Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 3 - 12, doi:
Scientific Paper, Slovak

, Peter Šurda, Justína Vítková, Peter Stradiot, Katarína Brezianská: Impact of grassland on the dynamics of water supply in the soils of Záhorská Lowland

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• Values of water supply in different soil horizons can be obtained by two ways - by direct measurement of soil moisture through the use of appropriate methods or by simulation on mathematical model of soil water regime. Currently, the simulation on the mathematical models is widely used, considering that the direct method of soil moisture measurements is time consuming, laborious and are relatively expensive. Despite the time, instrument and human resources demand, successful mathematical modeling is not possible without direct monitoring. Simulation of the water unsaturated soil zone using modified meteorological elements is carried out in numerous works in the field of soil hydrology, using mathematical models Global and Daisy. Their use for solving the dynamics of water supply in the soil of Záhorská lowlands is not so widely used, compared to their application in other regions of Slovakia. Especially from the aspect of the comparation of data obtained by simulating and direct monitoring. Presented article is based on the monitoring of soil moisture and simulation of soil water dynamics on the above mentioned mathematical models to quantify water supply in the unsaturated zone of soil at selected locations with grass cover in the area of Záhorská lowland
  
  KEY WORDS: monitoring of soil moisture, simulation on mathematical models, comparison of measured and simulated data
  
  Address:
  - Július Šútor, - Peter Šurda, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika
  - Justína Vítková, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika
  - Peter Stradiot, Výskumný ústav vodného hospodárstva, Nábrežie arm. Gen. L. Svobodu 5, 812 49 Bratislava, Slovenská republika
  - Katarína Brezianská, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 13 - 21, doi:
Scientific Paper, Slovak

Dana Pavelková, Branislav Kandra, Helena Hlavatá: Evaluation of long-term precipitation and temperature development in the central part of the East Slovakian Lowland

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• Presented paper deals with the evaluation of longterm development of precipitation and temperature in climate station Milhostov. Milhostov station is characteristic of East Slovakian Lowland (ESL) and located in its central part. Data from this location are used as inputs for mathematical models simulating the water regime. Annual and monthly climatic data (air temperature and atmospheric precipitation) during the period of 1961-2015 were primary sources for the further evaluation. Based on the monitored period lasting for 55 years, the deviations of average annual air temperature and average air temperatures during vegetation period (VP) were evaluated in comparison with long-term average temperatures (in case of annual also during VP). The course of long-term average monthly air temperature (1961-2015) was compared with the course of average monthly air temperature in 2015 (2014). The course of average monthly air temperature was also evaluated according to decades and their trend development. Similarly, the deviations of average annual precipitation and average precipitation during vegetation period were evaluated in comparison with long-term average precipitation as well as long-term average precipitation during VP within monitored period. The course of long-term average monthly precipitation (1961-2015) was compared with the course of average monthly precipitation in 2015 (2014, 2010). The course of average precipitation was also evaluated across decades during monitored period.
  
  KEY WORDS: precipitation, air temperature, statistical characteristics
  
  Address:
  - Dana Pavelková, Ústav hydrológie SAV Bratislava, Výskumná hydrologická základňa Michalovce, Hollého 42, 071 01 Michalovce, Slovenská republika (Corresponding author. Tel.:+42156 6425 147 Fax.: Email: pavelkova@uh.savba.sk)
  - Branislav Kandra, Ústav hydrológie SAV Bratislava, Výskumná hydrologická základňa Michalovce, Hollého 42, 071 01 Michalovce, Slovenská republika
  - Helena Hlavatá, Slovenský hydrometeorologický ústav Košice, Ďumbierska 26, 041 17 Košice, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 22 - 29, doi:
Scientific Paper, Slovak

Anežka Čelková: Transport parameters of ions of salinized solutes in modified saline soil

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• The present paper deals with the evaluation of transport parameters of ions of salinized solutes of sodium, calcium, magnesium and chlorine (Na+, Ca2+, Mg2+ and Cl-) in the modified saline soil in soil columns. The courses of changes of individual ion concentrations from binary solutions at various ion concentrations and at various proportions of inert material (glass sand) to the soil sample in the soil columns has been studied. Breakthrough curve was evaluated and the migration parameters i.e. dispersion coefficient (Di), retardation factor (Rfi) and distribution coefficient (ki) for each observed ion and each of case were determined.
  
  KEY WORDS: inert material, ion transport, migration parameters
  
  Address:
  - Anežka Čelková, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika (Corresponding author. Tel.:+ 421 2 32 293 516 Fax.: Email: celkova@uh.savba.sk)

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 30 - 36, doi:
Scientific Paper, Slovak

Ján Valach, Jaroslav Vido, Jaroslav Škvarenina: Drought occurence in the Horné Požitavie region over the period 1966 – 2013

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• This study focuses on the characterization of historical drought occurrences in the Horné Požitavie region of Slovakia using Standardized precipitation and evapotranspiration index (SPEI) over the period 1966-2013. The historical trend of the time series of the SPEI were identified and analysed for individual months. The drought impact on agricultural production in the region was also examined. The results revealed that dry periods occurred in the region regularly and had an increasing frequency towards the end of the examined period. The analysis of the SPEI trend (i.e., aridity or humidity) demonstrated that a decreasing trend of drought occurrences during the cold months of the year (i.e., October to March), while an increasing trend observed from April to August. The evaluation of the impact of drought on agricultural production documented that drought represents a significant natural risk for the agrarian sector of the region. The analyses revealed the increasing risk of drought impacts on the agricultural production.
  
  KEY WORDS: drought, SPEI, climate change, the impacts of drought, agroforestry
  
  Address:
  - Ján Valach, Katedra vodného hospodárstva krajiny, Stavebná fakulta, Slovenská technická univerzita, Radlinského 11, 813 68 Bratislava, Slovenská republika (Corresponding author. Tel.:0904 595 836 Fax.: Email: vurrval@gmail.com)
  - Jaroslav Vido, Katedra prírodného prostredia, Lesnícka fakulta, Technická univerzita vo Zvolene, Ul. T. G. Masaryka 24, 960 53 Zvolen, Slovenská republika
  - Jaroslav Škvarenina, Katedra prírodného prostredia, Lesnícka fakulta, Technická univerzita vo Zvolene, Ul. T. G. Masaryka 24, 960 53 Zvolen, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 37 - 42, doi:
Scientific Paper, Slovak

Michaela Červeňanská, Dana Baroková, Andrej Šoltész: Preliminary assessment of flood risk due to increasing of groundwater level

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• While in recent years the focus of assessment was at the risk of flooding caused by a significant temporary increase of water level in stream, mapping of flood risk due to internal waters is experiencing its inception. In Europe in recent years, there has been a recognition of the risk from the frequent occurrence of floods caused by the increasing groundwater level. Groundwater flooding is gradually coming into European and, consequently, into national legislation. The present paper deals with the identification of areas potentially at risk from increased levels of groundwater in Slovak republic and is a part of a pilot project assessing the risk of groundwater floods. The data, used for mapping, was the maximum measured levels of groundwater which occurred mainly in the years 1965, 1974, 1999 and 2010.
  
  KEY WORDS: flood hazard map, groundwater, flooding
  
  Address:
  - Michaela Červeňanská, Katedra hydrotechniky, Stavebná fakulta STU, Radlinského 11, 810 05 Bratislava, Slovenská republika (Corresponding author. Tel.:+421 2 59 274 563 Fax.: Email: michaela.cervenanska@stuba.sk)
  - Dana Baroková, Katedra hydrotechniky, Stavebná fakulta STU, Radlinského 11, 810 05 Bratislava, Slovenská republika
  - Andrej Šoltész, Katedra hydrotechniky, Stavebná fakulta STU, Radlinského 11, 810 05 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 43 - 50, doi:
Scientific Paper, Slovak

Ladislav Holko, Peter Škoda: Assessment of runoff changes in selected catchments of the High Tatra Mountains ten years after the windthrow

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• The article is devoted to re-evaluation of runoff data series from the small basins most affected by deforestation associated with windstorm which hit the High Tatra Mountains area in November 2004. A longer period that has elapsed since the windthrow facilitates evaluation of some runoff regime characteristics which could not have been evaluated with shorter data series. Further, we focused on the use of the flow duration curves (FDC). Comparison of FDCs calculated for daily data from the Velický and Slavkovský creek catchments showed that discharges with the highest probability of exceedance (Q90% and Q80%) in the decade following the windthrow (2005-2014) occurred more frequently than in period 1965-2004. We also found an increase in runoff minima characteristics, but similar values were observed in some years also before the windthrow. Frequency of flow reversals in the Velický and Slavkovský catchment increased as well. The identified changes cannot be unambiguously assigned only to the impact of the windthrow. However, in the first years after the windthrow they were probably influenced mainly by it. Our results suggest that we do not have suitable indicators of catchment runoff changes for the mountain catchments with area of several tens of square kilometres in which the forest reduction reached 20-32%. Nevertheless, evaluation of changes in frequency of flows with certain probability of exceedance is a promising research topic for catchments with clearly documented large disturbances.
  
  KEY WORDS: indicators of runoff regime change, small mountain catchments, windthrow, flow duration curve
  
  Address:
  - Ladislav Holko, Ústav hydrológie SAV, Experimentálna hydrologická základňa, Ondrašovecká 16, 03105 Liptovský Mikuláš, Slovenská republika (Corresponding author. Tel.: Fax.: Email: holko@uh.savba.sk)
  - Peter Škoda, Slovenský hydrometeorologický ústav, Jeséniova 17, 833 15 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 51 - 64, doi:
Scientific Paper, Slovak

Zdeněk Kostka, Ladislav Holko: Non-destructive visualization of infiltration using electrical resistivity tomography

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• Water infiltration into soil profile after the rainfall event is the decisive process at catchment runoff generation. Geophysical measurements of electrical resistivity tomography based on the relation of electrical resistivity on soil water content allow the indirect monitoring of water movement velocity and pathways in soil during infiltration. The measurements are performed without the disturbance of the site natural state. The repeated measurements of electrical resistivity vertical cross-sections with detailed spatial resolution were performed at short time lapse at the selected profiles. The measurements validated very fast response of water content to rainfall event within the upper 10 cm soil horizon as well as its consecutive decrease due to percolation into deeper horizons. The measurements performed at hillslope site established the lateral subsurface flow within the superficial soil horizon. The spatially nonuniform flow was evident at all the performed measurements despite of relatively homogeneous soil environment.
  
  KEY WORDS: infiltration to soil, hydrogeophysics, electrical resistivity tomography
  
  Address:
  - Zdeněk Kostka, Ústav hydrológie SAV, Experimentálna hydrologická základňa, Ondrašovská 16, 03105 Liptovský Mikuláš, Slovenská republika (Corresponding author. Tel.:+421445522522 Fax.: Email: kostka@uh.savba.sk)
  - Ladislav Holko, Ústav hydrológie SAV, Experimentálna hydrologická základňa, Ondrašovská 16, 03105 Liptovský Mikuláš, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 65 - 77, doi:
Scientific Paper, Slovak

Branislav Pramuk, Pavla Pekárová, Peter Škoda, Dana Halmová, Veronika Bačová Mitková: Identification of the Slovak rivers daily discharge regime changes

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• Submitted paper is focused on analysing long-term changes of discharge regimes of selected eight Slovak rivers. Water gauge stations were chosen with regard to high-quality continuous series of average daily discharge from natural area without huge water reservoirs. Rivers must fulfil conditions of eliminating water reservoir impact on the river discharge. We analyzed and statistically evaluated the long-term trends of several hydrological characteristics of daily discharge series using Indicators of Hydrological Alterations method (IHA). The method will be meaningful only with long series of input data. In this paper we were focused on identification of long-term trends of average annual discharges and on analysing changes of rise rate and fall rate of discharge waves for 84-years period (1931–2014).
  
  KEY WORDS: Slovak rivers, statistical analysis of daily discharges, method IHA, long-term trends identification
  
  Address:
  - Branislav Pramuk, Ústav hydrológie SAV, Dúbravska cesta 9, 841 04 Bratislava, Slovenská republika (Corresponding author. Tel.: Fax.: Email: pramuk@uh.savba.sk)
  - Pavla Pekárová, Ústav hydrológie SAV, Dúbravska cesta 9, 841 04 Bratislava, Slovenská republika
  - Peter Škoda, SHMÚ Bratislava, Jeséniova 17, 833 15 Bratislava, Slovenská republika
  - Dana Halmová, Ústav hydrológie SAV, Dúbravska cesta 9, 841 04 Bratislava, Slovenská republika
  - Veronika Bačová Mitková, Ústav hydrológie SAV, Dúbravska cesta 9, 841 04 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 78 - 88, doi:
Scientific Paper, Slovak

Veronika Bačová Mitková, Pavla Pekárová, Dana Halmová, Branislav Pramuk, Pavol Miklánek: Estimation of T-year maximum annual flows along the Danube River

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• The territory of the Danube River Basin is one of the most flood-endangered regions in Europe. Therefore there is a strong need to have complete and exhausting information on the flood regime in order to be able to generalize such information on the basis of long-term observations from the whole Danube territory. Estimation of T-year maximum flows belongs to the most important tasks for engineering hydrology. The Log-Pearson type III distribution is used to estimate the extremes in many natural processes and is the most commonly used frequency distribution especially in hydrology. In this paper the long term data of the annual maximum flows from more than 20 stations along the Danube River were used to determine the T-year maximum flows.
  
  KEY WORDS: The Danube River, Log-Pearson III. distribution, maximum annual discharge, T-year discharge
  
  Address:
  - Veronika Bačová Mitková, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika (Corresponding author. Tel.: Fax.: Email: mitkova@uh.savba.sk)
  - Pavla Pekárová, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika
  - Dana Halmová, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika
  - Branislav Pramuk, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika
  - Pavol Miklánek, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 89 - 98, doi:
Scientific Paper, Slovak

Marek Sokáč, Marta Jerković, Lidija Tadić: Mathematical simulation of water quality scenarios in the Drava River

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• A simulation model for water quality in the river Drava is presented in this paper, including the space extent of the model, modelling of physical, chemical and biological processes in the river, as well. Simulation of water quality was performed using the software MIKE 11 (Danish Hydraulic Institute). The main goal of the study was the simulation of the water quality for quasi- steady state in two scenarios of the short-term changes in water quality. We simulated in scenario no. 1 two-day failure of the waste water treatment plant in the agglomeration Belišće, in the second scenario, we simulated the impact of waste water from combined sewer overflows in the Osijek agglomeration. The model was used for modelling of various impacts of pollution point sources on the water quality in the Drava river.
  
  KEY WORDS: water quality, numerical modelling, point source pollution
  
  Address:
  - Marek Sokáč, Katedra zdravotného inžinierstva, SvF. STU Bratislava, Radlinského 11, 813 68 Bratislava, Slovenská republika (Corresponding author. Tel.:+421 2 59274 286 Fax.: Email: marek.sokac@stuba.sk)
  - Marta Jerković, Građevinski fakultet Osijek, Crkvena 21, Osijek, Croatia
  - Lidija Tadić, Građevinski fakultet Osijek, Crkvena 21, Osijek, Croatia

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 99 - 106, doi:
Scientific Paper, Slovak

Petr Dušek, Yvetta Velísková: Input options of river boundary condition in MODFLOW model and their comparison

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• The aim of this article is the comparison of input options of river boundary condition to the three dimensional numerical simulation model of groundwater flow MODFLOW. The water level in the stream flowing through the territory of the hydrogeological layer can be computed via three built-in modules: RIV (River), STR (Stream) and SFR (Streamflow – Routing Package). We used MODFLOW to simulate idealized aquifer and stream. The differences between computed groundwater table showed to be minimal, thus in case of modules STR and SFR they are equally usable as using module RIV with external one or two dimensional simulation of surface water flow, which is more time – consuming process. However, this applies only to idealized, simplified conditions of the modeled environment. For more complex simulation of flow in streams with irregular structure of the riverbed is necessary to use either an external simulation or use the SFR module, which includes the possibility to enter a more complex hydraulic flow parameters in the model.
  
  KEY WORDS: surface water, groundwater, interaction, numerical simulation, flow regime
  
  Address:
  - Petr Dušek, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika (Corresponding author. Tel.:+4212 3229 3509 Fax.: Email: dusek@uh.savba.sk)
  - Yvetta Velísková, Ústav hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 107 - 116, doi:
Scientific Paper, Slovak

Radoslav Schügerl, Yvetta Velísková, Renáta Dulovičová: Comparison of flow velocity determined by Flow Tracker device and by tracer experiments

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• Important aspect for recognising of hydrodynamics characteristics of a stream is flow velocity in it. This article presents comparison of two methods for determination of flow velocity by Flow Tracker device (ADV - Acoustic Doppler Velocimetry) and by tracer experiments (indicator method). Measurements were carried out in five cross-section profiles at the Hron River in the Brezno town residential area and seven cross-section profiles at the Váh River in the Liptovský Hrádok /Liptovská Porúbka villages residential area.
  
  KEY WORDS: FlowTracker, tracer experiments, velocity measurement, flow velocity
  
  Address:
  - Radoslav Schügerl, Ústav hydrológie SAV, Dúbravská cesta 9, 841 02 Bratislava, Slovenská republika (Corresponding author. Tel.:+421 02 3229 3501 Fax.: Email: schugerl@uh.savba.sk)
  - Yvetta Velísková, Ústav hydrológie SAV, Dúbravská cesta 9, 841 02 Bratislava, Slovenská republika
  - Renáta Dulovičová, Ústav hydrológie SAV, Dúbravská cesta 9, 841 02 Bratislava, Slovenská republika

Acta Hydrologica Slovaca, Vol. 17, No. 1, 2016, p. 117 - 124, doi:
Scientific Paper, Slovak

Valentín Sočuvka, Peter Ivan, Kamila Hlavčová, Silvia Kohnová, Yvetta Velísková: Clogging analysis of the Polder Svacenický jarok

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• Clogging of the valley reservoir can cause problems within their operation, mainly with regard to reducing their accumulation volume. Polder Svacenický jarok is a part of the flood protection of the territory, which is located in western part of Slovakia in cadastre of city Myjava. This contribution presents a description of the methodology and results of actual bathymetry of the polder. The measurements were provided by modern hydrographic instrument AUV (Autonomous Underwater Vehicle). From the measured data and original geodetic survey of the terrain at the time of construction of polders we calculated change of the storage volume of the polder during its five years of operation. The results show that in a given area there is gradual clogging of bottom of the polder caused by erosion.
  
  KEY WORDS: soil erosion, reservoir storage volume, sediment, bathymetry, Svacenický jarok
  
  Address:
  - Valentín Sočuvka, Ústav Hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava 4, Slovenská republika (Corresponding author. Tel.:+421 948 006 249 Fax.: Email: socuvka@uh.savba.sk)
  - Peter Ivan, Katedra vodného hospodárstva krajiny, SvF STU Bratislava, Radlinského 11, 810 05 Bratislava, Slovenská republika
  - Kamila Hlavčová, Katedra vodného hospodárstva krajiny, SvF STU Bratislava, Radlinského 11, 810 05 Bratislava, Slovenská republika
  - Silvia Kohnová, Katedra vodného hospodárstva krajiny, SvF STU Bratislava, Radlinského 11, 810 05 Bratislava, Slovenská republika
  - Yvetta Velísková, Ústav Hydrológie SAV, Dúbravská cesta 9, 841 04 Bratislava 4, Slovenská republika