Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 145 - 155, doi: 10.31577/ahs-2024-0025.02.0016
Scientific Paper, English

Ismehen SOUSSI, Amel TALIA, Belkacem Samir BEKKOUSSA, Imene BENSTAALI, Mohamed MEDDI: Sensitivity analysis of the GR4J hydrological model to potential evapotranspiration estimates in the Tafna watershed, northwestern Algeria

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• The aim of this study is to analyze the sensitivity of the GR4J hydrological model to estimates of evapotranspiration in the Tafna watershed, located in northwest Algeria. This region is characterized by a semi-arid climate and the prevalence of karst formations. Five models for estimating potential evapotranspiration (Abtew, Hargreaves-Samani, Oudin, Irmak, Jensen-Haise) were evaluated and compared with the Penman-Monteith model on a daily time scale from 1981 to 2015 using a network of 26 rainfall stations and 22 gauging stations. The Hargreaves-Samani method demonstrated robust performance in both the calibration and validation phases of the GR4J model. The Oudin model also performed especially during the validation phase. However, the Jensen-Haise, Irmak, and Abtew methods exhibited lower reliability and efficiency. The sensitivity of the GR4J model's parameters to various PET models underscores their susceptibility to the capacity of the production store (X1) and the groundwater exchange coefficient (X2), which are influenced by PET input. In comparison, the maximum capacity of the routing store (X3) and the time base of the unit hydrograph (X4) remained stable, highlighting the significant influence of PET estimates on parameters governing surface-to-groundwater interactions.
  
  KEY WORDS: Potential evapotranspiration formulas, GR4J model, Sensitivity analysis, Tafna watershed, Algeria
  
  Address:
  - Ismehen SOUSSI, Laboratory of Research on Biological Systems and Geomatic (LRSBG), Mustapha Stambouli University of Mascara, BP. 305, Algeria (Corresponding author. Tel.: Fax.: Email: ismehen.soussi@univ-mascara.dz)
  - Amel TALIA, Sciences and Techniques Water Laboratory (LSTE), Mustapha Stambouli University of Mascara, BP. 305, Algeria
  - Belkacem Samir BEKKOUSSA, Sciences and Techniques Water Laboratory (LSTE), Mustapha Stambouli University of Mascara, BP. 305, Algeria
  - Imene BENSTAALI, Sciences and Techniques Water Laboratory (LSTE), Mustapha Stambouli University of Mascara, BP. 305, Algeria
  - Mohamed MEDDI, National School of Hydraulics (ENSH), Water and Environment Engineering Laboratory, BP. 31 Soumaa, Blida, Algeria

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 156 - 167, doi: 10.31577/ahs-2024-0025.02.0017
Scientific Paper, English

Christophe HISSLER, Ladislav HOLKO, Michal DANKO, Jean François IFFLY, Soňa LIOVÁ: Trace elements origin and fluxes in the Upper Váh River basin

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• The study evaluates concentrations of trace metals, like Sr, Pb and Cd, and related rare earth elements and yttrium (REY) in water samples collected at 9 sites in the Upper Váh River basin, Slovakia, during the low flow conditions in August 2017. Major ions, stable isotopes of hydrogen and oxygen and water conductivity were used in the hydrochemical evaluation as well. The results showed that water chemistry was driven by the two main lithologies (silicate and carbonate) that constitute the basin. An increase in trace elements concentrations from the headwater subcatchments of the Western Tatra Mountains toward sampling sites located in the Liptovská kotlina valley was also documented. The REY patterns identified three groups of sites including (1) pristine mountain part of the Jalovecký Creek (as a representative of the headwater areas of the Western Tatra Mountains), (2) large main tributaties of the Váh River and (3) outlet of the entire Jalovecký Creek (a representative of the entire catchment of small mountain tributaries of the Váh River). REY concentrations did not identify specific pollution impacts in the study area but the increase in Fe- and Al-based colloidal fractions and associated trace metals concentrations in the collected water samples could be associated to local human activities.
  
  KEY WORDS: mountain rivers, metals, REY, hydrological tracers, colloids, water chemistry, stable isotopes
  
  Address:
  - Christophe HISSLER, CAT/ENVISION research group, Luxembourg Institute of Science and Technology, Belvaux, Luxembourg (Corresponding author. Tel.: Fax.: Email: christophe.hissler@list.lu)
  - Ladislav HOLKO, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Michal DANKO, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Jean François IFFLY, HOST/OCEB observatory plateform, Luxembourg Institute of Science and Technology, Belvaux, Luxembourg
  - Soňa LIOVÁ, Slovak Hydrometeorological Institute, Bôrická cesta 103, 011 13 Žilina, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 168 - 177, doi: 10.31577/ahs-2024-0025.02.0018
Scientific Paper, English

Kateřina HRUŠKOVÁ, Hana HLAVÁČIKOVÁ, Zinaw SHENGA, Danica LEŠKOVÁ, André SIMON, Mária DERKOVÁ: Testing sensitivity of hydrological operational models to finer resolution of input data for purpose of applying high resolution Destination Earth forecasts. Case study, part two

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• The Destination Earth's on-demand extremes digital twin (DT) is the initiative of the European Commission whose aim is to provide forecasts of extreme weather events at a high spatial resolution. Such forecasts are essential inputs for various applications, including hydrological models used in flood forecasting. In the first part of the paper, the May 2021 flood that occurred in the upper Hron River basin in central Slovakia was reconstructed as one of the nine European extreme flood events, and the results of the sensitivity analyses of two rainfall runoff models (HBV and HEC-HMS) were presented. This continuation presents a comparison of hydrological forecasts achieved by using national meteorological forcing data with those gained by using two sets of extreme DT data. The results provide the basis for the first analysis of the potential added value of DT forecasts for the needs of the national hydrological forecasting service. Although DT hydrological forecasts were comparable with the national ones and no significant improvement was evident when analysed one extreme event, several potential suggestions for enhancement have been identified. These include optimising the computing domain, finer spatial discretisation of hydrological models, or considering the uncertainty of the precipitation forecasts.
  
  KEY WORDS: Destination Earth, extreme events, hydrological forecasts
  
  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
  - Zinaw SHENGA, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Danica LEŠKOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - André SIMON, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic
  - Mária DERKOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 178 - 184, doi: 10.31577/ahs-2024-0025.02.0019
Scientific Paper, English

Liudmyla GORBACHOVA, Borys KHRYSTIUK, Oleksandr AFTENIUK, Viktoria PRYKHODKINA: Changes of river ice regimes in the Prypiat basin within Ukraine for the period 1921–2020

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• The ice regime is an important hydrological characteristic of the water flow of rivers, which has practical and scientific significance. In the current conditions of an increase in air temperature, which directly affects the formation of river ice regimes it is very important to have the knowledge its trends and changes. In Ukraine, research of river ice regimes is not given due attention, since in recent decades such studies have been carried out only in a few papers and only for some rivers. The main objective of this research is to determine the quantitative indicators of changes in the characteristics of river ice regimes in the Prypiat basin within Ukraine over a 100-year period. The research was carried out according to the basin-averaged values of the following characteristics: mean monthly air temperature for November, December, March; appearance date of ice; date of freeze-up; break-up date (i.e., melt onset); date of ice disappearance; duration of freeze-up; overall duration of ice. Statistical and graphical methods are used. It is shown that in the Prypiat Basin within Ukraine, the increase in air temperature in the winter-spring period caused to changes in the characteristics of river ice regimes.
  
  KEY WORDS: river ice regimes, Prypiat River, graphical methods, air temperature, trends
  
  Address:
  - Liudmyla GORBACHOVA, Ukrainian Hydrometeorological Institute, 37, Prospekt Nauky, 03028, Kyiv, Ukraine (Corresponding author. Tel.: Fax.: Email: gorbachova@uhmi.org.ua)
  - Borys KHRYSTIUK, Ukrainian Hydrometeorological Institute, 37, Prospekt Nauky, 03028, Kyiv, Ukraine
  - Oleksandr AFTENIUK, Ukrainian Hydrometeorological Institute, 37, Prospekt Nauky, 03028, Kyiv, Ukraine
  - Viktoria PRYKHODKINA, Ukrainian Hydrometeorological Institute, 37, Prospekt Nauky, 03028, Kyiv, Ukraine

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 185 - 194, doi: 10.31577/ahs-2024-0025.02.0020
Scientific Paper, English

Viktor VYSHNEVSKYI, Serhii SHEVCHUK: Short-term forecasting of spring flood on the Dnipro River using remote sensing data

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• The ongoing Russian-Ukrainian war has affected not only the social, economic and many other spheres of human life, but also the possibility of forecasting the parameters of the water regime on the transboundary rivers of Ukraine, Russia and Belarus. In this regard, a new approach to predict spring flood parameters based on the calculation of the flooded area on upstream territory is proposed. This flooded area can be determined using remote sensing data obtained by Landsat and Sentinel satellites. It was shown a good correspondence between the flooded area and water discharges at hydrological stations located downstream. Another tool for flood forecasting is model satellite images of the flooded area taken in natural colors for known water levels and discharges at hydrological stations located downstream of the flooded area. In case of significant cloudiness of the studied area, data of radar images taken by Sentinel-1 satellite can be used to predict runoff.
  
  KEY WORDS: the Dnipro River, spring flood, flooded area, forecast, discharge, remote sensing the Dnipro River, spring flood, flooded area, forecast, discharge, remote sensing
  
  Address:
  - Viktor VYSHNEVSKYI, National Aviation University, Liubomyra Huzara Ave., 1, Kyiv, 03058, Ukraine; Central Geophysical Observatory, Nauky Ave., 39/2, Kyiv, 03028, Ukraine (Corresponding author. Tel.: Fax.: Email: vishnev.v@gmail.com)
  - Serhii SHEVCHUK, Central Geophysical Observatory, Nauky Ave., 39/2, Kyiv, 03028, Ukraine

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 195 - 201, doi: 10.31577/ahs-2024-0025.02.0021
Scientific Paper, English

Peter RONČÁK, Patrik SLEZIAK, Irakli KORDZAIA, Zbyněk BAJTEK, George KORDZAKHIA: Different approaches for estimating the impact of climate change on runoff processes in Georgian basin

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• In this paper the authors analised the impact of climate change on a hydrological regime and total runoff components in a selected catchment of Georgia. Changed climate conditions, which are characterized in particular by changes in precipitation, air temperature, and potential evapotranspiration in future decades, have been predicted according to the outputs of the regional climate model RegCM4, with global ECHAM5 model boundaries. Assuming these scenarios, the hydrological regime characteristics were simulated by a distributed WetSpa rainfall-runoff model and The TUW (“Technische Universität Wien”) lumped conceptual rainfall-runoff model. On the basis of the achieved results, it is possible to assume that there will be a decrease in the total runoff due to climate change. When compared to the current state, changes in the total runoff and its components confirm the assumption of an increase in extremes of the runoff regime in the winter period and a decrease during the summer and autumn periods, causing possible droughts. This trend is confirmed by both hydrological models.
  
  KEY WORDS: Climate change, WetSpa rainfall-runoff model, TUW lumped conceptual rainfall-runoff model
  
  Address:
  - Peter RONČÁK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: roncak@uh.savba.sk)
  - Patrik SLEZIAK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Irakli KORDZAIA, National Environmental Agency of Georgia, 150 David Agmashenebeli ave., 0112, Tbilisi, Georgia
  - Zbyněk BAJTEK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - George KORDZAKHIA, National Environmental Agency of Georgia, 150 David Agmashenebeli ave., 0112, Tbilisi, Georgia

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 202 - 210, doi: 10.31577/ahs-2024-0025.02.0022
Short Communication, English

Zbyněk BAJTEK, Pavla PEKÁROVÁ, Pavol MIKLÁNEK, Katarína JENEIOVÁ: Homogenization and temperature trends of water in the Belá River basin

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• Environmental objectives are set to ensure the achievement of good surface water and groundwater status in the EU and to prevent water status from deteriorating at Community level. Verification of the achievement of environmental objectives is part of the assessment systems in place, which also have surface water quality as an objective. Physico-chemical indicators, including water temperature, are also included in the assessment systems used to assess ecological status/potential. In order to study the variability and trends in river water temperature and the effects of climate change, high quality and long term data series are needed. This paper presents the methods, corrections and homogenisation of the water temperature series of the Belá River from 1956 to 2020. The paper focuses on homogenisation, statistical analysis and evaluation of trend development of daily water temperature values measured at two stations (Podbanské and Liptovský Hrádok) in the high mountain basin of the Belá River. Two approaches to homogenise the data, namely the multiple regression model and the H2O ML algorithm, are compared with each other.
  
  KEY WORDS: Belá River, Water temperature, Homogenization, Multiple regression model, H2O ML algorithm
  
  Address:
  - Zbyněk BAJTEK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: bajtek@uh.savba.sk)
  - Pavla PEKÁROVÁ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Pavol MIKLÁNEK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Katarína JENEIOVÁ, Slovak Hydrometeorological Institute, Jeséniova 17, 833 15 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 211 - 219, doi: 10.31577/ahs-2024-0025.02.0023
Scientific Paper, English

Radoslav SCHÜGERL, Saeid OKHRAVI, Valentin SOČUVKA: Refining flow resistance estimates in lowland streams with distributed aquatic vegetation

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• This study investigates flow resistance in the Malina stream, located in the Zahorská lowland of western Slovakia, with a particular emphasis on refining the estimation of Manningʼs n in vegetated streams. Traditional flow resistance equations, such as Manning, Chézy, and Darcy-Weisbach, often assume uniform flow conditions, which limits their applicability in complex river systems characterized by bedforms and aquatic vegetation. This research evaluates various empirical equations for determining Manning’s n, as well as a nondimensional hydraulic geometry approach that integrates dynamic flow characteristics and the effects of vegetation. Field measurements collected during the growing season (April to September) demonstrated that vegetation density significantly influences flow velocity and roughness coefficients. Empirical equations that rely solely on median grain size exhibited limited predictive capability in lowland streams with uniform and homogeneous beds, while the nondimensional approach produced more accurate estimates, showing a strong correlation with measured data. The findings highlight the critical need to incorporate vegetation dynamics into flow resistance calculations to enhance hydrodynamic modeling and improve predictions of sediment transport and sediment budgets in riverine ecosystems.
  
  KEY WORDS: aquatic vegetation, empirical equation, flow resistance, hydraulic geometry approach, Manning’s equation, growing season
  
  Address:
  - Radoslav SCHÜGERL, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: schugerl@uh.savba.sk)
  - Saeid OKHRAVI, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic
  - Valentin SOČUVKA, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 220 - 232, doi: 10.31577/ahs-2024-0025.02.0024
Scientific Paper, English

María Cristina ARENAS-BAUTISTA, Camila GARCÍA-ECHEVERRI, Leonardo David DONADO: Comparing global sensitivity analysis approaches of a semi-distributed hydrological model in tropical regions. Study case: Middle Magdalena Valley, Colombia

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• The management of uncertainty in hydrologic modeling is contingent upon two key factors: the ability to select appropriate values for model parameters and the capacity to assess the extent to which their variation affects a simulated response. This study employs sensitivity and uncertainty analyses to assess the influence of pivotal parameters in the distributed watershed model, TopModel, for approximating surface runoff in the Middle Magdalena Valley, Colombia. A variance-based global sensitivity analysis (GSA) was conducted, employing Sobol's indices, in conjunction with a classical decomposition of variance and other recently developed indices that estimate the contribution of each model parameter. This was done for the purpose of measuring the contribution of parameters to the mean, variance, skewness, and kurtosis of simulation outputs. The analysis, based on 150,000 model simulations over a 12-year period, incorporated random parameter variations within ranges supported by existing literature and initial model calibration. The findings identified a reduced set of sensitive parameters, including the recession curve, maximum root zone storage deficit, and initial subsurface flow, which were found to significantly influence model performance.
  
  KEY WORDS: hydrologic modeling, sensitivity, Sobol’ indices, AMA indices, TopModel
  
  Address:
  - María Cristina ARENAS-BAUTISTA, Pontificia Universidad Javeriana, Bogotá, Colombia (Corresponding author. Tel.: Fax.: Email: maria.arenasb@javeriana.edu.co)
  - Camila GARCÍA-ECHEVERRI, Water group, Stockholm Environment Institute, Bogotá, Colombia
  - Leonardo David DONADO, Universidad Nacional de Colombia, Bogotá, Colombia

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 233 - 240, doi: 10.31577/ahs-2024-0025.02.0025
Scientific Paper, English

Lynda PAULÍKOVÁ, Silvia KOHNOVÁ, Milan ONDERKA, Zuzana DANÁČOVÁ: Peak runoff coefficient estimation in small catchments

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• One of the key issues in assessing possible flood hazards is the estimation of runoff coefficient, i.e. the amount of rainfall transformed into runoff. This study aims to estimate peak runoff coefficients using two approaches. The indirect approach based on the rational formula was applied in 29 small catchments in Slovakia. A direct approach based on the analysis of observed rainfall-runoff events was used in one of them as well. The rainfall intensity used in the indirect method was estimated by three different techniques. The Horné Orešany – Parná catchment was chosen to compare the peak discharge coefficients from the indirect and the direct estimations. The results showed that the indirect approach often resulted in high or unrealistic peak runoff coefficients. The study contributes to understanding the variability in estimating peak discharge coefficients for small catchments and their use in engineering practice.
  
  KEY WORDS: peak runoff coefficient; small catchments; rational method; IDF curves
  
  Address:
  - Lynda PAULÍKOVÁ, Department of Specific Research, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 811 07 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: lynda.paulikova@stuba.sk)
  - Silvia KOHNOVÁ, Department of Specific Research, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 811 07 Bratislava, Slovak Republic
  - Milan ONDERKA, Earth Science Institute SAS, Department of Atmospheric Physics, Dúbravská cesta 9, 840 05 Bratislava, Slovak Republic; Slovak Hydrometeorological Institute, Jeséniová 17, 833 15 Bratislava, Slovak Republic
  - Zuzana DANÁČOVÁ, Slovak Hydrometeorological Institute, Jeséniová 17, 833 15 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 241 - 249, doi: 10.31577/ahs-2024-0025.02.0026
Scientific Paper, English

Kostiantyn SOKOLCHUK, Marek SOKÁČ: Assessing the reduction of combined sewer overflow through green infrastructure implementation: A case study of Trebišov, Slovakia

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• This article presents the findings of a simulation of the combined sewer system outflow in Trebišov, Slovakia. The simulation aimed to estimate the volume of untreated wastewater entering receiving water bodies during sewer overflow events and assess the potential of green infrastructure to mitigate this. Hydraulic modelling used MIKE+ software to simulate runoff from short-term rainfall events of varying intensities. Three development scenarios were devised, comprising the implementation of permeable pavements, green roofs, and a combination of both, and these were compared to the current situation. The findings indicated that combined sewer overflow Nr. 1 (CSO 1), the primary overflow, could experience a 20–25% reduction in overflow volume with the implementation of green infrastructure, particularly in the form of combined solutions. However, it should be noted that the reduction was slightly lower during extreme 10-year rainfall events. CSO Nr. 2, which handles a smaller volume of water, demonstrated a 7–10% reduction. The results demonstrated that permeable pavements were more effective, achieving a 16–18% reduction in overflow volume compared to 5–8% for green roofs. These findings highlight the potential of green infrastructure to mitigate overflow volumes, particularly in the context of increasing rainfall intensity due to climate change as well as the new update of the European directive 91/271/EEC, which sets strong limits for the pollution transport to receiving water through CSO structures. This paper builds upon the analysis of the impact of green infrastructure on surcharge and flooding events in the urbanized catchment of the city of Trebišov, as presented in the previous issue of Acta Hydrologica Slovaca.
  
  KEY WORDS: green infrastructure, urban water management, climate change, adaptation measures, combined sewer overflows, MIKE+
  
  Address:
  - Kostiantyn SOKOLCHUK, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic; Institute of Landscape Engineering, Faculty of Horticulture and Landscape Engineering, Slovak University of Agriculture in Nitra, Tulipánová 7, 949 76 Nitra, Slovak Republic (Corresponding author. Tel.: Fax.: Email: sokolcuk@uh.savba.sk)
  - Marek SOKÁČ, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 250 - 259, doi: 10.31577/ahs-2024-0025.02.0027
Scientific Paper, English

Lea ČUBANOVÁ, Ján RUMANN, Peter DUŠIČKA, Alexandra VIDOVÁ: Impact of different methods on the variability of the Manning's roughness coefficient in artificial channel

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• The determination of Manning's roughness coefficient plays a crucial role in the design and performance evaluation of artificial channels, such as close-to-nature fish passes. This study investigates the effect of different methods on the determination of Manning's roughness coefficient for such structures. Various approaches, including the utilization of material description tables, empirical equations based on grain size, and calculation methods incorporating in situ measurements, are examined. An interesting feature is the use of optical granulometry to obtain the grain size distribution curves, which provides the characteristic grain diameter needed for several empirical equations. By comparing and analysing different methods to estimate Manning’s roughness coefficient, this research aims to provide insights into the most effective approaches in the context of close-to-nature fish pass design.
  
  KEY WORDS: Manning´s roughness coefficient, optical granulometry, empirical equations, fish pass
  
  Address:
  - Lea ČUBANOVÁ, Department of Hydraulic Engineering, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 2766/11, 810 05 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: lea.cubanova@stuba.sk)
  - Ján RUMANN, Department of Hydraulic Engineering, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 2766/11, 810 05 Bratislava, Slovak Republic
  - Peter DUŠIČKA, Department of Hydraulic Engineering, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 2766/11, 810 05 Bratislava, Slovak Republic
  - Alexandra VIDOVÁ, Department of Hydraulic Engineering, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 2766/11, 810 05 Bratislava, Slovak Republic

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 260 - 271, doi: 10.31577/ahs-2024-0025.02.0028
Scientific Paper, English

Abdelhak ALLEM, Noureddine MAREF, Djelloul BAAHMED: Assessment of sediment yield and soil sensitivity to erosion in the Wadi Taria basin (northwest of Algeria) using the QSWAT platform and the SWAT+ model

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• The objective of this study is to apply the Soil and Water Assessment Tool (SWAT+) model and the GIS platform (QSWAT) for the spatial modeling of sediment transport in Wadi Taria basin (northwest of Algeria). Various data were used for the application of this model such as: spatial data (Digital Elevation Model, land use and soil types) and weather data (daily precipitation, minimum and maximum of air temperature, solar radiation, wind speed and relative humidity). The SWAT+ model was calibrated from the observed of the daily sediment yield over a period (03/10/2013 to 09/27/2013) and validated for the period (09/28/2013 to 01/05/2014). The calibration process was carried out by the R-SWAT code and the performance evaluation of the model was based on the NSE, R² and PBIAS objective functions. The results obtained in the calibration phase indicate that the model presented a very good performance (NSE=0.77, R2=0.95 and PBIAS=5.23%). However, good performance was obtained during the validation phase (NSE=0.66, R2=0.76 and PBIAS=8.80%). Also, the application of the SWAT+ model in Wadi Taria basin showed that the sensitivity of soil to erosion in this basin oscillates between low and medium with spatial heterogeneity of soil loss across the basin.
  
  KEY WORDS: SWAT+; Model performance; Parameters; Soil sensitivity; Semi-arid basin
  
  Address:
  - Abdelhak ALLEM, Civil Engineering and Environmental Laboratory (LGCE), Department of Hydraulic, Faculty of Technology, University of Djillali Liabes, District of Ben M'Hidi, PO Box 89, 22000, Sidi Bel Abbes, Algeria
  - Noureddine MAREF, Civil Engineering and Environmental Laboratory (LGCE), Department of Hydraulic, Faculty of Technology, University of Djillali Liabes, District of Ben M'Hidi, PO Box 89, 22000, Sidi Bel Abbes, Algeria (Corresponding author. Tel.: Fax.: Email: m.noure@yahoo.fr)
  - Djelloul BAAHMED, Civil Engineering and Environmental Laboratory (LGCE), Department of Hydraulic, Faculty of Technology, University of Djillali Liabes, District of Ben M'Hidi, PO Box 89, 22000, Sidi Bel Abbes, Algeria

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 272 - 282, doi: 10.31577/ahs-2024-0025.02.0029
Scientific Paper, English

Ajla MULAOMEROVIĆ-ŠETA, Nerma LAZOVIĆ, Andrea PETROSELLI, Željko LOZANČIĆ, Haris KALAJDŽISALIHOVIĆ: Assessment of soil erosion using the USLE method and global data: The case study of Modrac reservoir basin

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• Soil erosion is a complex natural process influenced by climatic and geological factors, relief form, petrological and vegetation properties, often caused by human activities in the basin. Surface soil erosion has multiple negative impact on human activities and on environment (e.g. on agricultural production, pollution of watercourses with pesticides, reduction of watercourses and reservoirs capacity and increase of flood risk). Many methods have been developed to assess soil erosion. However, the quality and quantity of available data often narrows the choice to the simplest ones, whose results are often unreliable. In order to overcome the problem of data availability, global data can be used. Applying Universal Soil Loss Erosion (USLE) method on global data by using GIS tools soil erosion map of the Modrac reservoir basin is created. Mean annual soil loss is estimated at 20 tons per hectare. It has been shown that almost a quarter of the basin is affected by high to extreme erosion, which is one of the reasons for the decrease in reservoir volume confirmed by recently conducted bathymetric measurements. It is shown that results are in agreement with previous analyses of erosion conducted by method developed and calibrated for former Yugoslavia countries (Gavrilović’s Erosion Potential Method (EPM)), which confirms the possibility of using global data, at least for the initial assessment of the state of erosion in the watershed.
  
  KEY WORDS: Soil erosion, Erosion map, Universal Soil Loss Equation (USLE), Modrac reservoir
  
  Address:
  - Ajla MULAOMEROVIĆ-ŠETA, Sarajevo University – Faculty of Civil Engineering, Patriotske lige 30, 71000 Sarajevo, Bosnia and Herzegovina (Corresponding author. Tel.: Fax.: Email: ajla.mulaomerovic@gf.unsa.ba)
  - Nerma LAZOVIĆ, Sarajevo University – Faculty of Civil Engineering, Patriotske lige 30, 71000 Sarajevo, Bosnia and Herzegovina
  - Andrea PETROSELLI, Department of Agriculture and Forest Sciences (DAFNE), Tuscia University, 01100 Viterbo, Italy
  - Željko LOZANČIĆ, Sarajevo University – Faculty of Civil Engineering, Patriotske lige 30, 71000 Sarajevo, Bosnia and Herzegovina
  - Haris KALAJDŽISALIHOVIĆ, Sarajevo University – Faculty of Civil Engineering, Patriotske lige 30, 71000 Sarajevo, Bosnia and Herzegovina

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 283 - 290, doi: 10.31577/ahs-2024-0025.02.0030
Scientific Paper, English

Toufik HERIZI, Sofiane BENSEFIA: Estimating maximum discharges in Algerian wadis

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• Available observation data on 60 wadis provided by the National Agency for Water Resources of Algeria show that maximum water discharges can exceed 12000 m³ s-1. A new method for calculating maximum discharges as a critical parameter for designing reliable infrastructure is proposed. The dependence of maximum discharges on the catchment area, rainfall intensity, and average slope of the main wadi is obtained. After that, statistical modeling was carried out, which made it possible to get a calculation equation with an average error smaller than that of traditional methods.
  
  KEY WORDS: Maximum discharge; catchment area; rain intensity; average slope of the main wadi
  
  Address:
  - Toufik HERIZI, Environment and Health Laboratory, Department of Agricultural Sciences, Faculty of SNV-STU, University Mohamed El Bachir El Ibrahimi of Bordj Bou Arreridj, Algeria (Corresponding author. Tel.: Fax.: Email: toufik.harizi@univ-bba.dz)
  - Sofiane BENSEFIA, Environment and Health Laboratory, Department of Agricultural Sciences, Mohmed El-Bachir El-Ibrahimi University, BBA, El-Anasser, 34030, Algeria

Acta Hydrologica Slovaca, Vol. 25, No. 2, 2024, p. 291 - 299, doi: 10.31577/ahs-2024-0025.02.0031
Scientific Paper, English

Andrej ŠOLTÉSZ, Jakub MYDLA, Eva KOLESÁROVÁ: Determination of minimum residual discharge under Veľká Domaša Water Structure

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• The Veľká Domaša Water Structure (WS), constructed on the Ondava River in 1967, serves as a critical hydrological and ecological asset for the region, balancing flood protection, recreation, and hydropower generation. This study focuses on determining the minimum residual discharge required from the reservoir to ensure adequate water quality and quantity in the Ondava River while maintaining optimal water levels in the reservoir to support its multifaceted roles. Hydrological and water quality data for this analysis were provided by the Slovak Water Management Enterprise (SWME), supplemented by measurements of key qualitative markers and an inventory of pollution sources along the river, including BUKOCEL Hencovce, TP2-Chemko Strážske, and communal wastewater treatment plants. The study evaluated multiple discharge scenarios under varying hydrological conditions, considering both natural tributary inflows and anthropogenic impacts. Results highlighted the need for an updated operational strategy, accounting for the quantitative and qualitative dynamics of the river system. Adjustments to the handling order of the Veľká Domaša WS were recommended to optimize residual flow management while addressing competing water use demands. These findings provide a framework for sustainable water resource management in the Ondava River catchment.
  
  KEY WORDS: Water structure, minimum residual flow rate, biochemical oxygen demand (BOD), handling order
  
  Address:
  - Andrej ŠOLTÉSZ, Slovak University of Technology in Bratislava, Faculty of Civil Engineering, Radlinského 11, 810 05 Bratislava, Slovak Republic (Corresponding author. Tel.: Fax.: Email: andrej soltesz@stuba.sk)
  - Jakub MYDLA, Slovak University of Technology in Bratislava, Faculty of Civil Engineering, Radlinského 11, 810 05 Bratislava, Slovak Republic
  - Eva KOLESÁROVÁ, Slovak Water Management Enterprise, Bodrog River basin district, M.R. Štefánika 25, 075 01 Trebišov, Slovak Republic