•Hydrological modelling of karst catchments is carried out.•The lumped GR4J model is the most suitable for the investigated catchments.•Decision tree model yields the worst results.•Inclusion of ...additional meteorological variables does not improve modelling results.•Low and high flows are additionally investigated.
Hydrological modelling is a challenging and significant issue, especially in nonhomogeneous catchments in terms of geology, and it is an essential part of water resources management. In this study, daily rainfall-runoff modelling was carried out using the lumped conceptual model, the artificial neural network (ANN), the deep-neural network (DNN), and regression tree (RT) data mining models for the nonhomogeneous karst Ljubljanica catchment and four of its sub-catchments in Slovenia with different geological characteristics. Model performance was evaluated using several performance criteria and additional investigation of low and high flows was carried out. The results of the study indicate that the Génie Rural à 4 paramètres Journalier (GR4J) lumped conceptual model yielded better modelling performance compared to the data-driven models, namely ANN, DNN and RT models. Moreover, the enhanced version of the GR4J model (i.e. GR6J) also yielded good performance in terms of the recession part. The RT model yielded the worst performance regarding runoff forecasting among the examined models in the case of all five investigated catchments. However, ANN and DNN data-driven models were slightly more successful in modelling the hydrograph recession in the case of karst sub-catchments compared to the GR4J lumped conceptual model structure. Inclusion of additional meteorological variables to ANN and DNN does not significantly improve modelling results.
Hydrological modelling can be complex in nonhomogeneous catchments with diverse geological, climatic, and topographic conditions. In this study, an integrated conceptual model including the snow ...module with machine learning modelling approaches was implemented for daily rainfall-runoff modelling in mostly karst Ljubljanica catchment, Slovenia, which has heterogeneous characteristics and is potentially exposed to extreme events that make the modelling process more challenging and crucial. In this regard, the conceptual model CemaNeige Génie Rural à 6 paramètres Journalier (CemaNeige GR6J) was combined with machine learning models, namely wavelet-based support vector regression (WSVR) and wavelet-based multivariate adaptive regression spline (WMARS) to enhance modelling performance. In this study, the performance of the models was comprehensively investigated, considering their ability to forecast daily extreme runoff. Although CemaNeige GR6J yielded a very good performance, it overestimated low flows. The WSVR and WMARS models yielded poorer performance than the conceptual and hybrid models. The hybrid model approach improved the performance of the machine learning models and the conceptual model by revealing the linkage between variables and runoff in the conceptual model, which provided more accurate results for extreme flows. Accordingly, the hybrid models improved the forecasting performance of the maximum flows up to 40 % and 61 %, and minimum flows up to 73 % and 72 % compared to the CemaNeige GR6J and stand-alone machine learning models. In this regard, the hybrid model approach can enhance the daily rainfall-runoff modelling performance in nonhomogeneous and karst catchments where the hydrological process can be more complicated.
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•Hybrid models integrating conceptual and machine learning models were implemented in the karst Ljubljanica River catchment.•The conceptual model CemaNeige GR6J yielded a very good performance, but it overestimated low flows.•The stand-alone machine learning models yielded poor performance compared to the conceptual and hybrid models.•The hybrid models outperformed the stand-alone models, particularly in simulating low and high flows.
Hydrological modelling, essential for water resources management, can be very complex in karst catchments with different climatic and geologic characteristics. In this study, three combined ...conceptual models incorporating the snow module with machine learning models were used for hourly rainfall-runoff modelling in the mostly karst Ljubljanica River catchment, Slovenia. Wavelet-based Extreme Learning Machine (WELM) and Wavelet-based Regression Tree (WRT) machine learning models were integrated into the conceptual CemaNeige Génie Rural à 4 paramètres Horaires (CemaNeige GR4H). In this regard, the performance of the hybrid models was compared with stand-alone conceptual and machine learning models. The stand-alone WELM and WRT models using only meteorological variables performed poorly for hourly runoff forecasting. The CemaNeige GR4H model as stand-alone model yielded good performance; however, it overestimated low flows. The hybrid CemaNeige GR4H-WELM and CemaNeige-WRT models provided better simulation results than the stand-alone models, especially regarding the extreme flows. The results of the study demonstrated that using different variables from the conceptual model, including the snow module, in the machine learning models as input data can significantly affect the performance of rainfall-runoff modelling. The hybrid modelling approach can potentially improve runoff simulation performance in karst catchments with diversified geological formations where the rainfall-runoff process is more complex.
Prispevek obravnava poznosrednjeveško in zgodnjenovoveško enorezno hladno orožje iz Ljubljanice v zbirkah Narodnega muzeja Slovenije: 8 enoreznih mečev, v virih imenovanih messer, in 49 bojnih nožev, ...imenovanih tudi kmečki ali hišni noži (bauernwehr ali hauswehr). To raznovrstno orožje, značilno za srednjeevropski prostor, je bilo v 15. in 16. st. zelo razširjeno, vendar ga je – z izjemo precejšnjega števila najdb iz Ljubljanice – v slovenskih muzejskih zbirkah ohranjenega zelo malo. Uporabljali so ga kot orožje ali tudi kot orodje – v boju, za zaščito na poti ali pri lovu (kot lovske nože), za vsakdanjo uporabo in kot del osebne noše ljudi predvsem nižjega stanu. Razporeditev najdb, odkritih predvsem na območjih Podpeči, Blatne Brezovice in Rakove Jelše, se ujema z razporeditvijo drugih vrst in skupin predmetov, tudi orožja, iz poznega srednjega in zgodnjega novega veka. Povezuje se z logiko izrabe prostora oziroma potovanja po reki in okoliškem ozemlju, predvsem z domnevnimi lokacijami pristanov na reki ali prehodov čeznjo.
This paper gives a comprehensive explanation of the hydrogeological and hydrological characteristics of different water occurrence, which exists in the extremely complex Dinaric karst system. The ...area and boundaries of the Dinaric karst have never been precisely determined. It covers about 60,000 km² stretching the length of the eastern coast of the Adriatic Sea, from the Bay of Trieste in the north, to the Drim River basin in the south, and the Western Morava River valley in the east. Due to very high infiltration rates, overland and surface flows are rare in comparison with non-karst terrains. The Dinaric karst is an extremely heterogeneous medium which can be explained only by the use of a great number of measurements points and by continuously monitoring and measuring different parameters. The hydrogeological and hydrological regime of all water phenomena in the Dinaric karst depends mostly upon the interaction between groundwater and surface water. The dominant flow of the groundwater contained in the Dinaric karst is towards the Adriatic Sea through rivers and many permanent and intermittent coastal and submarine springs. The paper presents many examples of karst water phenomena from the Dinaric karst: (1) springs (Jadro, Ombla and Crnojevića Springs); (2) open streamflows (Ljubljanica, Pazinčica, Dobra, Lika, Gacka, Krka, Zrmanja and Cetina Rivers); (3) lakes and wetlands (Cerknica, Vrana, Plitvice, Vransko, Red and Blue Lakes); and (4) coastal and island karst (Brač Island).
The karst aquifer of the Ljubljanica River catchment, which has numerous springs and sinks, presents an interesting environment for studying hydrogeological processes. This study aims to explore the ...behavior of U isotopes and to evaluate their use as tracers of hydrogeochemical processes as an alternative to classical geochemical tracers (i.e., physicochemical parameters, elemental ratios, and alkalinity) involved in water–rock interactions and water flow in this karst water system. Basic hydrochemical parameters, as well as the spatiotemporal variations of total U concentrations, 234U/238U activity ratios, and δ238U values, were monitored in water samples from springs and sinks under different hydrological conditions. The bedrock as the source of dissolved and detrital U was also analyzed. Multi-collector inductively couple plasma-mass spectrometry results reveal variations of the 234U/238U activity ratios, which are consistently negatively correlated with the discharge at most analyzed sites. Large 238U/235U isotope fractionation occurred during bedrock weathering, and the large variability of the measured δ238U values is seemingly unrelated to the lithological characteristics of the bedrock or discharge. Our results confirm that 234U/238U activity ratios in water can be used as a tracer for studying changes in groundwater flows and the mixing of waters of different origins under different hydrological conditions.
Prispevek obravnava fenomen nenavadno velikega števila najdb srednjeveških mečev iz reke Ljubljanice na Ljubljanskem barju. Odsotnost ali pomanjkljivost najdiščnih podatkov, ki zaznamuje večino od ...več kot 56 odkritih primerkov, narekuje poglobljeno obravnavo t. i. notranjih pokazateljev posameznih najdb. Ti vključujejo stanje meča ob odkritju, sledove poškodb in manipulacij ter prisotnost ali odsotnost ostankov nožnice. Preučitev in upoštevanje tovrstnih dejavnikov nadgrajuje analizo tipološko-kronoloških značilnosti orožja, delno blaži izpad arheoloških podatkov o kontekstu in lahko do določene mere celo prispeva k osredotočanju interpretativnih nastavkov oziroma hipotez o okoliščinah in vzrokih potopitve. Kronološka strukturiranost mečev z vrhuncem med 12. in sredino 14. st. ter slabše oprijemljivim številom poznejših najdb, relativna maloštevilnost najdb sočasnega orožja na drogu ter konjske in konjeniške opreme, ki bi dokazovala intenzivnejše premike v obrečnem prostoru, nadalje zgoščeno pojavljanje mečev na določenih odsekih reke in končno omejena, iz okolja izvirajoča tveganja za naključne izgube v veliki meri izključujejo možnost ponavljajočih se dejanj iz trenutnih vzgibov in podpirajo domnevo, da je potopitev pomembnega dela obravnavanega orožja rezultat zavestnih odločitev oziroma namere.
Caves reaching the (epi)phreatic zone may provide the only access to groundwater in the internal parts of karst aquifers. Modern instruments enable unattended high frequency measurements of ...groundwater parameters in such caves. A network of distributed observation points may give new information on temporal and spatial pattern of groundwater flow. Such network, recording water level, temperature and specific electrical conductivity was established in all major ponors and active water caves of the karst aquifer between Planinsko Polje and springs of the Ljubljanica River, Slovenia. Up to three and a half years long records were analysed in view of available and relevant geological, speleological, meteorological and hydrological information, and basic hydraulic principles of the epiphreatic flow. The result of the interpretation were models of possible conduit networks of the three main flow subsystems draining Planinsko Polje. For each subsystem a hydraulic model comprising the main features of the inferred conduit network and inputs was made. The models were adjusted until their response to the typical flood situations gave a good qualitative fit to the response of the observation network. The results provide new insights into the mechanism of flood propagation through the system and its relation to the known conduit geometry. The hydraulic role of known cave passages is assessed and new flow pathways are proposed. Back-flooding within the aquifer causes an increase of head in the polje, followed by the activation of higher located ponor zones and flow pathways related to them. Hydrographs recorded in two caves located northwest from Planinsko Polje revealed possible high transmissivity zone of the Idrija Fault Zone and the mechanism of estavelles located at the polje's north-western border. The approach taken in this work offers new insights into the relation between the conduit network geometry and flood mechanism. It can be used elsewhere in conduit-dominated systems with multiple accesses to groundwater flow and well constrained recharge.
Typical of an as yet unidentified group of daggers with a semicircular pommel are distinctive brass rivets with heads decorated with a raised edge and a small raised circle in ...the center. Such rivets, together with brass sus-pension loops, are also characteristic of the associated sheaths constructed of metal shells (Scott Type A). The largest number of these daggers and sheaths come from the fortress of Dangstetten, therefore we suggest they be called after this site.The described daggers and sheaths come from sites and contexts that indicate a dating from the end of the early or the beginning of the middle Augustan Period to the end of the Augustan Period.
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