Hrvatske Vode

Osijek, Croatia

Hrvatske Vode

Osijek, Croatia
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Bonacci O.,University of Split | Ostric M.,Hrvatske Vode | Roje-Bonacci T.,University of Split
Hrvatske Vode | Year: 2017

The paper contains a hydrological analysis of overflow discharges measured at the Rječina spring. The available data included average daily overflow discharges measured in the period from 1 January 1948 to 31 December 2015. It should be noted that measurements at the spring were not conducted in the period from 1 January 1960 to 31 December 1965 and throughout 2001, i.e. the 68-year period contains complete overflow discharge data for 61 years. The average multiannual discharge in the available period equalled 6.85 m3/s. The lowest value of the average annual overflow discharge was recorded in 2011 and amounted to 3.53 m3/s, whereas the highest value was observed in 1951 and equalled 11.21 m3/s. It was determined that a series of average annual overflow discharges can be divided in two time subseries: (1) 1948-1979 and (2) 1980-2015. In the first subseries, the average annual overflow discharge equalled 7.86 m3/s, whereas in the second one it was lower by 1.76 m3/s, equalling 6.10 m3/s. The number of days per year (N) when the spring runs dry was analysed. Based on available data, the analysis of abstracted water quantities from the Rječina spring was conducted in the period from 1 January 1997 to 31 December 2015. It was reported that the hydrological regime of the spring had a strong natural variability, and it was recommended that detailed interdisciplinary investigations of the spring water should be carried out to ensure its sustainable use and facilitate further development.

Barbalic D.,Hrvatske vode | Kuspilic N.,University of Zagreb
Tehnicki Vjesnik | Year: 2015

Ecological status, according to EU Water Framework Directive, is an expression of the quality of the structure and functioning of aquatic ecosystems associated with surface waters. It can be compromised by different forms of hydrological alterations. In this paper some aspects of fast and frequent fluctuations of discharge, most often caused by production of electric energy to meet peek demands or so called “hydro-peaking” has been studied. Two “hydro-peaking” indicators defined in CEN guidance standard have been evaluated for the undisturbed gauging stations in the Danube River basin in Croatia and correlated to watershed size descriptors and fitting Indicators of Hydrological Alterations. Additional third indicator based on discharge, analogous to indicator from CEN, was introduced and studied in the same way. Results have revealed that on majority of examined gauging stations values of indicators exceed boundaries for “near-natural” and “slightly modified” state. It appears that the use of analogous discharge based indicator instead of level based indicator has some advantages such as easier application and potential for more reliable regionalisation. Reliability of relationship of the third hydro-peaking indicator, based on hourly flow data, to Indicators of Hydrological Alterations, based on daily flow data, indicates the possibility of using significantly larger pool of daily data for definition of reference (undisturbed) conditions for sub-daily flow variations. © 2015, Strojarski Facultet. All rights reserved.

Kralj D.,Ruder Boskovic Institute | Romic D.,University of Zagreb | Romic M.,University of Zagreb | Cukrov N.,Ruder Boskovic Institute | And 4 more authors.
Journal of Soils and Sediments | Year: 2016

Purpose: This study used multi-element signatures of stream sediments to assess both natural and human-induced impact on fluvial system in the River Neretva delta receiving environment over time. The river basin actually comprises several sub-catchments, and the geochemical features of major elements, trace metals radiometric and mineralogical characterisation of river bed sediments were used to assist the interpretation of the environment of deposition and its subsequent modifications caused by various anthropogenic pressures within the river basin. Materials and methods: Five sites were chosen for sediment sampling at key locations within the study area with assumed undisturbed, continuous sedimentation process. At each of the sites, three representative cores were taken by scuba divers. Sample sites were selected in order to reflect the influence of different sub-catchments they belong to and the land-use pattern of the surrounding area. Samples were analysed for pH, redox-potential, granulometry, mineralogy, thermogravimetry, major and trace element concentrations and radionuclide activities. The univariate and multivariate statistics were applied. The geochemical normalisation of data was done using Al, the procedure based on calculation of the regression line of the metal on the normaliser followed by testing the ratios metal/normaliser on all data-points. Results and discussion: All studied sediments are classified as silt, ranging from clayey silt to silt and sandy silt. Mineralogically, the sediments were dominated by carbonates and quartz. The chemical contaminant data are generally of good quality, mostly below guideline levels. Sedimentation rates were estimated using vertical distribution of 137Cs activities. Normalisation of TMs done by using Al shows strong R2 adj values for the regressions of Al and V, Al and Cr, and Al and Ni. However, Al cannot fairly explain the fluctuation of the concentrations of Cd, Cu, Pb and Zn in sediment cores from all of the sampling sites. Generally, inorganic scavengers such as clay minerals followed by Fe and Mn oxides and S (pyrite and gypsum) seem to be dominant factors controlling TMs in studied sediments. Conclusions: Although the River Neretva delta occupies a rather small area, the geochemical features of major and trace elements and 137Cs activities show complex sediment provenances. Each of the sampling sites reflect exactly different effects of anthropogenic intervention that particularly refer to the changes in river morphology and ecology, along with the altered flow regimes within the catchment on sediment loads and quality. © 2015, Springer-Verlag Berlin Heidelberg.

The analysis of seasonal occurrence of maximum annual flows, conducted at 95 gauging stations within the Danube river basin, is presented. Burn's vector method, and RVA - Range of Variability Approach method based on elementary statistical analysis of maximum annual flow dates, are used. The analysis shows that the lowest seasonal variability of maximum flows occurs in Gorski Kotar drainage basins, and that this maximum statistically occurs near the end of the year. The seasonal variability of maximum annual flows is much higher for other gauging stations included in the analysis.

Loncar G.,University of Zagreb | Matkovic M.,Hrvatske Vode | Androcec V.,University of Zagreb
Hrvatske Vode | Year: 2010

The numerical modelling was conducted of effluent transfer caused by operation of a submarine outfall with the models Cormix and Mike 3. The investigation objective was the definition of appropriate parameterization in model analyses of scalar field transfer by means of finding suitable turbulent diffusion coefficients. The investigation was focused on effluent spreading in the area of the far field zone, up to 1.000 m downstream of the bottom effluent discharge location. The spreading of the effluent cloud front along the monitored stretch was referenced to the results of the model Cormix, while the values of turbulent diffusion coefficient in the lateral direction, used in the model Mike 3, were calibrated according to these results. The analysis was carried out in rectangular numerical canals of the width 1500 m and depths 30m and 40m. The vertical velocity profiles in the model canal were uniform and barotropic along the monitored stretch, with vertical mean values of 0.05m/s and 0.10m/s. The used vertical profiles of temperatures, salinity and density of the marine receiving body were obtained by a synthesis of the results from several national and international monitoring programmes in the Adriatic area. The monitored effluent was treated as biologically non-degradable (tracer). The analyzed value ranges of the hydraulic and geometrical characteristics of the diffuser, discharge flow and hydrographical characteristics of the marine receiving body encompass the relevant characteristics of the effluent transfer process caused by the operation of a submarine outfall in the winter and summer period in the coastal area of Croatia.

Barbalic D.,Hrvatske Vode | Kuspilic N.,University of Zagreb
Gradjevinar | Year: 2014

For Indicators of Hydrological Alterations, nonparametric analysis of trend magnitude usingTheil-Sen method and Mann-Kendall trend significance test has been performed in the Danube river basin in Croatia. Analysis haue shown disturbing decreasing of May and June monthly flows resulting in extended low water season with possible negative impact on ecosystems and water usage. It is obvious that increase of water management resilience and adaptability is needed to fulfil more efficiently requirements of water users.

Mihalic S.,University of Zagreb | Ostric M.,Hrvatske vode | Krkac M.,University of Zagreb
Geofizika | Year: 2011

The first part of this paper is an overview of various methodologies for seismic-geotechnical hazard zonation that conform to the recommendations of International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE, 1999). The purpose of this review is to illustrate the variety of methodologies currently in use for preparation of seismic hazard maps and to evaluate basic principles of zonation for different purposes and at different scales. In the second part of the paper, input data for seismic microzonation are discussed. Promulgated seismic regulations are a prerequisite for delineation of seismic hazard zones. Guidelines and recommendations for seismic microzonation should be incorporated into seismic regulations. There are two principal approaches to earthquake loss mitigation; one relates to land use management, and the other deals with the design and construction of individual buildings. Both approaches must be considered as components of urban planning and building design, and the application and use of these approaches should be required and enforced by municipal authorities.

Estimation of actual daily evapotranspiration was conducted using SEBAL methodology, an approach based on surface energy balance equation that uses information derived from satellite image (NOAA AVHRR) and meteorological measurements from selected gauging stations, measured at the time of the satellite overpass. Apart from quantifying actual daily evapotranspiration, presented approach enables an insight into spatial characteristics of all energy balance components as well as spatial dynamics of evapotranspiration.

The paper's objective was to determine the qualitative status of ground water in the Samobor aquifer for the purpose of the EU Water Framework Directive implementation with regards to water quality status. Thus determined status establishes a framework for ground water protection with the purpose of ensuring sustainable water use based on long-term protection of available water resources. The results obtained by conducted chemical ground water analyses in the Samobor area and their assessment according to the EU Directive 2006/118/EU show that its chemical status is good. Due to sensitivity of this aquifer to various impacts, it is necessary to remove the existing and recorded negative occurrences in the recharge area, reverse consequences of the negative impacts and control the future status.

Holjevic D.,Hrvatske Vode | Petras J.,Hrvatske Vode
Hrvatske Vode | Year: 2011

Forecasting of sediment production for a catchment area is frequently based on the implementation of a calculation procedure, i.e. an existing parameter method for calculation of soil erosion. Equations for soil erosion quantification are based on evaluation of each individual factor in the entire erosion process, i.e. precipitation, soil, relief, vegetation and human impact. The results of the soil erosion investigation carried out in the period from 2000 to 2007 in the investigation area "Abrami" in lstria facilitated the implementation of a reliable evaluation procedure for individual erosion parameters within the soil erosion equation. On the example of the RUSLE equation (Revised Universal Soil Loss Equation), the evaluation procedure for these parameters and the obtained results were described. The obtained results enable a more reliable use of the parameter equation not only in lstria, but also in other coastal areas and islands in Croatia with similar climate, geological, pedological and vegetation conditions.

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