The International Committee on Large Dams (ICOLD) held its 27th International Congress in Marseille, France (12-19 November 2021). 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.