The main theme of Water2010, the joint ISSH-2010 and ICWRER-2010 Symposium is ‘Hydrology, Hydraulics and Water Resources in an Uncertain Environment’. In the current changing environment, water resources modeling and management are becoming more and more important and challenging. How to deal with the changing frequency and magnitude of droughts and floods or how to ensure access to drinking-quality water are only examples of difficulties that several countries are facing. In this context, the first decade of the century is an angular point for the decades to come in which hydrologists and water resources engineers will play an increasingly important role.