The International Decade for Predictions in Ungauged Basins (PUB) has entered its fourth Biennium. The immediate goals of this new biennium are several. One is to address the PUB Science Plan by working to reduce uncertainty in hydrological prediction by restricting model calibration and increasing hydrological understanding and by moving to the development of new innovative models based on an improved understanding in hydrology. Another is to undertake the renewal of the existing PUB Themes (basin intercomparison, process heterogeneity, uncertainty and diagnostics, new data collection, new theory, new models and PUB working groups) and the consolidation of their achievements by soliciting for new inputs from the scientific community to the Themes. A major thrust of the next two years will be moving from Themes to Teams by the solicitation of proposals for “Integration and Demonstration Projects” teams which will develop local solutions for prediction in national and regional ungauged basin situations.
This session calls for presentations that show:
• how to predict hydrology with restricted or no model calibration;
• how new models can take advantage of improvements in process and theoretical understanding;
• how the analysis of common morphology, climate features, and dominant processes can be used as a basis for describing catchment similarity, for explaining and mapping regional hydrological patterns, and for pooling together hydrologically homogeneous groups of sites;
• how to improve the assessment of uncertainty of streamflow prediction in ungauged sites.
It also calls for presentations that demonstrate how PUB can be achieved in various parts of the world, what the challenges are and what the early successes are.

Solicited speakers:

Alexander Gelfan (Russian Academy of Sciences, Moscow) - "Assessing the parameters of a physically based runoff generation model at lack of runoff data"

Thomas Kjeldsen (CEH Wallingford) - "On the use of heterogeneous pooling groups"

Hubert H.G. Savenjie (Delft University, EGU Darcy medallist 2008) - "Advances in hydrological modelling based on improvement in process and system understanding"