Jan Szolgay

Slovak University of Technology in Bratislava · Department of Land and Water Re­sources Management

Climate warming is causing an increase in extreme hydrometeorological events in most parts of the world. This phenomenon is expected to continue and will affect the frequency and intensity of extreme precipitation events. Although bias correction in regional climate model simulations has also been used to assess changes in precipitation extremes at...

Az Európát is érintő jelenlegi, napjainkban zajló éghajlatváltozás statisztikailag szignifikáns felmelegedési tendenciával jellemezhető. Az éghajlatváltozás hatása a csapadékviszonyok és az evapotranszspirációs folyamatok megváltoztatásán keresztül érinti a vízkörforgalmat, így a csapadék eloszlásának és mennyiségének várható változásai a folyamato...

Az Alföldet, azon belül is különösen a Homokhátságot érintő talajvízszint süllyedés, súlyos ökológiai és gazdasági következményekkel is járó problémakör. A jelenség hátterében álló lehetséges okokkal kapcsolatban több évtizede zajlik kutatómunka, ugyanakkor ezek relatív súlyának meghatározása a mai napig tudományos vita tárgyát képezi. Több szerző...

The effects of the changing frequency and severity of drought events in Central Europe may become a growing concern for its forests. In this study, we will look into how Hungary's forests have been affected by the 2022 compound heatwave and drought, following an arid period from 2018 to 2021. We used our active intensive monitoring plots of the For...

The effects of the changing frequency and severity of drought events in Central Europe may become a growing concern for its forests. In this study, we looked into how Hungary’s forests have been affected by the 2022 compound heatwave and drought, following an arid period from 2018 to 2021. We used our active intensive monitoring plots of the Forest...

Design flood hydrographs are often used to project safe and cost-effective hydraulic structures. This study proposes a system based on a combination of empirical and statistical approaches for constructing synthetic design flood hydrographs, that practitioners can easily apply. The system uses scaled observed seasonal flood hydrographs and respects...

The process of groundwater evapotranspiration and its subsequent recharge are fundamental aspects of the Earth’s natural water cycle and have significant implications for the preservation and functionality of various forested ecosystems. This study presents a case analysis examining the recent fluctuations in groundwater levels and their replenishm...

Megafloods that far exceed previously observed records often take citizens and experts by surprise, resulting in extremely severe damage and loss of life. Existing methods based on local and regional information rarely go beyond national borders and cannot predict these floods well because of limited data on megafloods, and because flood generation...

Flood hazard connected with the failure of hydraulic structures and flood risk associated with areas subject to flooding need to be estimated using flood hydrographs. Multivariate statistics of flood wave parameters enable quantitative conclusions about such flood hazards and risks. This study focuses on uncertainties in their estimates using unbou...

Potential changes in a hydrological regime caused by a changing climate represent a crucial source of uncertainty in water resources management. For example, in Slovakia, they may manifest themselves in a decrease in water resources, a change in the seasonality of runoff, and an increase in the extremes of floods and droughts. The research presente...

In a previous study, the topsoil and root zone ASCAT satellite soil moisture data were implemented into three multi-objective calibration approaches of the TUW hydrological model in 209 Austrian catchments. This paper examines the model parametrization in those catchments, which in the validation of the dual-layer conceptual semi-distributed model...

The decline in groundwater levels is a cause of concern in many regions of the world, including the Sand Ridge of Hungary. The causes of the regional depletion range from rising air temperatures, changes in precipitation, domestic and agricultural groundwater use and past amelioration and recent afforestation, including the effects of drilling for...

The major event that hit Europe in summer 2021 reminds society that floods are recurrent and among the costliest and deadliest natural hazards. The long-term flood risk management (FRM) efforts preferring sole technical measures to prevent and mitigate floods have shown to be not sufficiently effective and sensitive to the environment. Nature-Based...

Due to a changing climate, likely changes to a hydrological regime are one of the primary sources of uncertainty to consider in managing water resources. In Slovakia, a decline in the country’s water resources, combined with a change in the seasonality of runoff and an increase in the extremeness of floods and droughts, represents a potential threa...

The role of soil moisture is widely accepted as a significant factor in the mass and energy balance of catchments as a controller in surface and subsurface runoff generation. The paper examines the potential of a new dataset based on advanced scatterometer satellite remote sensing of soil moisture (ASCAT) for multiple objective calibrations of a du...

The changing climate is a concern with regard to sustainable water resources. Projections of the runoff in future climate conditions are needed for long-term planning of water resources and flood protection. In this study, we evaluate the possible climate change impacts on the runoff regime in eight selected basins located in the whole territory of...

Providing information on the impacts of climate change on hydrological processes is becoming ever more critical. Modelling and evaluating the expected changes of the water resources over different spatial and time scales can be useful in several fields, e.g. agriculture, forestry and water management. Previously a Budyko-type spatially distributed...

The paper introduces the Special Section on the Hydrology of the Carpathians in this issue. It is the result of an initiative of the Department of Land and Water Resources Management of the Slovak University of Technology in Bratislava, the Institute of Hydraulic Engineering and Water Resources Management of the TU Vienna and the Institute of Geoma...

In this paper we assess the irrigation water use in the Danube Basin, highlight its complexity, identify future challenges and show the relevance for a basin-wide integrative irrigation management plan as part of a more holistic and coherent resource policy. In this sense, we base our integrative regional assessments of the water-food-energy nexus...

Flood recovery is an important period in the flood risk management cycle. Recently, flood recovery has become viewed as an opportunity for future flood damage mitigation. Financial flows to cover flood damages and rules regarding their allocation are crucial for supporting or undermining mitigation efforts. In this paper, we map and compare state f...

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere¹. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe². Any changes in river floods would have lasting implications for th...

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, p...

In this study the authors looked at the impact of climate change on a hydrological regime and catchment runoff in selected catchments of Slovakia. 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 ou...

The paper focuses on the generation of floods as a principal soil threat and on soil erosion as an additional soil threat on arable lands of hillslope areas. As the most important component of floods causing the degradation of soils on arable lands, surface runoff is analysed in this study. The protective effect of crop management on the generation...

The Muskingum method is based on a linear relationship between a channel’s storage and inflow and outflow discharges. The applicability of using travel-time discharge relationships to model the variability of the K parameter in a Muskingum routing model was tested. The new parameter estimation method is based on the relationships between the travel...

Flow characteristics of intermittent rivers in Slovakia. Intermittent rivers are rivers that cease to fl ow, i.e. temporary, ephemeral, seasonal, and episodic rivers. Analysis of hydrological regime of such rivers is pivotal in assessment of water resources because changes in fl ow characteristics of such rivers may affect neighboring catchments or...

This paper analyses projected changes in short-term rainfall events during the warm season (April – October) in an ensemble of 30 regional climate model (RCM) simulations. The analysis of trend changes and changes in scaling exponents was done for the Hurbanovo, Bratislava, Oravská Lesná, and Myjava stations in Slovakia. The characteristics of maxi...

In many Austrian catchments in recent decades an increase in the mean annual air temperature and precipitation has been observed, but only a small change in the mean annual runoff. The main objective of this paper is (1) to analyze alterations in the performance of a conceptual hydrological model when applied in changing climate conditions and (2)...

Článok sa zaoberá hodnotením vplyvu zmeny klímy na využívanie hydroenergetického potenciálu vo vybraných povodiach na území Slovenska. Z.kladným ukazovateľom potenciálu využitia vodnej energie je výpočet tzv. hydroenergetického potenciálu (HEP). Zmenené klimatické podmienky charakterizované najmä zmenami zrážok, potenciálnou evapotranspiráciou a te...

V práci bol použitý koncepčný z-o model TUW, ktorý podľa priestorového rozdelenia môžeme pre dané povodie zostaviť ako celistvý, resp. polo-rozčlenený, kde vstupné údaje sú priestorovo rozčlenené po výškových zónach. Použili sme obidve verzie modelu TUW (t.j., celistvá a polo-rozčlenená), pričom sme ich kalibrovali v dvoch 10-ročných obdobiach, med...

Rainfall-runoff models are common tools for estimation of water balance components. In order to use these models in practical water resources studies, careful calibration is required. Uncertainty linked with the model calibration is a hot topic in various modeling studies. Several studies demonstrated that the use of different variants of objective...

Reliable estimates of water balance components are important for solving various tasks in water management, such as hydropower management, flood forecasting, etc. It is well known that the modeling of the water balance components is associated with several problems, e.g., uncertainty in inputs, model parameters and model structure. Considering vari...

The accurate estimation of snow is important, especially in alpine (mountainous) regions where the snow provides an important contribution to catchment runoff. In this study we assess the benefit of snow cover data in multi-variable calibration approach in terms of model performance. A lumped conceptual rainfall-runoff model (TUW model) is calibrat...

Monthly discharges can be modelled and predicted by the decomposition of the runoff process model into two components – deterministic and stochastic. For such approach the term hybrid was often adopted. In this study a hybrid (deterministic-stochastic) modelling approach for one step ahead forecasting of mean monthly discharges at the gauging stati...

The paper focuses on erosion processes in the Svacenický Creek catchment which is a small sub-catchment of the Myjava River basin. To simulate soil loss and sediment transport the USLE/SDR and WaTEM/SEDEM models were applied. The models were validated by comparing the simulated results with the actual bathymetry of a polder at the catchment outlet....

A warming climate is expected to have an impact on the magnitude and timing of river floods; however, no consistent large-scale climate change signal in observed flood magnitudes has been identified so far. We analyzed the timing of river floods in Europe over the past five decades, using a pan-European database from 4262 observational hydrometric...

This paper analyses the projected changes in short-term rainfall events during the warm season (April–October) in an ensemble of 30 regional climate model (RCM) simulations. The seasonality analysis was done for the Hurbanovo, Bratislava, Oravska Lesna, and Myjava stations in Slovakia. The characteristics of maximum rainfall events were analysed fo...

The effects of land use management practices on surface runoff are evident on a local scale, but evidence of their impact on the scale of a watershed is limited. This study focuses on an analysis of the impact of land use changes on the flood regime in the Myjava River basin, which is located in Western Slovakia. The Myjava River basin has an area...

Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-c...

The main focus of the study is to evaluate the time stability of model parameters used to simulate snow accumulation and melt by a conceptual hydrologic model. Previous studies showed the implications of time stability of catchment model parameters for climate impact analyses. The main goal of this research is to assess the effects of different obj...

The main objective of this study is to assess the spatial and temporal changes in sensitivity of model parameters in Austria. The sensitivity is assessed for a conceptual rainfall-runoff model (TUW model) by using Latin hypercube sampling method. The spatial variability in sensitivity of model parameters is evaluated over 213 Austrian basins. The t...

The main focus of the study is to evaluate the time stability of model parameters used to simulate snow accumulation and melt by a conceptual hydrologic model. Previous studies showed the implications of time stability of catchment model parameters for climate impact analyses. The main goal of this research is to assess the effects of different obj...

Parameter sensitivity analysis is a useful method in modelling studies to detect the most relevant model parameters for a catchments (Saltelli et al., 2006). A typical result of this method is a parameter list ranked according to their sensitivity for the period. In contrast to this approach, temporally resolved sensitivity analysis illustrates how...

It is widely acknowledged that in the hydrological and meteorological communities, there is a continuing need to improve the quality of quantitative rainfall and river flow forecasts. A hybrid (combined deterministic-stochastic) modelling approach is proposed here that combines the advantages offered by modelling the system dynamics with a determin...

Príspevok je zameraný na hodnotenie kvality simulácie vybraného zrážkovo-odtokového modelu (TUW model) v meniacich sa klimatických podmienkach. Model TUW bol kalibrovaný v období 1981 – 1990 a validovaný v období 2001 – 2010 pre dve rozdielne skupiny 213 rakúskych povodí (povodia so snehovým a dažďovým režimom odtoku). Parametre boli optimalizované...

The aim of this paper was to evaluate the possible impact of climate change on the runoff regime of the Hron River basin up to the Banská Bystrica profile until the year 2100. The daily rainfall-runoff model Hron which was developed at the Department of Land and Water Resources Management, SUT Bratislava, was used. The model was calibrated on a per...

The main objective of the paper is to understand how the model’s efficiency and the selected climatic indicators are related. The hydrological model applied in this study is a conceptual rainfall-runoff model (the TUW model), which was developed at the Vienna University of Technology. This model was calibrated over three different periods between 1...

The case study aims at selecting optimal bivariate copula models of the relationships between flood peaks and flood volumes from a regional perspective with a particular focus on flood generation processes. Besides the traditional approach that deals with the annual maxima of flood events, the current analysis also includes all independent flood ev...

The performance of hydrological models in different climatic periods is a frequent topic of scientific studies (Merz at al., 2011; Coron et al., 2012). There are many calibration procedures and strategies, but reaching clear conclusions on this topic is not easily achievable. In this study we investigate the performance of a conceptual rainfall-run...

The performance of hydrological models in changing climate conditions is a frequent topic of recent scientific studies. There are many calibration procedures and strategies, but reaching clear conclusions on this topic is not easily achievable. In this paper we investigate the performance of a conceptual-rainfall runoff model (TUW model) under chan...

The performance of hydrological models in changing climate conditions is a frequent topic of recent scientific studies. There are many calibration procedures and strategies, but reaching clear conclusions on this topic is not easily achievable. In this paper we investigate the performance of a conceptual-rainfall runoff model (TUW model) under chan...

Flood frequency analysis is usually performed as a univariate analysis of flood peaks using a suitable theoretical probability distribution of the annual maximum flood peaks or peak over threshold values. However, other flood attributes, such as flood volume and duration, are necessary for the design of hydrotechnical projects, too. In this study,...

This paper analyses the bivariate relationship between flood peaks and corresponding flood event volumes modelled by empirical copulas in a regional context in the North-West of Austria. Flood data of a total of 69 catchments in the region are analysed for the period 1976–2007. In order to increase the sample size and the homogeneity of the samples...

This paper analyses the bivariate relationship between flood peaks and corresponding flood event volumes modelled by empirical and theoretical copulas in a regional context, with a focus on flood generation processes in general, the regional differentiation of these and the effect of the sample size on reliable discrimination among models. A total...

The aim of this paper was to evaluate the possible impact of climate change on the runoff regime of the Hron River basin up to the Banská Bystrica profile until the year 2100. The daily rainfall-runoff model Hron which was developed at the Department of Land and Water Resources Management, SUT Bratislava, was used. The model was calibrated on a per...