The International Hydrological Programme (IHP) is an intergovernmental programme of the UN system devoted to water research, water resources management, and education and capacity building. Since its inception in 1975, IHP has evolved from an internationally coordinated hydrological research programme into an encompassing, holistic programme to facilitate education and capacity building, and enhance water resources management and governance. IHP facilitates an interdisciplinary and integrated approach to watershed and aquifer management, which incorporates the social dimension of water resources, and promotes and develops international research in hydrological and freshwater sciences. IHP is implemented in phases developed through a comprehensive consultative process with its 168 National Committees, international scientific associations and other UN bodies. As part of its Eighth Phase (2014-2021), IHP is aiming to improve water security in response to local, regional, and global challenges. IHP longstanding collaboration with IHA includes the joint UNESCO/IHA GHG Status of Freshwater Reservoirs Research Project.