Tailings are produced from the processing of mineral ores and are commonly stored within embankment dams. The design of the dams requires application of sound engineering principles and an understanding of the properties of the tailings. This Bulletin provides a framework for classifying different types of tailings, ranging from ultra-fine to coarse, based on their geotechnical properties and provides typical geotechnical parameters for the different tailings types. Technologies for dewatering tailings to reduce the risk of storage continue to be developed and the different technologies, from thickening to filtration, and re-application of old technologies are presented to illustrate the options available and, where appropriate, typical in situ properties. This bulletin is directed towards a wide audience of stakeholders: designers, owners, regulators, communities and various organizations and provides a reference for communicating tailings properties and the benefits and limitations of technologies. All mining operations, and thereby tailings operations, are unique. There is no one-solution-fits-all. Tailings dam designs need to account for site-specific conditions, such as climate, physiography, geochemistry, geomorphology, seismology, mining processes, environment, and community setting, with the application of technologies playing an important role in developing safe, sustainable tailings facilities. Les stériles miniers sont produits à partir du traitement des minerais et sont généralement stockés derrière des barrages en remblai. La conception des barrages nécessite l'application de principes d'ingénierie solides et une compréhension des propriétés des résidus. Ce bulletin fournit un cadre pour classer différents types de résidus, allant de l'ultra-fin au grossier, en fonction de leurs propriétés géotechniques et propose des paramètres géotechniques typiques pour les différentes sortes de résidus. Les technologies d'assèchement des résidus pour réduire le risque de stockage continuent à être développées ; les différentes technologies, de l'épaississement à la filtration, en passant par l’application des anciennes technologies, sont présentées pour illustrer les options disponibles et, le cas échéant, les propriétés in situ typiques. Ce bulletin s'adresse à un large public d'intervenants : concepteurs, propriétaires, régulateurs, communautés et organisations diverses et fournit une référence pour communiquer les propriétés des résidus et les avantages et les limites des technologies. Toutes les opérations minières et, par conséquent, les traitements des résidus, sont uniques. Il n'y a pas de solution unique pour tous. La conception des barrages de résidus doit tenir compte des conditions propres au site, telles que le climat, la physiographie, la géochimie, la géomorphologie, la sismologie, les processus miniers, l'environnement et le milieu communautaire, l'application de technologies jouant un rôle important dans le développement de parcs à résidus sûrs et durables.

Integrated operation of hydropower stations and reservoirs has become a trend of hydropower exploitation, as an effective technical measure, integrated operation can improve the utilization efficiency of water resources, reduce the risks of flood and drought disaster, increase the safety and stability power grid and make sure that hydropower stations and reservoirs operate in an appropriate and economical way. This bulletin gives an overview of the main functional and operational aspects relating to cascade hydropower stations and reservoirs, it was formed by reviewing of all the related aspects proposed and case studies provided by committee members. It collected and sorted out operation modes and practical experiences of hydropower stations and reservoirs in ICOLD member countries, summarized the feasibility measures, benefit evaluation methods and system platform construction of hydropower stations and reservoirs with comprehensive benefits, and shared case studies from 10 countries, including Brazil, China, France, Iran, Japan, Korea, Nigeria, Russia, Switzerland and USA. L'exploitation intégrée des centrales hydroélectriques et des réservoirs est devenue une mesure technique efficace de l'exploitation hydroélectrique. L'exploitation intégrée peut améliorer l'efficacité d'utilisation des ressources en eau, réduire les risques de catastrophe, d'inondation et de sécheresse, augmenter la sécurité et la stabilité du réseau électrique et faire fonctionner les centrales hydroélectriques et les réservoirs de manière appropriée et économique. Ce bulletin donne un aperçu des principaux aspects fonctionnels et opérationnels relatifs aux centrales hydroélectriques et réservoirs en cascade. Il passe en revue tous les aspects connexes proposés et des études de cas fournies par les membres du comité. Il rassemble les modes de fonctionnement et les expériences pratiques des centrales hydroélectriques et des réservoirs dans les pays membres de la CIGB. Il résume les mesures de faisabilité, les méthodes d'évaluation des avantages et la construction de plates-formes de systèmes de centrales hydroélectriques et de réservoirs avec des avantages complets. Il bénéficie des expériences et des études de cas de 10 pays, y compris Brésil, Chine, Corée, France, Iran, Japon, Nigéria, Russie, Suisse et USA.

Dams are planned, constructed, and operated to meet human needs - generation of energy, irrigated agricultural production, flood control, public and industrial supply, supply of drinking water, and various other purposes. Dams impound water in reservoirs during times of high flood that can be used for human requirements during times with inadequate natural flows. Positive impacts of dams are improved flood control, improved welfare resulting from new access to irrigation and drinking water. Without dams there would be insufficient food to feed the world's people and energy would be generated by burning fossil fuels that produce greenhouse gases. Despite this progress there remain significant concerns about the environmental impacts of dams. These environmental impacts are complex and far reaching, remote of the dam, and may occur in time with the dam construction or later and may lead to a loss of biodiversity and of productivity of natural resources. This bulletin compiles improvements in knowledge and state of the art technology to avoid or mitigate environmental impacts of dams on the natural ecosystem as well as to the people that depend upon them for their livelihood and also addresses the mitigation of environmental impacts on dams and reservoirs. Les barrages sont planifies, construits et exploites de maniere a repondre aux besoins humains. Les barrages retiennent l'eau dans les reservoirs pendant les periodes de forte crue, une eau qui peut etre utilisee pour les besoins de l'homme pendant les periodes d'insuffisance des debits naturels. Les impacts positifs de barrages sont le controle des crues et l'amelioration du bien-etre resultant du nouvel acces a l'irrigation et a l'eau potable. Sans barrages, la production alimentaire serait insuffisante pour nourrir la population du globe et l'energie serait generee en brulant des combustibles fossiles qui produisent des gaz a effet de serre. Malgre ces progres, d'importantes preoccupations subsistent quant aux retombees des barrages sur l'environnement. Les impacts environnementaux sont complexes et d'une grande portee. Ils peuvent se produire au moment de la construction du barrage ou plus tard et peuvent entrainer une perte de la biodiversite et de la productivite des ressources naturelles. Le present bulletin compile l'amelioration des connaissances et des technologies les plus recentes pour eviter ou attenuer les impacts environnementaux des barrages sur l'ecosysteme naturel ainsi que pour les personnes qui en dependent pour leur subsistance. Il aborde egalement l'attenuation des impacts environnementaux sur les barrages et les reservoirs.

The present Bulletin presents a complete response from the 'Technical Committee of ICOLD on Dams and Water Transfer (CDWT)' to the Terms of Reference. It starts with related global information, brings out related efforts made in countries with completely differing climate, economy, population distribution etc. about present status within and between river basins & countries - both surplus and or deficit, while recognizing the crucial role played by dams in water transfer to needy regions. It then enumerates guidelines followed in considering various options, while identifying geographical issues, limited by political territories & legal issues like water treaties. Essentially then, it dwells on possible need, potential and problems in water transfers that must be handled to overcome B/C issues faced by needy countries. In order to assist concerned professionals, the Bulletin finally elaborates on objections raised by different stake-holders in the subject and provides answers generated globally. The on-going debate world-over about WRD versus environmental impacts is then dealt with to help Member-countries overcome various issues. Le present Bulletin presente une reponse complete du " Comite Technique sur les barrages et les transferts d'eau ". Il commence par des informations mondiales, fait ressortir les efforts deployes dans des pays au climat, a l'economie, a la repartition de la population, etc. completement differents sur l'etat actuel au sein et entre les bassins fluviaux et les pays - a la fois excedentaire et / ou deficitaire, tout en reconnaissant le role crucial joue par les barrages dans le transfert d'eau vers les regions necessiteuses. Il enumere ensuite les lignes directrices suivies pour considerer diverses options, tout en identifiant les problemes geographiques, limites par les territoires politiques et les questions juridiques comme les traites sur l'eau. Essentiellement, il s'attarde donc sur les besoins, le potentiel et les problemes possibles des transferts d'eau qui doivent etre traites pour surmonter les problemes auxquels sont confrontes les pays dans le besoin. Afin d'aider les professionnels concernes, le Bulletin elabore enfin les objections soulevees par les differents acteurs du sujet et apporte des reponses generees globalement. Le debat en cours dans le monde entier par rapport aux impacts environnementaux est ensuite traite pour aider les pays membres a surmonter divers problemes.

As reservoir sedimentation has proven to be a serious problem in South Africa, research in this field has been ongoing for more than 70 years. This publication emanates from extensive research which has been undertaken over the past 30 years with the support of the South African Department of Water and Sanitation as well as the South African Water Research Commission. A great deal of information has fortunately also been obtained from China. Given the universal nature of hydraulic formulae it is not surprising, yet gratifying, that Chinese and South African data generally conform to the same mathematical relationships. This indicates that these relationships should be applicable in other countries as well. Much of the information contained here has been condensed from a more comprehensive publication. This ICOLD Bulletin follows on Bulletin 115 "Dealing with reservoir sedimentation", which gave guidelines for management of reservoirs to limit sedimentation. The guidelines on mathematical modelling of sediment transport dynamics in reservoirs in this document can be used during the planning and design of new dams, as well as for the management of existing dams. Comme la sedimentation dans les reservoirs s'est averee etre un probleme serieux en Afrique du Sud, la recherche dans ce domaine est en cours depuis plus de 70 ans. Cette publication emane de la recherche etendue qui a ete menee au cours des 30 dernieres annees avec l'appui du ministere sud-africain de l'eau et de l'assainissement, ainsi que de la commission sud-africaine de recherche sur l'eau. Un grand nombre d'informations ont egalement ete obtenues de la part de la Chine. Etant donne le caractere universel de formules hydrauliques, il n'est pas surprenant, mais tres gratifiant, que les donnees chinoises et sud-africaines se conforment generalement aux memes relations mathematiques. Ceci indique que ces relations devraient etre applicables dans d'autres pays egalement. Une grande partie de l'information contenue ici a ete condensee a partir d'une publication plus complete. Ce bulletin CIGB fait suite au bulletin 115 "Traite sur la sedimentation dans les reservoirs", qui a donne des directives pour la gestion des reservoirs en vue de limiter la sedimentation. Les directives sur la modelisation mathematique de la dynamique de transport des sediments dans les reservoirs de ce present document peuvent etre utilisees lors de la planification et la conception de nouveaux barrages et pour la gestion des barrages existants.

The Bulletin is intended as a general document aimed at a wide technical audience involved with or affected by hydropower. Basic background data and some statistics are presented, with specific reference to hydro-electricity production, hydropower dams, hydropower plants, in operation or under construction. Key aspects of hydropower are discussed. Data are presented about typical capital and both internal and external operating costs. Environmental and social impacts are discussed and reference is made to the impact reservoirs have on greenhouse gas emissions. A section is dedicated to the exploitation of tidal energy by means of barrage systems. The current extent of hydropower development and the influence of policies aimed to favour the development of renewable energies are also discussed. Reference sources of information, on hydropower in general and interesting case-histories, are provided. Le Bulletin se veut un document general destine a un large public technique implique ou affecte par l'hydroelectricite. Des donnees de base et quelques statistiques sont presentees, avec une reference specifique a la production hydroelectrique, aux barrages hydroelectriques, aux centrales hydroelectriques, en fonctionnement ou en construction. Les principaux aspects de l'hydroelectricite sont discutes. Les donnees sont presentees sur le capital type et les couts de fonctionnement internes et externes. Les impacts environnementaux et sociaux sont discutes et il est fait reference a l'impact des reservoirs sur les emissions de gaz a effet de serre. Une section est dediee a l'exploitation de l'energie maremotrice au moyen de systemes de barrage. L'ampleur actuelle du developpement hydroelectrique et l'influence des politiques visant a favoriser le developpement des energies renouvelables sont egalement abordees. Des sources d'information de reference, sur l'hydroelectricite en general et des etudes de cas interessantes, sont fournies.

Dam decommissioning or dam removal has been increasingly common since the past decade. The reason for considering dam removal may have to do with the safety of dams, high repair costs, high operating and maintenance costs, or effects on fish passage and water quality. However, the decision to remove a dam must be based on careful evaluation of the alternatives to address the specific problem at each dam. The ICOLD Committee for decommissioning dams was established in 2005 to develop information that can be used by ICOLD members to respond to questions about the dismantling of dams and to provide a forum for the exchange of information . This ICOLD Bulletin is not intended as a design guide, but as a guide to the decision making process, consultation and regulatory approvals, design and construction issues, sediment management and performance monitoring. The primary aim of these Dam decommissioning guidelines is to provide dam owners, dam engineers and other professionals with the information needed to guide decision making when considering dam dismantling as a project alternative. They are not meant to be used as a design guide, but as a guide to highlighting the points of interest. The guidelines in this ICOLD Bulletin apply only to flood defense structures and not to fall dams.

Dams are part of human achievements that induce great benefits for society but also bear a potential risk to people, property and the natural environment. The risk of a dam rupture is extremely low and diffi cult to quantify accurately. The aim of 'Dam surveillance' (ICOLD Bulletin 158), is to help reduce these risks by early detection of an undesirable event. The objective of dam surveillance is to make a precise and timely diagnosis of the behavior of dams, in order to prevent undesirable consequences. Both the monitoring system and surveillance program has to be designed and should be able to detect any abnormal behaviour. 'Dam surveillance' (ICOLD Bulletin 158), emphasizes the following aspects: * Routine visual inspection * Special inspection * Checking and testing of Hydro-electromechanical equipment * Monitoring parameters and devices * Automation * Maintenance of ageing monitoring systems * Re-instrumentation of existing dams * Recent developments * Data management * Dam documentation management * Assessment of dam condition and behaviour * Assessment of routine dam safety monitoring programme * Prioritization of maintenance, remedial and upgrading works.

Dam Safety Management is a major concern during the entire lifetime cycle of a dam scheme. This is particularly true for the operational phase of the scheme that represents by far the longest period in its lifetime cycle. Bulletin 154 presented a general approach and concepts to be applied to dam operation. The current Bulletin 175 extends the developed concepts to all phases preceding the operational phase. Many risks associated with the operation of existing dams have their origins in other phases preceding the actual operation. Although there are numerous ICOLD Bulletins addressing technical aspects of planning, design, construction and commissioning of dams, there is not a single Bulletin which covers the subject in a comprehensive manner. The current document is a first attempt to capture all relevant dam safety aspects in all preoperational phases by systematically characterizing the actors involved, their roles, the activities and complex interactions present in different phases of the dam lifecycle. An Overarching Safety Management System is specifically developed that can be applied to all actors involved. La gestion de la securite des barrages est une preoccupation majeure pendant tout le cycle de vie d'un projet de barrage. Cela est particulierement vrai pour la phase operationnelle du systeme qui represente de loin la periode la plus longue de son cycle de vie. Le Bulletin 154 presente une approche generale et des concepts a appliquer a l'exploitation des barrages. Le Bulletin 175 actuel etend les concepts developpes a toutes les phases precedant la phase d'exploitation. De nombreux risques associes a l'exploitation des barrages existants ont leur origine dans d'autres phases precedant l'exploitation proprement dite. Bien qu'il existe de nombreux bulletins ICOLD traitant des aspects techniques de la planification, de la conception, de la construction et de la mise en service des barrages, il n'existe pas un seul bulletin qui couvre le sujet de maniere exhaustive. Le document actuel est une premiere tentative de capturer tous les aspects pertinents de la securite des barrages dans toutes les phases pre-operationnelles en caracterisant systematiquement les acteurs impliques, leurs roles, les activites et les interactions complexes presentes dans les differentes phases du cycle de vie du barrage. Un systeme global de gestion de la securite est specifiquement developpe et peut etre applique a tous les acteurs impliques.

Earthquakes have always been a significant aspect of the design and safety of dams. This position paper deals with the seismic safety of large dams, based on experiences with large earthquakes in Japan (Tohoku earthquake, 2011, Richter magnitude 9.0), in China (Wenchuan earthquake, 2008, Richter magnitude 8.0) and in Chile (Maule earthquake, 2010, Richter magnitude 8.8). It presents ways to prevent key aspects of large dam failure under severe seismic conditions with a focus on design instead of on earthquake prediction. This is done by considering the prevention of uncontrolled rapid release of water of a storage dam under full reservoir conditions in relation to expected seismic conditions. This position paper is composed by the Committee on Seismic Aspects of Dam Design of The International Committee of Large Dams. Les tremblements de terre ont toujours ete un aspect important de la conception et de la securite des barrages. Ce document de synthese traite de la securite sismique des grands barrages, en se fondant sur l'experience acquise lors de grands seismes au Japon (seisme de Tohoku, 2011, magnitude 9,0 sur l'echelle de Richter), en Chine (seisme de Wenchuan, 2008, magnitude 8,0 sur l'echelle de Richter) et au Chili (seisme de Maule, 2010, magnitude 8,8 sur l'echelle de Richter). Il presente des moyens de prevenir les aspects cles de la defaillance des grands barrages dans des conditions sismiques severes en mettant l'accent sur la conception plutot que sur la prevision des seismes. Pour ce faire, on examine la prevention d'une liberation rapide et incontrolee de l'eau d'un barrage de stockage dans des conditions de reservoir plein par rapport aux conditions sismiques prevues. Cet argumentaire est compose par le Comite sur les Aspects Sismiques des Projets de Barrages de la Commission Internationale des Grands Barrages.

Hydrology and dams are two fields that are obviously closely related. Four bulletins have so far been published by the Committee: Selection of Design Flood - Current methods, Dams and Floods - Guidelines and cases histories, Role of Dams in Flood Mitigation - A review and Integrated Flood Management. These bulletins have essentially addressed floods, the risks they represent and their significance for the concerned populations. The present Bulletin deviates slightly from this path, adopting a somewhat more technical perspective. The text consists of three chapters, conceived to be accessible to the practitioners.

ICOLD Bulletin 177 'Roller-Compacted Concrete Dams' presents the state-of-the-art on roller-compacted concrete technology for dams, incorporating the advances of the RCC technology for dams over the last 15 years since the previous Bulletin on the topic was released in 2003. Hence, the present ICOLD Bulletin 177 supersedes ICOLD Bulletin 126 ('Roller-compacted concrete dams - State of the art and case histories', published in 2003) and ICOLD Bulletin 75 ('Roller-Compacted Concrete for Gravity Dams' published in 1989). While roller-compacted concrete technology could have still been considered a new technology in 2003, it is now true to say that construction by roller-compaction has become the standard approach for large concrete gravity dams. This Bulletin addresses all aspects of the planning, design, construction and performance of RCC in dams. Mixture proportioning and quality control are discussed and a comprehensive listing of references is included. Many aspects of RCC in dams have become better understood since the publication of Bulletin No 126 and the present Bulletin contains less information on the particular approaches applied in different countries, but includes more comprehensive information particularly in relation to design, mixture proportioning and construction. With greater understanding, it has further been possible to highlight more definitively the requirements of successful RCC dams, as well as the pitfalls and difficulties that can be associated with RCC dam design and construction. Le Bulletin CIGB 177, intitule " Barrages en Beton Compacte au Rouleau " presente les dernieres avancees en matiere de technologie du beton compacte au rouleau pour les barrages integrant les progres de la technologie BCR pour les barrages au cours des 15 dernieres annees, depuis que le dernier bulletin sur le sujet a ete publie en 2003. Par consequent, le bulletin 177 remplace le bulletin 126 (" Barrages en beton compacte au rouleau - Technique actuelle et exemples ", publie en 2003) et le bulletin 75 (" Beton compacte au rouleau pour barrages-poids - Technique actuelle " publie en 1989). Alors que la technologie du BCR pourrait encore etre consideree comme une nouvelle technologie en 2003, il est maintenant vrai de dire que la construction par le compactage par rouleaux est devenue l'approche standard pour les grands barrage-poids en beton. Ce bulletin aborde tous les aspects de la planification, de la conception, de la construction et de la performance du BCR dans les barrages. Le dosage du melange et le controle de la qualite sont discutes et une liste exhaustive des references est incluse. De nombreux aspects du BCR dans les barrages sont mieux compris depuis la publication du Bulletin no 126. Le present bulletin contient moins d'informations sur les approches particulieres appliquees dans differents pays, mais comprend des informations plus completes notamment en ce qui concerne la conception, le dosage du melange et la construction. Avec une plus grande comprehension, il a ete possible de mettre en evidence les exigences des barrages en BCR reussis, ainsi que les pieges et les difficultes qui peuvent etre associes a la conception et la construction du barrage en BCR.

ICOLD Bulletin 150, Cutoffs for Dams, discusses foundation treatment methods using cutoff-type barriers. High emphasis is given to alluvial deposits throughout this document; however, different materials may require cutoff. The construction of cutoffs has made significant advances mainly through the development of more powerful machinery for drilling and excavation, but also through the introduction of new concepts and techniques, such as jet grouting and deep soil mixing. The following types of cutoffs are presented in this Bulletin: - Diaphragm walls - Vib walls - Pile walls - Superimposed concreted galleries - Jet grouting - Deep mixing These methods are described, and the practical application of each method is illustrated by selected case histories. These case histories also demonstrate how certain difficulties specific to a particular dam site have been dealt with. The performance of cutoffs should be monitored so that their efficiency in reducing flow and piezometric head can be evaluated. Piezometers installed in the foundation upstream and downstream of the cutoff are needed to meet this objective.

The International Committee on Large Dams (ICOLD) held its 26th International Congress in Vienna, Austria (1-7 July 2018). The proceedings of the congress focus on four main questions: 1. Reservoir sedimentation and sustainable development; 2. Safety and risk analysis; 3. Geology and dams, and 4. Small dams and levees. The book thoroughly discusses these questions and is indispensable for academics, engineers and professionals involved or interested in engineering, hydraulic engineering and related disciplines.