Gábor Fleit

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

The effects of inland navigation on the aquatic ecosystem are numerous. One of the most relevant impacts from the ecohydraulic point of view is ship-induced waves, resulting in the local and temporary alteration of the hydrodynamic regime, especially in shallow water areas. In this paper, a novel hydrodynamic modeling-based evaluation framework is...

This paper presents a proof of concept that acoustic velocity and backscatter intensity measurements can provide essential information on ship wave-induced sediment transport processes in the littoral zone of a large river. Through a case study in the Hungarian section of Danube River, a combined application of an acoustic Doppler velocimeter (ADV)...

Ship-induced wave wash affects the hydromorphological and ecological state of rivers through various mechanisms. The direct proximity of the riverbank is usually the most exposed, as the hydrodynamic stresses are the highest in these shallow water areas. Contrary to the steady and almost still, natural flow conditions (i.e., no waves of anthropogen...

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...

A new measurement protocol, labeled Acoustic Mapping Velocimetry (AMV), has been successfully tested for in‐situ estimation of bedload transport features in sandy beds. The AMV has proven efficient in using the dune‐tracking method (DTM) for characterizing the bedform geometry and dynamics as well as for estimation of the rates of bedload transport...

We are excited to invite you to the EGU General Assembly 2025 (EGU25), taking place in Vienna and online in a hybrid format from 27 April to 2 May 2025. We warmly encourage you to contribute by submitting your abstract before the deadline: Wednesday, 15 January 2025, at 13:00 CET. We are hosting two dynamic sessions focused on hydro-morphological...

Digital elevation models (DEMs) are pivotal in river engineering and management, making their accuracy paramount. This paper introduces a novel interpolation method that addresses the challenges of data point distributions, anisotropic river topography, and meandering rivers. The windowed anisotropic local inverse distance-weighted (WALID) method i...

This paper demonstrates that the multivariate monitoring methods are capable to underpin the systematic investigation of the hysteretic behavior occurring during gradually-varied flows. For this purpose, we present simultaneous measurements of stage, index velocity, and free-surface slope acquired continuously with high-frequency sampling instrumen...

This paper demonstrates that the multivariate monitoring methods are capable to underpin the systematic investigation of the hysteretic behavior occurring during gradually-varied flows. For this purpose, we present simultaneous measurements of stage, index velocity, and free-surface slope acquired continuously with high-frequency sampling instrumen...

We are pleased to announce again that the upcoming EGU General Assembly will take place physically and online (in a hybrid format), including orals and posters. We are excited to announce the EGU General Assembly 2024 (EGU24) on 14-19 April. The abstract submission deadline is Wednesday, 10 January 2024, 13:00 CET. We are organizing two EGU sessi...

The level set method-based, multiphase hydro-and morphodynamic numerical model REEF3D is used for the simulation of the flow conditions and local scouring around submerged bridge decks. Presence of hydraulic jumps, bridge overtopping, pressurized jets and the resulting scouring make the selected test cases especially challenging from the numerical...

The impacts of navigation on the hydromorphological and ecological conditions of rivers are manifold. Most of the relevant effects can be linked to ship-induced waves, which temporarily alter the prevailing flow conditions. The impacts of waves are usually the highest in the shallower (littoral) zones, where the whole water column is affected by th...

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...

Bedload transport is an important factor to describe the hydromorphological processes of fluvial systems. However, conven- tional bedload sampling methods have large uncertainty, making it harder to understand this notoriously complex phenom- enon. In this study, a novel, image-based approach, the Video-based Bedload Tracker (VBT), is implemented t...

The river flow and the sediment that composes the riverbed are in constant interaction. Despite its importance, this interaction still has undiscovered aspects and unanswered questions. In alluvial rivers, one important factor that describes their morphological changes is the bedload yield. Defining its value however, remains a complex task, where...

Three-dimensional computational fluid dynamics modeling is ever more frequently used to solver various flow related problems. In case of the hydraulic engineering community, tasks usually range from the prediction of complex free surface flow conditions up to various sediment transport related questions, such as local scouring. In highly turbulent...

This PhD dissertation presents a novel framework for the detailed quantification and analysis of ship-induced waves and their impacts in the littoral zone of a large river. Firstly, a field measurement and data processing methodology is presented to reveal the hydrodynamic characteristics of ship waves in the near-bank area. Acoustic Doppler veloci...

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...

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...

This study proposes a spatiotemporally Adaptive Search Area (SA) size selecting algorithm for Particle image velocimetry (PIV), ASAPiv. The presented method releases the constraint of conventionally used static SAs, offering a significant computational performance increase through optimizing the dimensions of the SA according to the local flow cond...

The modelling of complex free surface flows over weirs and in the vicinity of bridge piers is presented in a numerical model emulating open channel flow based on the Reynolds Averaged Navier-Stokes (RANS) equations. The importance of handling the turbulence at the free surface in the case of different flow regimes using an immiscible two-phase RANS...

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...

Vessel generated waves are investigated with video based methods in the littoral zone of a river. LSPIV is used for the assessment of wave runup dynamics, while basic photogrammetric methods are used for the temporal analysis of small frequency waves.

The present study documents the successful application of a Reynolds-Averaged Navier-Stokes model with conventional turbulence closure to calculate discharge coefficients for submerged flow conditions at ogee-type weirs. The flow pattern downstream of submerged weirs is complex. At low submergence, there is a plunging jet and submerged hydraulic ju...

The inland navigation is clearly one of the most environment-friendly manners of transportation, however, it can also have negative effects on e.g. the riverine habitat. Investigations related to this topic are of great importance and provide research topics for several different disciplines. The more studies in these topics published, the clearer...

Accurate estimation of discharge capacity and local hydrodynamics are essential when designing hydraulic structures. Instead of the application of conventionally used empirical relationships, this study introduces a 3D numerical modeling technique which is capable to adequately predict both the discharge-upstream water level relationship and the fl...

Computational fluid dynamics (CFD) is getting more and more frequently employed not only in the hydroscience society, but by industrial hydraulic engineers as well for the solution of different spatial and time scaled problems. These tools offer a great advantage over the also rapidly developing field measurements as they are suitable for the inves...

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...

Computation Fluid Dynamics (CFD) is getting more and more frequently employed for the solution of hydraulic engineering related problems. These numerical models usually mean a less time and cost demanding alternative against the classically used physical models. Numerical models most frequently used by the industry are simple one-dimensional solver...