Bedform

Abstract: 1. Environmental Fluid Dynamics. 2. Entrainment and Transport of Sedimentary Particles. 3. Particle Motions at Low Concentrations: Grading in Pyroclastic-Fall Deposits. 4. Packing of Sedimentary Particles. 5. Orientation of Particles During Sedimentation: Shape-Fabrics. 6. Transition to Turbulence and the Fine Structure of Steady Turbulent Boundary Layers: Parting Lineation and Related Structures. 7. Models of Transverse Bedforms in Unidirectional Flows. 8. Empirical Character of Ripples and Dunes Formed By Unidirectional Flows. 9. Climbing Ripples and Dunes and Their Cross-Stratification Patterns. 10. Bedforms in Supercritical and Related Flows: Transverse Ribs, Rhomboid Features, and Antidunes. 11. Transverse Bedforms in Multidirectional Flows: Wave-Related Ripples Marks, Sand Waves, and Equant Dunes. 12. Ripples and Dunes in Changing Flows.

Abstract: The main objective of the book is to describe from a deterministic point of view the sediment transport in the general wave-current situation. For this purpose, the book is divided into two major parts. The first part of the book is related to flow and turbulence in combined wave-current. This part covers the turbulent wave boundary layer, bed friction in combined wave-current motion, turbulence in the surf zone, and wave-driven currents in the long- and cross-shore direction. The second part treats the sediment transport as a result of the wave-current action. This part includes an introduction to basic sediment transport concepts, distribution of suspended sediment in the sheet flow regime, description of bedforms formed by current and waves, and their influence on sediment transport pattern. Finally, the modelling of cross- and long-shore sediment transport is described. This book is useful for students with a background in basic hydrodynamics.

Abstract: A Symposium entitled "Classification of Large-Scale Flow-Transverse Bedforms" was convened at the 1987 Mid-Year Meeting of SEPM in Austin, Texas with the purpose of examining the problems involved in classifying large subaqueous flow-transverse bedforms developed in fluvial, intertidal, and marine environments, and recommending changes in nomenclature. The consensus of the participants is that despite the wide spectrum of morphologies of large-scale flow-transverse bedforms (excluding antidunes), they all occupy a similar position in the lower-flow-regime sequence between ripples and upper plane bed. The wide variety of forms is a reflection of secondary effects such as channelization, fluctuating water levels, and unsteady and reversing flows. The bedforms appear not to fall into size classes with naturally occurring boundaries but rather form a continuum with spacing from just under 1 m to over 1,000 m. The symposium panel proposes, therefore, that they should have only one name, DUNE. Dune is preferred as it has historical precedence over other terms in use, such as megaripple and sand wave. The term "dune" should be modified by primary descriptors of shape (i.e., 2-D or 3-D) and size based on spacing (small (0.6-5 m), medium (5-10 m), large (10-100 m) or very large (> 100 m) and the adjective subaqueous when it is important to distinguish them from eolian dunes. The panel recommends a morphologically based classification that is descriptive, with an underlying genetic rationale. Second order descriptors such a sediment size and bedform superposition may be used to describe more thoroughly the variety of subaqueous dunes in nature.