Uncertainty Analysis in Environmental Modeling: Towards Improved Evaluation and Diagnostics of Hydrological and Environmental Models (2nd International IAHS-PUB Workshop 15th-18th July 2007 in Bertinoro, Italy)

This paper reports back to the community some of the major findings from a recent discussion-based workshop to explore state-of-the-art uncertainty analysis techniques and their value for diagnostic model analysis. The participants of the previous 'uncertainty in environmental modelling' workshop in Italy in 2004 concluded that there is an urgent need for new and better diagnostic approaches to evaluate environmental models and to contribute to the shift from model calibration to understanding - the main focus of Prediction in Ungauged Basins (PUB) and of its working group on 'Uncertainty analyses and model diagnostics' who organized this workshop. Current, largely performance-based approaches tend to lack the power to extract information from model applications that helps to diagnose where models fail and how models could be improved. The focus of the recent second workshop was, therefore, 'diagnostic evaluation of hydrological and environmental models' and dealt with four specific science questions in the context of diagnostic model evaluation: [1] How should we measure model performance? [2] How can we separate and identify observation error versus model error? [3] What is the information content of hydrologic data? [4] How can we analyze temporal parameter variability to guide hydrological and environmental model diagnostics and improvement? We report here the major conclusions of the workshop and of the subsequent review papers prepared by the participants, with the main objective to further engage with the research community and to identify opportunities for future collaborations and developments within the PUB uncertainty working group.