The book "Hydrological Dimensioning and Operation of Reservoirs" offers a comprehensive analysis of the planning and operation of storage lakes, which serve as crucial tools for optimizing the distribution and use of water resources. It highlights the challenges arising from the often conflicting demands on water resource utilization and emphasizes the need to develop multifunctional reservoir systems. The authors discuss the impact of dam size on water accumulation and the associated costs, providing valuable insights into the development of effective methods for determining optimal reservoir parameters. The book is aimed at professionals and students involved in the planning and management of water resources, offering both theoretical and practical approaches to solving complex issues related to multi-reservoir systems.