János Józsa

Budapest University of Technology and Economics

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Tamás Krámer

Budapest University of Technology and Economics

József Szilágyi

Budapest University of Technology and Economics

Sándor Baranya

Budapest University of Technology and Economics

Gábor Fleit

Budapest University of Technology and Economics

Krisztián Homoródi

Budapest University of Technology and Economics

Laurent Touchart

Territoires

Thomas Andrén

Södertörn University

Wilhelm Granéli

Lund University

László Rákóczi

Water Resources Research Centre

Tibor Erős

Balaton Limnological Institute

Cooperative Institutions

Budapest University of Technology and Economics

Hungarian Academy of Sciences

Water Resources Research Centre

Balaton Limnological Institute

Hungarian Research Network

University of Palermo

Centre for Ecological Research

Budapest Business University

University of Nebraska–Lincoln

Wuhan University

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Effects of a nuclear power plant warmwater outflow on environmental conditions and fish assemblages in a very large river (the Danube, Hungary)

Ecohydrology (2022)

Vivien Füstös Péter Sály Zoltán Szalóky Balázs Tóth Zoltán Vitál

Abstract 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 channel, in Hungary. Seasonal surveys conducted both upstream and downstream from the outfall showed that its hydromorphological effects were generally local and comparable to natural or other anthropogenic hydromorphological changes. The effect of the returned cooling water was more apparent in the seasonally recorded surface water temperatures and depended highly on the spatial positioning of the sampling sites. However, environmental and spatial variables accounted only for a low amount of variance in case of both shoreline and offshore fish assemblage data. Overall, we found that the outflow exerted only a local scale effect on the structure of Danubian fish assemblages. Rather, fish assemblages varied largely both inshore and offshore, which dynamics overruled any effects of the artificially elevated temperature. Our study highlights the importance of the assessment of hydrogeomorphological variability of rivers and their influence on fish assemblage variability when examining spatial effects of thermal pollution.

Outflow

10.1002/eco.2512

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Shallow Lake Modelling Using Quadtree-Based Grids

Water science and technology library (1994)

Csaba Gáspár János Józsa Juha Sarkkula

Quadtree

10.1007/978-94-010-9204-3_127

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Sekély tavak szél keltette áramlásai – kaotikus elkeveredéshez vezető tér- és időstruktúrák

Tamás Krámer János Józsa

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Habitat mapping of riverine fish by means of hydromorphological tools

Ecohydrology (2018)

Sándor Baranya Gábor Fleit János Józsa Zoltán Szalóky Balázs Tóth

Abstract 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 the connection of habitat parameters and abundance of fishes (i.e., habitat modelling) in large rivers. The aim of this study is to fill this gap by introducing the so‐called habitat maps connecting the results of 3D hydrodynamic simulations and results of offshore fish ecological surveys. The steps of habitat modelling are introduced through the case study of the Danube River focusing on evaluating the habitat use and suitability of two fish species representative to this section of the river (i.e., the round goby Neogobius melanostomus and the Danube streber Zingel streber ). A novel method for mapping the bed material composition, playing a crucial role in the habitat assessment, is also presented along the numerical modelling.

Round goby

10.1002/eco.2009

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Citations (17)

Bengal Basin, Sediment Sink

Encyclopedia of earth sciences series/Encyclopedia of earth sciences (2012)

Laurent Touchart János Józsa László Rákóczi Tamás Krámer Thomas Andrén

BENGAL

Sink (geography)

10.1007/978-1-4020-4410-6_194

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Mixing properties of a shallow basin due to wind-induced chaotic flow

Advances in Water Resources (2007)

Margit Pattantyús-Ábrahám Tamás Tél Tamás Krámer János Józsa

Chaotic mixing

Shearing (physics)

10.1016/j.advwatres.2007.11.001

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An evaporation estimation method based on the coupled 2‐D turbulent heat and vapor transport equations

Journal of Geophysical Research Atmospheres (2009)

József Szilágyi János Józsa

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 change in the land surface moisture content as the environment dries. With the help of percent possible sunshine, air temperature, and humidity measurements at selected weather stations as well as land surface temperature values from MODIS data, monthly, warm‐season evaporation rates were estimated for five rectangular regions across the contiguous U.S. employing the WSE. The so‐derived monthly evaporation rates correlated very strongly ( R 2 = 0.95) with traditional complementary relationship‐derived evaporation estimates using the same weather‐station data. Even on an annual basis the correlation remained unchanged. WSE with no tunable parameters may in the future help in calibration and validation of other evaporation estimation techniques that may or may not rely on land surface temperature data.

Discontinuity (linguistics)

Potential evaporation

10.1029/2008jd010772

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The shallow flow equations solved on adaptive quadtree grids

International Journal for Numerical Methods in Fluids (2001)

Alistair G.L. Borthwick Susanna Leon János Józsa

Abstract 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 discretized boundary, bathymetric or flow‐related seeding points. It can be fitted in a fractal‐like sense by local grid refinement to any boundary, however distorted, provided absolute convergence to the boundary is not required and a low level of stepped boundary can be tolerated. Grid information is stored as a tree data structure, with a novel indexing system used to link information on the quadtree to a finite volume discretization of the governing equations. As the flow field develops, the grids may be adapted using a parameter based on vorticity and grid cell size. The numerical model is validated using standard benchmark tests, including seiches, Coriolis‐induced set‐up, jet‐forced flow in a circular reservoir, and wetting and drying. Wind‐induced flow in the Nichupté Lagoon, México, provides an illustrative example of an application to flow in extremely complicated multi‐connected regions. Copyright © 2001 John Wiley & Sons, Ltd.

Quadtree

Shallow water equations

10.1002/fld.192

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A Shear Reynolds Number-Based Classification Method of the Nonuniform Bed Load Transport

Water (2019)

Gergely T. Török János Józsa Sándor Baranya

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 estimate the locally unique behavior of the sediment transport. However, the literature offers only few studies regarding this issue, and they are concerned with uniform bed load. In order to partly fill this gap, we suggest here a decision criteria which utilizes the shear Reynolds number. The method was verified with data from field and laboratory measurements, both performed at nonuniform bed material compositions. The comparative assessment of the results show that the shear Reynolds number-based method operates more reliably than the Shields–Parker diagram and it is expected to predict the sand or gravel transport domination with a <5% uncertainty. The results contribute to the improvement of numerical sediment transport modeling as well as to the field implementation of bed load transport measurements.

Beach morphodynamics

10.3390/w11010073

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Citations (17)

Hajók keltette hullámzás hatásának terepi feltárása a litorális zónában

Gábor Fleit Sándor Baranya Tamás Krámer János Józsa

Jelen tanulmanyban a hajok keltette hullamok partkozelben megjelenő aramlastani hatasait vizsgaltuk a Duna Sződligeti szakaszanak egy limanyos teruleten, kulonos tekintettel a fenek-csusztatofeszultsegre. Kellően nagy feszultsegnovekmenyek eseten, a mederfeneken elő makrogerinctelenek es halikrak elsodrodhatnak olyan aramlasi sebessegek uralta teruletekre, ahol tulelesi eselyuk zerushoz kozeli. Ezen parameter szamszerűsitese szinkronizalt akusztikus sebessegmerő műszerek terepi alkalmazasat igenyelte. A nagy időbeli felbontasu sebesseg-idősorok alapjan statisztikai modszerekkel jellemeztuk kulonboző elhalado hajok (szallodahajo, uszaly, szarnyashajo, motorcsonak) hatasara kialakulo hidrodinamikai valtozasokat a mederfeneken. A cikk tovabba bemutatja a Large Scale Particle Image Velocimetry (LSPIV) egy ujszerű alkalmazasat, mellyel a hullamzas part menti mozgasanak időben valtozo sebessegmezővel valo leirasat vegeztuk el. Az eredmenyek ramutatnak a hullamjelensegek terbeli es időbeli osszetettsegere, de egyuttal igazoljak azok kimerhetőseget is.

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