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Poljes are flat closed karst depressions prone to regular flooding. The floods can be several meters high, last for months and damage significantly human infrastructures. To predict the maximum level reached, the polje water balance needs to be implemented. This technique encounters the difficulty that important part of the inflow and outflow flowing through many poljes is ungauged, as it is challenging to measure accurately the numerous springs and ponors activating temporarily with the rise of water level. This work aims to see whether this problem can be handled and the polje water balance reconstituted. To do so, a typical Dinaric polje is equipped with several water level stations installed over its surface and in the nearby water active caves. Combining a 1*1m digital elevation model of the polje surface with water levels and inflow records of the main two springs allowed assessing the variation of flooded volume and reconstructing the water balance. The highest total inflow values reached during the observed period were of about 140-150 m3/s, with up to a third of it being ungauged. In addition, the effect of a large estavelles group on the polje inflow and outflow could be identified, and helped to characterize the outflow, with values comprised between 65 and 75 m3/s. Finally, intense rainfall over the polje flooded surface showed to be a temporary important source of inflow. The values found by the water balance analysis have been used as input and calibration data in a numerical model reproducing the flood dynamics in the polje and its surrounding aquifer. Results validated both polje water balance and conceptual hydrogeological model. They justify the significance of combining water level measurements with a digital elevation model to monitor the floods. The method can be applied to other poljes flooding in a complex way of superposed input and output signals. Finally, the places to be equipped in priority if the polje has no measurement network or if available funding is limited are discussed.

Karst aquifers are abundant, but vulnerable water resources. Therefore, a deeper understanding of possible mechanisms that determine the properties of karst springs is crucial. In this work, we present an example of Unica Spring and Malni Spring, the two main outlets of a large karst system in the Notranjska karst region, Slovenia. Although the two springs share same catchment area, the flow distribution between them shows an interesting behaviour: At low-flow conditions, Malni Spring is the main outlet, while Unica spring receives almost no water. During high water events, discharge of Malni Spring stays limited and Unica Spring becomes the main outlet. We relate these observations to the local geometry of the channels and breakdowns in the remote part of the Planinska Jama (Planina Cave), called Mysterious Lake. There, waters from Rakov Škocjan and Javorniki aquifer merge and further diverge to both springs. At low water conditions, the outflow towards the Unica Spring is restricted by the breakdown, so that most of the inflow is directed towards the Malni Spring. With increasing recharge, the level in Mysterious Lake rises until the water starts to flow over the breakdown along a system of large channels (Rak Branch of Planinska Jama) to the Unica Spring. The breakdown level keeps the hydraulic head and the flow towards Malni Spring limited. To verify this scenario, a hydraulic conduit model was made based on the known and predicted channels, and inflows calculated from the historical data of discharge measurements at related springs and ponors. An inversion procedure was used to obtain a satisfactory fit to the observed discharge data and to constrain the selected model parameters. The model accurately reproduced the observed discharge behaviour under low- and high-flow conditions.

Escherichia coli, one of the primary intestinal commensal bacteria in humans and endothermic animals, is commonly considered an indicator of faecal pollution. E. coli strains were isolated from karst rivers under different hydrological conditions, from footpaths in tourist caves and from bat guano. Isolates were tested for phenotypic resistance to ampicillin, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline and trimethoprim. The highest percentage of antimicrobial resistant E. coli was found in karst waters, followed by those from surface swabs and from bat guano. Several isolates from rivers and swabs exhibited multidrug-resistant phenotype. Environmental conditions impact the populations of E. coli; a positive correlation between dissolved oxygen and E. coli counts, and a negative correlation between conductivity and E. coli concentrations have been observed for karst rivers. Malenščica (Slovenia), a drinking water resource with an extensive catchment area, contained a relative high percentage of antimicrobial-resistant E. coli strains. None of the isolates from bat guano was resistant to ampicillin, chloramphenicol, and tetracycline. Future monitoring of bats should consider a regular follow-up of indicative microbial disease indicators in fresh guano. Regular cleansing of tourist footpaths in caves and disinfection barriers at the cave entrances reduce the concentration and transmission of E. coli significantly. A future, more detailed, study on characterization of additional E. coli isolates is needed to reveal their pathogeneicity, mechanisms of antibiotic resistance, mobile genetic elements, and gene transfer frequencies to other members of the karst microbiome.

Tracer tests are rarely applied in mountainous karst aquifers due to difficult or limited basic data acquisition, problems of access and expected strong tailing effects in tracer breakthrough. They are, however, a straightforward method for learning about the characteristics of underground water flow. The main aim of this study was to better understand the processes of flow and storage in the karst aquifer and its unsaturated (vadose) zone, which is several hundreds of metres thick. A tracer test was conducted with injection from the surface into a shaft in the central part of the aquifer. The results were compared to a previous tracer test with similar injection characteristics (the same tracer, injection into shaft vs karren) but with a significantly different vadose zone thickness. For this purpose, direct information obtained through tracer breakthrough curves analysis was modified in accordance with the distance factor, normalised as a function of tracer mass injected, and expressed as a residence time distribution. A conceptual model of flow and transport duality through the karst system was elaborated: part of the tracer flows rapidly through the primary drainage channels, while the other part is predominantly characterised by prolonged retention in less permeable zones. The results obtained support the idea that the thickness of the vadose zone has a very strong influence on residence times and dispersion. The subsequent outflow of the tracer and its detection greatly depend on the meteorological conditions. Our study suggests that the greater the thickness of the vadose zone, the better its protective function. In addition, the study was also relevant from the regional perspective, in that it enabled us to identify more closely the location of the Adriatic–Black Sea watershed. Key words: karst hydrogeology, tracer test, unsaturated zone,conceptual model, groundwater flow and storage, source protection. Vplivi nezasičene cone na značilnosti toka podzemne vode in prenosa topnih snovi v gorskih kraških vodonosnikih - primer Javorniško - Snežniškega masiva (JZ Slovenija) Sledilni poskusi sodijo med metode, ki neposredno prikazujejo značilnosti toka podzemne vode. Zaradi oteženih ali omejenih dostopov do osnovnih podatkov, zahtevnosti terenskega dela in pričakovanega dolgotrajnega podaljšanja pojavljanja sledila se sledilni poskusi v gorskih kraških vodonosnikih redko izvajajo. Glavni namen te študije je bil boljše razumevanje procesov toka in skladiščenja v kraškem vodonosniku in njegovi nezasičeni (vadozni) coni, ki je lahko debela več sto metrov. Opravljen je bil sledilni poskus v osrednjem delu vodonosnika z injiciranjem v brezno. Rezultate smo primerjali s preteklim sledilnim poskusom s podobnimi lastnostmi injiciranja (enako sledilo, injiciranje v brezno oz. škraplje) toda s precejšnjo razliko v debelini vadozne cone. V ta namen so bile neposredne informacije, pridobljene z analizo sledilne krivulje, spremenjene v skladu s faktorjem razdalje, normalizirane kot funkcija količine uporabljenega sledila in izražene kot porazdelitev zadrževalnega časa. Izdelan je bil konceptualni model dvojnosti toka in prenosa topnih snovi skozi kraški sistem: del sledila se pretaka hitro skozi primarne drenažne kanale, medtem ko je za del tega značilno podaljšano zadrževanje v manj prepustnih območjih. Dobljeni rezultati podpirajo trditev, da debelina vadozne cone močno vpliva na zadrževalne čase in disperzijo. Poznejši odtok sledila in njegovo zaznavanje sta v veliki meri odvisna od meteoroloških razmer. Naša študija kaže, da je z večjo debelino vadozne cone njena zaščitna funkcija večja. Poleg tega je bila študija pomembna tudi z regionalnega vidika, saj nam je omogočila, da natančneje opredelimo jadransko-črnomorsko razvodnico. Ključne besede: kraška hidrogeologija, sledilni poskus, nezasičena cona, konceptualni model, tok in skladiščenje podzemne vode, zaščita vodnih virov.

Povzete so ugotovitve predhodne študije o vplivu načrtovanega avtocestnega odseka Trebnje - Hrastje na kraško vodo, ki je bila izdelana na osnovi terenskega ogleda in pregleda dosedanjih raziskav. Sledilni poskus je pokazal pretakanje vode iz Lukovškega potoka do izvira Zijala s hitrostjo 0.45 cm/s in nato do izvira Prečne, ki se pomembno obogati z vodo iz kraškega vodonosnika Suhe krajine, s hitrostjo 4.1 cm/s. Ob visokih in najvišjih vodostajih lahko pričakujemo opazno hitrejše pretakanje in z vodo tudi hiter prenos morebitnega onesnaženja. Hitrost in način odtoka padavin s površja neposredno v kraško notranjost še ni bil raziskan. Povezavo Bršljinskega z Lukovškim potokom pa glede na rezultate sledenja ocenjujemo kot vprašljivo. Results of the preliminary study of influences of the planned highway sector Trebnje - Hrastje on karst waters are summarized. The study was based on field survey and review of previous researches. Underground water flow from the stream Lukovški potok to the Zijalo spring with average velocity 0.45 cm/s and further on to the Prečna spring with velocity 4.1 cm/s was proved. This second part of flow is significantly enlarged by recharge from the karst aquifer of Suha krajina. At high and highest waters rather faster flow can be expected and at the same time also fast spreading of eventual pollution. Velocity and mode of infiltration of rain directly into the karst underground was not defined yet. Based on the results of tracing test the underground connection between the Bršljinski potok and Lukovški potok can be estimated as questionable.

Že od leta 1995 sodelujejo sodelavci IZRK ZRC SAZU na slovensko-kitajskih projektih s področja krasoslovja. V letu 1998 so rezultate raziskav objavili v knjigi “South China Karst”. Tudi v letu 1999 so raziskave opravljali v Yunnanu, in sicer v lunanskem osrednjem “shilinu” (kamnitem gozdu) kot tudi v turistično manj znanih “shilinih”. Poleg tega so spoznavali značilnosti stolpastega krasa okoli krajev Babao in Puzhehei (jugovzhodni Yunnan). From 1995 researchers from Karst Research Institute ZRC SAZU are working on slovene-chinese karstological projects. In 1998 their studies were published in the book “South China Karst”. Also in the year 1999 researches took place in Yunnan, that’s in central Lunan shilin (stone forest) as well as in less touristically known shilins. Beside this they have been recognising characteristics of cone and tower karst in the regions of Babao and Puzhehei.

V letih 1986 in 1987 je bilo zajetih 7 serij vodnih vzorcev na 36 do 47 mestih na Babnem, Loškem in Cerkniškem polju, na Blokah in Loškem potoku za fizikalno-kemične analize, ki so pokazale na kakovostno stanje teh voda.Z apnenčastega in dolomitnega sveta, ki obdaja Babno, Loško in Cerkniško polje se steka padavinska voda v izvire, ki napajajo ponikalnice. Večina izvirnih voda označuje vsebnost nitratov pod 4 mgNO3 -/l, kloridov pod 5 mg Cl-/l in vsebnost fosfatov okoli 0.05 mg PO43-/l. Bakteriološke analize so pokazale oporečno vodo, le nekaj izvirov pa je bilo občasno neoporečnih. Znatno slabšo kakovost imajo Pudobski, Podgorski in Mežnarjev studenec s poseljenim zaledjem ter ponikalnice na ponorih, kjer smo določali do 20 mg/l nitratov in kloridov, fosfatov pa do 5 mg/l. Ponikalnice na svoji poti po kraških poljih sprejemajo onesnaženje zaradi poseljenosti in industrije. Ker pa se voda ponikalnic pojavlja zaporedno na več niže ležečih poljih, pomeni to prenos in kopičenje onesnaženja po toku navzdol, tudi v izvire, ki so zajeti za oskrbo prebivalstva s pitno vodo. In 1986 and 1987 seven series of samples were taken at 36 to 47 sampling points on Babno, Loško and Cerkniško Polje and on Bloke and at Loški potok in order to find out their physico-chemical properties and their quality. Rainwater flows from the limestone and dolomite landscape around Babno, Loško and Cerkniško polje into springs feeding the sinking streams. The nitrate level at most of the springs was below 4 mg NO3-/l and chloride below 5 mg Cl-/l; the o-phosphate level varied around the value of 0.05 mg PO4 3-/l. The bacteriological analyses of the spring waters showed that they are not of drinking quality and only few springs were seasonally of good quality. Poorer quality was found in springs with populated catchments, such as are Pudobski Izvir, Podgorski and Mežnarjev Studenec and, obviously in all the sinking waters at swallow-holes where the nitrate and chloride level was up to 20 mg/l and phosphate up to 5 mg/l. Flowing over karst poljes this water receives pollution due to habitations and industry. As the water of these sinking streams reappears downstream in several lower-lying karst poljes this results in the transport and accumulation of pollution downstream even in springs that are captured for water supply.

Podani so rezultati sledenja na območju Tianshengan-a, Lunan v provinci Yunnan na Kitajskem. Sledenje je bilo nadaljevanje raziskav pretakanja vode na tem delu krasa v sodelovanju s kitajskimi raziskovalci v okviru slovensko-kitajskega znanstvenega sodelovanja. Sledenje je bilo izvedeno septembra 1997 ob visokem vodostaju in je pokazalo 2 krat večje hitrosti v primerjavi s pretakanjem vode na tem območju ob srednjem vodostaju julija 1996. The results of water tracing in the Tianshengan region, Lunan, Yunnan province, China are given. This water tracing presents a continuation of water flow studies in this part of the karst based on Slovene-Chinese scientific co-operation. In September 1997 a water tracing test at high water level was carried out and showed greater velocities double compared to water flow in this area at medium water level in July 1996.

Sledilni poskus z injiciranjem v ponor Tržiščice (JV Slovenija) je v hidroloških pogojih upadanja pretokov od srednjih do nizkih voda pokazal koncentriran odtok v smeri Tominčevega studenca ter Javornikovega in Debeljakovega izvira ob Krki pri Dvoru. Navidezne hitrosti pretakanja so bile med 2,4 in 4,6 cm/s, povrnjena količina uranina v teh izvirih pa je bila ocenjena na 2/3 injicirane količine. Navidezna hitrost pretakanja v smeri Podpeške jame, kjer se je sledilo pojavilo manj izrazito in šele po izdatnejših padavinah, ki so nastopile po dveh mesecih stalnega upadanja pretokov, je bila 0,1 cm/s. Ugotovitve skupaj z rezultati starejših sledenj kažejo na značilno odvisnost raztekanja vode iz Tržiščice od hidroloških razmer. A tracing test with injection of uranine in the sinking stream Tržiščica (SE Slovenia) was carried out at the hydrological conditions of recession from medium to low waters. Concentrated flow towards the springs Tominčev studenec, Javornikov izvir and Debeljakov izvir near the village Dvor in the Krka valley was proved. Apparent flow velocities between 2.4 and 4.6 cm/s were obtained, and the share of recovered tracer was estimated to 2/3 of the injected amount. In the Podpeška jama cave the tracer in lower concentrations was detected only after heavy rain occurred after two months of low water. The apparent flow velocity of 0.1 cm/s was calculated. Obtained results, together with the outcomes of the previous tracing tests, indicate that hydrological conditions significantly influence the underground water flow from the Tržiščica sinking stream.

Reka Reka, s prispevno površino 422 km2 , ponika v Škocjanskih jamah, ki jih je UNESCO leta 1986 proglasil za svetovno dediščino. V sedemdesetih letih je bila Reka ena od najbolj onesnaženih rek v Sloveniji. V času visokih vod leta 1999 in 2000 smo izvedli meritve hitrosti, kalnosti, vrste fizikalnih in kemičnih parametrov ter teste strupenosti. Glavni cilji teh pionirskih meritev so bili preveriti mersko opremo v terenskih pogojih visokih voda, zbrati čimveč podatkov ter primerjati uporabnost opreme. The river Reka, with 422 square kilometres of drainage area sinks into the Škocijan Cave system, which was proclaimed by UNESCO as a World Heritage Site in 1986. In the seventies, the Reka river was one of most polluted rivers in Slovenia. During floods in 1999 and 2000, experimental measurements of velocity, water level, suspended sediment transport, chemical parameters and toxicity tests were conducted. The main tasks in the first stage of the investigation: check the equipment in field conditions and test the toxicity of water in particular cross sections. In the paper, the measurements and some discussion of the results and applicability of equipment are presented.

Podani so rezultati meritev temperature, pH, specifične el. prevodnosti in raztopljenega kisika ter analiz vsebnosti nitratov, o-fosfatov, kloridov, biokemijske in kemijske potrebe po kisiku v poplavnem valu konec marca 2000, ko je pretok Reke pri Cerkvenikovem mlinu porasel s 13,2 na 112 m3 /s. Napravljena je ocena prenosa onesnaženja po merjenih komponentah in primerjava z manjšim poplavnim valom maja 1999. This article aims to offer the results of temperature, pH, specific electric conductivity and dissolved oxygen measurements as well as analyses of nitrate, o-phosphate and chloride levels and biochemical and chemical oxygen demand in a flood pulse at the end of March 2000 when the Reka discharge at Cerkvenikov mlin increased from 13.2 to 112 m3/s. An estimation of pollution transport according to measured components and comparison with a smaller flood pulse in May 1999 are given.

Podane so osnovne fi zikalno-kemične značilnosti voda v zaledju Malenščice in povezave, ki jih nakazujejo. Dolomitna voda Cerkniščice odteka predvsem v Rak v Rakovem Škocjanu, Kotliči pa kažejo na povezavo s Svinjsko jamo in Malo Karlovico. Rak na ponoru predstavlja ob zelo nizkih vodostajih pretežno vodo Kotličev s Ca/Mg okoli 3,5 in z najnižjo vrednostjo 2,2 ob najnižjih vodostajih, ko v Svinjsko jamo ponika le Cerkniščica, kar se kasneje odrazi tudi v Malenščici. Ob visokih vodostajih v ponor odteka mešanica Raka in Kotličev s Ca/Mg okoli 4. Dotok voda iz doline Pivke označuje višje razmerje Ca/Mg in večje vrednosti pokazateljev onesnaženja, medtem ko označujejo infi ltracijsko vodo iz slabo prepustnega dela Javornikov vrednosti Ca/Mg okoli 5. Zaradi zapletenosti sistema ostaja še vrsta odprtih vprašanj, ki bi jih lahko pojasnile le dodatne raziskave. Basic physico-chemical properties of waters within the area of Malenščica are given, and so are the connections that they indicate. Dolomitic water of the Cerkniščica mostly fl ows into the Rak in Rakov Škocjan valley, while Kotliči springs show the connection with Svinjska jama (cave) and Mala Karlovica. When water levels are low the Rak river at its swallowhole mostly comprises waters from Kotliči, with Ca/Mg about 3, 5 and the lowest value 2,2 when the water levels are the lowest, when only the Cerkniščica sinks into Svinjska jama; this later reflects also in the water of the Malenščica. When water levels are high, the mixture of Rak and Kotliči fl ows into the swallowhole, and Ca/Mg is about 4. The infl ux of waters from Pivka Valley is designated by higher ratio of Ca/Mg and higher values of pollution indicators, when the infi ltration water from poorly conductive part of Javorniki is designated by Ca/Mg values about 5. Due to the complexity of the system there are still some unanswered questions left which can only be answered by carrying out additional researches.

Poseben hidrološki pojav zahodnega dela kraškega masiva Javornikov so presihajoča Pivška jezera. Za celotno območje je značilna tesna povezava podzemnih in površinskih voda. V kraškem vodonosniku se vode pretakajo večinoma podzemno, ob močnejših in dolgotrajnejših padavinah pa se nivo podzemne vode dvigne in voda se na številnih mestih preliva na površje. Tako postanejo aktivni občasni kraški izviri ob reki Pivki, z vodo pa se napolnijo tudi kraške depresije in nastane večje število presihajočih kraških jezer. Nekatera se pojavljajo dokaj pogosto in imajo vodo tudi do pol leta, večinoma pa so bolj redka ali so zalita samo izjemoma v času močnejših poplav. V članku so predstavljene hidrogeološke značilnosti območja, ki se odražajo v režimu pretakanja kraške vode in načinih njenega pojavljanja na površju. A special hydrological feature of the western part of the Javorniki karst massif is the intermittent karst lakes of Pivka. For the whole area a close connection between underground and surface water is characteristic. In the karst aquifer water flows mostly underground, but after more intensive or long-lasting precipitation the water table rises and water emerges on the surface at different locations. Intermittent karst springs along the Pivka river are activated. Also karst depressions are filled with water and several intermittent karst lakes can be formed. Some of them appear very often and contain water for up to six months, but mostly they are very rare and filled up only exceptionally in the time of big floods. In the article the hydrogeological characteristics of the area are presented, which are reflected in the flow regime of karst water and in the forms of its appearance on the surface.

In three selected drips in the Postojna cave in SWw Slovenia and in the nearby Korentan spring, which in general belongs to the same karst aquifer, the discharge and electrical conductivity were measured at 15-minute intervals. Simultaneously, the meteorological parameters in Postojna were measured and the effective infiltration was assessed. The data obtained in the period of one hydrological year, 2003–2004, was compared in order to study the influence of the vadose flow on the characteristics of groundwater flow in a karst system and on the functioning of a karst spring. The highest discharges of the Korentan spring are the result of the inflow of water through a hierarchy of fissures of various permeabilities within the vadose zone, but the contribution of stored water from low-permeability zones is especially important. One of our most significant findings is that in the conditions of high saturation of the vadose zone, the network of small fissures is hydraulically connected, which enables an integral reaction of the system to the pressure pulse induced by infiltrated precipitation. On the other hand, a detailed comparison of effective infiltration and discharge indicates that in dry periods with a lower saturation of the vadose zone, the infiltrated precipitation is mainly stored in the system and only the most permeable fissures enable a rapid transfer of the recharge impulses toward the spring. Data on measured discharge and conductivity were additionally compared in order to study the complex conditions of the actual mass flow of water through the system. Key words: karst aquifer, vadose zone, Postojna Cave, Korentan spring, Slovenia

Distinctive karst hydrology arises from a combination of high carbonate rock solubility and well developed secondary porosity (fissures). Soil CO2 is the most important influence on solubility of carbonate rock (Ford & Williams 2007). Human activity on the karst surface results in pollution that has an important influence on water quality. Degradation of organic pollution (e.g. waste water, leachates from landfill sites) results in inorganic acids too. These acids could have an important additional influence on dissolution of carbonate rocks in the vadose zone. In the framework of more than 20 years of research on precipitation percolation and transfer of contaminants (direct outflow of waste water from a small military facility where about twenty troops were stationed) through the 100-m thick vadose zone of Postojna Cave, contaminated water was observed in drips and trickles in the cave (up to 60 mg Cl-/l, up to 180 mg NO3-/l, up to 2.8 mg PO43-/l, and up to 50 mg SO42-/l). At the same time the sum of calcium and magnesium (Ca+Mg) of trickles was up to two times larger than the Ca+Mg of either the uncontaminated reference trickle or the input waste water. The amount of dissolved limestone carried by waste water to trickles and drips in the cave was directly proportional to the concentration of contaminant anions present. This demonstrates that there is an accelerated widening of fissures below source points of wastewater. Water with contaminants can penetrate faster and deeper into the vadose zone along the increasingly permeable fissures without losing its dissolving power, and thus significant dissolution occurs ever deeper in the vadose zone. This results in ever faster penetration of contaminants through the vadose zone. In the final phase of such development, which takes many decades or longer, relatively rapid transfer of contaminants through the aquifer all the way to karst springs with minimal self-cleansing effects can be expected.

Tracer tests are one of the most useful researchmethods in karst hydrogeology and they have proved a valuable tool in various applied projects. In recent years we carried out a se­ries of tracer tests, and their results were used as the bases for planning the monitoring of water quality in the influence ar­eas of various pollution sources. In this paper, a case study of tracing at the landfill near Mozelj in southeastern Slovenia is described. The first goal was testing of the functioning of three monitoring boreholes, whichwere drilled at the margins of the landfill. As often happens in heterogeneous karst systems, they did not intersect the main flow paths from the landfill and are not suitable as monitoring points. On the other hand, the find­ings about the characteristics of tracer transport in the karst system and outflow throughthe karst springs were used for identifying the most suitable springs for monitoring and pre­paring an adequate sampling plan, whichshould be adapted to hydrological conditions.

In the catchment area of the Unica River two combined tracer tests with fluorescent dyes have been performed aiming to characterize the properties of groundwater flow and transport of contaminants through the vadose zone and well developed system of karst channels in the epiphreatic and phreatic zone in different hydrologic conditions. Tracers were injected directly into the ponors and to the oil collector outlet on the karst surface. Prior to tracing monitoring network has been set up, including precipitation, physical and chemical parameters of the springs and cave streams. Field fluorimeters were used to detect tracers in the underground river and conventional sampling techniques and laboratory analyses were used at the springs. Some of the results were quantitatively evaluated by QTRACER2 Program. During the first tracer test, when injection was followed by rain event, flow through the well conductive cave system was characterized by apparent dominant flow velocities of 88–640 m/h. Breakthrough curves were continuous, uniform and single peaked, and almost complete recoveries were observed. During the second tracer test, when water level was in constant recession, the transport velocities through the well developed karst conduits were significantly slower (apparent maximal flow velocities being 2–4 times lower). Results also show lower dispersivity during the second tracer test, which corresponds to lower flow velocities. The tracer injected at the karst surface arrived with the expected delay (vdom around 9 m/h) and showed irregular and elongated breakthrough curves with secondary peaks. In this paper only tracer test results are presented, which are a part of a comprehensive study of groundwater flow through the complex karst aquifers aiming at improving karst water resources understanding, protection and management. The presented assessment will beyond be utilized for further detailed analysis, studies and modelling.

In upper reaches of the Chang (Yangtze) river, in Deqen prefecture, in northwestern part of the Yunnan province, karst is developed in Devonian carbonate rocks. The Shuilian cave, more than a kilometre long, formed along the contact of fine bedded metamorphosed calcitized sandy siltstones and calcitized siltstones. The cave has two entrances, the upper one being dry and the lower entrance with a steady water flow. It is situated in the steep slope about 70 m above the river level (1,965 m a.s.l.). In the paper a detailed analysis of rocks that host the cave is presented, and also a comprehensive description of the rock morphology and shapes of the cave conduits. Physico-chemical properties of water from cave and from a nearby spring were measured. The temperature and specific electric conductivity determinations indicate a relatively long underground residence time of water which, however, relatively poorly dissolve slowly dissoluble base rock. This could be the explanation for stagnation of the karst deepening with respect to erosional downcutting of the river Chang. In addition, further research is proposed.

Križna jama and Križna jama 2 are of important natural value. They have been known for more than hundred years from spe­leobiological, paleontological, geomorphological and touristic points of view. In 2007 the establishment of a water treatment plant on Bloke plateau raised important question: can partly cleaned water from the water treatment plant contaminate both caves and decrease their value? To answer this question a tracer test was carried out at the Bloke plateau. It showed gen­eral underground water flow from Farovščica ponor at Bloke plateau toward the Šteberščica spring at Cerknica polje. Mi­nority of recovered tracer appeared at Žerovniščica and Izvir v Podložu springs. The tracer was not detected at Studenec v Ložu and Zlatovec springs. Between ponor and springs three karst caves were observed. The highest concentration of tracer was detected in the cave Mrzla jama pri Bločicah and a much smaller concentration in the Križna jama and Križna jama 2. This shows that at middle water level the underground Farovščica stream does not flow directly through Križna jama and Križna jama 2 but near or below them. Since the tracer ap­peared in both caves only after the precipitation, underground water course can be significantly different at high water level. Tracing test also showed some characteristics of underground water flow through dolomite and characteristics of a composed aquifer with alogenic-autogenic recharge.

The characteristics of flow from the landfill near Sežana in the area of Kras were studied by the use of tracer test. In well permeable fissure on the karren surface near the landfill the fluorescent dye uranine was injected in order to study the directions and velocities of its flow through the karst aquifer. Monitoring of tracer concentrations in the period of one year and a half enabled us to make some conclusions about the dynamics of groundwater flow in the directions towards the Timava, Brojnica and Sardoč springs. Detailed observations were organised also at the Klariči pumping station, which is the main source of drinking water for the Kras region. Increased concentrations of tracer were measured only during extremely high waters. Different explanations are possible, but we can not exclude the possibility of a weak, not permanent underground water connection with the landfill. Calculation of the amount of recovered tracer confirmed the main flow direction towards the Timava springs (recovery rate 93%) and a secondary direction with lower flow velocity towards the Brojnica and Sardoč springs. Outflow through the Klariči pumping is estimated to only 0.003% of injected uranine.Key words: tracer test, landfill, Sežana, Kras, Slovenia.

Researches based on seasonal and later continuous measurements of precipitation on the surface and discharges of typical trickles in Postojnska Jama, 100 m below the surface, showed the dynamics of percolation in a period of a hydrological year. They registered summer periods lasting several months when all the rainfall, even more abundant, is stored in a vadose zone. After a longer dry period the first discharge reactions of trickles to rainfall strongly differ while there is no substantial difference in a wet period. The water outflow in decreasing parts of water pulses essentially differs among various trickles and we recognised the types of trickles feeding karst aquifers even during low water level or low discahrges of karst springs.

The Mala gora landfill near Ribnica is one of the nine still active landfills on Slovene karst. According to our legislation the monitoring of its impact on groundwater have to be performed, but this can only be effective when the characteristics of the underground water flow in the area of the landfill are well known. Therefore a tracer test was carried out on the Mala gora landfill and the main underground water connections towards the Tominčev studenec, Javornikov izvir, Debeljakov izvir and Šica springs near the settlement Dvor in the Krka valley were proved. In lower concentrations the uranine was detected in the Podpeška jama and Kompoljska jama Caves, as well as in the Šica near Mala Račna spring and both springs of the Krka river. At high waters the flow from the landfill towards the Globočec spring was proved also, but this important source of water supply is primary recharged from other parts of the karst aquifer. The appearance of tracer is forwarded by favourable hydrological conditions and increased concentrations of uranine were measured at all springs after more intensive precipitation events even one year after the injection. Obtained results were considered in the preparation of the monitoring plan.

The Yunnan Province lies on the eastern rim of the collision zone between the Indian plate and Eurasia. This region is characterized by complex Cenozoic structures and active seismotectonics. In the year 2004 the areas north from Kunming and the NW part of Yunnan were studied. The measurements of the temperature, conductivity and the analyses of carbonate, phosphate and nitrate were performed in Quinglongtan spring and in the accumulation lake that is situated lower than the spring. The springs are situated in the wider zone of the Xiaojiang fault along which left horizontal movements are taking place. Along the wider zone of the Zhongdian fault between the town of Zhongdian and the Yangtze River on the south there are more springs. Tiansheng Qiao (T = 57.5ºC) and Xiageiwenquan (T = 48,3 − 66.8ºC) are thermal springs along which tufa is deposited. The Baishuitai spring has high mineralization and lower temperature (T = 11.1 − 13.3ºC) and deposits calcium carbonate in the form of gours. All studied springs are connected with active fault zones. The studied areas mostly represent the contact areas between carbonate and non-carbonate rocks.

The basic physico-chemical properties of the karst spring Podstenjšek, depositing carbonates in the past shown by travertine blocks in its riverbed are given. Measurements and analyses of the spring and its water flow downwards at several sampling points showed that during the whole year the water precipitates calcium carbonate. The intensity of deposition depends on discharge and warming or cooling of water. From one litre of water at the distance of one kilometre from some to 36 mg CaCO3/l are deposited, the majority at the first 400 m.