Rivers are complex entities. In addition to being valuable wildlife habitats, they support human activities by providing water for human usage, renewable energy and convenient transportation. Rivers may also pose threats to riverine communities, in the form of floods and other natural or man-induced hazards. Contemporary societies recognize their responsibility in ensuring the sustainable use of rivers and in preserving river's intrinsic ecological and landscape values. This obligation is often in conflict with riverine economic exploitation and with risk management concerns. As a discipline, Fluvial Hydraulics makes a significant contribution to the development of strategies for sustainable river use by providing new modelling tools and engineering techniques based on advances in phenomenological understanding and in computational modelling. River Flow 2012 comprises the Proceedings of the sixth edition of the International Conference on Fluvial Hydraulics, organized under the auspices of the Committee on Fluvial Hydraulics of the International Association for Hydro-Environment Engineering and Research (IAHR). The book covers issues such as river hydrodynamics, morphodynamics and sediment transport. Other contributions describe interdisciplinary approaches and experiences, particularly regarding interfacial activities involving environmental sciences and information technologies. River Flow 2012 contains the most recent theoretical accomplishments, numerical developments, experimental investigations and field studies in Fluvial Hydraulics. It is an excellent resource for researchers, civil and environmental engineers, and practitioners in river-related disciplines.