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UDC 556.537(497.5) Ognjen Bonacci & Ivo Andrić: Sinking Karst Rivers Hydrol- ogy: Case of the Lika and Gacka (Croatia) In this paper a case of very special hydrological behaviour of two neighbouring sinking karst rivers, Lika and Gacka, (Di- naric karst of Croatia), is analysed. The Lika River has a tor - rential hydrological regime. At the Sklope...
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Context 1
... conclusion can be sup- ported by the facts that the minimum mean monthly discharges in the period of 1951-2005 on the Lika River at Sklope are higher than at the Gacka River at Vivoze only in December, and that maximum mean monthly discharges on the Gacka River at Vivoze in the same period are higher in July and August than on the Lika River at Sklope. Figure 13 represents master depletion curves for Lika at Bilaj and Gacka at Vivoze. Their equations are given in Figure 13. ...
Context 2
... conclusion can be sup- ported by the facts that the minimum mean monthly discharges in the period of 1951-2005 on the Lika River at Sklope are higher than at the Gacka River at Vivoze only in December, and that maximum mean monthly discharges on the Gacka River at Vivoze in the same period are higher in July and August than on the Lika River at Sklope. Figure 13 represents master depletion curves for Lika at Bilaj and Gacka at Vivoze. Their equations are given in Figure 13. Based on them the values of retention times t L (for the Lika River at Bilaj) and t G (for the Gacka River at Vivoze) are defined as: ...
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This paper provides information about small hydro power plants in Croatia. The MAHE program (National Program of Small Hydro Power Plants Construction) has been described. Hydrological potential, costs and the prospects of small hydro plants in Croatia have been also described.
Groundwater is a vital resource, when considering its role in the water supply for human activities. Regardless their
location, the quality of groundwater resources is influenced by different natural and anthropic factors, especially if the
hydro geomorphological settings allow the pollutants to reach the aquifer from the ground surface. Various me...
An efficient conversion of kinetic energy of river water into mechanical or electrical energy without building barrages is provided by micro-hydropower stations. Increased efficiency is achieved by an optimum position of the blades with hydrodynamic profile. The micro hydro power plant is posted in the river water flow. The position of blades compa...
Citations
... Several Croatian rivers flow into the Adriatic Sea and a large number of smaller watercourses (Fig. 1). Although each estuary is specific in its own way, all estuaries in Croatia share a common environment: the karst area (Bonacci 1987;Kresic 2013;Bonacci 2015). Flash floods are characteristic of karst areas because of their geological and hydrogeological characteristics, which enable relatively fast interactions and dynamics of surface and underground waters (Bonacci et al. 2006;Kresic 2013). ...
... Rising sea levels and extreme climatic conditions (IPCC 2023) will increase inundation hazards in estuaries. Considering the complexity of this system, flood risk assessment in estuaries and coastal areas requires specific approaches that are not identical to the classical analyses of river floods (Bonacci 1987;Martin-Vide et al. 1999;Bonacci et al. 2006;Camarasa-Belmonte 2016). Flood risk estimates are traditionally based on univariate flood frequency analysis, i.e., fitting distribution functions to ordered sequences of observed flood peaks (often annual maximum flow) and applied for assessment of riverine flood hazard (Lóczy et al. 2012;Ljubenkov et al. 2023). ...
The Miljašić jaruga is one of the most important watercourses in Zadar County (Dalmatia, Croatia). The total length of this area is approximately 16 km, with an associated topographic catchment of approximately 191 km ² . The downstream portion of the stream is influenced by the sea (estuary).
The hydrological regime of the Miljašić jaruga is strongly influenced by climatic features; therefore, for most of the year, there is an outflow of catchment waters, whereas in the summer dry months, the river bed is mostly without outflow. It is also common for extreme precipitation to occur after a long dry period, resulting in sudden increase in water levels and flash floods.
One such extreme event occurred on September 11, 2017, when a severe storm followed by heavy rain affected Zadar and its hinterlands. On that occasion, approximately 240 mm/m ² fell in Zadar over a period of 6 h, with an intensity of up to 70 mm/m ² /h. Such extreme rainfall activated violent and torrential runoff, flooding, and damage in the entire catchment area of the Miljašić jaruga, particularly in the most downstream part of the basin, in the area of the estuary and the town of Nin. Numerous infrastructural and communal facilities have been damaged, including the Nin Salt Works.
This paper presents the hydrological analysis of a flash flood event in the Miljašić jaruga estuary. A hydrological series of 26 and 27 years were compared, whereas the longer series include historical flood, using three distributions: normal, log-normal and Gamma. The relevant hydrological parameters (water levels and flows) used for dimensioning the flood defense system show great variability depending on the available data (time series) and calculation methodology. For example, variation of flow rate reached 41 m ³ /s for 100-year high waters, that is, from 60 m ³ /s (n = 26, normal distribution) to 101 m ³ /s (n = 27, log-normal distribution). In engineering practice, the unreliability of the estimation of statistical quantities should be considered to improve the effectiveness of flood defense systems. The rehabilitation and reconstruction work conducted after a flood on hydrotechnical structures (embankments) in the estuary area is described. In addition, there is a need for adequate water management across the entire basin, such as the construction of retention and barriers, which would increase the level of flood protection in the most downstream parts, i.e., the estuary.
... Morphological structures have a predominant and typical Dinaric orientation of NW-SE direction. The estimated catchment size ranges from 250 to 500 km 2 [32,33], as only southern and northern catchment boundaries (mainly topographic) are determined with a higher level of certainty. The western and eastern boundaries are hypothetically delineated based on several tracer tests [34e38]. ...
... Contrary to this great morphological variation within population/species, similar selection pressures would promote similar traits in distantly related species (= homoplasy) (Reier et al., 2022). Regarding the impact of ecological factors on the interspecific phenotypic divergence, it is important to highlight that the native distribution of the majority of Dinaric karst fishes, including the studied species, is characterized by an aboveground and underground hydrological network consisting of complex interconnectedness of ephemeral karstic streams, springs, marshes or small lakes (Bonacci, 1987). Some of the studied species occur sympatrically in Šator Lake (introduced populations of P. alepidotus and A. huegelii), Dabarsko Polje (Suški Stream, Kanal and Pribitul River) (D. ghetaldii, T. dabar), Nevesinjsko Polje (Zalomka River) (Ph. ...
A remarkable diversification of the freshwater ichthyofauna in the Peri-Mediterranean is an outstanding legacy of the complex paleogeographical and evolutionary history of southern Europe. The Dinaric karst on the Balkan Peninsula harbours endemic cyprinoid genera including Phoxinellus and Delminichthys (fam. Leuciscidae), an ancient monotypic genus Aulopyge (fam. Cyprinidae) and endemic species of the Dinaric Telestes, Squalius and Phoxinus genera (fam. Leuciscidae). In this study, evolutionary body shape changes of these endemic European cyprinoid were explored using a geometric morphometrics approach in a phylogenetic framework. By projecting phylogeny obtained from cyt b mtDNA sequences into a morphospace, a strong phylogenetic signal was found in fish body shape, but not in size. Principal component analysis on both uncorrected and size-corrected (allometry free) shape variables revealed that closely related species tend to be clustered in the same area of morphometric space implying that evolutionary allometry did not significantly influence morphological evolution. Therefore, body shape might be used as a reliable taxonomic trait and indicator of phylogenetic relationships. The observed phylogenetic signal in body shape suggests that phylogenetic constraint affects the pattern of shape variation. The phylogenetic comparative method in exploring the evolutionary trend in the body form of Dinaric cyprinoids has not yet been assessed, and our preliminary findings suggested that the body shape diversification proceeded predominantly in the head region and body depth. The diversification of the freshwater ichthyofauna supported by both molecular phylogeny and morphological evolution is mostly a consequence of the complex paleogeographical and evolutionary history of the Peri-Mediterranean area. Keywords Cyprinidae · Leuciscidae · cyt b mtDNA phylogeny · Body size and shape · Evolutionary allometry
... water left in cave pools, wood debris). The second way of introduction of surface waters into the wider area of these caves is by water runoff (water losses) through the Lika and Bakovac riverbeds and existing accumulation (artificial lake) Kruščica due to the karstification of this area (Pavičić 1997), a phenomenon that is very common in karst areas (Bonacci 1987;Bonacci and Rubinić 2009). Thus, the impact of surface waters of the Lika and Bakovac rivers together with the artificial lake Kruščica can also be present outside of the period of flooding. ...
Testate amoebae are phylogenetically a very diverse group of eukaryotic microorganisms. They can be found in marine and freshwater habitats and in soil. Some of these single-celled organisms inhabit both surface and cave habitats, but their diversity in caves has barely been explored. Recent studies in the Dinaric region imply that testate amoebae in caves show a high diversity. The aim of this study was to identify the alpha diversity of testate amoebae in the Lika region (Dinaric karst, Croatia) and to compare the habitats of different caves based on testate amoebae assemblages. In eight caves we found more than 40 testate amoebae taxa, including a new testate amoeba species, Psammonobiotus dinarica sp. nov. The greatest diversity of testate amoebae was found in Markov ponor (27 taxa). The Bray-Curtis Similarity Index showed that testate amoebae assemblages in caves inhabited by the endemic and endangered cave bivalve Congeria jalzici (Markov ponor, Dankov ponor and Dražice ponor) differ from caves not inhabited by this species. This differentiation is attributed to the impact of the sinking Lika river, which occasionally completely submerges these caves, creating specific habitats for eukaryotic microorganisms. This study contributes to our understanding of the diversity, biogeography and ecology of testate amoebae in caves, as well as providing further insight into the conditions that sustain populations of C. jalzici .
... This method aims determining the polje inflow and outflow under different hydrological conditions, and is of particular importance to understand the flooding dynamics (Kovačič, 2010). Many authors such as Bonacci (1987), López-Chicano et al. (2002), Milanović (2004), Kovačič (2010) and Kovačič and Ravbar (2010) mentioned or applied it to several poljes. They were able to provide numbers regarding both inflow and outflow (e.g., López-Chicano et al., 2002;Milanović, 2004;Kovačič, 2010;. ...
... To remedy this problem, an alternative method consists to postulate that the variation of lake stage upon time is linked to the surplus water creating the flood (Bonacci, 1987;López-Chicano et al., 2002;Kovačič, 2010). Therefore, combining the measured water level to an accurate digital elevation model (DEM) of the polje allows computing the change of volume during the flood (Kovačič, 2010). ...
... The equation describing the polje flooding dynamics allows assessing its water balance (Bonacci, 1987;López-Chicano et al., 2002;Kovačič, 2010). The relationship is based on a simple inflow-outflow difference representing the variation of flooded volume upon time, and corresponds to the water level derivative multiplied by the polje surface: ...
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.
... Poljes are mostly topographically enclosed basins that may receive water inflow from springs, autogenic and allogenic runoff, and direct precipitation, whereas the water mostly leaves the depressions via ponors (i.e. swallow holes) and diffuse infiltration (Bonacci, 1987). Flooding often occurs in the polje floors due to the water table rise or when the water entering the polje exceeds the drainage capacity of the ponors and infiltration zones (e.g., Sweeting, 1972;López-Chicano et al., 2002;Blatnik et al., 2017;Bayrakdar et al., 2020). ...
Karst poljes, despite their large dimensions and significant applied interest, have received limited attention in the geomorphological literature, and references to gypsum poljes are incidental. This work analyses the morpho-structural setting, characteristics, origin and controlling factors of thirteen poljes mapped in the gypsum karst of Sivas, Turkey. The poljes occur along a 38 km long belt associated with the allogenic Kızılırmak and Acısu rivers, which constitute the regional base level of the karst system. The path of these drainages is controlled by the trailing morpho-structural trough of the antiformal ridge associated with the front of the active Sivas Thrust. The floor of most of the poljes is connected with the floodplain of the main rivers, but largely lies at lower elevation, functioning as semi-closed basins that can be flooded by water table rise and the incorporation of floodwaters from the adjacent fluvial systems. The depressions, with their floors situated within the epiphreatic zone, are classified as base-level poljes. Three types of base-level poljes are differentiated based on cartographic relationships and attending to their evolutionary path: poljes associated with relict valleys; poljes developed in abandoned valley sections, poljes related to the coalescence of bedrock collapse sinkholes. The poljes expand by lateral solution planation, involving the retreat of the marginal slopes and their replacement by a solution plain (polje floor) controlled by the water table. The retreat of the slopes is mainly achieved by solutional undercutting during floods, mass movements, and the rapid removal of the gypsiferous landslide deposits. These processes are expected to operate in gypsum bedrock at much higher rates than in carbonate rocks. Dissolution acting at the foot of the scarped gypsum slopes during floods locally produce floodwater footcaves with the typical water injection features (e.g., spongework, solution pockets, tapering dead-end passages). These caves locally produce bedrock collapse sinkholes that can be incorporated into the polje depressions generating characteristic embayments. The main factors that seem to favor the development of poljes in Sivas include: (1) a morpho-structural trough with relatively low uplift rate that confined the path of the main drainages; (2) abundant aggressive water supplied by allogenic rivers; (3) a fluviokarst landscape including fluvial landforms that can transform into poljes; and (4) presence of clusters of bedrock collapse sinkholes that experience rapid expansion.
... Karst landscapes originate from water dissolving soluble base rocks (e.g., limestone and dolomite) and are characterized by an array of surface and underground geomorphological features, as well as a complex water system [1]. One of the best researched karst areas is Dinaric Karst, located in the western Balkans and extending from Italy to Albania along the Adriatic coast. ...
The waters of the Dinaric Karst drain into both the Adriatic and the Black Sea basins. Precipitation is high, yet surface waters are scarce, with the exception of sinking streams. Dinaric Karst is a biodiversity hotspot, with diverse speleo-and epigean freshwater fauna. The distribution patterns of taxa in Dinaric Karst have arisen from a combination of vicariance and dispersal and their alteration over time. Within fishes, there are genera that include both species that are widespread and species with restricted ranges (e.g., Phoxinus, Telestes), and genera with only restricted distributions (e.g., Delminichthys, Phoxinellus). Some (Delminichthys, Phoxinellus and Dinaric Telestes) have a similar lifestyle, specialized for dwelling in sinking streams in karst poljes. The present study compares the distribution ranges of Phoxinus, Delminichthys, Phoxinellus and Telestes in Dinaric Karst based upon their mitochondrial genetic lineages, including dating of divergence times and reconstruction of ancestral geographic ranges. The biology of Phoxinus has played a major role in its wider distribution than the other three genera, which exhibit some limited ability to migrate underground, but which cannot disperse along main river courses due to their specific adaptation for dwelling in the sinking streams of karst poljes.
... An interpretation for rhythmic springs functioning by siphon systems was proposed (Katzer 1909;Lazarević, 1990;2000). Bonacci (1987) presented the schematics of the functioning mode of RKS. His work stated that all the water in the cave-reservoir will outflow suddenly once the water level reaches a siphon water level. ...
... Previous studies on rhythmic springs mostly focus on the qualitative analyses, siphon process description (Katzer, 1909;Casteleyn, 1977;Bonacci, 1987), and classification of the rhythmic springs (Gavrilović. 1967). ...
Rhythmic Karst Springs (RKSs) are rare geologic features that rhythmically outflow water. A mechanical model for the rhythmic flow with rhythmic spill-over configuration was constructed in this work. The evolution of the RKS was revealed by using geological process analysis. The analytical model can directly explain the existence of RKSs in soluble rock regions and their formation mechanism in nature. Visual observations and flow measurements were performed using a laboratory physical model of RKS. The physical model components included a soluble rock simulation area, karst pipes, cave-reservoir, karst depression terrain, water tank, rhythmic spring, and the outflow measurement system. Groups of tests were carried out to recreate the process of RKS functioning and to confirm the rhythmic cycle duration and the threshold of replenishment intensity. This research helped to interpret the behavior of rhythmic springs using the recharge and evacuation of the subsurface cave-reservoir by means of fluid mechanics and groundwater hydraulics theories.
... RAPS is a well-known method based on a visual determination of a subseries from original (given) series of data. By using the average value and standard deviations of the observed time series, RAPS values provide insight into the parts, where occurrence of the trends, data grouping, fluctuations, and similar appearances happen during the time: (1) where is the value of the analyzed member (parameter) of the analyzed time series, is an average value of the analyzed time series, is the standard deviation of the considered time series; n is a number of members of the analyzed time series, and k = 1, 2,..., [8]. ...
The production of electric energy from rivers by using mini, as well as micro hydroelectric power plants, is a very promising solution, especially in rural and isolated areas. Numerous waterways in Croatia and their hydrological and hydrogeological diversity present an opportunity, but also a challenge, for the construction of hydroelectric power plants. Due to the complexity of the water courses’ hydrology, as well as hydrogeological characteristics, it is very hard to determine an appropriate flow pattern (amount), which will be used as an input value for the sizing of hydroelectric power plants. Such analysis will be provided for real case studies in Croatia with special regard to present geological media—media with intergranular porosity (Bednja River), karst media (Gornja Dobra River), and flysch media (Mirna River). Considering different geological media increases the possibility of using the presented methodology on other locations in Croatia, as well in the world. It has been shown that the analyzed rivers definitely have potential for electric energy production, regarding the potential and kinetic river energy. The presented analysis is scientifically original, but also shows the procedure for the determination of the hydro-energy potential of the rivers, as well as for the sizing on the hydropower plants. Hydrology and hydrogeology analyses rounds out the usual hydro-energy analysis, which is in most cases based on basic statistical parameter analysis.
... Determining the parameters of aquifers by interpreting spring discharge is one of the oldest methods used in hydrogeology, developed intensively since as early as the 19 th century (Maillet 1905;Bonacci 1987). Springs recharged by groundwater penetrating within a shallow active zone are generally characterized by quick response time, even to single rainfall events. ...
... In addition to assessing the rate of depletion of aquifer resources during dry periods, the dynamics of spring discharge after periods of recharging the catchment with rainfall are also interpreted. This makes it possible to draw conclusions about the time of water residence in aquifers and the recharge pattern, in particular the rate of groundwater flow and pressure transfer (Bonacci 1987;Halihan and Wicks 1998;Lee and Lee 2000;Kovács et al. 2005;Fiorillo and Doglioni 2010;Diodato et al. 2014). The main difficulty in interpretation is the fact that the increased spring discharge following the rainfall does not necessarily result from the simple mechanism of inflow of fresh water, but usually from a general pressure increase in the aquifer and the release of "old" stored water pushed out by the "new" water infiltrated from the surface (Maloszewski et al. 2002). ...
... The evaluation of the spring discharge response to rainfall presented in the paper is a new approach in the study of the spring recharge pattern of the flysch part of the Carpathians. In southern Poland, research into the discharge response to rainfall or snowmelt has so far been carried out in karst aquifers (Leszkiewicz and Różkowski 2000;Dobek 2007;Humnicki 2013); in Europe, this method is widely used for springs in areas built of calcareous rocks (Bonacci 1987;Padilla and Pulido-Bosch 1995;Lee et al. 2006;Jemcov 2007;Fiorillo and Doglioni 2010). In mountainous flysch areas, perennial springs with discharge of several litres per second can constitute a significant part of the river runoff and are an important source of water supply for the population, therefore, an analysis of their dependence on precipitation and potential changes in the discharge regime is truly fundamental (Diodato et al. 2014). ...
Flysch-type aquifers in the Eastern Carpathians usually feed periodic and low-discharge springs. However, in some areas, such as in the upper part of the Połonina Wetlińska Massif, perennial springs with a relatively high discharge were identified. Therefore, the aim of this study was to identify recharge and groundwater flow patterns of three high-discharge springs based on the response of spring discharge to rainfall and on the relationship between specific electrical conductivity of water and spring discharge. The relation between spring discharge and rainfall was investigated by cross-correlation analyses. Generally, cumulative rainfall over a period from 10 days to 3 months is most strongly correlated with discharge; however, the response time of spring discharge varies throughout the year. Faster response to rainfall occurs in the spring after snowmelt, while in the summer and autumn months the response time increases. Two flow systems were identified: 1) a relatively deep, fissure-pore flow system with a long response time to precipitation and 2) a shallow, fissure-dominated system with a short response time, which is superimposed on the longer response. A small range of specific electrical conductivity combined with the varying discharge of two springs suggests that dilution of groundwater by rainwater does not play a significant role. The differences in the studied springs' response to rainfall can be attributed to the recharge area, regolith features and local bedrock structures, i.e. occurrence of joints and faults, monoclinal dip of rock layers and gravitational slope deformations including ridge-top trenches, which, thus far, have been underestimated in determining groundwater storage capacity in the flysch part of the Carpathians.
