Computational River Dynamics

Comprehensive text on the fundamentals of modeling flow and sediment transport in rivers treating both physical principles and numerical methods for various degrees of complexity. Includes 1-D, 2-D (both depth- and width-averaged) and 3-D models, as well as the integration and coupling of these models. Contains a broad selection

This book focuses on the fundamentals of sediment transport in surface waters. It covers sediment properties, open channel flows, sediment particle settling, incipient motion, bed forms, bed load, suspended load, total load, cohesive sediments, water-sediment two-phase flows, hyperconcentrated flows, debris flows, wave-induced sediment transport, turbidity currents, and physical modeling. Besides the primary context of river sedimentation, this book extensively covers sediment transport under coexisting waves and currents in coasts and estuaries, hyperconcentrated and debris flows in rivers, as well as turbidity currents in lakes, reservoirs, channels, and the ocean. It includes a chapter on the water-sediment two-phase flow theory, which is considered the basis of many sediment transport models. It introduces some special topics have that emerged in recent years, such as the transport of mixed cohesive and noncohesive sediments, biofilm-coated sediments, and infiltrated sand within gravel and cobble beds. The text merges classical and new knowledge of sediment transport from various sources in English and non-English literature and includes important contributions made by many scientists and engineers from all over the world. It balances the breadth, depth, fundamental importance, practical applicability, and future advancement of the covered knowledge, and can be used as a text and reference book. The chapters are arranged in a useful sequence for teaching purposes. Certain homework problems are prepared, which also highlight the important topics for instructors to select. Solutions to homework problems are available from the author by request.

With contributions from key researchers across the globe, and edited by internationally recognized leading academics, Gravel-bed Rivers: Processes and Disasters presents the definitive review of current knowledge of gravel-bed rivers. Continuing an established and successful series of scholarly reports, this book consists of the papers presented at the 8th International Gravel-bed Rivers Workshop. Focusing on all the recent progress that has been made in the field, subjects covered include flow, physical modeling, sediment transport theory, techniques and instrumentation, morphodynamics and ecological topics, with special attention given to aspects of disasters relevant to sediment supply and integrated river management. This up-to-date compendium is essential reading for geomorphologists, river engineers and ecologists, river managers, fluvial sedimentologists and advanced students in these fields.

A comprehensive overview of the geomorphological processes that shape rivers and that should be considered in river management.

Simulating dynamic river networks at continental scales has been a long-term goal of the hydraulic and hydrologic communities. However, difficulties in computational costs, data availability, and numerical stability have been major obstacles in applying the full, dynamic Saint-Venant equations over such scales - i.e., creating simulations of "Continental River Dynamics." Recent research has provided progress in addressing both computational costs and data availability, but numerical instability for large-scale models has been problematic (until addressed by the study herein). Prior methods for ensuring numerical stability for short river reaches are inadequate for large-scale Saint-Venant simulations due to their expensive computational cost or incompatibility with numerical schemes designed for large-scale systems. The present research addresses and provides solutions for three major sources of numerical instability in river network modeling: (i) poorly defined initial conditions, (ii) non-smooth source terms in the governing equations, and (iii) channel geometry that is insufficiently smooth or perhaps improperly defined. In the first part of this study, a robust steady Saint-Venant model (SSM) is developed. This new model applies a concept from graph-theory to provide consistent initial conditions for every computational element in a large-scale river network simulation - which is a necessary step for efficiently starting a large-scale unsteady simulation. The present SSM method can effectively generate the initial condition for different scale of river network up to 5000 x faster than the traditional method, and save up to 99% of unnecessary numerical iterations. In the second part of this work, the problem of non-smooth source terms in the governing equations is solved. A new “reference slope” concept is proposed to ensure smooth source terms and eliminate potential numerical oscillations. It is shown that a simple algebraic transformation of channel geometry can provide a smooth reference slope while preserving the correct cross-sectional flow area and the piezometric pressure gradient that drives the flow. The reference slope method ensures a Lipschitz-continuous source term while maintaining all the underlying complexity of the real-world geometry. The method systematically alleviates the oscillatory numerical behaviors provoked by non-smooth bed slope (although it cannot address problems associated with non-smooth cross-sectional area). In the third section of this work, a new sweep-search algorithm (SSA) is developed to identify locations in a network where changes in the channel cross-sectional geometry are responsible for numerical convergence failures that prevent large-scale simulation of a large-scale river network. By taking advantage of computational speed in SSM (developed in the first part of this research), the SSA can recursively examine the numerical stability of each computational element in the network. The new SSA approach provides for automated identification of problem locations in large river network data sets, which is necessary to effectively apply the full dynamic Saint-Venant equations to large-scale river networks. In summary, the research in this study provides further building blocks toward making Continental River Dynamics simulations a reality

Completely updated and with three new chapters, this analysis of river dynamics is invaluable for advanced students, researchers and practitioners.

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 194. Stream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools brings together leading contributors in stream restoration science to provide comprehensive consideration of process-based approaches, tools, and applications of techniques useful for the implementation of sustainable restoration strategies. Stream restoration is a catchall term for modifications to streams and adjacent riparian zones undertaken to improve geomorphic and/or ecologic function, structure, and integrity of river corridors, and it has become a multibillion dollar industry. A vigorous debate currently exists in research and professional communities regarding the approaches, applications, and tools most effective in designing, implementing, and assessing stream restoration strategies given a multitude of goals, objectives, stakeholders, and boundary conditions. More importantly, stream restoration as a research-oriented academic discipline is, at present, lagging stream restoration as a rapidly evolving, practitioner-centric endeavor. The volume addresses these main areas: concepts in stream restoration, river mechanics and the use of hydraulic structures, modeling in restoration design, ecology, ecologic indices, and habitat, geomorphic approaches to stream and watershed management, and sediment considerations in stream restoration. Stream Restoration in Dynamic Fluvial Systems will appeal to scholars, professionals, and government agency and institute researchers involved in examining river flow processes, river channel changes and improvements, watershed processes, and landscape systematics.

River Processes deals primarily with flow and sediment dynamics in alluvial channels. It emphasises water flows (basic principles and characterisation), fluvial sediment, processes of erosion and sediment transport, bedforms that result from flow-bed sediment interactions in sand and gravel, flow and sedimentary processes in curved, braided and confluent channels, as well as aquatic habits. River Processes provides a comprehensive synthesis of current knowledge about physical processes in alluvial channels, with an emphasis on the recent work on flow-bed-sediment transport interactions. It is intended primarily for undergraduate students interested in fluvial studies as part of physical geography, earth sciences, environmental sciences and ecology courses. The textbook is fully illustrated throughout with line drawings and photographs.

This edited book covers all aspects of River related disasters, challenges, and opportunities. Step-by-step descriptions are provided of river dynamics and associated hazards, and their applications in hazard assessments, accompanied by several experimental, filed and numerical studies. In addition, a systematic table of content is given to aid in identifying River hazards challenges and opportunities. Essential information is provided on River dynamics, hydrological processes and climate change issues, and an individual chapter is devoted to ecological restoration and river hazard management. Further topics include the stability of hydraulic structures, sediment transport, and debris flow in the hilly streams. This book will provide students, researchers, scientists, water resources managers with a comprehensive overview of the River dynamics and flood hazards in various sectors of water-related disasters and will enable them to explore the scope of application of the computational techniques and will enable them to explore the scope of River related disasters, allied branches and their field-specific problems. Professionals and policymakers may also explore the implementation of these approaches in their workplace to tackle complex river dynamics and hydrological phenomena occurring in their study area.