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Managed aquifer recharge (MAR) refers to a suite of methods by which excess surface water is diverted underground where it is stored for subsequent recovery. Although MAR has a long history of implementation in aquifers with intergranular porosity, its application in the karst environment presents major challenges due to the high heterogeneity of karst aquifers (Dillon et al., 2019). This research was focused on conducting a MAR feasibility study on the island of Vis, a small karstic island in the Croatian part of the Adriatic Sea, where favorable geological and hydrogeological conditions enabled the formation of high-quality karst aquifers, making the island autonomous in terms of water supply. The island’s main aquifer is protected from seawater intrusions by several hydrogeological barriers, however, climate change and high seasonal pressures related to tourism pose a threat to the future availability of freshwater. To investigate whether a MAR operation is feasible and suitable for the karst aquifer on Vis, detailed field and laboratory investigations were carried out. Field investigations included in-situ measurements of physicochemical parameters on water samples from springs and boreholes, groundwater monitoring (conductivity, temperature, and water levels), geophysical methods (ERT, magnetotellurics, and seismic refraction), and structural measurements. Laboratory analyses included measurements of stable water isotopes, principal cations and anions, tritium activity, and analyses of stable isotopes from dissolved sulphates. The results corroborated the available conceptual model of the water resources detailing the geometry of the carbonate aquifer and of the fracture systems driving the water circulation. A 3D numerical model (FEFLOW) of the island will be developed to simulate various scenarios of climate change, with and without MAR. The integration of the obtained results with historical data and previous research will be used for implementing efficient and sustainable management of the karst aquifer through MAR or alternative solutions on Vis island.

Implementation of managed aquifer recharge (MAR) systems in karst environments is generally considered challenging due to the high heterogeneity of karst aquifers and only a handful of global examples demonstrated optimal methods for research and sustainable operation of such systems. Throughout the project DEEPWATER‐CE, an integrated approach to the investigation of the feasibility of MAR systems in various geological and hydrogeological environments in Central Europe was fostered. In particular, our research was focused on conducting a MAR feasibility study on the island of Vis, a small karstic island in the Croatian part of the Adriatic Sea, where favourable geological and hydrogeological conditions enabled the formation of high‐quality karst aquifers, making the island autonomous in terms of water supply.

Vis, a small remote island in the Adriatic Sea, inhabited since the time of ancient Greeks and Romans, exhibits a unique historical and natural environment. With an area of 89.7 km2, the island is mostly composed of karstified carbonate rocks and belongs to Dinaric karst region, locus typicus for karst landforms. Its distance from the mainland is around 50 km from the city of Split, 147 km from the Italian coastline and 18 km from neighbouring Hvar island. The climate on the island is Mediterranean with dry and hot summer and mild, rainy and humid winter (Csa). Vis island, due to its remote location, is not connected to the mainland by submarine water pipeline so it has autonomous water supply due to favourable geological and hydrological conditions which enabled the formation of excellent karst aquifers. The majority of water is abstracted from drilled wells in the central part of the island (Korita extraction site), around 40 l/s, while additional quantities are obtained from coastal spring of Pizdica. Although predominantly of good quality, existing groundwater quantities on Vis are extremely vulnerable to the effects of climate change, namely increase in temperature, quantitative and temporal variability in precipitation trends as well as seawater intrusion. Moreover, Vis island is an attractive location for summer bathing tourism which causes the highest pressure on drinking water resources precisely during the hydrological minimum. An idea to apply artificial recharge of karst aquifer on Vis emerged during the 1970s, however, only on the theoretical level.Through the scope of the DEEPWATER-CE project, funded by Interreg Central Europe Programme, the aim is to develop implementation frame for managed aquifer recharge (MAR) solutions. Simplified, MAR is a process by which excess surface water is directed into the ground — either by spreading on the surface, by using recharge wells, or by altering natural conditions to increase infiltration to replenish an aquifer (DILLON et al., 2019). Globally, various designs of MAR schemes have successfully been implemented in unconsolidated aquifers, but there is little experience with artificially recharging karst aquifers (ROLF, 2017). A particular challenge for the technical implementation and operation of MAR is posed by strong hydraulic anisotropy and heterogeneity of karst aquifers and by their high vulnerability to contamination (XANKE, 2017). To investigate whether a MAR operation is feasible and suitable for karst aquifer on Vis, a detailed field and laboratory investigations were carried out. Field investigations included in-situ measurements of physicochemical parameters on water samples from springs and boreholes, groundwater monitoring (conductivity, temperature and water levels), geophysical methods (ERT, magnetotellurics, and seismic refraction) and structural measurements. Laboratory analyses included measurements of stabile water isotopes, and principal cations and anions. Hence, by conducting extensive investigations, coupled with historical data and previous research, a foundation for implementing efficient and sustainable management of karst aquifer through MAR on Vis island will be provided.

Turizam poprima sve veću važnost u svjetskoj ekonomiji, tako se već dugi niz godina mnogi gospodarstvenici orijentiraju na tu granu gospodarstva. U hrvatskim otočnim destinacijama stanovništvo se bavi turizmom koje je temeljeno na iskorištavanju dostupnih i besplatnih prirodnih resursa. Dugogodišnja zatvorenost otoka Visa ograničila je njegov turistički razvoj. Nakon otvaranja otoka prema posjetiteljima, njegov razvoj se koncentrirao oko urbanih i administrativnih središta Visa i Komiže. Što se tiče malih mjesta u unutrašnjosti otoka, tek su u začetcima razvojne inicijative temeljene na ruralnim ili etno konceptima turističkog razvoja. Turizam je do današnjih dana slabo razvijen, dominira privatni smještaj koji čini preko 79% ukupnog smještajnog kapaciteta otoka. Posluju samo četiri hotela nižih kategorija i dva kampa u privatnom vlasništvu. Prisutna je vrlo visoka sezonalnost, što znači da je otok u potpunosti orijentiran na proizvod sunca i mora. Ovaj rad istražuje učinkovitost zemljopisnog podrijetla kao temelj za tržišno segmentiranje posjetitelja otoka Visa. Ispitivanjem podataka sa šest glavnih emitivnih tržišta (Slovenija, Poljska, Ujedinjeno Kraljevstvo, Njemačka, Italija, Češka) pokušalo se utvrditi je li zemlja podrijetla zaista predstavlja učinkovit kriterij tržišne segmentacije kako bi se uspostavili profili posjetitelja. Utvrđeno je da se karakteristike posjetitelja razlikuju prema zemlji podrijetla. Uvažavanjem navedenih razlika stvara se osnova za ostvarivanje ekonomske koristi od turizma, čijem razvoju je potrebna zajednička vizija i sinergija svih dionika u turizmu. Tourism has become increasingly more important in the world economy, for many years businessmen have been pointing to this branch of the economy. In Croatian island destinations, the population is engaged in tourism based on the exploitation of available and free natural resources. Long-term closure of the island of Vis has limited its development in tourism. After opening the island to its visitors, its development concentrated around the urban and administrative centers of Vis and Komiža. As for small places in the interior of the island, they are only at the beginning of a developmental initiative based on rural concepts of tourism development. Tourism is currently poorly developed, dominated by private accommodation, which accounts for over 79% of the island's total accommodation capacity. Only four hotels of lower categories and two privately owned camps are operating in the island of Vis. There is a very high seasonality, which means that the island is fully oriented to the “sun and sea” product. This paper explores the effectiveness of geographic origin as the basis for market segmentation of Vis visitors. By examining data from six major geographic markets (Slovenia, Poland, United Kingdom, Germany, Italy, Czech Republic), it was attempted to determine whether the country of origin was indeed an effective market segmentation criterion to establish visitor profiles. It was found that the characteristics of the visitor differed according to the country of origin. The acknowledgment of these differences creates the basis for achieving economic benefits from tourism, whose development requires a common vision and synergy of all stakeholders in tourism.

Karst poljes are the most characteristic feature of Dinaric karst area. The number of poljes identified on the island of Vis (Croatia) differs according to the various authors who have studied the island. Considering the various existing definitions of polje in previous studies, in this paper we propose a set of criteria for identifying poljes in karst terrain using Geographic Information System. This enabled the identification of six poljes on the Vis Island, whose formation is predetermined by tectonic structures. Moreover, processes are frequently inferred by neotectonic (both uplift and subsidence) according to the analysis of longitudinal and transverse profiles gradients affecting balance of these morphologies. Since they are not hydrologically active in present hydrological conditions, poljes on Vis Island can be considered to be paleo - overflow or structural poljes.

Klimatske promjene utječu na poljoprivrednu proizvodnju, a time i na ekonomske prilike nekog područja. Promjene klime uključuju varijabilnost u količini oborina, intenzitetu vjetrova i porastu temperature. Oborine zabilježene na nekom području uglavnom potječu od vlage pristigle s područja mora i oceana, no smatra se da je čak jedna trećina oborina lokalnog porijekla proistekla od evaporacije („reciklirana vlaga“). Regionalne studije za područje Mediterana pokazale su da u drugoj polovici 20-tog stoljeća postoji opći trend smanjenja količina oborina, a predviđanja su da će se taj trend nastaviti. Stoga su na primjeru otoka Visa, tijekom petogodišnjeg razdoblja, korištenjem HYSPLIT modela i primjenom kalkulacija za utvrđivanje izdizanja vlage zraka izračunate unazadne putanje zračnih masa, lokacije izdizanja vlage i udio reciklirane vlage zraka u ukupnoj količini oborina. Climate changes directly affect agricultural production and economy of certain area. Changes of climate include variability of rainfall, wind intensity and increase of temperature. Precipitation collected on a specific location is mostly derived from sea and ocean moisture, although it is considered that approximately one-third of precipitation is derived from locally originated moisture by evaporation (recycled moisture). Regional studies for the Mediterranean area have shown a general trend of decrease of amount of precipitation in the second half of 20th century. Furthermore, predictions show that this trend will continue. In order to investigate this we used HYSPLIT model to calculate back trajectories of air masses bringing precipitation over Vis Island, Croatia. Application of calculations for specific humidity allowed us to determine locations of moisture uptake and percentage of recycled moisture in precipitation.

Turizam je postao svjetski fenomen i jedan od najvažnijih sudionika u međunarodnoj trgovini te u svom progresivnom razvoju i rastu uključuje veliki broj dionika na koje ostavlja mnoge posljedice, kako pozitivne, tako i negativne . Glavni cilj ovog rada bio je istražiti važnost i ulogu lokalne zajednice na otoku Visu u turističkom razvoju otoka, ukazati na dosađašnju ulogu lokalne zajednice te ukazati na mogućnosti daljnjeg osnaživanja i poticanja cijele lokalne zajednice i stanovništva da se uključe u proces planiranja i razvoja turizma na otoku Visu. U tu svrhu kreiran je anketni upitnik u kojem je lokalno stanovništvo otoka Visa izrazilo svoje mišljenje o pitanjima vezanim za sudjelovanje lokalne zajednice u turističkom razvoju, sudjelovanje lokalne zajednice u donošenju odluka relevantnih za razvoj turizma, ulogu turizma na otoku i mogućnostima utjecaja na daljnji razvoj i planiranje turizma. Istraživanje je pokazalo da se ne može potvrditi kako lokalna zajednica Visa značajno doprinosi razvoju turizma na otoku. Odluke vezane uz razvoj turizma donosi grupa pojedinaca u lokalnoj zajednici, a većina ispitanika nije nikada prisustvovala bilo kakvom obliku sastanka s javnim tijelima kada se raspravljalo o razvoju turizma na otoku. Istraživanje je također, potvrdilo kako su ispitanici čvrstog stava kad se govori o edukaciji lokalne zajednice i stanovništva za obavljanje poslova u turizmu budući da velika većina tvrdi kako je edukacija u turizmu iznimno važna. U konačnici, istraživanje potvrđuje kako je turizam doveo do povećanja potrošnje i stvorio nova radna mjesta na otoku te je za daljnji razvoj potrebno osnažiti lokalnu zajednicu za turistički razvoj kako bi svi stanovnici i dionici u turizmu imali kontrolu i utjecaj na cijeli proces razvoja turizma na otoku. Tourism has become a worldwide phenomenon and one of the most important participants in the international trade. Its progressive growth and development involves a large number of stakeholders and affects them, both positive and negative way. The main aim of this study was to research the importance and role of the local community on the island of Vis for tourism development on the island, to indicate the current role of local communities and point to the possibility of the further strengthening and empowering the whole community and the population to be involved in the planning and tourism development on the island Vis. For this purpose, a questionnaire was created for the local population of the island of Vis to express their opinion on the issues related to community participation in tourism development, community participation in decision-making for the development of tourism, the role of tourism on the island and possibilities of their influence on the further development and tourism planning. Research has shown that it can not be confirmed that the local community on the island significantly contributes to tourism development on the island. Decisions related to the development of tourism makes a group of individuals in the local community and majority of the respondents had never attended any form of meeting with public authorities when discussing about the development of tourism on the island. The study also confirmed that respondents have firm attitude regarding to the education of local community and the population for the performance in tourism industry since majority of them claim that education in tourism is extremely important. Ultimately, the research confirms that tourism has led to an increase in consumption and created new job opportunities on the island. For the further development it is necessary to strengthen and empower the local community for tourism development, so that the residents and stakeholders in the tourism industry have control and influence on the whole process of tourism development on the island.

The paper presents some basic features of vertical landscape structure of the southern partof Vis Island, Croatia. Its aim is the determination of geocomplex types with a certain degreeof stability and resistance to external influences, and confirmation or rejection of hypothesisthat with the application of appropriate methods, the spatial relation between geocomplextypes as well as the identification of specific dominant/stable and vulnerable/labile geocomplextypes can be precisely determined. The results should serve as the basis for estimationof current status and future trends in the development of geocomplex types as well as theenvironmental changes.

Rad razmatra populacijsku dinamiku otoka Visa te geografske, demografske i društvene značajke povezane s tim procesom. Podatci demografske statistike i rezultati istraživanja pokazuju da je na otoku Visu riječ o snažnoj populacijskoj regresiji. Taj je proces nastao početkom 20. stoljeća, a zahuktao se poslije drugoga svjetskog rata. Depopulacija je generirana zaostajanjem u društveno-gospodarskom razvoju, a izravno uzrokovana stoljetnim iseljavanjem. Početkom 1960-ih godina kao značajan čimbenik depopulacije javlja se i negativna prirodna promjena. Ona je rezultat odgođenog učinka iseljavanja, demografskih gubitaka u svjetskim ratovima i tranzicije nataliteta (promjene odnosa prema broju djece u obitelji). Dugotrajni nepovoljni demografski procesi (iseljavanje, depopulacija, demografsko starenje, smanjenje rodnosti), doveli su do slabljenja (bio)reproduktivne snage i vitalnog potencijala. Sve to odražava se i na dobni sastav. Populacija otoka Visa jako je ostarjela i pripada demografskom tipu – vrlo duboka starost. Depopulacija je, pak, prešla put od posljedice društvenih zbivanja do važnog čimbenika društvenih i prostornih procesa., The paper discusses population dynamics of Vis Island along with geographic, demographic and social features related to this process. Data from demographic statistics and research results show that Vis Island has been affected by strong populational regression. This process originated at the beginning of the 20th century, and intensified after the Second World War. Depopulation was generated by retardation in socio-economic development, but it was directly caused by centennial emigration. At the beginning of 1960s, natural decrease occurred as another important cause of depopulation. It was the result of postponed effect of emigration, demographic losses in world wars and birth rate transition (changes in number of children per family). Long-term unfavorable demographic processes (emigration, depopulation, demographic aging, reduced birth rates) have led to weakening of (bio)reproduction and vital potential. The above-mentioned fact has also influencedthe age structure of the population. Population of Vis Island has aged and belongs to a particular demographic type named very old population. However, depopulation, that used to be the result of social phenomena, has become an important factor of social and spatial processes.

The paper presents some basicfeatures of vertical landscape structure of the southern part of Vis Island, Croatia. Its aim is the determination of geocomplex types with a certain degree of stability and resistance to external influences, and confirmation or rejection of hypotesis that with the application of appropriate methods, the spatial relation between geocomplex types as well as thze identification of specific dominant/stable and vulnerable/labile geocomplex types can be precisely determined. The results should serve as the basic for estimation of current status and future trends in the development of geocomplex types as well as the environmental changes.

The morphology of surrounding hillslopes of karst poljes of Vis Island reflects past and present tectonic, climatic and biologic processes that drive soil production, mobilization, and transport. Rock mass and soil transport results in modelling of hillslopes and positioning of inflexion points. Today, Vis Island is characterized by the lack of water, so intense formation of hillslopes occurred during more humid period in the geologic past, when the rainfall amount was greater than the potential evapotranspiration. To get more detailed insight into morphogenesis of the hillslopes, a number of profiles of the surrounding slopes of the poljes were analysed. The shape analysis was based on the digital elevation model. Convex slopes indicate younger uplifts and are dominated by destructive processes, while concave slopes are genetically older and are dominated by accumulation processes. In this area, younger uplifts occurred in Neogene-Quaternary Neotectonic tangential phase characterised by stress of N-S direction. This stress regime leads to a transformation of hillslope landscape, refolding of the existing structures and the formation of new ones. Reactivation of the existing discontinuity during neotectonic phase is a consequence of the fact that each new tectonic cycle, with the new regime of the main stress direction, uses existing discontinuities (that take a part of directed pressure). If the hillslope profiles and tectonics are compared, it can be seen that the hillslope shapes and existing faults and fracture systems are in correlation and in an almost "ideal position" for the reactivation in neotectonic cycle. Analysis of hillslope shapes and correlation with tectonics can be used to explain evolution stages, related processes and relative age differences between hillslopes, related karst poljes, and, consequently, the relief features of southern part of Vis Island. Also, it can be used to predict future stages of evolution, which is of great importance for numerous practical purposes.

In this study, the analysis and typology of karst landscapes of the southern part of the Vis Island was conducted. Typology is based on the analysis of structural and functional characteristics and patterns, which was obtained from parameters of lithology, geomorphology (slopes) and vegetation. The aims of the analysis were to distinguish homogenous (complex) landscape types and to determine their structural and functional features, on the basis of their dimensions, morphology, frequency of occurence in the landscape and their interrelations. This is of importance, because specificity of this landscape features is of great influence on stability and sensitivity of existing geo and ecosystems, as well as on their internal and external dynamics. The results obtained by analysis and comparison of frequencies of occurences of the particular combination of parameters in homogenous landscype types, morphology, extent and interrelations of different landscape types, can be reliable indicators of abiotic and biotic landscape elements balance, as well as of existing processes. Also, they can be useful as methodological framework for estimation of future landscape and environmental changes in whole. This can be platform for corresponding conclusions which can be useful for making decisions in landscape management relevant for preserving karst landscapes of the Vis Island, as well as other similar areas in Adriatic and Mediterranean. The use of GIS, as very important tool in landscape analysis and evaluation, enabled more detailed analysis of specific parameters relevant for determination of complex landscape types, as well as synthesis, through determination the relationships between elements of internal structure, spatial function, interrelations between landscape types and their complex influence on natural and changed cultural landscapes and environment of the southern part of the Vis Island.

Carbonate rocks cover more than 50% of Croatian territory. Together with tectonics, carbonate weathering is the main driver (most important process) of karst relief formation. For area of investigation south-western part of the Vis Island was selected. Vis Island represents symmetric anticline ; east-west orientated, and is built of Cretaceous carbonate sediments, clastic sediments with gypsum and anhydrite in association with pyroclasts as well as spilites and diabases of Triassic age, and quaternary cover. Due to intensive agricultural production, surface of Vis Island is almost completely covered by thin soil cover, with anthropogenic terra rossa, calcocambisol and colluvium as most common soil types. Since, surface of the Island is covered by soil cover, percolated water that reaches carbonates in the base is enriched by dissolved humic and fulvo acids from organic matter. That dissolution causes carbonate weathering that results in different morphological forms compared to those exposed only to meteoric conditions. Three locations in the south-western part of the Vis Island were selected ; one covered by calcocambisol, and two by anthropogenic terra rossa. Soil analyses included determination of humus content (Tjurin method), composition of humus (Schnitzer, 1982) and E4/E6 ratio by UV- VIS spectrophotometer. Humus content varied from 4, 9 to 8, 7 % on first location (calcocambisol), 1, 8 to 4, 8 % on second (anthropogenic terra rossa) and from 3, 5 to 7, 2 % on third location (anthropogenic terra rossa). In all samples E4/E6 ratio exceeded 5, which indicates fulvo acids domination, therefore increases carbonate weathering. Since soil layer that covers carbonate rocks retents more moisture, time of rock exposal to such solution is prolonged. Therefore, weathering of those rocks results in different morphological forms compared to those exposed only to meteoric conditions.

On the eastern part of the Vis Island the analysis and typology of karst landscapes was conducted. Analysis of structural and functional characteristics and patterns, obtained from parameters of lithology, geomorphology (slopes) and vegetation, was the base for this kind of research. Main goal was to distinguish complex landscape types and to determine their structural and functional features, on the basis of their dimensions, morphology, frequency of occurence in the landscape and their interrelations. Since specificity of this landscape features is of great influence on stability and sensitivity of existing geo and ecosystems, as well as on their internal and external dynamics this kind of research had to be provided. Obtained results can be reliable indicators of abiotic and biotic landscape elements balance, as well as of existing processes. They can be also useful as methodological framework for estimation of future landscape and environmental changes in whole and for future landscape management relevant for preserving karst landscapes of the Vis Island, as well as other similar areas in Adriatic and Mediterranean. For more detailed analysis and evaluation of specific parameters relevant for determination of complex landscape types we used GIS. It enabled us to synthesise, through determination the relationships between elements of internal structure, spatial function, interrelations between landscape types and their complex influence on natural and changed cultural landscapes and environment of the eastern part of the Vis Island.

The basic assumption of this paper is the relationship between geological basics, geomorphological and pedological characteristics with structural features of the natural and cultural landscape. Based on this assumption the influence of geological, geomorphological and pedological characteristics on structural features of natural and cultural landscape of Vis Island have been analyzed using multivariate statistical methods. The aim of this paper was to determine extent and intensity of mentioned characteristics as criterion for the differentiation of various types of natural and cultural landscape of Vis Island. Typological map based on this analysis was made and can be used for estimation of landscape vulnerability caused by processes and forms derived from analyzed characteristics. This kind of analysis can also be applied to other karst areas in Croatia. It can contribute to better understanding of karst area problems and can serve as a base for landscape management.

Na primjeru otoka Visa prikazan je pristup hidrogeološkim istraživanjima na većim jadranskim otocima. Infiltracija, nakupljanje i istjecanje podzemnih voda odvijaju se u okršenoj stijenskoj masi. Hidrogeološki odnosi su uvjetovani geološkom građom terena, a pritom se ističe posebna važnost postojanja potpune hidrogeološke barijere u komiškom zaljevu, te relativne barijere u području krških polja. Radi rasvjetljavanja hidrogeoloških odnosa tijekom istraživačkih radova 1999. i 2000. godine, uz korištenje prethodnih rezultata, načinjena je opsežna strukturnogeološka razrada terena koja je uz ostala hidrogeološka istraživanja pomogla u identifikaciji oblikovanja i održavanja ovog krškog vodonosnika. Prikazan je i orijentacijski izračun hidrauličke vodljivosti stijenske mase i razina njegove primjenjivosti na ovakvim terenima. Na temelju svih tih metoda došlo se do zaključka kako se na otoku Visu slana morska voda ne proteže ispod cijelog otoka, već poput klina prodire u unutrašnjost po relativno nepropusnoj podlozi, a njena dubina može se procijeniti na više desetaka metara ispod današnje razine mora. Na temelju takvih zaključaka i vodeći računa o hidrološkoj bilanci, može se očekivati ostvarivost povećanja crpnih količina na viškome vodocrpilištu "Korita", kao i izvedba dodatnih zdenaca., An approach to the hydrogeological investigations on Adriatic islands is presented on the Island of Vis case study. Infiltration, accumulation and discharge of the groundwater occur in karstified rock mass. Hydrogeological relations are mostly a consequence of the geological setting, because of the complete hydrogeologic barrier in Komiža bay, and relative barrier in the area of karst poljes. Significant research was performed in the 1999 – 2000 period aimed of better understanding of hydrogeological relations. These investigations, as well as reinterpretation of some previously known data, included structural geology, hydrogeology, hydrology and hydrochemistry. Approximate rock mass hydraulic conductivity calculation is also shown, as well as level of its usability in such terrain. Based on all these methods, it is possible to conclude that on the Island of Vis there is no saline water present underneath the entire island. There is only a saline water wedge which is formed on the top of relatively impermeable base rock, some few tens of meters under recent sea level. With such a model, and taking in account the hydrological balance, it is possible to conclude that there is possibility of higher amount of groundwater exploitation then it is today.

The Vis Island belongs to the group of the Middle Dalmatian islands. It comprises an area of about 90, 2 km2. Morphologically, three belts of highlands and two depressions with karst poljes are significantly marked. The highest point on the island is Hum with 587 m a.s.l. Island’ s water supply is organized from the water-supply station “ Korita” , situated in the central part of island, in the tectonically formed depression. On the Vis Island there are two additional captured objects: well K-1 above the Komiža town and the spring “ Pizdica” . The most important hydrogeological role on the island have two hydrogeological barriers, one in the Komiža Bay, completely made of impermeable magmatic and clastic rocks, and another one, recently recognized relative barrier in the area of Dračevo, Plisko and Velo poljes. Due to the fact that the island karst aquifer is in permanent dynamic relation with seawater, classical geologic, structural and hydrogeologic investigations have been extended with application of hydrogeochemical methods taking into account the natural chemical tracer content of groundwater and its variations in different hydrologic and vegetation conditions. Precipitation regime in this area is very unfavorable with regard to the recharging of island’ s aquifer because dry periods are usually very long. During the summer tourist season, when the number of inhabitants and fresh water consumption considerably increase, amounts of island’ s groundwater suitable for water supply and irrigation rapidly decrease. Sometimes, insufficient quantity of fresh water on the Vis Island causes restrictions. Concerning the development of tourist potential and present agricultural activities, summer lack of water is a seriously restrictive factor. Some results of performed hydrogeological study, important as a basis for island’ s fresh water potential assessment, will be presented.