Predictions in Ungauged Basins (PUB) is an IAHS initiative operating throughout the decade of 2003-2012, established with the primary aim of reducing uncertainty in hydrological predictions. It is a 'grass-roots' movement intended to engage the interest of hydrologists around the world, and has grown to encompass an enormous variety of approaches and settings.

PUB aims to encourage a paradigm shift in the methods used to predict streamflow, sediment and water-quality variables, away from traditional methods reliant on statistical analysis and calibrated models, and towards new techniques which are based primarily on improved understandings and representations of physical processes within and around the hydrological cycle.

Specific areas of interest include flood estimation, climate variability and drought, erosion and sedimentation, snow- and ice-melt, nutrient fluxes and eutrophication issues, land-use and salinity.

PUB is now in its 5th and final 'biennum'; this website provides descriptions of the aims, methods and progress of the scientific programmes with which it is associated, and a linking resource through which to explore wider issues related to hydrological research in a world of increasing environmental uncertainty.