Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 161 - 172, doi: 10.31577/ahs-2023-0024.02.0018
Scientific Paper, English

Veronika BAČOVÁ MITKOVÁ: Evaluation of water dissolved oxygen under climate change and its modeling in Bodrog River at Streda nad Bodrogom

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• The oxygen is one of indicators of water quality that plays a crucial role in affecting the biological processes in surface water. In the context of the climate change, there are also changes in the oxygen regime of the water in the streams. The paper presents an evaluation of the changes in long-term data of the dissolved oxygen (DO), water temperature Tw, biochemical oxygen demand (BOD) and chemical oxygen demand (COD), and flows (Q) in the Bodrog River at Streda nad Bodrogom, during the period of 1965–2021. The aim of the study is to detect whether significant trends occur in the time series of analyzed data. The first part of the paper dealt with the trend analyses of monthly and annual data. The results can be useful to quantify the possible threat to its balanced regime. The study shoved an increasing trend in the long-term trend of the DO and a decreasing trend in biochemical oxygen demand. The following section is focused on regression between selected components of the hydrosphere and modelling them. The ability to model the components of the hydrosphere is an essential part of water resource management.
  
  KEY WORDS: flow, oxygen water regime, water temperature, long-term trends, interrelationships
  
  Address:
  - Veronika BAČOVÁ MITKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 84104 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: mitkova@uh.savba.sk)

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 173 - 181, doi: 10.31577/ahs-2023-0024.02.0019
Scientific Paper, English

Touraj SABZEVARI, Andrea PETROSELLI, Ali Torabi HAGHIGHI, Hamidreza R. BABAALI: Comparison of saturation models in complex hillslopes

 Full Text in PDF     38 DOWNLOADS

• Hillslopes of natural catchment have a complex geometry. In complex hillslopes, combining different cases of plan shape (convergent, parallel and divergent) and profile curvature (concave, convex and straight) nine different geometries are created. In prediction of the surface and subsurface runoff of catchments based on saturation excess runoff mechanism, the saturated and unsaturated zones of hillslopes must be first separated. Subsurface travel time of hillslope is dependent on saturation attributes. In this research, a new saturation model, called Gamma, was developed to predict the saturated zone length and subsurface travel time in complex hillslopes. An analytical formula was introduced to calculate saturation zone length in Gamma model. Results of Gamma model, namely the saturation zone length and subsurface travel time, were compared with the results given by two other complex saturation models W and Sigma. The results of the three models were relatively close to each other in convergent and parallel hillslopes of different profile curvature type. However, due to the existence of an analytical equation for estimation of saturated zone length in the Gamma model, this model is recommended. It should be noted that for straight divergent and convex divergent hillslopes, the Gamma model is not suitable and Sigma or W model should be used.
  
  KEY WORDS: saturation excess runoff mechanism, complex hillslope, subsurface travel time
  
  Address:
  - Touraj SABZEVARI, Department of Civil Engineering, Estahban Branch, Islamic Azad University, Estahban, Iran (Corresponding author. Tel.: Fax.: Email: touraj.sabzevari@iau.ac.ir)
  - Andrea PETROSELLI, Department of Agriculture and Forest Sciences (DAFNE), Tuscia University, 01100 Viterbo, Italy (Corresponding author. Tel.: Fax.: Email: petro@unitus.it)
  - Ali Torabi HAGHIGHI, Water, Energy and Environmental Engineering Research Unit, University of Oulu, Finland
  - Hamidreza R. BABAALI, Department of Civil Engineering, Khorramabad Branch, Islamic Azad University, Khorramabad, Iran

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 182 - 186, doi: 10.31577/ahs-2023-0024.02.0020
Scientific Paper, English

Ákos TARNAWA, Katalin M. KASSAI, Zoltán KENDE, Márton JOLÁNKAI: Changes of drought indices in relation with the geographic altitude of the crop site

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• The water availability of the crop site is a determining factor regarding plant growth and development. An assessment study has been done at the MATE University, Gödöllő to evaluate the magnitude of aridity in relaion with the geographic location of the crop site. Field crop species (Sugar beet Beta vulgaris, winter barley Hordeum vulgare, winter wheat Triticum aestivum, maize Zea mays, potato Solanum tuberosum, and alfalfa Medicago sativa) were examined in the study. Long term data of twelve meteorological stations (Békéscsaba, Budapest, Debrecen, Miskolc, Mosonmagyaróvár, Nagykanizsa, Nyíregyháza, Pécs, Siófok, Szeged, Szolnok, Szombathely) representing all regions of Hungary were used as a basis of evaluation. PAI indices of each station were processed with vulnerability indices of the field crops studied. The results obtained suggest, that of cereals proved to be the least susceptible, while potato and maize were proved to be highly influenced by aridity x vulnerability interactions. Strong climatic impact could be detected in the case of alfalfa and sugar beet. The geographic altitude of the crop site has shown negative correlation with the magnitude of drought indices.
  
  KEY WORDS: drought, field crops, altitude, crop site, vulnerability
  
  Address:
  - Ákos TARNAWA, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Páter Károly utca 1, Hungary
  - Katalin M. KASSAI, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Páter Károly utca 1, Hungary
  - Zoltán KENDE, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Páter Károly utca 1, Hungary
  - Márton JOLÁNKAI, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Páter Károly utca 1, Hungary (Corresponding author. Tel.: Fax.: Email: jolankai.marton@uni-mate.hu)

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 187 - 196, doi: 10.31577/ahs-2023-0024.02.0021
Scientific Paper, English

Mitra TANHAPOUR, Anna LIOVÁ, Kamila HLAVČOVÁ, Silvia KOHNOVÁ, Jaber SOLTANI, Bahram MALEKMOHAMMADI, Hadi SHAKIBIAN: A comparative analysis of continuous and event-based hydrological modeling for streamflow hydrograph prediction

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• A precise evaluation of streamflow hydrographs and their attributes is one of the key components of hydrological applications. This research investigates a comparative analysis between event-based and continuous hydrological modeling of streamflow using the HBV rainfall-runoff model. The Dez river basin in southwest Iran was selected as a case study. Model performance was examined for a total of nine streamflow events during time period 2012–2019. The results of the model were compared for event-based and continuous simulations of streamflow using goodness-of-fit measures involving Nash-Sutcliff efficiency (NSE), normalized root mean square error (NRMSE), and mean absolute percentage error (MAPE). Besides, the most sensitive parameters were identified using sensitivity analysis. Results revealed that although HBV model has a reliable performance for both modeling approaches, continuous modeling of streamflow hydrographs slightly outperforms the EB simulation approach. These outcomes provide an efficient information to improve the operation of water systems and hydrological forecasts.
  
  KEY WORDS: Streamflow hydrograph, HBV rainfall-runoff model, event-based simulation, continuous modeling
  
  Address:
  - Mitra TANHAPOUR, Water Engineering Department, Faculty of Agricultural Technology, University College of Agriculture & Natural Resources, University of Tehran, Tehran, Iran
  - Anna LIOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovak Republic
  - Kamila HLAVČOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovak Republic
  - Silvia KOHNOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovak Republic
  - Jaber SOLTANI, Water Engineering Department, Faculty of Agricultural Technology, University College of Agriculture & Natural Resources, University of Tehran, Tehran, Iran (Corresponding author. Tel.: Fax.: Email: jsoltani@ut.ac.ir)
  - Bahram MALEKMOHAMMADI, Department of Environmental Planning and Management, Graduate Faculty of Environment, University of Tehran Tehran, Iran
  - Hadi SHAKIBIAN, Department of Computer Engineering, Faculty of Engineering, Alzahra University, Tehran, Iran

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 197 - 204, doi: 10.31577/ahs-2023-0024.02.0022
Scientific Paper, English

Zbyněk BAJTEK, Pavla PEKÁROVÁ, Katarína JENEIOVÁ, Pavol MIKLÁNEK: Estimation of water temperature changes in the Ipeľ River based on future scenarios

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• Water is an irreplaceable resource for life and ecosystems, and among its key parameters is its temperature. The temperature of water and its fluctuations have a significant impact on aquatic ecosystems, highlighting the need for accurate prediction and monitoring. Therefore this study focuses on the analysis and simulation of monthly and daily water temperatures in the Ipeľ River Basin at two measuring stations. The first part of the study deals with the statistical analysis of daily water and air temperature values. The second part examines regression models for predicting daily and monthly water temperatures in the Ipeľ River Basin. The results of this analysis indicate that due to climate change, there is a gradual increase in temperatures in the Ipeľ River. This trend can have a negative impact on aquatic ecosystems and biodiversity, especially in extreme scenarios. Additionally, elevated water temperatures can affect water management and the utilization of the Ipeľ River, including the availability of drinking water and the quality of water sources. Overall, this study holds significant importance for the protection of aquatic ecosystems, and the insights gained can serve as a foundation for future strategies and measures to adapt to changing conditions and safeguard the valuable aquatic environment of the Ipeľ River Basin.
  
  KEY WORDS: prediction of water temperature, change in water temperature, Ipeľ River, climatic scenarios
  
  Address:
  - Zbyněk BAJTEK, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: bajtek@uh.savba.sk)
  - Pavla PEKÁROVÁ, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic
  - Katarína JENEIOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Pavol MIKLÁNEK, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 205 - 213, doi: 10.31577/ahs-2023-0024.02.0023
Scientific Paper, English

Peter ŠURDA, Justína VITKOVÁ, Anton ZVALA, Ľubomír LICHNER: Analyzing fire-induced water repellency and runoff in forest soil from beech forest: A controlled laboratory experiment

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• Forest fires are a common ecological disturbance affecting soil properties and hydrological processes. In this study, we investigated the impact of fire on surface runoff and soil water repellency (SWR) in beech forest through a laboratory experiment. Our main goals were to quantify the severity of SWR caused by low-intensity fires (simulated at 300°C in a muffle furnace) using contact angle measurements with an optical goniometer and to analyze the relationship between heat-induced alterations in SWR and subsequent surface runoff generated by a rainfall simulator in laboratory conditions. The secondary goal of this study was to propose an innovative laboratory approach as an alternative for fire experiments in real forest environments. We collected six monoliths, each with a forest soil surface layer measuring 20 cm x 15 cm x 10 cm, from the Zvolen-Budča site. These monoliths were heated at 300°C for 20 minutes in a muffle furnace to simulate the impact of low-intensity wildfires. Subsequently, the burnt monoliths and the Control were exposed to artificial rain from a rainfall simulator, and surface runoff was measured. The results showed a significant increase in surface runoff from the burnt monoliths compared to the Control, indicating the impact of fire-induced changes in soil structure and SWR. Additionally, contact angle measurements using an optical goniometer showed increased SWR in the burnt disturbed samples. The findings of our study underscore the significance of the interplay between fire-induced alterations in SWR and surface runoff. They offer valuable insights into the post-fire hydrological responses and erosion risks in forest ecosystems. These insights could help develop effective strategies to mitigate the environmental impacts of forest fires.
  
  KEY WORDS: forest fires, soil hydrophobicity, surface runoff, contact angle
  
  Address:
  - Peter ŠURDA, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: surda@uh.savba.sk)
  - Justína VITKOVÁ, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic
  - Anton ZVALA, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic
  - Ľubomír LICHNER, Institute of Hydrology SAS, Dúbravská cesta č. 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 214 - 220, doi: 10.31577/ahs-2023-0024.02.0024
Scientific Paper, English

Rajaprasad SVS, Rambabu MUKKAMALA: A CNN Bidirectional LSTM framework for predicting monsoon rainfall in India

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• Rainfall prediction has evolved as a paramount research significance in recent times due to its complexities and ongoing demand such as water resource planning and management. Agriculture is a major source of employment in India, as well as a substantial contributor to gross domestic product, and crop output is dependent on the monsoon season. Rainfall prediction is useful to authorities for water storage and timely release to increase crop productivity. The current study proposes a Deep Neural Network (DNN) based hybrid model using a combination of convolutional neural network bi-directional long short-term memory (CNN BiLSTM) to predict monthly rain fall during monsoon seasons. The DNN models were used to analyze the average monthly rainfall data collected across the country from 1871 to 2019 during the monsoon seasons. Furthermore, the hybrid model's results were compared to the Bidirectional LSTM (BiLSTM) architecture. In predicting rainfall in India, the proposed hybrid model framework has been found to be more accurate than the BiLSTM. The findings of the study suggest that a DNN frame work can be successfully adopted for time series analysis in water resource management and related domains to reduce the associated risks.
  
  KEY WORDS: rainfall, prediction, DNN, CNN-BiLSTM, monsoon
  
  Address:
  - Rajaprasad SVS, National Institute of Construction Management and Research (NICMAR) Hyderabad India (Corresponding author. Tel.: Fax.: Email: rajaprasad@nicmar.ac.in)
  - Rambabu MUKKAMALA, National Institute of Construction Management and Research (NICMAR) Hyderabad India

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 221 - 231, doi: 10.31577/ahs-2023-0024.02.0025
Scientific Paper, English

Dana PAVELKOVÁ, Branislav KANDRA, Andrej TALL, Helena HLAVATÁ, Milan GOMBOŠ: Comparison of meteorological drought over two normal periods

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• The frequency of extreme meteorological events, including drought, has risen in the last years. This is, among, due to climatic changes occurring in the atmosphere. These extremes have been monitored also on the East Slovakian Lowland. Dry periods are defined as periods of water scarcity in their various forms. In order to quantify changes in the climate at a particular location, it is useful to compare the climatic characteristics monitored over two normal periods. The basic assumption of this work is that Earth's climate has been warming and therefore the drought incidence has been increasing. The aim of this work is to quantify differences in the climate at a particular location over two consecutive normal periods. The two normal periods (NP) are the years 1961–1990 (NP1) and 1991–2020 (NP2). Compared atmospheric elements were monitored at the meteorological station of SHMÚ (Slovak Hydrometeorological Institute) in Milhostov, which is in the central part of the East Slovakian Lowland. Normal periods were analysed in terms of precipitation, temperature, potential evapotranspiration, and selected drought indices. The analysis has shown that the normal period of 1991–2020 (NP2) is both annually and monthly drier than the period of 1961–1990 (NP1), with a significant increase in temperatures and potential evapotranspiration.
  
  KEY WORDS: drought index, normal period, meteorological elements
  
  Address:
  - Dana PAVELKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: pavelkova@uh.savba.sk)
  - Branislav KANDRA, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Andrej TALL, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Helena HLAVATÁ, Slovak Hydrometeorological Institute, Regional Office Košice, Ďumbierska 26, 041 17 Košice, Slovak Republic
  - Milan GOMBOŠ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 232 - 241, doi: 10.31577/ahs-2023-0024.02.0026
Scientific Paper, English

Lotta BLAŠKOVIČOVÁ, Katarína JENEIOVÁ, Katarína KOTRÍKOVÁ, Ľubica LOVÁSOVÁ, Katarína MELOVÁ, Soňa LIOVÁ: Challenges in selecting the new reference period for long-term hydrological characteristics in Slovakia

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• Establishment of a new reference period is an ongoing topic in Slovakia as the currently used reference period is 1961–2000. This contribution focuses on the assessment of spatial and temporal changes in the mean long-term yearly discharges and long-term mean monthly discharges at 140 water-gauging stations. The years 2021 and 2022 have been further evaluated at selected 13 water-gauging stations to assess the possible impacts of using different reference periods (1991–2020, 1981–2020, 1971–2020 and 1961–2000) on the water management. The analyses have confirmed that there are significant changes between long-term values, especially for the period 1991–2020 compared with the reference period 1961–2000, with the highest negative changes in monthly discharges being in April and highest positive changes being in January. Evaluation of mean monthly and annual discharges in 2021 and 2022 for 13 selected water-gauging stations, according to the four above mentioned reference periods, has identified changes especially in set categories of monthly discharges. The same average monthly but also annual flows in one station have fallen into different assessment categories, in several cases. For annual flows the changes have manifested in 6 water-gauging stations in the year 2021 and 2 stations in the year 2022. The number of stations with changes in categories between different reference periods used for particular months have varied from 2 to 8 water-gauging stations in 2021 (62 cases for the whole year) and from 2 to 6 water-gauging stations in 2022 (40 cases for the whole year). The highest number of changes for both years were detected in June (14) and August and December (11). The selection of the reference period can therefore lead into different set of applied water management rules.
  
  KEY WORDS: reference period, design values, mean monthly discharges, annual discharges
  
  Address:
  - Lotta BLAŠKOVIČOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: lotta.blaskovicova@shmu.sk)
  - Katarína JENEIOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Katarína KOTRÍKOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Ľubica LOVÁSOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Katarína MELOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Soňa LIOVÁ, Slovak Hydrometeorological Institute, Bôrická cesta 103, 011 13 Žilina, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 242 - 253, doi: 10.31577/ahs-2023-0024.02.0027
Scientific Paper, English

Kateřina HRUŠKOVÁ, Hana HLAVÁČIKOVÁ: Case study: Assessment of radar-based and ground precipitation data during the flood situation in May 2021 in the Upper Hron River basin in Slovakia

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• Precipitation is a major factor influencing the results of rainfall-runoff modelling. Errors in precipitation propagate to other phases of water quantity and quality analysis. In the field of operational hydrology, the primary focus is on simulated and predicted discharges. This paper provides a comprehensive analysis of radar-estimated precipitation in comparison with precipitation obtained from rain gauge stations during the monthly period when flooding occurred in the Upper Hron River basin in central Slovakia. The precipitation is analysed from the point of view of its further use in the HBV hydrological model applied for hydrological forecasts in the operational hydrological service of the SHMU. Even though, there are high correlation coefficients between measured and radar precipitation, the underestimation of radar precipitation was investigated, with a clear west-east trend. The radar product generally recorded more hours of rain. Low intensities up to 3 mm hr-1 prevailed, while precipitation with higher intensities (above 5 mm hr-1) was detected less frequently compared to ground data. Hydrological evaluation of radar precipitation has shown that bias correction methods applied to precipitation data prior to input to the model can enhance subsequent discharge simulation. The improvement was observed mainly in upstream subbasines, especially in the Čierny Hron subbasin. The NSE was calculated at 0.915. The error in peak flow was also reduced, but the underestimation of the maximum discharge was still observed. The assessment included one month's data, therefore more site-specific situations would need to be analysed for more general conclusions.
  
  KEY WORDS: precipitation uncertainty, hydrological forecasts, HBV model
  
  Address:
  - Kateřina HRUŠKOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: katerina.hruskova@shmu.sk)
  - Hana HLAVÁČIKOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 254 - 265, doi: 10.31577/ahs-2023-0024.02.0028
Scientific Paper, English

Ján SZOLGAY, Pavol MIKLÁNEK, Roman VÝLETA: Interactions of natural and anthropogenic drivers and hydrological processes on local and regional scales: A review of main results of Slovak hydrology from 2019 to 2022

 Full Text in PDF     39 DOWNLOADS

• The need to increase understanding of the impacts of changing natural and anthropogenic drivers on hydrological processes on local and regional scales is an essential prerequisite for advancing hydrology and a precondition for solving water resources management tasks. Slovakia exhibits abundant spatial and temporal variability of hydrological processes complicating the generalisation of runoff regimes. Changing climate and recent extreme floods and droughts put additional pressure on improving the observing, monitoring, describing, and modelling of hydrological processes. This paper reviews the response of hydrologic research in Slovakia to these challenges published in international journals from 2019 to 2022. It continues the practice of publishing the review part of the Slovak National Reports to IUGG on behalf of the IAHS (Szolgay, 2003; 2007; 2011; 2015; 2019), which follows the custom of National IUGG Committees to prepare a Quadrennial Report for the IUGG General Assemblies containing comprehensive summaries of national activities in geodesy and geophysics (Szolgay, et al., 2023).
  
  KEY WORDS: climate change, hydrological processes, runoff regimes, hydrological research, Slovakia
  
  Address:
  - Ján SZOLGAY, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: jan.szolgay@stuba.sk)
  - Pavol MIKLÁNEK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Roman VÝLETA, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 266 - 274, doi: 10.31577/ahs-2023-0024.02.0029
Scientific Paper, English

Tatiana KOHUTOVÁ, Matúš TOMAŠČÍK, Michaela DANÁČOVÁ, Kamila HLAVČOVÁ: Assessment of the impact of the accuracy of the DMR on the calculation of soil erosion using the USLE and USLE-2D models

 Full Text in PDF     28 DOWNLOADS

• Slovakia has recorded a potentially significant increase in water erosion, especially after consolidating the plots of hundreds of hectares of agricultural area with monocultures of marketable crops. This is also due to large blocks of land being created on sloping sites. Due to its simplicity, the Universal Soil Loss Equation (USLE) is most commonly used to calculate potential soil erosion. This study compares the classical USLE and the USLE-2D methods, which consider the combined spatially variable slope length and steepness. The slope length is replaced in USLE-2D by the contributing area based on a raster digital model relief model. Data from Tulčík cadastre in east Slovakia demonstrates the results of water erosion on 26 plots used as agricultural areas. As expected, differences were found, which were further analysed concerning slope lengths and steepness. Comparing the grid size (1, 10 and 20 m) for the USLE-2D model showed that more significant differences were obtained for plots with a smaller area and a higher slope. It was confirmed that at a lower pixel resolution, the results are overestimated.
  
  KEY WORDS: soil erosion, DMR, LS-factor, USLE, USLE-2D
  
  Address:
  - Tatiana KOHUTOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic
  - Matúš TOMAŠČÍK, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic
  - Michaela DANÁČOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: michaela.danacova@stuba.sk)
  - Kamila HLAVČOVÁ, Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 275 - 284, doi: 10.31577/ahs-2023-0024.02.0030
Scientific Paper, English

Yvetta VELÍSKOVÁ, Marek SOKÁČ, Maryam BARATI MOGHADDAM: Numerical tests and sensitivity analysis of pollution source localisation tool applied on open channel system

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• This paper is focused on solving the inverse problem of pollution spreading in open channel system in order to find the location of pollutant sources. The goal was to propose localisation procedure, which should be operative and fast enough to enable quick interventions to prevent the spread of pollution. The proposed method, as well as the overall localisation procedure was numerically tested on a real sewer system data, which represents in this case an extensive open channel network structure with free surface flow. As part of the numerical tests of the model, a sensitivity analysis was also carried out. The sensitivity analysis was focused on the resulting localization error depending on concentration measurement errors. The numerical test results were successful and confirmed applicability of proposed localization tool in real conditions, the sensitivity analysis points to the influence of individual parameters on localization accuracy.
  
  KEY WORDS: inverse problem, source localisation, pollution source, sensitivity analysis, numerical test
  
  Address:
  - Yvetta VELÍSKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: veliskova@uh.savba.sk)
  - Marek SOKÁČ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Maryam BARATI MOGHADDAM, Department of Water Engineering and Management, Faculty of Agriculture, Tarbiat Modares University of Tehran, Irán

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 285 - 293, doi: 10.31577/ahs-2023-0024.02.0031
Discussion, English

Lenka BALÁŽOVIČOVÁ, Cyril SIMAN, Katarína MIKULOVÁ: Variability and trends of selected snow cover characteristics in the Tatra Mountains region in Slovakia 1981–2020

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• Over the last decades, snow seasons in Europe were reported to become shorter with lower abundance of snow. However, at some stations situated about certain elevation, the amount of snow cover was found to be increasing. This is also the case of high mountains in Slovakia, where number of snow-related studies showed some differences related to the elevation. In this study we report on the trends of selected snow cover characteristics such as the number of days with snow cover (DSC) for 1, 10 and 20 cm depths, summed snow depths (SSD) and mean snow depths (MSD). The data used in this study were collected by the Slovak Hydrometeorological Institute (SHMI) at eight stations in the Tatra Mountains during the 39 seasons 1981–2020 (01/07 to 30/06 the following year). Some increasing trends were observed for stations above 1100 m while stations below this elevation had generally decreasing estimates. The DSC for 1 cm ranged from 297 days at station elevated at 2635 m a.s.l. to 25 days for station at 640 m a.s.l. The MSD ranged from 100 to 7 cm on average for the whole period. Apart from global warming, other factors play role, and these can be complex in the mountainous regions making any trends more ambiguous to interpret.
  
  KEY WORDS: snow cover, Western Carpathians, Tatra Mountains, climate change
  
  Address:
  - Lenka BALÁŽOVIČOVÁ, Department of Geography and Geology, Faculty of Natural Science, Matej Bel University, Tajovského 40, 97401 Banská Bystrica, Slovak Republic (Corresponding author. Tel.: Fax.: Email: lenka.balazovicova@umb.sk)
  - Cyril SIMAN, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Katarína MIKULOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 294 - 302, doi: 10.31577/ahs-2023-0024.02.0032
Scientific Paper, English

Tatiana SOĽÁKOVÁ, Martina ZELEŇÁKOVÁ, Hany ABD-ELHAMID, Milan GOCIC, Helena HLAVATÁ, Peter BUJANSKÝ, Miroslav GARAJ: An assessment of historical short-time precipitation deficiency in eastern Slovakia and northern Serbia according to the SPI-3

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• Short-term precipitation deficiency is one of the primary causes of agricultural drought, which can have far-reaching consequences on various aspects such as society, environment, and the economy. This complex natural phenomenon attracts more attention due to changes in precipitation pattern. The use of the SPI-3 index for the quantitative measure of precipitation anomalies over a three-month period across the eastern part of Slovakia and the northern part of Serbia is a valuable approach in understanding and managing drought conditions in these countries with different climate conditions. The SPI-3 can be highly beneficial for the farmers, policymakers, and water resource managers when it comes to making informed decisions about irrigation, crop selection and water allocation during drought events. In northern Serbia and eastern Slovakia, the extreme precipitation anomalies often occur during the autumn season. Predicting extreme rainfall anomalies, especially during the growing season, is highly justified and essential for effective natural risk management in agriculture-dependent countries. The average inter-arrival time of an extreme precipitation deficit is in the north of Serbia ranges from 3.1 to 5.1 years, while in the east of Slovakia it ranges from 3.2 to 5.9 years.
  
  KEY WORDS: precipitation deficiency, agricultural drought, SPI, Slovakia, Serbia
  
  Address:
  - Tatiana SOĽÁKOVÁ, Faculty of Civil Engineering, Technical University of Košice, Vysokoškolská 4, 040 01 Košice, Slovak Republic
  - Martina ZELEŇÁKOVÁ, Faculty of Civil Engineering, Technical University of Košice, Vysokoškolská 4, 040 01 Košice, Slovak Republic (Corresponding author. Tel.: Fax.: Email: martina.zelenakova@tuke.sk)
  - Hany ABD-ELHAMID, Faculty of Civil Engineering, Technical University of Košice, Vysokoškolská 4, 040 01 Košice, Slovak Republic
  - Milan GOCIC, University of Nis, Faculty of Civil Engineering and Architecture, Aleksandra Medvedeva 14, 18000 Nis, Serbia
  - Helena HLAVATÁ, Slovak Hydrometeorological Institute, Regional Office Košice, Ďumbierska 26, 041 17 Košice, Slovak Republic
  - Peter BUJANSKÝ, Faculty of Civil Engineering, Technical University of Košice, Vysokoškolská 4, 040 01 Košice, Slovak Republic
  - Miroslav GARAJ, Faculty of Civil Engineering, Technical University of Košice, Vysokoškolská 4, 040 01 Košice, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 303 - 309, doi: 10.31577/ahs-2023-0024.02.0033
Scientific Paper, English

Lucia TOKOVÁ, Natália BOTKOVÁ, Justína VITKOVÁ, Lenka BOTYANSZKÁ, Peter RONČÁK: Study of the saturated hydraulic conductivity by falling–head method for different soil types amended with different biochar fraction size

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• Saturated hydraulic conductivity is an important soil property related to soil water regime. Generally, loam soil has a convenient moisture regime. However, if this type of soil is gradually drying out, its moisture regime may change for the worse. Our task is therefore to search for methods to increase the hydraulic conductivity of the loamy soils. In contrast, one of the goals of sandy soil management is slowing down flow velocity. In our research, we focused on the effect of biochar particle size on saturated hydraulic conductivity changes in three different soil types. The soils were selected based on their textures – sandy, silt loam and silty clay. Our results confirmed that addition of biochar with particle size <125 µm produced from paper fiber sludge and grain husks significantly (p<0.05) reduced saturated hydraulic conductivity in sandy soil by approximately 61% compared to control with sandy soil. Further, the results indicated that biochar with a fraction size >2 mm effectively increased the saturated hydraulic conductivity of silt loam soil by approximately 165% compared to pure silt loam soil. The difference was also statistically significant (p<0.05). Biochar amendment to the finest textured soil used in this study (silty clay) also increased the saturated hydraulic conductivity of the soil. The biochar with a fraction size of 125 µm–2 mm and >2 mm significantly (p<0.05) increased the saturated hydraulic conductivity by approximately 629% and 1063%, respectively when compared to pure silty clay soil.
  
  KEY WORDS: biochar fraction size, soil type, saturated hydraulic conductivity, falling–head method
  
  Address:
  - Lucia TOKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: tokova@uh.savba.sk)
  - Natália BOTKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic; Institute of Landscape Engineering, Faculty of Horticulture and Landscape Engineering, SUA, Hospodárska 7, 949 76 Nitra, Slovak Republic
  - Justína VITKOVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Lenka BOTYANSZKÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Peter RONČÁK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 24, No. 2, 2023, p. 310 - 321, doi: 10.31577/ahs-2023-0024.02.0034
Scientific Paper, English

Kaveh OSTAD-ALI-ASKARI, Mohsen GHANE, Peiman KIANMEHR: Soil and water assessment tool model for runoff reaction to land use variations by SWAT model package

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• Hydro-climatic degeneracies, for example moist and dissipations, have most likely enlarged owing to climatical modification and could due to diffident possessions on socio-economic, mechanical and ecological regions. To plan and concept most hydraulic structures, e.g., dams, it is vital to regulate the runoff of the rivers. If the river absences any position to live the yield, the hydraulic mockups are frequently used to estimate it. SWAT is one of the greatest widely-applied computerized models. In this prototypical, we'd like to feed such influential climatological data as precipitation, temperature, wind speed, radiation and ratio, also as, watershed data including the Curve Number (CN) and roughness coefficient to calculate the watershed runoff. Some watershed contains few weather stations, and there is a risk that the registered data in a station do not represent the whole watershed. Consequently, the amount of the runoff estimation error needs to be determined. The obtained results indicate that with a 32.07% decrease in the average monthly precipitation, sunshine, relative humidity, wind and temperature, we witness 65.36% decrease, 116.82% increase, 46.78% decrease, 127.16% increase, and 39.52% increase in modeled runoff, respectively. The wind speed and therefore the radiation are the foremost sensitive and temperature is that the least sensitive components within the runoff approximation.
  
  KEY WORDS: Meteorological Parameters; Rainfall Runoff; Sensitivity Analysis; SWAT model; Curve Number (CN)
  
  Address:
  - Kaveh OSTAD-ALI-ASKARI, Department of Civil Engineering, School of Engineering, American University in Dubai, Dubai, 28282, United Arab Emirates; Department of Natural Sciences, Manchester Metropolitan University, Manchester M1 5GD United Kingdom; World Top 2-Percent Researcher, Standford University, USA, 2022 (Corresponding author. Tel.: Fax.: Email: ostadaliaskari.k@of.iut.ac.ir, kaveh.oaa2000@gmail.com)
  - Mohsen GHANE, Department of Water Resources Management and Water Engineering, Semnan University, Semnan, Iran
  - Peiman KIANMEHR, Department of Civil Engineering, School of Engineering, American University in Dubai, Dubai, 28282, United Arab Emirates