This bulletin 178, Operation of Hydraulic Structures of Dams, is an update of Bulletin 49A (1986), which was the second edition of Bulletin 49 (1984). The current update was prepared using developments and progress made in the last 30 years with operation equipment, staff building and training, and regulatory requirements. Bulletin 178 addresses the need for safe reservoir discharge under a variety of conditions, the dam operator's staffing, evaluation (inspection) of the condition of operating equipment, and operation during unusual or extreme conditions. The operation during unusual or extreme conditions is generally focused on flood and the current abilities to predict significant precipitation events, monitor the flood approach and impact, and communicate and implement the actions needed for safe operation. An annex is provided with seven case studies that provide relevant histories for the subject matter.

Ce Bulletin 178 est une mise à jour du Bulletin 49A (1986) qui était la deuxième édition du Bulletin 49 (1984). Cette mise à jour a été préparée en considérant les développements et les progrès réalisés au cours des 30 dernières années sur l'équipement d'exploitation, la constitution des équipes, la formation du personnel ainsi que les exigences réglementaires. Le bulletin traite de la nécessité d'un déversement sécuritaire du réservoir dans diverses conditions, de la dotation en personnel de l'exploitant du barrage, de l'évaluation (inspection) de l'état de l'équipement d'exploitation et de l'exploitation dans des conditions inhabituelles ou extrêmes. L'opération dans des conditions inhabituelles ou extrêmes est généralement axée sur les crues et la capacité actuelle de prévoir les précipitations importantes, afin de surveiller l'approche et l'impact des inondations, de communiquer avec le public pour mettre en oeuvre les mesures nécessaires à une exploitation sécuritaire. Une annexe présente sept études de cas qui fournissent des antécédents pertinents pour le sujet.

The Commission Internationale des Grands Barrages (CIGB) / International Commission on Large Dams (ICOLD) is a non-governmental International Organization which provides a forum for the exchange of knowledge and experience in dam engineering.

The Organization leads the profession in ensuring that dams are built safely, efficiently, economically, and without detrimental effects on the environment. Its original aim was to encourage advances in the planning, design, construction, operation, and maintenance of large dams and their associated civil works, by collecting and disseminating relevant information and by studying related technical questions.

Since the late sixties, focus was put on subjects of current concern such as dam safety, monitoring of performance, reanalysis of older dams and spillways, effects of ageing and environmental impact. More recently, new subjects include cost studies at the planning and construction stages, harnessing international rivers, information for the public at large, and financing.