Deposition of fine cohesive sediments in a turbulent flow field was studied in a system of a rotating annular channel and ring. The percentage of the total sediment that a given flow can maintain in suspension depends only on the bed shear stress and is independent of the initial sediment concentration. The percentage (C) of the depositable sediment deposited at time t has been found to vary with time according to the law (C = alpha logt + beta), where the coefficient a is independent of the flow conditions and sediment concentration, while the coefficient b is a function of the bed shear stress only. Both a and b depend on the physiochemical properties of the sediment and the water environment. Deposition rates are proportional to the depositable sediment concentration and inversely proportional to time.

Deposition of Fine Sediments in Turbulent Flows

The main focus of this Special Issue of Water is the state-of-the-art and recent research on turbulence and flow–sediment interactions in open-channel flows. Our knowledge of river hydraulics is deepening, thanks to both laboratory/field experiments related to the characteristics of turbulence and their link to erosion, transport, deposition, and local scouring phenomena. Collaboration among engineers, physicists, and other experts is increasing and furnishing new inter-/multidisciplinary perspectives to the research of river hydraulics and fluid mechanics. At the same time, the development of both sophisticated laboratory instrumentation and computing skills is giving rise to excellent experimental–numerical comparative studies. Thus, this Special Issue, with ten papers by researchers from many institutions around the world, aims at offering a modern panoramic view on all the above aspects to the vast audience of river researchers.

This book presents observations on the phenomena of fine sediment transport and their explanations under process-related divisions such as flocculation, erosion, and deposition.The text is a compilation of the author's lecture notes from nearly four decades of teaching and guiding graduate students in civil and coastal engineering. Illustrations of fine sediment transport processes and their complexities given in the book are taken from field and laboratory-based observations by the author and his students, as well as numerous investigators.The wide-ranging composition of particles (of inorganic and organic matter), their universal presence and their complex interactions with hydraulic forces make this branch of science a difficult one to deal with in a single treatise. It is therefore essential to study fine sediment transport as an independent subject rather than cover it in no more than a single chapter as many texts on coarse sediment transport have done.Even though the entire coverage is “introductory”, the twelve chapters collectively include more material than what can be reasonably dealt with in a one semester, three-credit course.The book includes an extensive description of the components of fine-grained — especially cohesive — sediment transport. It covers the development of the subject in scientific and engineering applications mainly from the 1950s to its present state. Solved examples and chapter-end exercises are also included.This text is aimed at senior civil engineering undergraduates and graduate students who, in the normal course of their study, seldom come across the subject of fine sediment transport in their curricula. Interested students should have a basic understanding of the mechanics of fluid flow and open channel hydraulics.