Predictions are used in both science and in policy making, for testing of scientific hypotheses and decision making, respectively. Examples include forecasting of floods and droughts, of availability of water and energy, and prediction for climate change adaptation. Prediction in policy making, however, has an uneasy role, as predictive uncertainties may be large: future boundary conditions are unknown, model parameter values may be less than optimal and the system considered may change over time, thus invalidating the model used.

The present session aims to contribute to a better understanding of the role and value of prediction in science and policy, through real-world examples showing the success and failure of the use of predictions in either discipline.

For the purpose of this session, ‘predictions’ may include different types (e.g. single valued forecasts, probability forecasts and the use of scenarios) for different time scales (short-term, medium-term, long-term) and for different spatial scales (from local to regional to global). Contributions are solicited from both scientists and decision-makers in the field of all policy making related to hydrological sciences, including water resources management, natural hazards (e.g. floods and droughts), management of rivers and deltas, and climatic change.