J. Józsa

• PhD, member of the Hungarian Academy of Sciences
• Head of Department at Budapest University of Technology and Economics

Evaporation rates and land surface temperatures can be modified by planned water availability as well as land use and land cover changes. In general, a higher evaporation rate via its associated latent heat flux yields a cooler surface. Here we demonstrate that increasing energy at the land surface necessitates more intense latent heat fluxes for t...

Considering currently operative European and worldwide regulations, preserving and/or improving the state of remnant alluvial floodplains is a high-priority goal for experts. One of the threats is the decrease of lateral connectivity: due to the erosion in the mainstem riverbed and the sedimentation of the floodplain and its channels, the bed eleva...

A Gemenci-erdő és Béda-Karapancsa területek hullámterei nagy kiterjedésük okán (is) kiemelt természeti értéket képviselnek. A Duna és a mellékágak mederszintjei között az elmúlt időszak süllyedési és feltöltődési folyamatai nyomán egyre nő a különbség, ami beavatkozás nélkül súlyos ökológiai következményeket vetít előre. Egy átfogó morfodinamikai k...

This paper describes the in-situ implementation of a recently developed bedload transport estimation method, called Acoustic Mapping Velocimetry (AMV). The method combines components and processing protocols from acoustic and image-based methods to provide velocity maps of bedforms migrating in the riverbed. The AMV implementation is illustrated wi...

Direct or indirect effects of nuclear power plants' (NPPs) warmwater effluents on the structure of biotic assemblages are poorly known in very large rivers. We examined changes in physical habitat structure, temperature condition and their possible effects on the structure of Danubian fish assemblages due to the outflow of the Paks NPP's warmwater...

Aquatic ecosystems are affected by anthropogenic influence in many aspects. One among those is thermal pollution, which may be caused by discharging used cooling water of nuclear power plants back to the recipient water body. Research targeting this effect tends to focus more on coastal areas and small rivers, while less is known about the impact o...

Az emberi tevékenység többféle módon terhelheti a vízi ökoszisztémát. Erre egy példa a hőszennyezés, amely eredhet pl. atomerőművek használt (ezáltal felmelegedett) hűtővizének visszavezetéséből. Egy biológus-vízmérnök összetételű csoporttal terepi méréseket végeztünk a Paksi Atomerőmű hűtővíz-visszavezetését befoglaló 15 folyamkilométeres Duna-sza...

Quantification of fish habitat relationships is a prerequisite in environmental management. Here, we compare the results of a 2D and a 3D hydrodynamic simulation in modeling fish habitat relationships in a very large river (Danube River, Hungary). We show that despite the great spatial variability of significant hydro-morphological variables (water...

Computational Fluid Dynamics (CFD) modeling has become a widely used research tool in the hydraulic engineering community, however, for many problems the numerical model setup and even the selection of the suitable hydrodynamic solver is still a challenging task. This is the case for fine scale analysis of flow features around hydraulic structures...

From an analysis of 3,738 river gauging stationsof catchments ranging from 5 to 100,000 km2, Blöschl et al. constructed a map that depicts trends of annual maximum discharges across Europe for the 1960-2010 period. On that map Hungary, one of the most flood-prone countries in Europe, appears with nearly unanimously decreasing flood discharges which...

In this study, the field measurement-based validation of a novel sediment transport calculation method is presented. River sections with complex bed topography and inhomogeneous bed material composition highlight the need for an improved sediment transport calculation method. The complexity of the morphodynamic features (spatially and temporally va...

Although Hungarian experts made several contributions in the domain of space research and activities, there is no aerospace engineering or space engineering curriculum in Hungary. After informal and formal discussions started years ago, the Budapest University of Technology and Economics is starting the formal process of establishing the space engi...

Az ökohidraulika vagy élőhely-hidraulika az ökológia és a hidraulika határán elhelyezkedve, a vízi környezetbeli élő és élettelen, másszóval biotikus és abiotikus paraméterek között keres összefüggéseket. A tudományterület fő célja a hidromorfológiai változók és a vízi élőlények térbeli előfordulása és mennyiségi viszonyai közötti kapcsolatok minél...

The temporal alteration of the hydrodynamic regime in rivers due to navigation has significant effects on riverine ecosystems. Most of the key mechanisms and interactions between hydrodynamic and ecological variables have already been revealed; however, the quantitative evaluation of biotic and abiotic variables still stands a challenge. This paper...

The aim of this study is to introduce a novel method which can separate sand- or gravel-dominated bed load transport in rivers with mixed-size bed material. When dealing with large rivers with complex hydrodynamics and morphodynamics, the bed load transport modes can indicate strong variation even locally, which requires a suitable approach to esti...

The aim of this study is to introduce a novel method which can separate sand or gravel dominated bed load transport in rivers with mixed-size bed material. In engineering practice, the Shields-Parker diagram could be used for such purposes, however, the method has certain applicability limits, due to the fact that it is based on uniform bed materia...

Riverine ship traffic results in the temporal alteration of the flow regime in the close proximity of the vessels, but waves propagating in the direction of banks may also have significant hydrodynamic effects. Ecohydraulic problems related to vessel induced wave wash (e.g. bank erosion; drift of larval fish or macroinvertebrates) are getting incre...

Hydromorphological features of rivers, such as flow depth, flow velocity, and the composition of bed material play a crucial role in the habitat selection of fish. Although these basic hydromorphological parameters can be determined with high spatial and temporal resolution using state‐of‐the‐art investigation methods, only few studies deal with th...

Waves induced by ship movement might be harmful for the habitat in the littoral zone of rivers due to the temporally increasing bed shear stress, the high-energy breaking waves and the consequently related detachment of benthic animals. In order to understand the complex hydrodynamic phenomena resulting from littoral waves, we present the testing o...

Infrasound measurements are used to detect seismic waves and a large effort is devoted to eliminating the turbulence-related infrasound signal, usually considered as noise. Here we take a complementary approach, investigating whether infrasound can provide information on atmospheric turbulence. Microphone measurements of infrasound from an experime...

The effect of emergent aquatic canopy on over-lake wind field was investigated through detailed field measurements. The aerodynamic roughness length above reed canopy and above open water was determined from eddy-covariance data. It was found that the aerodynamic roughness length at short fetches could be more sufficiently estimated from wave age r...

The PABLS13 (Pannonian Atmospheric Boundary Layer Study 2013) was a measuring international campaign that took place in Szeged (Hungary) in late November 2013. The aim of this campaign was to study the characteristics of the daily cycle of the ABL in the center of the wide Pannonian plain and its interaction with the underlying surface. Data were c...

Sediment transport in fluvial systems is a key driver of basin-wide global soil loss, river sedimentation, and the movement and transformation of organic, inorganic, and nutrient materials, all of which can contribute to severe eco-environmental degradation. Since the late 1800s, much research effort has focused on the physics of sediment entrainme...

Die unterschiedlichen Nutzungen der Donau für die Schifffahrt, zur Energiegewinnung und zur Trinkwasserversorgung beeinflussen die ökologische Qualität des Flusses. Einengung durch Regulierungen sowie Modifikationen des Sedimenthaushaltes wie Rückhalt im Einzugsgebiet und Unterbrechung des Sedimentkontinuums ergeben Veränderungen der flussmorpholog...

A laboratory flow past a groyne with complex hydrodynamics was investigated using surface Particle Tracking Velocimetry (PTV) technique for detecting chaotic features in fluvial mixing processes. In the reconstructed velocity field particles were deployed and tracked numerically in a Lagrangian way. Calculating some appropriate parameters (e. g. fl...

An experimental campaign was held from November 20 to December 11, 2013 in the airport of Szeged (Hungary), at the center of the Pannonian plain, with an Intensive Observation Period from 26 November to 1st December. Several research teams participated with their instrumentation which included a complete surface-energy budget station, with a novel...

A micrometeorological field measurement campaign dedicated to study the surface energy budget and the structure of the boundary layer focusing on the transient layer forming periods during night-time was organized in the period of 10th of November to 3rd of December 2013 in the nearby of Szeged, Hungary. A temporary micrometeorological measurement...

The Tonle Sap Lake of Cambodia is the largest freshwater body of Southeast Asia, forming an important part of the Mekong River system. The lake has an extremely productive ecosystem and operates as a natural floodwater reservoir for the lower Mekong Basin, offering flood protection and assuring the dry season flow to the Mekong Delta. In light of t...

The paper demonstrates that the wind stress curl as an external vorticity source plays an important role in shaping large scale shallow lake circulations. The analysis of purpose-oriented simultaneous wind and current measurements data from the Hungarian part of Lake Neusiedl reasonably fits well the internal boundary layer development theory over...

Gradient-driven interactions and exchange mechanisms of the reed-open water interface in shallow lake environment were investigated by localised field measurements and detailed data analysis. High frequency 3D flow velocities were recorded in several points throughout a typical interface zone of Lake Fertő. Based on the data the flow distribution,...

A comprehensive flow analysis for a confluence of two medium-sized (Qmean ≈ 30–50 m3/s) Hungarian rivers was carried out by means of a three-dimensional Reynolds-averaged Navier–Stokes modelling. The model was validated against detailed fixed and moving Acoustic Doppler Current Profiler velocity profiling. Unsteady simulations with steady-state bou...

An estimation procedure for suspended sediment concentrations based on the intensity of backscattered sound of acoustic Doppler current profilers (ADCP) is introduced in this paper. Based on detailed moving and fixed boat ADCP measurements with concurrent sediment sampling, we have successfully calibrated the estimation method for a reach of River...

Shallow lakes and reservoirs often present extended reed cover with significant spatial complexity. These zones (mostly as littoral ones) differ significantly from pelagic areas as to their aerodynamic, hydro-, sediment as well as thermodynamic conditions, thus various, gradient-driven interaction and exchange mechanisms take place at the littoral-...

One-km resolution MODIS-based mean annual evapotranspiration (ET) estimates in combination with PRISM precipitation rates were correlated with depth to groundwater (d) values in the wide alluvial valley of the Platte River in Nebraska for obtaining a net recharge (Rn) vs. d relationship. MODIS cells with irrigation were excluded, yielding a mixture...

Monthly evapotranspiration (ET) rates (2000 to 2009) across Nebraska at about 1-km resolution were obtained by linear transformations of the MODIS (MODerate resolution Imaging Spectroradiometer) daytime surface temperature values with the help of the Priestley-Taylor equation and the complementary relationship of evaporation. For positive values of...

The main goal of this paper is to introduce a suitable procedure for the assessment of reach-scale hydro-morphological conditions of rivers. For this purpose a 4 km long reach of River Tisza in Hungary was chosen and investigated by means of comprehensive field measurements and three-dimensional numerical modelling. The river can be characterized w...

Remote-Sensing Based Groundwater Recharge Estimates in the Danube-Tisza Sand Plateau Region of Hungary Mean annual recharge in the Danube-Tisza sand plateau region of Hungary over the 2000-2008 period was estimated at a 1-km spatial resolution as the difference of mean annual precipitation ( P ) and evapotranspiration ( ET ). The ET rates were deri...

Secondary settling is the final step of the activated sludge-based biological waste water treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent. A further important function of SSTs is the sufficient thickening to achieve highly concentrated return sludge and biomass within the biological reactor....

Cited By (since 1996):1, Export Date: 19 September 2013, Source: Scopus, doi: 10.3311/pp.ci.2012-1.11, Language of Original Document: English, Correspondence Address: Zsugyel, M.; Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering, Muegyetem rakpart 3. Kmf. 12, H-1111 Budapest, Hungary, Referenc...

Wind-induced waves play an important role in shallow lake hydro- and sediment dynamics. But most of the field measurement methods can give information about the wave properties only at single point, which calls for wave estimation methods to take the effect of waves into account in multidimensional hydro- and sediment dynamic models. The aim of thi...

Wind-induced waves play an important role in shallow lake hydro- and sediment dynamics. That is why field measurements are important for the validation of their estimation methods, especially in shallow waters. In the first part of the present paper a method is introduced to improve the interpretation of the measured data, applicable both for press...

A confluence zone of two rivers of different sizes was chosen to study the complex flow and morphological features with up-to-date measurement techniques. The main stream is River Danube with a mean flow of 2000m 3/s, an average depth of 6m and an average width of 500 m, which approaches the junction zone in a sharp bend. The second river is a trib...

For detecting chaotic features in fluvial mixing processes laboratory flowwith complex geometry was investigated using surface ParticleTrackingVelocimetry (PTV) technique. In the reconstructed velocity field particles were deployed and tracked numerically in a Lagrangian way. Calculating some appropriate parameters (e.g. flushing time, finite-size...

Mean annual recharge in the Sand Hills of Nebraska (USA) over the 2000–2009 period was estimated at a 1-km spatial resolution as the difference of mean annual precipitation (P) and evapotranspiration (ET). Monthly P values came from the PRISM dataset, while monthly ET values were derived from linear transformations of the MODIS daytime land-surface...

A horizontally variable density flow model is used to simulate hydraulic bore interactions with idealised urban obstacles. The 2D non-linear shallow water equations are solved using a second-order Monotonic Upstream-centered Schemes for Conservation Laws-Hancock Godunov-type HLLC approximate Riemann scheme. Validation test results are reported for...

The transferability is an important requirement of hydrological modelling. The calibrated model parameters should perform well for other time periods as well. This is not easy because of the temporal variability in the climate variables. The length of the observation period and representativeness of the data series used for model calibration have g...

Chaotic motion of particles in fluid flows was recognized decades ago but this phenomenon has only been acknowledged recently in civil engineering. Herein it is shown that chaotic advection has a wide range of important hydraulic and environmental applications. The most important characteristics of chaotic particle transport, such as the filamentar...

By combining the complementary relationship of evaporation with the coupled long-term water-energy balance of Porporato et al. (2004) in a Budyko-type framework, one can, from atmospheric measurements alone, derive important ecosystem characteristics, such as the mean effective relative soil moisture and the maximum soil water storage, as well as p...

The existence of a symmetrical complementary relationship (CR) in evaporation has been hypothesized in the hydrologic literature but the conditions required have not been investigated in much detail. In this study it is shown that under near-neutral atmospheric conditions and a constant energy term at the evaporating surface, the analytical solutio...

The original and modified versions of the advection-aridity (AA) model of regional evapotranspiration are tested with data from the Solar and Meteorological Surface Observation Network (SAMSON). The resulting long-term mean annual evapotranspiration estimates are validated against water balances of 25 watersheds that are minimally affected by human...

Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature (Ts>) by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the complementary relationship of evapo...

The analytical solution of the coupled turbulent diffusion equations of heat and vapor transport across a moisture discontinuity under near-neutral atmospheric conditions and constant energy available at the evaporating surface yields a simple equation (i.e., the wet-surface equation [WSE]) that relates the change in surface temperature to the chan...

Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature () by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the complementary relationship of evaporat...

Surface PTV technique was implemented in observing and quantifying laboratory dam break flood wave dynamics. Applying a modified version of the velocity gradient tensor (VGT) method the technique handles flows with strong strains. As to error filtering of the raw vector fields, instead of studying the local similarity of the velocity vectors within...

Detailed hydrodynamic survey of two critical river reaches has been performed from hydro- and sediment dynamics points of view, in order to explore the main features, moreover, provide calibration and verification data to related 3D flow and sediment transport modelling. Special attention has been paid to compare moving and fix boat measurement mod...

A novel approach has been found to estimate the equilibrium surface temperature (T-e) of wet environment evaporation (E-w) on a daily basis. Employing this temperature in the Priestley-Taylor equation as well as in the calculation of the slope of the saturation vapor pressure curve with pan measurements improved the accuracy of longterm mean evapor...

As important environmental features, mixing properties of inland water bodies in unsteady flow conditions are investigated. Time-dependent motion, often resulting in chaotic behavior, requires the Lagrangian description of the transport. As a simple example, unsteady hydrodynamics driven by periodical wind forcing in a simplified shallow lake geome...

In activated sludge systems the mechanically treated wastewater is biologically cleaned by biomass (activated sludge). The basic requirement of an efficient biological wastewater treatment is to have as a high biomass concentration in the biological reactor (BR) as possible. The activated sludge balance in activated sludge systems is controlled by...

The methodology and application of particle tracking velocimetry (PTV) for surface flow velocity measurements are presented in a conventional laboratory scale model characterised both by large vortices and turbulence, making use of the fact that PTV allows to take reliable measurements in flows exposed to strong deformations typical in turbulent sh...

A finite-volume numerical model is employed to investigate the adaptation of the atmospheric boundary layer to a change in the underlying surface roughness, such as that existing in the transition from land to the free surface of a water body. Numerical results are validated by comparison with neutral stratification atmospheric data and compared wi...

A solution-adaptive algorithm is presented and tested for the shallow water equations. Specifically, we focus on the two-dimensional modelling of wind-induced hydrodynamics in shallow waters, characterised by a strong influence of variable bed topography and aquatic vegetation. The numerical solution is obtained using a Godunov-type finite-volume s...

The paper deals with the hydrodynamic investigation of the junction of two rivers in north-west Hungary in an urban area. The goal of the investigation was to study the flow conditions by means of a 3D k-" turbulence CFD model and hydraulic scale model. The project gave the opportunity to compare the outcome of the distorted scale model with the on...

Turbulence features in an operating vertical slot fish pass were explored by means of analyzing 3D ADV data as well as 3D k-ε CFD modelling. Beside turbulent kinetic energy, the Eulerian integral time- and space-scale were quantified, which are expected to provide valuable information on the dominant eddy size in the flow thus contributing to the a...

In this paper wind-driven horizontal and vertical large scale circulations in shallow lakes are analysed. As an improved approximation of the external forcing field, the wind speed acceleration due to the abrupt reduction in the surface roughness between the land and the water is quantified along the fetch using a semi-empirical approach which allo...

Spatial complexity of turbulent flow conditions has been investigated by means of ADCP measure-ments and CFD modelling in river Danube. The study area was a meandering river reach, characterized by shallows and strongly influenced by various river training works. High resolution bed survey and freezing plate sampling provided input river bed data f...

The paper deals with the analysis of in situ flow measurements carried out in a fish pass at Denkpál. Turbulence and mean flow features in a representative zone of the vertical slot type upstream part of the fish pass have been explored by means of a high resolution Acoustic Doppler Velocimeter.

Acoustic Doppler Velocimeters (ADV) provide high enough time resolutions and small enough sampling volumes to explore turbulent flow features and can be used in field conditions. The paper describes the essentials of the operating principles and gives an overview on the calculation of the most important mean flow and turbulence parameters.

Turbulence features in a operating vertical slot fish pass were explored first by means of analyzing in situ ADV data. The mean velocity field, its vorticity and important turbulence parameters were quantified. The swirling character of the flow was made visible, and the vertical velocity component proved to play an important role at places. As to...

Bei der Dimensionierung von Nachklärbecken (NKB) nach den aktuellen Bemessungsvorschriften werden die beckeninternen Prozesse und die Betriebsweise kaum berücksichtigt, auch wenn diese großen Einfluss auf eine wirksame Abscheidung besitzen. Die Strömungs- und lónzentrationsverteilungen eines NKB können anhand vonIN SITU, hochauflösenden Geschwindig...

In the design of Secondary Settling Tanks (SST) the detailed inner hydrodynamic behaviour and the operation parameters are still often poorly addressed. Coupled fine scale flow and concentration measurement in operating tanks can give more insight into the interconnected flow and concentration pattern, furthermore, provide validation data for advan...

Hydrodynamic processes greatly determine the morphological and ecological evolution of lakes such as Lake Neusiedl, which is extremely shallow and has an extended and patchy reed cover. The hy-drodynamic response to prevailing wind events is explored by two-dimensional numerical modelling, including wind-current interaction and non-uniform wind she...

An in-house numerical solver for the unsteady, free-surface, homogeneous 3D Navier-Stokes equations has been used to investigate the response of Lake Balaton (Hungary) to synthetic wind forcing with special attention paid to the unsteady development of recirculating patterns and water transfer processes induced by the complex topography. The eddy v...

As an alternative to the particle tracking-based residence time calculations, a finite difference approach using the conventional advection-diffusion-reaction kinetics equation for describing the evolution of the residence time field is derived. Advection and mixing of water masses is accompanied with their ageing following a simple zero-order kine...

Water exchange mechanisms are assessed via modelling the spatial distribution of the mean residence time in lakes and coastal areas. A grid-based numerical solution of the deterministic advection-diffusion-reaction kinetics equation with the ageing of water as transport variable is applied. The composition of residence time from times spent over se...

This paper describes an adaptive quadtree grid-based solver of the depth-averaged shallow water equations. The model is designed to approximate flows in complicated large-scale shallow domains while focusing on important smaller-scale localized flow features. Quadtree grids are created automatically by recursive subdivision of a rectangle about dis...

Natural shallow-flow domains have irregular boundaries which can strongly influence the interior flow field. Here, the nonlinear shallow water equations are solved on adaptive quadtree grids that can approximate any two-dimensional boundary topology and are easy to enrich or coarsen. A special indexing system matches the quadtree structure to conve...

The paper deals with a 100 ha wetland in an estuary of the capital area of Finland. The area has gone through major changes in the last decades due to land based and river bome nutrient loads, resulting in unfavourable living conditions for aquatic birds. In order to restore the overgrown areas, opening inner ponds and brook channels by dredging is...

A new method for solving the unsteady, two-dimensional Navier-Stokes equations of incompressible flow is proposed. The method applies the usual discrete vortex approach. At each time step, the problem is split into a pure advection part, a pure diffusion part as well as a Poisson equation for the stream function. The advection is solved in the usua...

Despite the measures to protect the aquatic environment a lot of pollutants are intentionally or unintentionally released both to surface and subsurface waters, resulting in short, medium or long term water quality problems. Environmental impact assessments related to these problems often require reasonably accurate qualitative and quantitative sim...

Wind-induced horizontal transport phenomena have been analysed in shallow lakes with a coupled 2-D circulation-fluid element tracking model. Advective currents are calculated by a depth-integrated ADI-type finite difference model. In subdomains the influence of small scale bottom topography on the velocities is taken into account by local grid refi...

The application of chaos theory in the context of fluid dynamics in general, and fluvial conditions in particular is still an evolving research field. In order to present the chaotic advection behaviour and its basic features in River Danube in Hungary buoys supplied with GPS were released in the vicinity of groins and a detailed analysis of their...