Reservoir management is the academic and applied discipline focused on the systematic planning, operation, and optimization of resource systems contained within natural or engineered reservoirs. This field investigates the complex interplay of physical, chemical, and biological processes within the reservoir, resource inflow and outflow dynamics, operational strategies, and associated environmental and socio-economic impacts. Characterized by its multidisciplinary nature, reliance on modeling and simulation, and long-term planning horizon, it seeks to balance resource utilization with conservation, sustainability, and risk mitigation.