Reservoirs allow water to be moved forward in time and are central to the performance and operations of many water resource systems. This chapter reviews the history and purposes of reservoirs in water resource systems, their physical planning and design, and the design of their operation. Emphasis is
placed on the review of different technical and institutional approaches to establishing reservoir operating rules and adapting them to changing circumstances. Because the operation of reservoirs has changed considerably over the decades, as society’s water problems, institutions, and technologies have changed, and as the economic structures and populations have changed, several trends in reservoir operation are then discussed.
