Suleyman NaqshbandWageningen University & Research | WUR · Faculty of Environmental Sciences
Suleyman Naqshband
PhD
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44
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Introduction
Additional affiliations
October 2016 - October 2021
July 2015 - present
February 2010 - December 2014
Publications
Publications (44)
Systematic identification and characterization of bedforms from bathymetric data are crucial in many studies of fluvial processes. Automated and accurate processing of bed elevation data is challenging where dune fields are complex or irregular and (especially) where multiple scales co-exist. Here, we introduce a new tool to quantify dune propertie...
Systematic identification and characterization of bedforms from bathymetric data are crucial in many studies focused on fluvial processes. Automated and accurate processing of bed elevation data is challenging where dune fields are complex, irregular and, especially, where multiple scales co-exist. Here, we introduce a new tool to quantify dune pro...
Hydraulic roughness is a fundamental property in river research, as it directly affects water levels, flow strength and the associated sediment transport rates. However, quantification of roughness is challenging, as it is not directly measurable in the field. In lowland rivers, bedforms are a major source of hydraulic roughness. Decades of researc...
Sedimentary bed configurations that are stable under weak fluid‐driven transport conditions can be divided into two groups: (1) mesoscale features that influence flow and sediment transport through roughness and drag partitioning effects (“mesoforms”) and (2) grain‐scale features that can effectively be ignored at the macroscopic scale (“microforms...
Dunes dominate the bed of sandy rivers and they respond to flow by changing shape and size, modifying flow, and sediment transport dynamics of rivers. Our understanding of and ability to predict dune adaptation, particularly dune growth and decay, remain incomplete. Here, we investigate dune growth from an initial flatbed in a laboratory setting by...
Trains of secondary bedforms, superimposed on primary dunes, have been observed in rivers worldwide. To date, it has remained unclear how these secondary bedforms affect the sediment transport dynamics in a fluvial system. In this study, a field campaign was conducted to acquire a data set with a high spatial and temporal resolution, enabling to tr...
The joint probability distribution of streamwise particle hop distance, lateral particle hop distance, and travel time constrains the relationships between topographic change and sediment transport at the granular scale. Previous studies have investigated the ensemble characteristics of particle motions over plane bed topography; however, it is unc...
During high river discharge extremes, the growth of dunes can reach a maximum beyond which a transition to upper stage plane bed may occur, enhancing the river's conveyance capacity and reducing flood risk. Our predictive ability of this bedform regime shift in rivers is exclusively built upon high Froude number flows dominated by asymmetric dunes...
As dunes and larger scale bed forms such as bars coexist in rivers, the question arises whether dune dynamics are influenced by interaction with the underlying bed topography. The present study aims to establish the degree in which dune characteristics in two and three dimensions are influenced by an underlying topography dominated by non‐migrating...
Tijdens een uitgebreide pilotstudie in de Waal is onderzocht wat de effecten
van langsdammen met bijbehorende oevergeulen zijn op stromingspatronen,
morfologie en de sturing daarvan.
As part of a general trend towards river management solutions that provide more room for the river, longitudinal training dams (LTDs) have recently been constructed in the inner bend of the Dutch Waal River, replacing groynes. LTDs split the river in a main channel and a bank-connected side channel with a sill at the entrance. In the present study,...
Longitudinal training dams (LTDs) have been built over a length of 10 km in the Dutch River Waal as an alternative to groyne fields, splitting the river in a fairway and a bank-connected side channel in the inner bend. Here, we study the physical mechanisms governing the three-dimensional flow and its effect on local morphology at the flow divide u...
Dunes commonly dominate the bed of sandy rivers and they are of central importance in predicting flow resistance and water levels. In the present study, we show that by using light-weight polystyrene particles as substrate in a laboratory setting, promising morphodynamic similarity is obtained between dunes in shallow flow (flume) and deep flow (fi...
Sandy river beds are dominated by rhythmic features known as dunes. Experimental investigations of turbulent flow and sediment transport over dunes have predominantly focused on equilibrium flows that are rare in natural rivers. Using a novel acoustic instrument over migrating dunes in a laboratory setting, we quantify a number of dynamical propert...
The mechanics of sediment transport are of fundamental importance for fluvio-deltaic morphodynamics. The present study focuses on quantifying particle motions and trajectories across a wide range of flow conditions. In particular, a continuous model is presented that predicts particle travel distances for saltation and suspension based on Rouse num...
Sediment transport is a key process in the morphodynamics of alluvial rivers. Much work has been done historically and recently to understand the motions of individual grains and to integrate that understanding into reach-scale or basin-scale flux models. In the present paper, we aim to 1) present a brief summary of research on sediment transport a...
Sediment transport is a key process in the morphodynamics of alluvial rivers. Much work has been done historically and recently to understand the motions of individual grains and to integrate that knowledge into reach-scale or basin-scale flux models. A majority of these studies have focused on saltating grain motion under relatively low flow condi...
This video is supporting material to "Naqshband, S., van Duin, O., Ribberink, J., and Hulscher, S. (2015), Modeling river dune development and dune transition to upper stage plane bed. Earth Surf. Process. Landforms, doi: 10.1002/esp.3789."
Large asymmetric bedforms known as dunes commonly dominate the bed of sand rivers. Due to the turbulence generation over their stoss and lee sides, dunes are of central importance in predicting hydraulic roughness and water levels. During floods in steep alluvial rivers, dunes are observed to grow rapidly as flow strength increases, undergoing an u...
The hydraulic roughness of the main channel of most lowland rivers is dominated by bed forms. River bed forms act as roughness to the flow, thereby significantly influencing the water levels, which are essential for flood forecasting. We compared a time-lag model and a physically based pickup and deposition model to predict dynamic bed form evoluti...
Accurate estimation of sediment transport is critical for many fluvial processes, but remains challenging due to high-frequency dynamics. Using novel acoustic flow instrumentation, we quantified the contribution of turbulent bed and suspended sediment fluxes to the total sediment fluxes along an entire dune profile and over the full flow depth. We...
This video is supporting material to "Naqshband, S., J. S. Ribberink, D. Hurther, P. A. Barraud, and S. J. M. H. Hulscher (2014), Experimental evidence for turbulent sediment flux constituting a large portion of the total sediment flux along migrating sand dunes, Geophys. Res. Lett., 41, 8870–8878, doi:10.1002/2014GL062322."
Dunes are the most common bedforms present in nearly all fluvial channels. Dunes are generally asymmetric with gentle stoss side slopes and steep lee side slopes possessing intermittent or permanent flow separation zones where the water flow detaches the dune surface. They migrate in downstream direction and are almost out of phase with respect to...
Dunes are the most common bed forms in lowland river channels consisting of sand and gravel, generated by divergences and convergences of sediment over the bed. They act as roughness to the flow leading to increasing water levels. To be able to model dune evolution and dune dimensions adequately, knowledge on flow and sediment transport processes a...
The present study focuses on distribution of sediment transport along migrating dunes under non-equilibrium flow conditions. To this end, using ACVP (Acoustic Concentration and Velocity Profiler), we have obtained simultaneous, co-located, high temporal-spatial resolution measurements of the multi-component flow velocity and sediment concentration...
Forecasts of water level during river floods require accurate predictions of the evolution of river dune dimensions, because the hydraulic roughness of the main channel is largely determined by the bed morphology. River dune dimensions are controlled by processes like merging and splitting of dunes. Particularly the process of dune splitting is sti...
Dunes are common bed forms in sand bed rivers and are of central interest in water management purposes. Due to flow separation and associated energy dissipation, dunes form the main source of hydraulic roughness. A large number of dune dimension data sets was compiled and analyzed in this study-414 experiments from flumes and the field-showing a si...
Dunes dominate the bed of sand rivers and are of central importance in predicting flow roughness and water levels. The present study has focused on the details of flow and sediment dynamics along migrating sand dunes in equilibrium. Using a recently developed acoustic system (ACVP: Acoustic Concentration and Velocity Profiler), new insights are obt...
Dunes form the main source of hydraulic roughness of the river bed due to the flow separation and associated energy dissipation. Engelund and Hansen [1967] showed that hydraulic roughness due to dunes can be twice larger compared to grain roughness. During floods in several rivers, initially dunes are observed to grow rapidly as flow strength incre...
The present study focuses on distribution of sediment transport along mobile dunes in equilibrium. To this end, using ACVP (Acoustic Concentration and Velocity Profiler), we have obtained simultaneous, co-located, high temporal-spatial resolution measurements of the multi-component flow velocity and suspended sediment concentration above dunes. In...
Our aim in this paper is to illustrate the importance of free water surface effects and sediment transport mode in the morphological evolution of sand dunes to upper stage plane beds. We have analyzed a large number of bed form data, 414 experiments from flumes and field, showing significantly different evolution of dune height and length in shallo...
Dunes are common bed forms in sand bed rivers and estuaries and are of central interest in wa-ter management purposes. The present study focuses on co-located, high temporal-spatial resolution meas-urements of the multi-component flow velocity and suspended sediment concentration above mobile sand dunes. Experiments have been conducted in the Hydra...
Bed forms result from interactions between water and sediment, and are very diverse depending on flow and sediment conditions. They act as roughness to the flow leading to increasing water levels. In order to determine the water levels accurately, reliable predictions of bed form evolution and associated roughness are essential. Dunes are the most...
River dunes are generated by divergence and convergence of sediment. To be able to model dune evolution and dune dimensions adequately, knowledge on sediment transport processes is crucial. It is often assumed that bed load is the dominant transport mechanism in generating dunes and therefore suspended load is not taken into account in modeling dun...
Three wave boundary layer streaming models are compared under characteristic wave conditions in the North-Sea: a constant viscosity model (Longhuet-Higgins, 1953), a time-dependent viscosity model (Davies and Villaret, 1999) and a 1-DV numerical POINT SAND model (Uittenbogaard, 1999). Furthermore, two analytical models for bed shear stress are veri...