gains increasing importance in the development of solution conduits. As these situations are encountered in the field, these model will be even more useful in the future. Many other topics in karst could also benefit from process-based modeling. Karst morphogenesis at all scales still holds many open questions to which models could contribute greatly. Some efforts have been made (Kaufmann and Braun 2001; Perne and Gabrovsˇek 2010), but this field of study is still wide open. A deeper understanding of many ongoing processes, such as the transport of heat in karst systems, could also have practical implications. There is an increasing interest in all these topics, and karst with all its complexity is drawing the attention of researchers from various fields of studies where problems are based on similar physical processes.

Fig. 3 Model of conduit evolution at a dam site (adopted from Dreybrodt et al. 2005). Calcite aggressive water flows from the accumulation lake with the water height H around the ground curtain (width W and depth G) and causes the evolution of conduits in a fractured limestone

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Studies of karst aquifers and their protection Karst aquifers are important sources of water supply, but due to their specific characteristics they are very vulnerable to various human activities. For the efficient planning of conservation measures, it is essential to understand and consider the characteristics of groundwater flow and the transport of substances. Various important processes occur in the upper vadose zone due to the longer retention of infiltrated water. Based on the results of continuous long-term measurements of precipitation on the surface and of selected trickles in the vadose zone of the Postojna Cave (Fig. 4), it was established that the dynamics of percolation through the vadose zone was directly related to precipitation and depended not only on its quantity and intensity, but that continuous percolation along the entire hierarchy of fissures in the vadose zone occurred only with good saturation of the soil and of the vadose zone. During the dry periods (2.5–6 months) of summer, a large amount of the less intense precipitation (up to 390 mm) is stored in the vadose zone (Kogovsˇek 2010). The calculations of the annual volumes in three consecutive hydrological years show substantially different ratios between the annual quantity of water that infiltrates the vadose zone and the quantity of water that flows through it and supplies the deeper parts of the aquifer. The proportion of freshly infiltrated water in percolation water in flood waves only reaches up to 14% and in the nearby spring up to 13% (Kogovsˇek 2010). The transfer of contaminants through the vadose zone is directly related to the dynamics of infiltrated precipitation. The weakest transfer of contaminants occurs in dry periods when discharges are minimal, and the most intense transfer takes place during flood waves that follow longer dry periods. Tracer tests with artificial tracers showed different retention times of the infiltrated precipitation and contaminants in the vadose zone (Kogovsˇek and Sˇebela 2004). The results of these tests were also supported by isotopic analyses of oxygen that reflected residence times ranging from several months to 1 year and more. The long-term monitoring of the transfer of pollution confirmed that the leaching of even minor pollution from the surface took several decades (Fig. 4) before the original conditions were restored (Kogovsˇek 1997). In dry periods, water from the vadose zone supplies karst springs from their wider catchment areas. During this time, the discharges of the sinking streams that usually carry pollutants are minimal or the streams are dry. The quality of karst springs is therefore relatively good in such periods. On the other hand, the abundant precipitation that follows dry periods of flushes accumulated pollution


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Fig. 4 a Hydrogeological map of the recharge area of the Malensˇcˇica and Unica karst springs (1 karst aquifer, 2 fissured aquifer, 3 porous aquifer, 4 poorly permeable rock, 5 cave, 6 surface stream, 7 test site with selected trickles, 8 spring, 9 tracer injection point, 10 datalogger, 11 main and secondary underground water connections); b the

transfer of nitrates and other contaminants through different trickles in the 1988–2005 period was reflected in greater electric conductivity (the measurements from the uncontaminated trickle a are presented for comparison). c Uranine breakthrough curves, discharges and precipitation for the two tracer tests in the Postojna area

through the recharge areas of karst springs, leading to the most intense transfer of contaminants. This is reflected in higher concentrations of contaminants in the initial flood waves. The very complex structures of the recharge areas in which surface and underground flows merge additionally complicate the functioning of karst springs. The relationship between individual catchment areas depends greatly on meteorological and hydrological conditions and changes very rapidly (Kogovsˇek 2001, 2004; Petricˇ 2010). This problem was studied in more detail in the common recharge area of the Malensˇcˇica (Qmin = 1.1 m3/s, Qavg = 6.7 m3/s, Qmax = 11.2 m3/s) and Unica karst springs (Qmin = 0.04 m3/s, Qavg = 11.2 m3/s, Qmax = 69.3 m3/s) (Fig. 4). A monitoring network was set up in 2007 (3 rain gauges and 9 dataloggers for recording discharge, temperature and electrical conductivity). Additionally, two combination tracer tests were carried out involving each time two different tracers injected at two different points.

High oscillations of water temperature at springs indicate a significant proportion of secondary recharge from surface water bodies. By comparing the positions of the peaks (maximum) or saddles (minimum) of the temperature curves for the Kotlicˇi and Malensˇcˇica springs, the flow velocity in the karst system between them was estimated at 145–215 m/h (Kogovsˇek and Petricˇ 2010b). Similar values were calculated from five tracer tests performed previously in this area. The temperature and electrical conductivity curves of the Unica spring show an important influence of the recharge from the sinking Pivka stream that is not characteristic for the Malensˇcˇica spring. In all springs, extreme temperatures are detected during high waters as a reflection of the dominant recharge from surface water bodies, while during low waters the recharge is slower and the retention time of water in the karst underground is longer. Under such conditions, the proportion of primary recharge from the Javorniki–Snezˇnik karst aquifer is larger.

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The first tracer tests in May 2008 proved the main groundwater flow from the sinking Mala Karlovica stream on the Cerknica karst polje to the Kotlicˇi spring and further on toward the Malensˇcˇica spring (Fig. 4) (Gabrovsˇek et al. 2010). In contrast, the flow toward the Unica spring was slower and the proportion of recovered tracer was lower. During the second tracer test in November 2008, a tracer was injected into an oil collector that collected runoff from the expressway that crossed the studied aquifer. Outflow from the collector infiltrates the vadose zone of the studied karst system. During the dry period in early November, the flow through the vadose zone was slow and the tracer appeared in very low concentrations at the springs. Only the intense rain at the end of November pushed it more efficiently out of the system. Under both these hydrological conditions, the main direction of flow from the oil collector toward the Unica spring and only a weak connection with the Malensˇcˇica spring were proved. Since the oil collector is a source of pollution (Kogovsˇek 1995a, b), these are advantageous circumstances for the Malensˇcˇica spring, which is a regionally important source of water supply. On the other hand, this spring is seriously threatened by pollution from Cerknica polje and more strict protection measures should be applied in this relatively densely populated area based on the known characteristics of groundwater flow and transport of substances. Tracer tests have proven to be a valuable research tool in various other applied projects (Kogovsˇek 1999; Kogovsˇek et al. 1999; Kogovsˇek and Petricˇ 2004; Petricˇ and Sˇebela 2005; Kogovsˇek and Petricˇ 2006; Kogovsˇek and Petric 2007, 2010a). In recent years, a series of tracer tests were carried out, and their results were used as the basis for planning the monitoring of water quality in the influence areas of various pollution sources (e.g., landfills, military training area, petrochemical depot, roads and expressways, railways). The interpretation is based on long-term sampling, detailed analysis and parallel measurements of physical parameters of the water tested. In a case study of the municipal landfill site near Mozelj in southeastern Slovenia (Kogovsˇek and Petricˇ 2010a), the functioning of three monitoring boreholes at the margins of the landfill was tested by a combination tracer test. The findings about the characteristics of tracer transport in the karst system and the outflow through karst springs were additionally used to identify the most suitable springs for monitoring and preparing an appropriate sampling regime. The lack of tracers appearing in one borehole, only one tracer appearing in the second and the appearance of both tracers in the third in relatively low concentrations indicated that due to the heterogeneity of karst aquifers, springs or other natural watercourses should be selected as monitoring points. The rapid flow toward the Bilpa spring and high concentrations of tracers confirmed that this spring was the

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most suitable monitoring point. However, the interpretation of the results of monitoring is difficult because the sinking Rinzˇa River, which is contaminated by various pollution sources, also recharges the spring. To assess its influence, the simultaneous monitoring of Bilpa and Rinzˇa is necessary. Furthermore, some characteristic contaminants have to be selected and the monitoring concentrated mainly on them. The main underground flow toward the Bilpa spring additionally receives a primary recharge of unpolluted water from its wider catchment area. This leads to a dilution of contaminants that is highly influenced by precipitation and hydrological conditions. As a consequence, the water quality of the Bilpa spring is better than that of Rinzˇa. Since the overlapping of negative and positive influences from various sources is possible, a good understanding of the functioning of karst aquifers and parallel measurements of precipitation, discharges and the physical parameters of water are all necessary to interpret the results of monitoring.

Assessment of vulnerability and contamination risk To effectively protect the most sensitive areas of karst aquifers, several European countries use the concept of assessing vulnerability to determine water protection zones. Furthermore, assessment of contamination risk is increasingly important in land use planning. European guidelines for making such assessments (Zwahlen 2004) were elaborated in the framework of the international COST Action 620 project. Based on these guidelines, numerous methods for assessing and mapping the vulnerability of the karst groundwater were elaborated, which considered the differences between individual karst aquifer systems, differences in the accessibility of data and differences in economic capacities. These methods have been used and tested in various test areas throughout the world. Surveys of the existing methods have been made by Zwahlen (2004), Ravbar (2007), Goldscheider (2010) and others. The recently proposed Slovenian approach (Ravbar and Goldscheider 2007) follows the European guidelines most comprehensively. The method includes the assessment of vulnerability and degree of hazard (Fig. 5). These two assessments form the basis for calculating the contamination risk to groundwater or water sources. The final result of the natural vulnerability assessment can be transformed into water protection zones. The identification of the most vulnerable areas and areas with the highest risk of contamination allows the optimization of water protection zones, appropriate and prudent management of water sources and a foundation for planning the monitoring of water quality.


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Fig. 5 Assessment scheme and factors required for vulnerability and risk mapping according to the Slovene approach. For more information see Ravbar and Goldscheider (2007)

Unlike other methods in assessing the vulnerability of groundwater, the Slovenian approach considers the water flow under different hydrological conditions and offers a possibility of linking the protection of surface waters and groundwater. The Slovenian approach offers the possibility of assessing the importance of groundwater or water sources on a basis on which it is possible to predict potential damage and elaborate a priority list of rehabilitation measures. The Slovenian approach ranks among extremely sophisticated methods, because its application requires a large amount of data, time, and financial and technical resources. Moreover, validity tests on the acquired results showed that compared with simpler methods, the use of such a method is quite reasonable because it provides more reliable and less subjective results (Ravbar and Goldschieder 2009).

Fauna of dripping water in caves as monitors of cave ecosystem health The epikarst habitat is the highly vulnerable and important uppermost layer of limestone (Culver and Pipan 2009). As

first described by Mangin (1974) and Williams (1983), the epikarst holds a considerable reservoir of subterranean water that percolates both vertically and horizontally through a network of small cavities and crevices in the rock. This makes the epikarst very vulnerable to any spills of pollutants either on the surface or from leaking underground storage tanks (Kogovsˇek and Petricˇ 2007; Petricˇ and Sˇebela 2005). Because the epikarst is honeycombed with small fractures and solution pockets, contaminants tend to persist (White 2004). Monitoring obligate cave-dwelling invertebrates (aquatic stygobionts and terrestrial troglobionts) has been problematic and intriguing (Culver and Sket 2002). Many of the species found are rare, and the effective censusing of any rare animal is difficult. An additional problem relative to many rare cave-dwelling invertebrates is that their primary habitat consists of small voids and fissures in the epikarst that cannot be accessed directly. The most abundant animals in the epikarst are copepods, which enter caves in relatively large numbers. Using the continuous sampling device developed by Pipan (2005), epikarst fauna and the practicality of using epikarst fauna as a monitor of subterranean aquatic ecosystem health were investigated. Sampling was done in the Postojna-Planina

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cave system (Slovenia) where 20 drips were sampled continuously for more than 1 year. The drips exhibited considerable environmental heterogeneity (Pipan et al. 2006). The drip rates ranged between 1.7 and 202 ml/min with most drips rates below 50 ml/min. The conductivity varied between 238 and 548 lS/cm, probably reflecting different residence times of the water in the epikarst. A total of 23 copepod species (4 Cyclopoida and 19 Harpacticoida) were found in the drips, including eight undescribed species. Of these 23 species, 6 are endemic to the Postojna-Planina cave system. A total of five species were of the single genus Bryocamptus. Species composition was extremely heterogeneous; differences in drip rate, ceiling height and nitrate concentrations were correlated with differences in species composition (Fig. 6). There was also a strong distance effect, with drips closer than 100 m being more similar than those farther away. The scale of variation of epikarst communities is remarkable: even drips\100 m apart often have different species. This likely reflects the semiisolated nature of the small cavities that comprise the epikarst. The epikarst is more than a source of population and a connecting corridor to other caves; it is also a major source of carbon and nutrients. Water coming into the entrance of a cave may carry organic carbon and nutrients, but it is Fig. 6 Ordination diagram based on species composition and abundance data of copepods in epikarst drips in relation to the 12 environmental variables of the five caves. Species are abbreviated by the first three letters of the genus and species names. For complete names, see Pipan (2005) and Pipan et al. (2006)

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unlikely to be either frequent or quantitatively important (Simon et al. 2007). A significant source of organic carbon is dissolved in the dripping water. The presence of surfacedwelling organisms in drips is not a sign of contamination, but rather a sign of ecosystem health. Any reduction in stygobionts and any reduction in overall inputs would be an indicator of contamination, as would the presence of organisms specific to polluted waters such as tubificid worms. Sampling epikarst fauna is a useful way to assess ecosystem health, since the epikarst is the major source of organic carbon and nutrients, the major source of stygobiotic migrants into caves and the primary habitat of many stygobionts. The health of the epikarst can be assessed by long-term continuous collection of the fauna entering the cave, especially the number of stygobiotic individuals and the overall number of both copepods and all invertebrates.

Microbial fingerprints of human activity in the underground Caves contain much valuable information on hydrogeological, geochemical and biological processes that have


occurred on the surface and underground. For this reason and from the perspective of nature preservation, there arises the key question: how do we preserve caves in their pristine condition? Various environmental parameters such as those outlined in Groundwater Directive 2006/118/EC can be used to evaluate the anthropogenic impact on the underground. In addition to the usually applied physical and chemical parameters, microbial indicators can offer additional information on underground conditions. Microbial indicators and underground water status The availability and quality of water in karst areas are of crucial importance for the water supply of the population and for agriculture. In well-karstified areas, the retention time of water in the underground is usually short, meaning that the level of mineralization between a ponor and a spring is low. Since karst areas face constant and increasing anthropogenic pressure, regular monitoring of underground rivers should be more widely applied. Values for physical, chemical and biological parameters of subterranean rivers should be carefully interpreted, taking into consideration dilution and possible additional pollution in the underground. Regular monitoring using indicator groups of microorganisms can give better understanding of the underground interactions, since there is no UV stress and quantitatively fewer higher predators. For example, during the 2-year monitoring in the Postojna Cave (Slovenia), the ratio of coliform bacteria to total bacterial counts dropped from 0.80 to 0.20 at low discharge (*0.6 m3/s) over the 9 km of the underground flow between the ponor and the spring. Absolute numbers and comparisons between microbial groups are not only important to assess water quality and estimate the trophic level (Toranzos and McFeters 1997), but also to get an insight into ecological interactions along the gradient of the underground river flow. There are several quantitative microbial detection kits currently available on the market whose price, sensitivity, specificity and easy transport in the underground make such studies feasible (Mulec et al. 2012). Airborne microorganisms and human activities A correlation between aerobiology and biodeterioration was observed in caves with prehistoric art, since the air in the cave acts as a vehicle for the dispersion of microorganisms (Saiz-Jimenez and Gonzales 2007). Airborne microorganisms are usually subjected to a variety of environmental stresses such as UV radiation, chemical pollutants, desiccation and temperature extremes (Buttner et al. 1997), but once microbes become airborne in caves some of these stresses, e.g., UV radiation and desiccation, are eliminated.

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This raises an important question regarding allochthonous airborne microbes: how long can they persist in underground conditions? Various methods can be applied to sample cave air, but an initial insight into air quality can be acquired simply by depositional air sampling for 20 min (Mulec 2008). The influence on a cave of airborne biological particles introduced as a consequence of mass tourism has never been studied in detail. However, based on bioaerosol monitoring in 2009 and 2010 in the Postojna Cave, which is visited by 500,000 tourists annually, the influence of humans on air quality is clearly evident (Mulec and Walochnik 2010). Alteration of solid surfaces in caves The most evident result of human alteration of normal underground conditions is the presence of lampenflora in natural and artificial caves. Lampenflora is a complex community of organisms growing on illuminated areas such as rocky surfaces, sediment and artificial materials around lamps. In this community, various aerophytic cyanobacteria and algae, as well as some mosses and ferns, dominate. They usually strongly adhere to the substratum and are consequently responsible for substratum deterioration (Mulec and Kosi 2009). A floristic analysis of lampenflora tells the stage of species succession; in the later stages after several years of uninterrupted exposure to light, cyanobacteria become more abundant compared to algae in the community (Mulec et al. 2008). If the duration of illumination is not restricted, even extremely low photon fluxes such as 0.2 lmol photons/m2/s can support the growth of bryophytes (Mulec and Kubesˇova´ 2010). Besides the development of a procedure to kill lampenflora with minimum impact on caves, more attention should be devoted to implementing lighting regimes that do not support the growth of lampenflora (Mulec and Kosi 2009). Much effort is currently invested in the installation of lamps that restrict the growth of lampenflora. LED lamps appear to be a plausible candidate, but additional studies are needed to define the proper characteristics of such lamps to fit the criterion mentioned above (Mulec 2011).

Cadastre of caves in Slovenia To date, 10,030 caves have been discovered and registered in Slovenia. The number of discovered and explored caves rises every year by around a 100. The unified cadastre of caves is a collection of data on the known underground caves in Slovenia that provides an overview of the vast number of known caves.

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The first descriptions of caves in Slovenia date from the seventeenth century. In the second half of the nineteenth century, the number of known caves increased to more than 200. In 1910, the Cave Exploration Society was founded and established a collection of observations from scientific expeditions, reports and cave plans; initially, however, the collection was poorly organized. Later, the collected material was rearranged by numbering the caves consecutively, creating the foundation for a cadastre that has remained basically unchanged to the present day. By 1938, the number of registered caves had increased to 647. In the middle of the twentieth century, maintaining the cadastre became a joint project of the Speleological Association of Slovenia and the Karst Research Institute in Postojna. The cadastre has two sources of data. Amateur speleologists contribute the largest part of data. Their data are organized according to the discovery of the caves and oriented toward new exploration in known caves. The other materials are contributed by institutions professionally involved in karst research and cave exploration. Despite the differences in the quality and orientation of the data, the cadastre is an excellent and very useful collection of data. The cadastre of caves contains almost 70,000 pages and a digital database of fundamental data. Only caves longer or deeper than 10 m are registered. A form is kept for each registered cave that contains the coordinates of the entrance, a description of access to the cave, basic dimensions (length, depth), the date of exploration and data on the explorers. The form also contains sections for a description of the cave as well as geological, hydrographical, meteorological, archeological and biological information about the cave. A plan of the cave must also be submitted. The basic form can be complemented by reports on further explorations of the cave, photographs and other material. The cadastre of caves is a basic collection of data about caves in Slovenia. Its registration system, the use of uniform identification numbers, cave names and quality data, and the fact that it has been in use for more than half a century, make it a valued resource for all scientific, professional, administrative and other users who need information about the karst and caves in Slovenia. A database on caves, which has been extracted from this resource, is provided annually to the Ministry of the Environment and Spatial Planning for the needs of environmental protection and spatial planning activities and is also used by the Office of Civil Protection and Disaster Relief at the Ministry of Defense. Postojna Cave, which stretches to 20.5 km, is the longest cave. Five more caves are longer than 10 km, and six ˇ ehi 2 is the deepest caves exceed the depth of 1,000 m. C cave with 1,533 m. The average cave length is 76 m, and the average depth is 26 m. The total length of all known

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caves in Slovenia is 733 km. The altitude of the entrance of the lowest cave is 7 m above sea level, while the highest entrance is 2,550 m above sea level.

Professional supervision and consulting in managing the Postojna and Predjama cave systems In the framework of the Professional Supervision and Consulting in Managing Cave Systems, Climatic and Biological Monitoring of Cave Systems (sponsored by Postojnska jama which manages the caves) and Measurements and Analysis of Selected Climatic Parameters in Karst Caves: Example of the Postojna Cave System (cofinanced by the Slovenian Research Agency) projects, the Karst Research Institute has undertaken regular climatic and biological monitoring of the Postojna and Predjama cave systems since 2009 at selected locations, as well as performing the tasks of karstology consultant or cave custodian in the implementation of the concession contract. Professional monitoring of the state of both caves is performed with an emphasis on the impact of the use of caves as natural assets. The Postojna (20,570 m) and Predjama (13,092 m) caves rank among the most visited karst caves in Slovenia. In 2009, Postojna Cave was visited by almost 500,000 visitors and the Predjama Cave system by 5,500. The two cave systems are listed in the Register of Natural Assets as assets of national importance. The duty of the cave custodian is professional supervision and consulting relative to management to insure the sustainable development of both cave systems, developing guidelines for the use of cave systems as natural assets, and the climatic and biological monitoring of both systems. Work tasks in the Short-Term Program for the use of natural assets of the Postojna and Predjama cave systems (2009–2013) include climatic and biological monitoring of lampenflora, regular communication with the Nova Gorica Regional Unit of the Institute of the Republic of Slovenia for Nature Conservation about the implementation of the concession and the state of the cave, the implementation of a rehabilitation program to eliminate the impacts caused by the use of these natural assets, drawing attention to external factors endangering the caves, monitoring and supervision of major encroachments and events in the cave (Fig. 7), recording research, making an inventory of encroachments and maintaining a list of the cultural heritage in both cave systems. In climatic monitoring in the Postojna Cave system, temperatures are measured at a number of locations using various measuring instruments, as well as measuring atmospheric pressure, relative humidity, CO2 and wind (Fig. 7). Temperature is usually measured on an hourly


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Fig. 7 a Measuring sites for climatic and biological monitoring in the Postojna Cave system: Climatic monitoring (hourly measurement of air temperature and atmospheric pressure). Climatic monitoring (station for measuring air temperature, wind velocity, wind flow, specific electric conductivity). Climatic monitoring (air temperature). Climatic monitoring (air temperature and humidity). Biological monitoring (monitoring of fauna in percolated water). Biological

monitoring (seasonal sampling of bioaerosols and atmospheric data including air temperature, relative humidity, CO2, wind velocity, atmospheric pressure). b Exhibited replicas of two dinosaur skeletons in the Koncertna dvorana cavern during the Postojna Cave system exhibition in 2009 (Photo: Stanka Sˇebela). c Climatic monitoring in the Lepe jame cavern, meteorological station (Photo: Stanka Sˇebela)

basis, and periodically at shorter intervals. In 2010, two meteorological stations were installed in the cave, the first located in the Lepe jame cavern (Fig. 7) and the second in the main passage between the Veliki dom and Kongresna dvorana caverns. Both stations employ a number of sensors for temperature, a sensor for water temperature in a pool, an ultrasonic wind speed monitor, a sensor for measuring the concentration of CO2 in the air and a sensor for measuring relative humidity. Both stations are equipped with data recorders that take data every 10 min from all the sensors and save them on a memory card. During events and festivities held in the cave that attract a larger number of visitors, the normal values for CO2 increase by two or three times, with a simultaneous rise of

air temperature by up to 0.3°C. When the number of visitors returns to normal, the CO2 values and the temperature return to their normal values. In both cave systems, biological monitoring shows the importance of protecting the rich underground fauna and recording the existing state. In accordance with the legislation, the monitoring of the Pivka River that sinks into the Postojna Cave is undertaken by the Ministry of the Environment and Spatial Planning. The pollution of the Pivka River is an important issue related to the proper operation of the communal water treatment plant in Postojna, which must encompass all the waters that sink into the cave system. The underground Pivka River must not be additionally

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polluted from other sources inside the cave system (e.g., toilets in the cave). Based on the experience of conducting climatic and biological monitoring in the Postojna and Predjama cave systems, a protocol is being developed with a suitable legal basis to be applied in other karst caves in Slovenia as well. Regular written reports of visits to both cave systems are made, supported by observations and findings on the management of both cave systems. Regular meetings are held with the concessionaire and representatives of the Nova Gorica Regional Unit of the Institute of the Republic of Slovenia for Nature Conservation on urgent and ongoing issues.

Karstological assessment of other spatial encroachments on the karst landscape In the past decades, the Classical Karst region was relatively exempt from intensive urbanization. Major changes in the preserved natural environment and healthy local lifestyle only began to appear in the last few years due to the proximity of the expressway. This increased the pressures on the sensitive karst environment where the limitations of the natural environment must be respected. With this in mind, karstologists from the Karst Research Institute were invited to assess the expansion of the golf course at the Lipica Stud Farm. The resort’s desire was to expand the existing golf course to the adjacent wooded and well-preserved karst area, so the course would meet the standards required for the organization of international tournaments. Impacts on the soil, water and natural heritage from the karstological viewpoint were assessed. The risk to the soil and water would increase due to additional fertilization using artificial fertilizers, summer irrigation and the modification of the karst surface (reduced rockiness, increased soil thickness, partial filling of dolines, partial removal of cultural heritage, e.g., dry stone walls). The project was judged to be feasible, provided specific mitigation measures are implemented such as partial changes in the arrangement of fairways, limits relative to fertilization, the use of pesticides and irrigation, partial preservation of the rockiness of the surface, and total preservation of the natural and cultural heritage of national importance (e.g., karst caves, dry walls). In another study, the impact on underground karst in the case of the Fara pri Blokah sewage treatment plant from where water presumably flows toward the Krizˇna jamaKrizˇna jama 2 cave system, an internationally important site of very high underground biodiversity with more than 50 underground lakes and a major excavation site of cave bear (Ursus spelaeus) remains, was assessed. While sewage treatment plants are desirable in karst areas, problems

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can occur with the inadequate processing of sewage due to the concentration of the runoff to the underground and occasional pollution resulting in the impoverishment of the underground hydrological, geomorphological and biological heritage. A tracer test was conducted at the runoff point of the treatment plant and samples were collected at five underground and five surface sampling points (springs). Although only 2% of the injected tracer appeared in the Krizˇna jama Cave, the results indicated that a substantially higher proportion of partly treated wastewater could flow into the cave with higher water levels. With high water levels, the pollution of the Krizˇna jama Cave can be anticipated, but at the same time the large amount of water would most probably dilute the pollutants. At low water levels, the cave is less threatened. The institute is trying to establish the impact of the existing sewage treatment plant on underground processes using micrometer measurements and limestone tablets on the sensitive rimstone barriers separating the underground lakes that grow up to 0.09 mm/ year. The impact and possibility of opening a previously unopened cave for tourists in the UNESCO Phong Nha-Ke Bang Park in central Vietnam was evaluated. In cooperation with the local community and the company that manages Postojna Cave, the Vietnamese cave was explored, measured and evaluated during 2-week-long field expeditions and evaluated from the geological, geomorphological, hydrological, and partly biological and archeological viewpoints. Specific tourist attractions in the cave were documented and photographed, and a visiting regime and the route of tourist trails through the cave were recommended. Proposed paths were visualized using a 3D computer program, several possible access routes were suggested, and market research was conducted on the attractiveness of the cave and the entire Phong Nha-Ke Bang National Park. A team of five karstologists and two tourism workers was involved in the project. The Karst Research Institute is expanding the awareness of the value of the karst and its vulnerability through the European Union’s Karst Underground Protection project that includes the organization of two International ‘‘Classical Karst’’ Karstology Schools (Fig. 8), the cleanup of six Slovenian and six Croatian caves, biospeleological studies in southwestern Slovenia and northwestern Croatia, filming an educational documentary, and the purchase of equipment needed for these activities. Although the primary aim of the project is to promote cross-border cooperation with Croatia, improved knowledge of karst and ways to promote it from the visual, professional, educational and biology viewpoints will be examined, as well as the potential for rehabilitation of polluted caves in the catchment areas of drinking water springs.


Fig. 8 Organization of cave cleanups (activity of the project Karst Underground Protection) will directly result in improved quality of drinking water

Conclusion By applying high-quality karstological research results from individual spheres of karstology and interdisciplinary studies, the institute wishes to prepare a foundation for rational planning of sustainable life in karst regions that will consider the natural and cultural characteristics and vulnerability of karst landscapes, supersede the inevitable profit motive, and base environmental planning on real socioeconomic conditions, which will benefit the population in karst regions as well as their long-term and shortterm development. While the primary mission is to deepen the knowledge of karst, karst phenomena and karst waters, the institute is also aware of the need to continually and effectively present karstological discoveries to the wider public by participating in major projects, working with relevant government ministries, agencies and companies and providing educational programs about the karst. To this end, karstology courses at the university and graduate levels have been established and a center for planning on karst through which karstological knowledge will be more widely available is underway.

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