In the past, boundary conditions in the building of dams have changed, as technological developments have been influential on dam planning, construction, operation and maintenance processes. It is ICOLD's mission to not only consider these developments but also adequately deal with environmental aspects and related infrastructure issues. Altered water cycles, more extreme weather conditions and an increasing number of natural hazards clearly affect the safe and economical operation of dams and reservoirs. Moreover, emission-free hydropower production as the most important form of "liquid" solar energy and the provision of water for irrigation and potable water supply is becoming more and more important to meet the world's fast growing demand for energy and food in a sustainable way. Dams and Reservoirs Under Changing Challenges covers subjects ranging from dam engineering through the benefits and drawbacks of dams, including the latest developments dealing with dams and reservoirs under changing environmental and socioeconomic conditions. It is a valuable resource for professional and dam engineers, water manager, governmental organizations and commercial consultants responsible for dam design and management.

Hydraulic engineering of dams and their appurtenant structures counts among the essential tasks to successfully design safe water-retaining reservoirs for hydroelectric power generation, flood retention, and irrigation and water supply demands. In view of climate change, especially dams and reservoirs, among other water infrastructure, will and have to play an even more important role than in the past as part of necessary mitigation and adaptation measures to satisfy vital needs in water supply, renewable energy and food worldwide as expressed in the Sustainable Development Goals of the United Nations. This book deals with the major hydraulic aspects of dam engineering considering recent developments in research and construction, namely overflow, conveyance and dissipations structures of spillways, river diversion facilities during construction, bottom and low-level outlets as well as intake structures. Furthermore, the book covers reservoir sedimentation, impulse waves and dambreak waves, which are relevant topics in view of sustainable and safe operation of reservoirs. The book is richly illustrated with photographs, highlighting the various appurtenant structures of dams addressed in the book chapters, as well as figures and diagrams showing important relations among the governing parameters of a certain phenomenon. An extensive literature review along with an updated bibliography complete this book.

Contains the state-of-the-art on this still non-conventional hydraulic structure, and demonstrates that dam engineering currently experiences a strong revival of labyrinth oriented weirs.

Every year the Swiss Commission for Flood Protection (KOHS) of the Swiss Association for Water Management (SWV) organizes a symposium where professionals, officers of public administrations, and researchers exchange their experiences on special topics and key projects in river engineering and restoration. In 2014, this symposium was organized as a special session of the seventh International Conference on Fluvial Hydraulics "River Flow 2014" at Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland. In addition to the Swiss participants, scientists and professionals from all over the world were informed about Swiss competences in river engineering and restoration. The aim of the book is to enrich flood protection and river restoration projects all over the world.

Despite the mechanisms of reservoir sedimentation being well known for a long time, sustainable and preventive measures are rarely taken into consideration in the design of new reservoirs. To avoid operational problems of powerhouses, sedimentation is often treated for existing reservoirs with measures which are efficient only for a limited time. The today's challenge of dam owners and engineers is to guarantee with adequate mitigation measures the future sustainable use of the vital reservoirs supplying water for drinking, food and energy production. Research and development is still urgently needed to identify efficient mitigation measures adapted to the main sedimentation processes involved in reservoirs. During the seventh International Conference on Fluvial Hydraulics "River Flow 2014" at Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland, scientists and professionals from all over the world addressed the challenge of reservoir sedimentation in a special session and exchanged their knowledge and experiences. Invited and selected contributions, which give an overview on the latest developments and research regarding reservoir sedimentation including case studies, are presented in this book, in the hope that they can contribute to better sustainable use of the vital reservoirs worldwide.

Dam engineering is currently experiencing a strong revival of labyrinth oriented weirs. Labyrinth weirs, with a repetitive constructional character and an increased specific discharge capacity, are a very good technical-economical compromise. The concept of Piano Key Weir (PKW), with alveoli developed in overhangs from a reduced support area, enables the installation of non-linear crests at the top of concrete dams. As a result it eliminates the main drawback of classical labyrinth weirs, and enables their use to rehabilitate numerous existing dams. Since the first implementation of piano key weirs by Electricite de France on Goulours dam (France) in 2006, at least eight PKWs have been built in France, Vietnam and Switzerland. Their operation over a few years has already provided the first prototype data. Other projects are under study, construction or planning in varied countries. On another hand, research programs are under progress all over the world. Following a first edition in 2011, Labyrinth and Piano Key Weirs II - PKW 2013 collects up-to-date contributions from people with various backgrounds, from engineers and researchers to academics. Summarizing the last developments on labyrinth oriented weirs, the book constitutes the state-of-the-art in research and application of piano key weir solutions, and will be invaluable to professionals and scientists interested in Dams Engineering.

Labyrinth spillways are almost as old as dam engineering. In spite of the fact that they appear as a very good technical-economical compromise, only 0.1% of large dams are equipped with such weirs. The main reason for this is that traditional labyrinth weirs usually cannot be installed on top of concrete gravity dams as they require a large foundation surface. In 2003 an improved concept of traditional labyrinth spillway emerged, with alveoli developed in overhangs from a reduced support area: the Piano Key Weir (PKW). The Piano Key Weir is a weir of particular geometry, associating to a labyrinth shape the use of overhangs to reduce the basis length. The main advantage of Piano Key Weirs is that it can be directly placed on a dam crest. As a result of extreme fl oods in the recent past, a growing demand for safety in society, and revised hydrological calculations, the need for reliable spillways has consequently become higher. In this context, the Piano Key Weir proves to be an interesting solution to increase the hydraulic capacity of spillway devices.

The book contains the state-of-the-art on this still non-conventional hydraulic structure, and is divided into six main themes:

• Physical Modeling. Hydraulic capacity
• Physical Modeling. Downstream fittings
• Numerical Modeling
• Hydraulic Design
• Planned and achieved projects
• Nomenclature, Database, Future developments.

The papers in Labyrinth and Piano Key Weirs demonstrate that dam engineering currently experiences a strong revival of labyrinth oriented weirs, and are particularly of interest to academia, researchers and professionals working in the area of hydraulic engineering, and to dam control authorities and dam owners.

Hydraulic engineering of dams and their appurtenant structures counts among the essential tasks to successfully design safe water-retaining reservoirs for hydroelectric power generation, flood retention, and irrigation and water supply demands. In view of climate change, especially dams and reservoirs, among other water infrastructure, will and have to play an even more important role than in the past as part of necessary mitigation and adaptation measures to satisfy vital needs in water supply, renewable energy and food worldwide as expressed in the Sustainable Development Goals of the United Nations. This book deals with the major hydraulic aspects of dam engineering considering recent developments in research and construction, namely overflow, conveyance and dissipations structures of spillways, river diversion facilities during construction, bottom and low-level outlets as well as intake structures. Furthermore, the book covers reservoir sedimentation, impulse waves and dambreak waves, which are relevant topics in view of sustainable and safe operation of reservoirs. The book is richly illustrated with photographs, highlighting the various appurtenant structures of dams addressed in the book chapters, as well as figures and diagrams showing important relations among the governing parameters of a certain phenomenon. An extensive literature review along with an updated bibliography complete this book.

The behaviour of river systems is a result of the complex interaction between flow, sediments, morphology and habitats. Furthermore, rivers are often used as a source of water supply and energy production as well as a waterway for transportation. The main challenge faced by river engineers today, in collaboration with environmental and ecological scientists, is to restore the channelized rivers under the constraints of high urbanization and limited space, as well as sustainable water use. During the seventh International Conference on Fluvial Hydraulics "River Flow 2014" at Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland, scientists and professionals from all over the world addressed this challenge and exchanged their knowledge regarding fluvial hydraulics and river morphology. This book comprises the proceedings of the high quality contributions of the participants, which reflect the state-of-the-art in the fields of river hydrodynamics, morphodynamics, sediment transport, river engineering and restoration. The conference was organized under the auspices of the Committee on Fluvial Hydraulics of the International Association for Hydro-Environment Engineering and Research (IAHR). Past River Flow conferences have witnessed a significant increase in participation of our community of river engineers and researchers, confirming the need for such a forum.