Studies of sediment transport problems in mountainous rivers with steep slopes are difficult due to rapid variations in flow regimes, abrupt changes in topography, etc. Sediment transport in mountainous rivers with steep slopes is a complicated subject because bed materials in mountainous rivers are often heterogeneous and contain a wide range of bed material sizes, such as gravel, cobbles, bou...

Numerical morphological modeling of braided rivers, using a physics-based approach, is increasingly used as a technique to explore controls on river pattern and, from an applied perspective, to simulate the impact of channel modifications. This paper assesses a depth-averaged nonuniform sediment model (Delft3D) to predict the morphodynamics of a 2.5 km long reach of the braided Rees River, New ...

Akademisk avhandling som med tillstånd av KTH i Stockholm, framlägges till offentlig granskning för avläggande av Teknisk Doktorsexamen, tisdagen den 20 december kl. iii To my beloved parents iv v Abstract This study focuses on two different types of micro-particles selected from different stages off iron and steelmaking processes. These particles are dust particles generated due to mechanical ...

Recent studies have observed deviation from normal (Fickian) diffusion in sediment tracer dispersion that violates the assumption of statistical convergence to a Gaussian. Nikora et al. (2002) hypothesized that particle motion at short time scales is superdiffusive because of inertia, while long-time subdiffusion results from heavy-tailed rest durations between particle motions. Here we test th...

A class of reptiles known as sand swimmers adapts to hot environments by submerging beneath desert sands during the day and so provide a unique probe into the dynamics of intruders in granular beds. To understand the mechanism for swimming in an otherwise solid bed, we study a simple model of periodic contraction and extension of large intruders in a granular bed. Using an event-driven simulati...

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application of particle tracking velocimetry (PTV) to a bed-load experiment with lightweight sediment. The key characteristics of the investigated sediment transport conditions were the presence of...

Sediment tracers are increasingly employed to estimate bed load transport and landscape evolution rates. Tracer trajectories are dominated by periods of immobility (“waiting times”) as they are buried and reexcavated in the stochastically evolving river bed. Here we model bed evolution as a random walk with mean-reverting tendency (Ornstein-Uhlenbeck process) originating from the restoring effe...

Sediment transport is an intrinsically stochastic process, and measurement of bed load in the environment is further complicated by the unsteady nature of river flooding. Here we present a methodology for analyzing sediment tracer data with unsteady forcing. We define a dimensionless impulse by integrating the cumulative excess shear velocity for the duration of measurement, normalized by grain...

The discusser wishes to congratulate the authors for their excellent paper. He would like to discuss some possible drag reduction effects. The discusser has reanalyzed the authors' data assuming quasi-uniform flows at the end of the channel. For the clearwater flow experiments (runs C-1 and C-2), the data suggest an equivalent roughness height k, of the flume (smooth plexiglass) between 0.15 mm...

when a dam is constructed on a river path, inevitably sedimentation of alluvial materials occurred. therefore, the initial capacity of the reservoir reduce gradually, and if don’t predict the effects of this phenomena and its proper control methods, the application of the reservoir may be affected. the findings of this thesis confirm that, the sedimentation in reservoirs and the variations of t...