Tamás Krámer

Tamás Krámer
Budapest University of Technology and Economics · Department of Hydraulic and Water Resources Engineering

Doctor of Philosophy

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26
Publications
6,019
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170
Citations

Publications

Publications (26)
Article
Full-text available
Turbulent momentum and heat exchanges at the air‐water interface of lakes are complex processes due to diverse characteristics such as climate, fetch limitation, and geometry; however, their parameterizations are necessary for hydro‐ and thermodynamic modeling. In this study, we performed comprehensive research on turbulent exchanges of a shallow,...
Article
Full-text available
Lake Balaton has undergone rapid eutrophication in the last decades causing dramatic deterioration in water quality. Although water quality has been successfully improved, significant algal blooms have been experienced over the past years again. Since the high level of phosphorus is primarily responsible for algal blooms, it is necessary to explore...
Article
Full-text available
Hypolimnetic withdrawal (HW) is a lake restoration method that is based on the removal of phosphorus (P) along with near-bottom water. While it has often proven to be effective, the method also sets challenges: it is about balancing between effective P removal and maintenance of the thermal stratification of the lake. The success of different HW pr...
Article
Full-text available
Wind-induced waves play a key role in air–sea momentum and heat exchange. Fetch-limited shallow lakes differ significantly from open ocean circumstances since the wave field is characterized by young and growing waves that (i) are steeper and can collapse by white-capping at lower wind speeds, and (ii) travel with lower phase velocity. Consequently...
Article
Full-text available
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...
Article
Full-text available
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...
Conference Paper
The physical interaction of aquatic vegetation with flow and sediment has long been investigated as it affects ecological conditions around submerged macrophytes, determines the effectiveness of shore protection by vegetation, and governs the natural evolution of vegetation patches through enhanced sedimentation. Tower-based imaging techniques such...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
The wave induced vertical turbulent mixing is modelled and analysed for a medium-sized shallow lake. Firstly, there is an additional turbulent kinetic energy production due to wavebreaking and whitecapping at the water surface. Secondly, the wave-induced orbital motion of non-breaking waves intensifies mixing all along the water column. The latter...
Article
Full-text available
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...
Article
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In this paper a three-dimensional circulation model has been applied to determine the spatial distribution of the temperature and mixed-layer depth (MLD) of a medium-sized shallow lake. In order to reproduce the vertical thermal structure of the lake, the impact of waves has been incorporated using several recently published schemes. These schemes...
Article
Full-text available
In this paper a simple diagnostic wind field calculation scheme is presented which provides a spatially variable wind stress field over the lake surface for hydrodynamic modeling purposes. The goal was to develop a scheme that requires routine wind time series as input from stations located over or around the lake. The main idea is to embed an inte...
Article
Full-text available
A Duna vizének 1992-es elterelése a szigetközi hullámtérben víz- és talajvízszint csökkenést eredményezett. A közös magyar-szlovák stratégiai környezeti vizsgálat keretében, a hullámtéri vízpótlórendszer-változatok hosszú távú tájléptékű hatásának vizsgálatára alkalmas szimulációs modellt dolgoztunk ki. Az egyes élőhelyek átalakulását 1. rendű 2. f...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Conference Paper
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...
Article
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...
Article
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...
Chapter
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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...
Article
Full-text available
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...
Article
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...

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