The coastal area around the settlement of Stara Baška (Krk Island, NE channel zone of Adriatic Sea) is in a delicate geodynamic balance. The main causes are the geological structure, hydrological and ...hydrogeological conditions and the direct exposure of the coast to the waves and storm surges. In this paper, the effects of the expected sea level rise on the geological vulnerability of the coast are investigated. Detailed field research was conducted. The complex coastal morphology was surveyed using an Uncrewed Aerial Vehicle (UAV), and the UAV-derived data was used as a 3D point cloud and orthophoto for analysis. In the investigated coastal zone, more resistant Quaternary talus breccias predominate over more susceptible flysch rock mass. One major and two smaller landslides are in a creeping condition and pose a hazard to the surrounding homes. During storm surges, the pocket beaches are completely inundated due to the narrow beach width and waves reach the toe of the slopes. According to the expected sea level rise, coastal processes could become more intense and threaten the current coastal equilibrium. The vulnerability of a large part of the Stara Baška settlement will increase significantly. The conducted research showed the advantages of UAV-derived data for the study of complex rocky coasts and emphasized the need for repeatable UAV surveys.
The article presents findings of a two-year systematic study of stable isotope content in two karst groundwater resources in Primorsko-goranska county (Croatia): the Martinšćica wells (MWs) and the ...Dobrica spring (DBC). The temporal and spatial variation of hydrogen and oxygen isotopes is commonly studied in conjunction with hydrogeological conditions such as groundwater dynamics and discharge conditions. However, since this information was incomplete, we were forced to work with limited data and rely on analyses of stable isotope monitoring results. The obtained results show that winter precipitation is the most common recharge source for the systems, and the average residence time of water in the subsurface is less than a year. Furthermore, the MWs system is a typical dual-porosity system with dominant base flow. The results of the nonparametric regression analysis show that the possibility of seawater intrusion into the spring affecting DBC isotope content cannot be ruled out. We believe that the results presented in the paper demonstrate that when combined with statistical analyses, environmental stable isotopes are a powerful tool for gaining insights in karst hydrogeology.
The Bokanjac–Poličnik system, as a complex set of mutually interrelated Dinaric karst catchments and sub-catchments, is a highly vulnerable and limited groundwater source for the wider Zadar area in ...northern Dalmatia, Croatia. Based on hydrogeological, hydrochemical, and hydrological research, including the prediction of groundwater discharge by the end of the twenty-first century, a complex study was performed with the following main aims: (1) groundwater protection in the present state, (2) assessment of future groundwater protection, and (3) prediction of drinking water availability and quality under the predicted climate change conditions. Long-term prediction of changes in groundwater quantity, as well as investigations of trends in groundwater quality, will allow us to protect this essential natural resource with respect to possible negative trends. The results showed that a significant decrease in the quantity of available groundwater is possible and that extraction will have to be well planned because any decrease in the groundwater pressure in this area will cause a further decrease in quality, especially regarding the possibility of seawater intrusions into the aquifer. The results of this study were incorporated in sanitary protection zones.
The Plitvice Lakes National Park is inscribed on UNESCO’s World Heritage List. The lake system is composed of 16 cascading lakes of different sizes separated by tufa barriers, which are the park’s ...key phenomenon. The lakes are characterized by highly diverse trends of the characteristic hydrological indicators—mean annual water levels, discharges, and tufa barrier growth. The analyses carried out in this paper identified that in the period before the early 1990s, Kozjak Lake had a trend of decreasing discharges, together with a trend of increasing water levels and growing tufa barriers. In contrast to this, in the period after 2001, a trend of increasing discharges was recorded, as well as a trend of decreasing water levels and decreasing tufa barriers. A potential cause of the barriers decreasing in size were the extremely high discharges during the last decade, which resulted in increased erosion of the tufa barriers. Losses of water due to the sinking from the lake system as well as the upper Korana course were confirmed, and it was identified that during the analyzed period the losses had not changed significantly. It was determined that the losses of water from Kozjak Lake occurred during low-water periods; however, they depended not only on the quantity of water flowing through the lakes but also on the hydrological conditions underground. The analyses carried out and the methodological procedures used in the analyzed area of the Plitvice Lakes are useful examples for the performance of analyses at similar lakes in karst formed by tufa deposition processes.
This paper analyses impacts of climate change and anthropogenic pressure on groundwater resources in the Mirna river catchment used for water supply in Northern Istria (Croatia) up to 2050. Using ...Regional Climate Models simulations and hydrologic model, the future average annual and the characteristic (in critical period) water resource availabilities were calculated. Current and five future water demand scenarios were analysed. Water Exploitation Index (WEI) and modified Characteristic Water Exploitation Index (CWEI) were calculated. In 2050, the analysed springs will be subject to climate change consequences, with more extreme changes and intense variations. The WEI for average conditions indicates little risk of unmet future water demand. Considering seasonal variability, the future CWEIs indicates strong risk for most future water demand scenarios and overexploitation for water demand increases over 20%. The 2012 drought, more extreme than any considered future scenario, was also examined.
U ovom radu provedena je hidrološka analiza voda izvorišnog dijela rijeke Gacke. Provedene su standardne statističke obrade nizova podataka o karakterističnim mjesečnim i godišnjim protocima te ...analize krivulja recesije. Radi kompletiranja nizova podataka korištenih u analizi, provedeno je i produljivanje nizova podataka pomoću metoda strojnog učenja, pri čemu je provedena usporedba i diskusija rezultata modeliranja dobivenih po nekoliko upotrijebljenih modela neuronskih mreža i regresijskih stabala odlučivanja. Na temelju provedenih testiranja na nizovima podataka, koji nisu bili uključeni u generiranje modela, utvrđeno je da se korištenim modelima mogu dobro nadomjestiti nedostajući nizovi podataka.
The paper contains a hydrological analysis of the source region of the Gacka River. Standard statistical analyses of data series about the characteristic monthly and annual discharges and recession curve analyses were made. In order to complete the data series used in the analyses, data series were extended using machine learning methods, comparing and discussing the modelling results obtained from several neural network and regression decision tree models used. Based on the conducted testing of the data series that weren’t included in the model generation, it was identified that the models used can properly replace the missing data series.
This research focuses on the analysis of soil-water interaction at the carbonate-flysch contact on the Istrian peninsula in Croatia. As a result of the interaction of surface and groundwater and the ...position of flysch and carbonate rocks in the geotechnical profile, two problems occur in the study area: numerous instabilities and the occasionally high turbidity of drinking water. As an example, the St. Ivan spring was considered. The paper presents a complex mechanism of groundwater circulation in geological structures at carbonate-flysch contacts, differences in runoff through karst aquifers and flysch rocks during heavy rainfall under current and predicted (climate change) conditions, and the mentioned geohazards as a result of extreme precipitation. The analyses carried out showed the decisive influence of the existing geological structure on the dynamics of infiltration and precipitation runoff, as well as the risks of pronounced spring water turbidity and instability events. The main drivers of these geohazards are continuous long-term precipitation for landslides and intense daily precipitation for turbidity. Possible consequences of climate change are the increase in precipitation intensity, amount and higher variation, which subsequently brings risks such as the increase in maximum runoff, i.e., the expected more frequent occurrence of high turbidity and the more frequent occurrence of higher cumulative precipitation triggering instabilities in the area.
Complexity of karst groundwater networks requires implementation of standard hydrogeological monitoring and unconventional methods of investigation. We present the results of isotope composition ...analysis for three karst springs and rain water collected in their hinterland. During two years, spring water samples were collected on a weekly and rain samples on a monthly basis. The main findings are: winter precipitation of Mediterranean origin dominates springs' recharge, a dual porosity model is a fit for the studied systems, and hinterlands of the springs have different retention capabilities.
U radu su analizirane geomorfološke promjene u naplavnim dolinama i ušćima rijeke Dragonje, Mirne i Raše koje teku po istarskom poluotoku. Promjene su ustanovljene usporedbom povijesnih karata sa ...suvremenim. Najstarije karte za područje doline Raše datiraju iz druge polovice 18. stoljeća, a za područje Dragonje i Mirne iz prve polovice 19. stoljeća. Usporedba je pokazala izrazito veliku progresiju ušća Raše, a manje promjene na ušću Mirne, dok na ušću Dragonje nisu vidljive promjene zbog uređenja solane. Produkcija nanosa događa se zbog erozije lapora i fliša u uzvodnim područjima slivova. Većina sedimenata do ušća dolazi u obliku suspenzije. Nakon radova na regulaciji zaustavljeno je plavljenje u dolini Mirne i Raše, a u dolini Dragonje pedesetih godina 20. stoljeća. Nakon toga, promjene su vidljive samo po smanjenju dubine morskog dna oko ušća. Primjetno je smanjenje pronosa nanosa već od kraja 20. stoljeća, zbog smanjene obrade zemljišta i širenja šuma.
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