The Flow Regimes from International Experimental and Network Data (FRIEND–Water) is an international collaborative network of experts that aims to generate new understanding about regional hydrology and multi scale water cycle processes. FRIEND Water is investigating long term variations and changes in hydrological variables to better understand the climate, river basin and human interventions on the spatial and temporal distribution of water. The research and training supported by the FRIEND–WATER programme are critical for evidence based decision-making and ensuring capacity for Water Resources Management, Socio-Economic development, safeguarding the environment and assessing the impact of global change, including climate change and human activities.

As a cross cutting theme of UNESCO's Intergovernmental Hydrological Programme (IHP), FRIEND–Water contributes to research on (1) regional water resources, (2) water related disasters such as floods and droughts, (3) global change and water cycle, and water education and capacity building. The FRIEND Water programme complements and interacts with many national projects and international initiatives.

FRIEND–Water interacts with and is relevant to all six-core IHP-VIII themes. It was launched during the third phase of IHP from (1984–1988) with the initial focus on the data-rich basins of northwest Europe and progressively expanded with the different phases to all the regions. The programme has evolved in more than 35 years of its existence. Since then it kept growing interest among the scientific community with up to eight regional components around the world, that is: SA FRIEND–Water (Southern Africa), CONGO FRIEND–Water, FRIEND–Water NILE, AMIGO FRIEND–Water (Latin America), EURO-FRIEND–Water, MEDFRIEND-Water (Mediterranean countries), AOC FRIEND–Water (West and Central Africa), ASIAN PACIFIC FRIEND–Water.

The 8th series of the Global FRIEND–Water conference held in 6–9 November 2018, in Beijing China was co-organized by UNESCO with Government of China through the Department of Hydrology, Ministry of Water Resources of the People's Republic of China within the framework of the UNESCO Intergovernmental Hydrological Programme (IHP) in Beijing China.

The Conference focused on the theme of hydrological processes and water security in a changing world and was a contribution to the United Nations 2030 Agenda for Sustainable Development, and provided the opportunity to reflect on the interactions between society and the hydrological system in a changing environment. Furthermore, participants of the conference also stressed the relevance of adopting multidisciplinary approaches to understand better climatic and anthropogenic impacts on the hydrological cycle ranging from local to global scales.

I would like to thank the Government of China for all the support and the conference organizing committee for brining participants from more than 40 countries to present scientific and research findings during the oral and postal sessions. This proceeding constitutes the main outcome of the conference, and covers the following areas: hydrological processes and climatic impact; data monitoring, observation, and analysis extremes such as floods and droughts and water resources and environmental impacts and management.

I would like to thank the conference organizing committee, editorial members and International Association of Hydrological Sciences for compiling papers in the Proceedings of the International Association of Hydrological Sciences (PIAHS) publication. UNESCO will continue to support countries to address the local, national, regional and global challenges towards achieving water security by promoting and leading international hydrological research, facilitating education and capacity development and enhancing governance for sustainable and peaceful water resources management.