COBISS: 1.01 KARST wATER MANAGEMENT IN SLOVENIA IN THE FRAME OF VULNERABILITY MAPPING UPRAVLJANJE S KRAŠKIMI VODAMI V SLOVENIJI V OKVIRU KARTIRANJA OBčUTLJIVOSTI Nataša RAVBAR1, Gregor KOVAčIč2 Abstract UDC 556.3:65.012(497.4) 556.3:504.06(497.4) Nataša Ravbar & Gregor Kovačič: Karst water management in Slovenia in the frame of vulnerability mapping Slovene karst sources are of great national importance for drink-ing water supply. Since karst aquifer systems are very susceptible to contamination, these sources require appropriate and care-ful managing. Unfortunately, in the acts of Slovene legislation, the special characteristics of water fow within karst regions are not very seriously taken into consideration in determining the criteria for karst water sources protection. In contrast, in some other countries, the concept of groundwater vulnerability mapping has been successfully used for protection zoning and land use planning in karst. Regarding the diferences between particular karst aquifer systems, data availability and economic resources, diferent methods of karst water vulnerability assess-ment and mapping have already been developed. Already these methods have been many times tested and implemented in different test sites worldwide. However, experience in application using diferent methodolo-gies for vulnerability mapping of karst aquifers is very mod-est in Slovenia. Te present paper deals with potential meth-odological problems that might arise while applying the most commonly used methods for karst water vulnerability assess-ment to Slovene karst regions. key words: karst water management, karst sources protection, drinking water, vulnerability assessment and mapping, Slovenia. Izvleček UDK 556.3:65.012(497.4) 556.3:504.06(497.4) Nataša Ravbar & Gregor Kovačič: Upravljanje s kraškimi vodami v Sloveniji v okviru kartiranja občutljivosti Kraški izviri so v Sloveniji izjemnega pomena za vodooskrbo. Ker so kraški vodonosniki zelo občutljivi na onesnaženje, kraški vodni viri zahtevajo primerno in previdno upravljanje. Na žalost pa posebne značilnosti pretakanja voda v kraških pokrajinah niso zadovoljivo upoštevane pri določevanju kriterijev za zavarovanje kraških virov znotraj slovenske zakonodaje. Nasprotno se v nekaterih drugih državah koncept kartiranja občutljivosti podtalnice uspešno uporablja pri določevanju vodo varstvenih pasov in načrtovanju rabe prostora na krasu. Upoštevajoč razlike med posameznimi kraškimi vodonosnimi sistemi, razlik v dostopnosti do podatkov in v ekonomskih zmožnostih so bile izdelane številne metode ocenjevanja in kartiranja občutljivosti kraške podtalnice, ki so bile tudi večkrat uporabljene in preizkušene na različnih testnih poligonih po svetu. V Sloveniji so izkušnje pri aplikaciji različnih metod kartiranja občutljivosti kraških vodonosnikov zelo skromne. V članku so opisani potencialni metodološki problemi, s katerimi se lahko srečamo pri aplikaciji posameznih običajno uporabljanih metod ocenjevanja občutljivosti kraške podtalnice v Sloveniji. ključne besede: upravljanje s kraškimi vodami, varovanje kraških izvirov, pitna voda, ocenjevanje in kartiranje občutljivosti, Slovenija. 1 Karst Research Institute, ZRC SAZU, Titov trg 2, SI-6230 Postojna, Slovenia, e-mail: natasa.ravbar@zrc-sazu.si 2 University of Primorska, Faculty of Humanities Koper, Glagoljaška 8, SI-6000 Koper, e-mail: gregor.kovacic@fs-kp.si Received / Prejeto: 15.09.2006 ACTA CARSOLOGICA 35/2, 73–82, LJUBLJANA 2006 NATAŠA RAVBAR & GREGOR KOVAčIč INTRODUCTION Groundwater from karst aquifers is becoming more and more valuable for drinking water supply. In many regions worldwide it forms the only available drinking water resource. About one quarter of the global popu-lation is supplied by karst waters (Goldscheider 2002), while in some Alpine countries karst water contributes up to 50% of needs. In the case of Slovenia this amount reaches 43% (Brečko Grubar & Plut 2001). Extensive ar-eas on the western, south-western, southern and south-eastern parts of Slovenia are almost entirely dependent on karst water sources (Fig. 1). Terefore karst aquifers are becoming more and more strategically important and should be appropriately and carefully managed. fig. 1: Te map shows the carbonate rocks extension and the most important karst water sources in Slovenia. Sl. 1: Karta prikazuje razširjenost karbonatnih kamnin in najpomembnejše kraške vodne vire v Sloveniji. Te wide areas of karst regions in Slovenia are either uninhabited or scarcely populated with almost no agri-cultural activities or only with traditional ones, which is very favourable for water protection. Terefore, the karst aquifers are ofen considered as an abundant high-quality drinking water resource, though they are very vulnerable to pollution and should be managed and protected on a sustainable basis. Unfortunately, in the acts of Slovene legislation, the special characteristics of water fow with-in karst regions are not very seriously taken into consid-eration of determining the criteria for karst water sources protection. Furthermore, experience of karst aquifer protection within the frame of vulnerability assessment and mapping is very limited in Slovenia and more efort should be given to this subject in the future. KARST wATER PROTECTION IN SLOVENIA Important karst aquifers in Slovenia are mainly remote in general, is still relatively high, though some signs of and uninhabited areas. Te quality of karst groundwater, contamination have already been recorded in some of the 74 ACTA CARSOLOGICA 35/2 – 2006 KARST wATER MANAGEMENT IN SLOVENIA IN THE FRAME OF VULNERABILITY MAPPING springs (Kovačič & Ravbar 2005). Since the water pro-tection refects in land-use restrictions, the protection of karst water resources is ofen neglected in land-use man-agement. Even where the water protection zones and re-gimes are established, the implementation of regulations is usually not efective and the control over polluters is weak. Te example of the Bistrica karst spring illustrates some problems of water management in the area of an uninhabited Snežnik karst plateau (Nw Dinarids), where sufcient protection zones have not yet been set up and water protection regulations have not been implemented properly (Kovačič 2003a). Despite relatively favourable conditions for karst water sources protection in Slovenia compared to some other karst areas worldwide, many of the karst water sources still remain insufciently protected. LEGISLATIVE FRAMEwORK Basic legislative provisions concerning karst groundwa-ter protection policy in Slovenia are based on waters Act 2002. Pursuant to the abovementioned Act it is govern-ments responsibility to establish water protection areas and regimes in karst areas with respective drinking water sources and to ensure the implementation of the provisions in each protection zone. According to the Rules on criteria for the designation of a water protection zone 2004, the hydrological back-ground (i.e. protection area) of a specifc captured karst spring or well should be divided in three basic protection zones. Te outer zone coincides with the boundaries of the entire catchment area, while the frst zone is deter-mined on the basis of transfer time of fow shorter than 12 h. Regarding the abovementioned Rules, the boundaries of water protection zones of karst aquifers should be determined on the basis of data on the velocities of karst groundwater, directions of groundwater fow, depth of water table, attenuation of actual and potential pol-lutants, chemical characteristics of karst groundwater and the extent and karstifcation degree of hydrological background. Te Rules (2004) recommend several difer-ent methodologies for gathering the data. Carrying out a tracer test in the catchment area of a specifc spring is not an obligatory one, though it is authors’ opinion that it is one of the most appropriate hydrological methods that gives results on the underground fow paths, hydraulic properties of the aquifer and a helpful tool to delineate the catchment area of the particular water source. Such a confguration of legislation, unfortunately, lets the pos-sibility of less accurate delineation of particular water protection zones. Te concept of intrinsic vulnerability assessment and mapping is not directly included in the methodology described in the Rules. PRESENT SITUATION AND PROBLEMS Since the new waters Act 2002 has been in force only for a relatively short period, majority of the karst sources are still protected in accordance with old legislation. According to the old waters Act of 1981 the designation of wa-ter protection areas fell within the responsibility of local communities. Tus adequate protection was hindered by administrative borders between these communities. Due to the conficts of interest in land use planning between neighbouring municipalities, protection zone extending over a territory of another municipality has usually not been accepted and the protection regime not established. In the case of the Rižana karst springs, which are tapped for the water supply of the Slovene coastal region, most of the second water protection zone extends over the neighbouring municipalities and even over the neighbouring country (Croatia) and hence is not protected (Kovačič 2003a). As with the Rižana karst springs, for the same reasons many other springs like the Malenščica and the Globečec springs are not suitably protected as well. Te Malenščica spring is an important and the only source of drinking water supplying 20,000 inhabitants and econo-my of the Postojna and Pivka municipalities. Even though the water protection zones have been delineated and the necessary provisions defned two decades ago (Habič, 1987), the required decrees have not been accepted due to the conficting interests in land use. fig. 2: illustration of the origin-pathway-target model and the concept of the resource and source protection (afer Goldscheider 2005). Sl. 2: ilustracija modela izvor-pot-cilj ter koncept zaščite vodnega vira in podtalnice (po Goldscheider 2005). Te Globočec spring is a regionally signifcant water source, but only protected in the administrative area of one municipality even though more than half of its infu-ential area extends also to the neighbouring administrative areas (Ravbar 2005). Since diferent approaches for the designation of wa-ter protection zones have been in use in Slovenia in past decades (Breznik 1976; Rismal 1993; Petauer & Veselič ACTA CARSOLOGICA 35/2 – 2006 75 NATAŠA RAVBAR & GREGOR KOVAčIč 1997), this has resulted in non-comparable water protec-tion areas and regimes of diferent karst water sources, which is rather problematic for sufcient land-use plan-ning in karst areas (Prestor 2002). Common character-istics of all three approaches are the transfer time delin-eation criteria, which defne diferent water protection zones, and the division of hydrological background in three basic water protection zones. However, they difer markedly in their method for the determining the extent of individual protection zone, using diferent parameters. Due to the lack of sufcient data, the individual water protection zones were ofen not established on a solid hydrogeological basis, and were thus based only on avail-able information on the geological structure. Neverthe-less, for proper protection sufcient studies on source re-charge, tracer tests in their catchments and other hydro-logical surveys are needed. Tus such protection zones are ofen insufcient and may be inefective. Nowadays situation in the feld of karst water protection management in Slovenia is, unfortunately, more or less a refection of an old legislation. Since the protection of karst aquifers fell within the responsibility of the gov-ernment, establishment of karst water protection areas is now not any more hindered by the conficts between land use and the demands for water protection on a local scale. Not many previously established water protection zones have been recently adapted to the new legislation. Tus some inadequately designated water protection zones are still valid. One of the most unfavourable consequences of unregulated conditions in the feld of water protection Te concept of groundwater vulnerability mapping is an alternative approach for successful protection zoning delineation and land use planning in karst. Te concept of groundwater vulnerability indicates the liability of a hydrologic system to contamination, using diferent col-ours to symbolize diferent degrees of vulnerability Te fundamental idea is to show that the protection provided by the natural environment varies at diferent locations (Vrba & Zaporozec 1994). As a result the most vulnerable areas can be identifed, and consequently at least those can be protected. However, this concept is not restricted to karst, but is most relevant when applied to karst land-scapes (Goldscheider 2005). Regarding the diferences between particular karst aquifer systems, data availability and economic resourc-es, diferent methods on karst water vulnerability assess-ment and mapping have been developed. In addition, legislation is that there is practically still no control over potential and actual polluters of karst groundwater. Te concept of karst water protection is still based only on the transfer time from the point of infltration to the point of outfow (spring or well). Nevertheless, evaluation of diferent fow velocities (contamination transport times) in a sense of water protection and spatial distribution of diferent values of fow velocities within the background of an outfow is rather challenging. Te characterization of fow and solute (contaminant) transport mechanisms in heterogenous karst aquifers (e. g. diferent values for difuse and point recharge) could meet several problems, as well. Nevertheless, crucial criteria for karst sources protection zones delineation are groundwater velocities. where groundwater fow velocities are high, protection zones would cover large areas, ofen the entire catchment. However, it is impossible to require a high protection for large areas. Such spatial planning would be unreasonable and not practical. Above all, in areas with great market value of the land, rigorous land use restrictions would be controversial (Ravbar 2006). Furthermore, groundwater velocities are not the only crucial aspects to determine higher/lower suscepti-bility of karst groundwater to contamination. Some other factors afecting the natural attenuation capacity of karst aquifers (e.g. function of protective cover, concentration of fow, karstifcation rate) are of at least the same im-portance, but are still not properly included in the karst water protection legislation in Slovenia. these have been many times tested and implemented in diferent test sites worldwide. Te existing methods take into account a variety of factors that control the infltration of water and contaminants from the land surface to-wards the groundwater, such as overlying layers, infltration conditions, degree of karstifcation and precipitation regime. Te frst existing method with special consideration to karst aquifers was the EPIK method (Doerfiger & Zwahlen 1998), which strongly infuenced the later methods. quite a few of the lately developed methods are based on the work undertaken by the COST Action 620 that developed the Eu-ropean Approach (Zwahlen 2004), a conceptual framework for karst groundwater intrinsic vulnerability assessment and mapping. Individual groups and individuals within the COST Action 620 have taken this approach as the basis for the particular methodology development. Te European VULNERABILITY MAPPING AS AN ALTERNATIVE CONCEPT 76 ACTA CARSOLOGICA 35/2 – 2006 KARST wATER MANAGEMENT IN SLOVENIA IN THE FRAME OF VULNERABILITY MAPPING Approach takes into consideration four parameters (over-laying layers, concentration of fow, karst network develop-ment and precipitation regime). A signifcant infuence to the European Approach came from the previously developed PI method (Gold-scheider 2002). It is based on an origin-target-pathway model. Te origin is the term used to describe the loca-tion of a contaminant release. Te term pathway is a fow path of a contaminant from the point of release (origin) to the target, which may be the groundwater surface or a drinking water abstraction point e.g. spring or well (Daly et al., 2002; Goldscheider 2005). Tere are two general ap-proaches of a water protection: resource protection aims to protect the whole groundwater body and source protection that aims to protect a particular spring or well. GENERAL CHARACTERISTICS OF SLO VENE KARST LANDSCAPES Direct application of some existing vulnerability map-ping methods could meet several difculties frst of all due to the specifc characteristics of the Slovene karst. In Slovenia karst regions extend over 43% of the country spreading from the Karavanke range and the plateaus of the Julian and Kamniške-Savinjske Alps at an altitude of 2500 m to the shore of the Mediterranean Sea and Dinar-ic karst on the south. Large karst massifs and karst plateaus, intersected by shallow karst areas, karst poljes and valleys, characterize these landscapes. Tick sequences of very pure and deeply karstifed limestones and dolomites of the Mesozoic era prevail. Te depth of the unsaturated zone can reach several hundreds of meters, in the moun-tain massifs even 1500 m and more. Carbonate rocks are of very good to medium permeability the groundwater fow velocities are ranging between 0.02 and 29.6 cm/s, respectively from 0.72 m/h to 1065.6 m/h (Novak 1993). Less permeable or impermeable deposits traversing karst areas, border karst aquifers and prevent the under-ground runof; so do fysch and less permeable dolomite layers caused by folding and thrusting. Slovene karst landscapes are strongly tectonically modifed. Fault zones that intersect or border karst areas can act as hydrologi-cal barrier as well. Consequently, karst underground wa-ter emerges to the surface through numerous efcacious springs at the aquifers edges. Catchment areas of most of them are very complex, covering karst and non-karst areas as well. Catchments ofen extend over several tens or even hundreds km2 and In some of the countries respective vulnerability mapping approaches have also been integrated in the states legislation e.g the Irish Method in Ireland (GSI 1999), the SINTACS method in Italy (Civita & De Maio 1997). Te EPIK method (Doerfiger & Zwahlen 1998) has been integrated in Swiss legislation only for karst sources. Te GLA method (Hölting et al., 1995) is a supplement to the German groundwater protection schemes. However, in Slovenia experiences of such application are very modest. Only two karst spring vulnerability studies have been done so far; Janža & Prestor (2002) us-ing the SINTACS and Petrič & Šebela (2004) using the EPIK method. are hydraulically connected over long distances. water-sheds are ofen overlapping and the fow paths proved by tracer tests ofen cross each other. Furthermore, it is practically impossible to defne the position of individual springs’ watersheds, precisely due to their high variability in time and strong dependence on the respective hydro-logic conditions. Namely, in dependence on the respective hydrologic conditions in several karst areas frequent and very high groundwater fuctuations appear (several tens up to few hundred meters). Consequently, also vari-able fow velocities, changing fow directions and sur-face-underground fow interactions result. Very thin or mostly absent protective soil cover and common absence of other protective overlaying layers, such as subsoil and non-karst rocks is signifcant. Te av-erage annual precipitation amounts ranges from 1000 up to 4000 mm in the mountainous areas. METHODOLOGICAL PROBLEMS AND OPEN qUESTIONS Regarding the peculiarity of individual intrinsic vulner-ability mapping methods, the adequacy of the criteria such as parameter selection and the method of parameter weighting, diferent difculties might arise when apply-ing a particular method to Slovene karst. In many of the existing methods the characteristics of the layers lying above the saturated zone are the most important factor controlling natural protection of groundwater against contamination (self-cleaning or carrying capacity). Some among the methods provide assessment schemes, where protective function assess- METHODOLOGICAL PROBLEMS AND SPECIFICS OF KARST AqUIFER VULNERABILITY ASSESSMENT AND MAPPING IN SLOVENIA ACTA CARSOLOGICA 35/2 – 2006 77 NATAŠA RAVBAR & GREGOR KOVAčIč ment consists of up to four layers of the unsaturated zone (topsoil, subsoil, non-karst rocks and karst rocks). Such a very detailed system of protective function assessment requires a vast amount of data, which is a special problem in Slovenia, discussed below. Te assessment of the over-lying layers protective function has been shown to be one of the major problems in one of the previous applications as well (Janža & Prestor 2002). Because of the common absence of soil and/or sediment cover in Slovene karst, the protective function value would mainly be infuenced by the depth of the unsaturated zone. Due to the enormous thickness of the unsaturated zone, the protective values would ofen be classifed as “moderate”, not showing the vulnerability diferences within the aquifer itself Terefore, the selec-tion of only two parameters (soil and lithological charac-teristics of the unsaturated zone) together with a not very detailed system of protective function assessment could be suitable as well (Fig. 3). fig. 3: An example of a bare karst surface on Kanin high mountain plateau (2587 m), where the depth of the unsaturated zone exceeds 1500 m (photo: G. Kovačič). Sl. 3: Primer golega kraškega površja na visoki kraški planoti Kanin (2587 m), kjer je debelina nezasičene cone večja od 1500 m (foto: G. Kovačič). Tere is a problem in assessing a hydrological function of epikarst, where storage of water and concentra-tion of fow occur. Te frst process increases the natural protection of karst aquifer, while the latter increases vul-nerability of the karst system. Te problem of epikarst is that its existence is not always easily recognizable by the surface karst features. Furthermore, great spatial diferences of its development on short distances are present 78 ACTA CARSOLOGICA 35/2 - 2006 due to heterogeneity of karst landscapes (Kovačič 2003b). Te concept of mapping surface karst features indicat-ing the existence of diferent tectonically crushed zones within karst aquifer and consequently the occurrence of more or less developed epikarst zones was successfully introduced by Petrič & Šebela (2004). Furthermore, there is still a question how to consid-er areas with great groundwater level oscillations, where KARST wATER MANAGEMENT IN SLOVENIA IN THE FRAME OF VULNERABILITY MAPPING groundwater level varies for several tens or even hun-dreds of meters in a short time and causes great change of drainage divides and fow directions. Te protective-ness of the unsaturated zone in highly karstifed rocks is generally considered to be fairly low. Variable thickness of this zone would consequently have limited impact on fnal vulnerability value. However, groundwater level fuctuations might alter catchment boundaries, which is crucial for source vulnerability mapping and should therefore be additionally considered (Ravbar & Golds-cheider, in press). Due to great groundwater level oscillations, some karst landscapes in Slovenia are also characterised by surface and groundwater fow alteration that is relevant with respect to groundwater vulnerability (Figs. 4 & 5). Intermittent river fows and lakes, some of which appear several times per year, while others occur only very ex- rainfall” conditions that occur several times per year (Goldscheider 2002). Te degree of vulnerability of the area characterised by surface and groundwater fow alteration may vary drastically in dependence on respective hydrologic conditions. Terefore, when making vulner-ability maps, a distinction should be made between zones of concentrated infltration that are permanently drained into swallow holes and those that are only occasionally drained into karst. In the vulnerability assessment, special empha-sis must be given on the function of the sinking rivers, which occur within karst poljes or recharge in non-karst areas and sink on the contact with carbonates. Te lat-ter can have either huge or small catchments, which has to be considered in vulnerability assessment, since swal-low holes are points of concentration of fow, causing fast infltration of surface waters and contaminants towards fig. 4 and 5: Te intermittent lake Petelinjsko jezero is fooded up to six months per year. At low groundwater level a shallow karst depression is dry (lef), while at high groundwater level it is fooded and forms a lake (right). Te degree of vulnerability of the area may vary drastically depending on respective hydrologic conditions (photo: N. Ravbar). Sl. 4 in 5: Presihajoče Petelinjsko jezero je poplavljeno do šest mesecev na leto. Ob nizkem vodostaju je kraška depresija suha (levo), medtem ko je od visokih vodah poplavljena in spremenjena v jezero (desno). v odvisnosti od trenutnih hidroloških pogojev se lahko stopnja občutljivosti na tem območju izrazito razlikuje (foto: N. Ravbar). ceptionally, as well as temporary springs, swallow holes and estavelles are signifcant. Consequently only in a case when a water body (river, lake) is frequently or perma-nently sinking into karst, a contaminant release would always and rapidly reach the groundwater without signifcant attenuation. On the other hand, a contaminant transport and its attenuation capacities might vary dras-tically where there are no temporary or perennial water fow conditions (Ravbar & Goldscheider, in press). So far the existing methods do not provide suf-cient tools to cope with hydrologic variability Te EPIK method takes into account temporary or perennial water fow conditions (Doerfiger & Zwahlen 1998). Similarly the PI method takes into consideration “average storm the groundwater. A question arises, how to delineate the infuence area of such surface fow on karst aquifer, since the surface fows have their own self-cleaning capacities (Kovačič 2003b). Furthermore, Slovene legislation demands indi-vidual water source protection. Nevertheless, resembling some European countries, no resource protection policy has been provided so far. For source vulnerability assessment where captured springs and wells are the targets (see the origin-pathway-target model above), the ad-ditional horizontal fow path in the saturated zone, the so-called K factor, has to be considered. So far only the EPIK method provided tools for the K factor assessment. Te European Approach is foreseeing incorporation of ACTA CARSOLOGICA 35/2 – 2006 79 NATAŠA RAVBAR & GREGOR KOVAčIč the K factor into the vulnerability assessment as well, but does not specify how it should be measured or catego-rized. Terefore in many cases an additional step from resource to source vulnerability mapping should be done if we would like an application to be adequate to Slovene legislation. when applying the SINTACS method Janža and Prestor (2002) added an extra criterion of cave density for implementing the unsaturated zone attenuation ca-pacity and hydraulic conductivity range of aquifer into the proposed method. However, the information on cave density is not relevant criterion for the karstifcation de-gree assessment as it can refect the degree of research work in a certain area. Furthermore, size, connection and density of karst conduits or caves are ofen results of previous climate conditions. In general, the conduit size aspect cannot be acceptable criteria, because even a relatively small degree of karstifcation (e.g. conduits 10 cm wide) can result in very high travel times and very rapid contaminant transport without signifcant attenuation. On the contrary for the mostly horizontal path-way through the saturated karst bedrock to the source, the groundwater fow characteristics and distance to the source have to be considered. Te European Approach considers also the assessment of the P (precipitation regime) factor, which modi-fes other parameters and thus the fnal assessment of vulnerability as well. Some of the methods (SINTACS, PI and COP) have already introduced the precipitation characteristics into their schemes. Te question is, whether it is practical to assess the value of precipitation regime within the small area of the same aquifer, since it is not very likely that the diferences in intensity and amounts of precipitation vary signifcantly between particular parts of a catchment and thus not essentially infuence its vulnerability However, it has already been shown that when applying the COP method in many dif-ferent aquifers across Europe, the P factor itself has small correlation with the fnal vulnerability values and shows important diferences only when the method is applied to the aquifers with diferent climate characteristics (Vías et al, 2006). Nevertheless, if introducing the P factor it would be recommendable to consider the efective infltration instead, since it presents the true amount of water infl-trating into the subsurface. Furthermore, higher vulner-ability (i.e. higher transport velocities, shorter transit time, more turbulent fow, more efective transport of sediments and bacteria, mobilisation of DNAPL - Dense Non-Aqueous Phase Liquid, more surface fow etc.) does not only depend on the actual amount of water infltrat-ing into the subsurface but also on the previous soil and epikarst zone water saturation. However, there is a methodological problem, how to evaluate the protective function of a P factor as well. Do the greater amounts of infltrating water increase the vul-nerability of a karst system (faster contaminant wash-of, shorter transfer time - less time for appropriate interven-tion) or do they contribute to the groundwater protec-tion (dilution, faster reduction of contaminants’ concen-trations, shorter duration of contamination)? As mentioned before, in Slovene karst many areas drain into several abundant springs at the aquifers mar-gins. In case of springs’ watersheds overlapping, vulner-ability maps of diferent sources might show diferent values of vulnerability due to respective springs. Tis raises a question, which source vulnerability map/value should be considered as more important. In terms of pro-tection degree and spatial planning, the highest degree of vulnerability should be considered. However, when planning the implementation of sanitary provisions in water protection zones, also an additional parameter indicating the economic and/or social importance of a particular water source should be considered. Accurate and detailed studies are essential for vul-nerability assessment. Several problems are expected and have also been confrmed while applying some of the existing vulnerability mapping methods in Slovene karst landscapes due to poor database, data availability and assessment. If the method requires very large amount of detail data, it does not only makes vulnerability assessment more expensive, but also makes the application less fexible and ofen unsuitable, as very rarely is a large amount of data available. Particularly scarce are data in remote and mountainous karst areas. In addition, methods that require grid input information (e.g. the SINTACS method) are not very appropriate for the application in karst areas, since the karst aquifers are very heterogenous systems characterised by great and inherent changes in small area. 80 ACTA CARSOLOGICA 35/2 – 2006 KARST wATER MANAGEMENT IN SLOVENIA IN THE FRAME OF VULNERABILITY MAPPING CONCLUSION In Slovenia karst aquifers are of special economic impor-tance. Even though the quality of the groundwater is still relatively high, some sources of contamination have al-ready been recorded, showing the shortcomings of water management even in the uninhabited alpine karst areas, which are ordinarily very favourable for water protection (Kovačič & Ravbar 2005). In order to protect the quality and quantity of water sources and resources for future generations the concept of groundwater vulnerability mapping and assessment has been in the past decades more and more coming to the fore. Assessment of groundwater vulnerability evalu-ates the intrinsic characteristics of the aquifer systems and subdivides an area into several units showing dif-ferent degrees of natural protection. It provides a useful conceptual framework, which could be the basis for the water protection zones and regimes establishment (Vrba & Zaporozec 1994). Nowadays various methodologies are in use, among which also methods with special consideration of karst aquifers have been introduced. However, experiences on application using methods for vulnerability mapping of karst aquifers are very limited in Slovenia. In future, application of some of the most common-ly used methods should be stimulated in order to subject eventual methodological problems that may arise during the application. Comparison of diferent methods in a single test site is therefore advisable. Considering spe-cifc characteristics of Slovene karst (very thin or mostly absent protective cover, very complex and large catch-ment areas, lack of quality and representative research, poor database, problem of data availability, etc.) selec-tion among the simplest methods would be reasonable. Methods that require very detailed data on protective cover characteristics or require very thorough database on catchment area should thus be avoided. Eventually, according to adequacy of particular criteria, such as parameter selection, parameter weight-ing and fnal assessment reckoning the most satisfactory among the existing methods should be selected and im-proved if necessary To propose a common method for karst water source vulnerability mapping its validation using hydrological and statistical methods is essential. Finally, a common method, which would be the basis for the water protection zones and regimes establishment, could be used for resource protection and land use planning in karst aquifers. Furthermore, it could be a supplement to the existing legislation for karst sources protection. According to the Rules (2004), the main criterion for the delineation of the source protection zones is the travel time of groundwater in the aquifer. However, a vul-nerability assessment and mapping could be an addition-al criterion for karst sources protection. It could present a supplement for reduction and/or enlargement in the size of the zones where necessary according to the intrinsic properties of a particular catchment area. Furthermore, source and resource maps could be practical tool for future land use management, spatial planning of human activities and for the sanitary provi-sions planning in water protection zones as well. REFERENCES Brečko Gruber, V. & D. Plut, 2001: Kakovost virov pitne vode v Sloveniji.- Ujma, 14-15, 238-244, Ljubljana. Breznik, M., 1976: Metodologija zaščite podzemne pitne vode ter določitve varstvenih območij in pasov. Regionalni prostorski plan RS 3/4. Zasnove uporabe prostora. Vodno gospodarstvo Ljubljana, Zavod SRS za družbeno planiranje, 176 p. Civita, M. & M. De Maio, 1997: SINTACS: Un sistema parametrico per la valutazione e la cartografa della vulnerabilita degli acquiferi all’inquinamento. Met-odologia & automatizzazione. Pitagora Editrice, 208 p., Bologna. Daly, D., Dassargues, A., Drew, D., Dunne, S., Golds-cheider N., Neale, S., Popescu, I.C. & F. Zwahlen, 2002: Main concepts of the »European approach« to karst-groundwater-vulnerability assessment and mapping.- Hydrogeology Journal, 10, 340-345. Doerfiger, N. & F. Zwahlen, 1998: Practical Guide, Groundwater Vulnerability Mapping in Karstic Re-gions (EPIK). Swiss Agency for the Environment, Forests and Landscape (SAEFL), 56 p., Bern. Goldscheider, N., 2002: Hydrogeology and vulnerabi-lity of karst systems - examples from the Northern Alps and Swabian Alb.- PhD Tesis. University of Karlsruhe, Faculty for Bio- and Geoscience, 236 p., Karlsruhe. ACTA CARSOLOGICA 35/2 – 2006 81 NATAŠA RAVBAR & GREGOR KOVAčIč Goldscheider, N., 2005: Karst groundwater vulnerabil-ity mapping: application of a new method in the Swabian Alb, Germany.- Hydrogeology Journal, 13, 555-564. GSI (1999): Groundwater protection schemes. Geologi-cal Survey of Ireland, 24 p. Habič, P. , 1987: Raziskave kraških izvirov v Malnih pri Planini in zaledja vodnih virov v občini Postojna.-Tipkano poročilo, 58 p., Archive Karst Research Institute SRC SASA, Postojna. Hölting, B., Haertlé, T., Hohberger, K. H., Nachtigall, K. H., Villinger, E., weinzierl, w. & J. P. wrobel, 1995: Konzept zur Ermittlung der Schutzfunkzion der Grundwasserüberdeckung.- Geol. Jb., C63, 5-20. Janža, M. & J. Prestor, 2002: Ocena naravne ranljivosti vodonosnika v zaledju izvira Rižane po metodi SIN-TACS.- Geologija, 45/2, 401-406, Ljubljana. Kovačič, G., 2003a: Te protection of karst aquifers: the example of the Bistrica karst spring (Sw Slovenia).-Acta Carsologica, 32/2, 219-234, Ljubljana. Kovačič, G., 2003b: Parametrične metode kartiranja občutljivosti kraških vodonosnikov – pregled, primerjava in kritika.- Seminarska naloga. Univerza na Primorskem, Fakulteta za humanistične študije, 77 p., Ilirska Bistrica. Kovačič, G. & N. Ravbar, 2005: A review of the potential and actual sources of pollution to groundwater in selected karst areas in Slovenia.- Natural Hazards and Earth Systems Science, 5/2, 225-233. Novak, D., 1993: Hydrogeological research of the Slove-nian karst.- Naše jame, 35, 1, 15-20, Ljubljana. Petauer, D. & M. Veselič, 1997: Metodologija določevanja zaščitenih območij podzemnih voda. Ministrstvo za okolje in prostor, 13 p., Ljubljana. Petrič, M. & S. Šebela, 2004: Vulnerability mapping in the recharge area of the Korentan spring, Slovenia.-Acta Carsologica, 33/2, 151-168, Ljubljana. Prestor, J., 2002: Problematika določanja varstvenih pasov in razporeditve ukrepov za zaščito vodnih virov.- Zbornik seminarjev Varstvo in kvaliteta pitne vode, Inštitut za sanitarno inženirstvo, 69-77. Ravbar, N., 2005: Spill of dangerous substances in the catchment area of the Globočec karst spring, SE Slo-venia.- In: Stevanović, Z., Milanović, P. (Eds.) wa-ter resources and environmental problems in karst, 193-200, Belgrade. Ravbar, N., 2006: Te protection of karst water sources in Slovenia.- In: Duran, J. J., Andreo, B. & F. Carrasco (Eds.). Congreso Internacional sobre el agua subter-ranea en los paises Mediterraneos. Karst, climate change and groundwater, 231-237, Malaga. Ravbar, N. & N. Goldscheider, (in press): Integrating temporal hydrologic variations into karst ground-water vulnerability mapping - examples from Slovenia.- 8th Conference on Limestone Hydrogeology, Neuchâtel. Rismal, M., 1993: Zaščita podtalnice - Strokovno navodilo za izdelavo normativnih aktov za zavarovanje kakovosti podtalnice, FAGG, Ljubljana. Rules on criteria for the designation of a water protection zone. 2004: Ofcial Gazette of the Republic of Slovenia, 64, 8111-8128. Vías, J. M., Andreo, B., Neukum, C. & H. Hötzl, 2006: Aplicación del método COP para la evaluación de la vulnerabilidad del aquífero carboná tico de Baus-chlotter Platte (Alemania). Comparación de resulta-dos con otros aquíferos del sur de Espana.- In: Duran, J. J., Andreo, B. & F. Carrasco (Eds.). Congreso Internacional sobre el agua subterranea en los paises Mediterraneos. Karst, climate change and ground-water, 249-256, Malaga. Vrba, J. & A. Zaporozec, (Eds.) 1994: Guidebook on mapping groundwater vulnerability.- International association of hydrogeologists. Verlag Hienz Heise, Vol. 16, 131 p., Hannover. waters Act. 1981: Ofcial Gazette of the Republic of Slovenia, 38, 2308-2320. waters Act. 2002: Ofcial Gazette of the Republic of Slovenia, 67, 7648-7680. Zwahlen, F, 2004: Vulnerability and Risk Mapping for the Protection of Carbonate (Karstic) Aquifers. Final report COST action 620.- European Com-mission, Directorate-General for Research, 297 p., Brüssel, Luxemburg. 82 ACTA CARSOLOGICA 35/2 – 2006