Mapping bed-level evolution in laboratory flumes by means of structured light

Experimental work in river morphology has already become a key factor to assess and analyze physical and numerical models that describe bed-level evolution in channels (Paola et al, 2009). Different techniques could be used to measure bed topography in laboratories ranging from traditional to high-technology methods. In this work, the structured...

Validation and Optimization of a Design Formula for Stable Geometrically Open Filter Structures

Granular filters are used for protection against scour and erosion of base material. For a proper functioning it is necessary that at the interfaces between the filter structure, the subsoil and the water flowing above the filter structure no material will be transported. Different types of granular filters can be distinguished, this paper...

Overtopping Flow Impact on a Vertical Wall on a Dike Crest

In this paper the impact process and mechanism of overtopping flow on a vertical wall on a dike crest are investigated by means of a series of physical model tests. A double-peaked force was recognized in a time series of an overtoping flow. Four stages were summarized for the whole overtopping flow impact process. An empirical relationship...

New laboratory techniques to determine the grain size distribution of a sandgravel bed surface and substrate (abstract)

Grain size changes in a river dominated by mixed sediment are the outcome of sedimentary grain sizeselective processes. Progress in the measurement techniques that define the spatial and temporal variation in grain size is necessary to provide new insights in this field. Techniques as image analysis and acoustic methods have emerged in the last...

Effects of vegetation on sediment transport, experience from laboratory measurements (abstract)

Research on river bank accretion

Image analysis techniques used to determine the grain size distribution of a sand-gravel bed surface and substrate

Hydrodynamic load on the building caused by overtopping waves

Wide crested dike can reduce the kinetic energy of the overtopping wave and make the overtopping wave to flow back to the seaside. If a coastal town were built on or near a dike, the overtopping wave running on the dike crest generates the force which can affect the buildings located in its path. However, quantifying the hydrodynamic load on the...

Flow resistance of vegetated oblique weir-like obstacles during high water stages

At high water stages obstacles in the floodplains of a river contribute to the flow resistance. In particular the elevated vegetated parts are expected to play an important role. The objective of this study is to estimate and parameterize the form drag due to vegetated oblique weir-like obstacles. An experimental study has been carried out in...

Numerical and physical modelling of rapidly varying flow over weir-like obstacles in rivers and floodplains

Experimental observations on long-term behavior of migrating alternate bars

Migrating alternate bars form in alluvial channels as a result of morphodynamic instability. Extensive literature can be found on their origin and short-term development, but their long-term evolution has been poorly studied so far. In particular, it is not clear whether they eventually reach an equilibrium shape, since short-term experiments...

A parameter study on bank shear stresses in curved open channel flow by means of large-eddy simulation

Meandering rivers and streams are a common planform in the world’s populated areas. Furthermore the recent increased focus on renaturalization projects has lead policy makers to also consider the partial remeandering of previously trained rivers. Economic factors such as navigation, man-made infrastructure and valuable farm land set the boundary...

Horizontal mixing in shallow flows

Shallow shear flows play an important role in the transverse transport of mass and momentum in rivers. In order to understand structure of the flow and the mechanism resulting in the particular turbulence properties, three types of shallow mixing layers are investigated each with a different cause for the velocity difference: inflow conditions,...

Experimental study on entrainment of large wood in lowland rivers

Wood transport in rivers, typically occurring during flood events, represents a relevant hazard for its potential to create obstruction at bridges and narrow cross-sections. Therefore, the understanding and prediction of entrainment and transport dynamics of woody material of different shapes, density and dimensions is of great interest for...

Long-duration laboratory experiment of slow development of steady alternate bars

The current view is that migrating bars are the result of morphodynamic instability in straight or mildly-sinuous alluvial channels and are therefore an inevitable feature of alluvial river beds. Steady bars, instead, require some external forcing or specific morphodynamic conditions to develop. Yet, recent numerical tests showed that steady...

The form drag due to vegetated weir-like obstacles interpreted as expansion losses

The Objective of this study is to estimate the form drag due to vegetated weir- like obstacles. Head loss due to submerged vegetated dikes and groins has been modeled by expansion loss form drag model (Energy and momentum balance principles) and it has been compared with experimental data. An experimental study has been carried out on a scaled...