Can end-users' flood management decision making be improved by information about forecast uncertainty?

In the course of the D-PHASE project, a visualisation platform was created, which provided a large amount of meteorological and hydrological information that was used not only by scientists, but also by scientifically aware laypeople in the field of flood prevention. This paper investigates the benefits of the platform for its end-users' situation analysis and decision making, and in particular, its usefulness in providing an ensemble of models instead of already interpreted forecasts. To evaluate the platform's impact on users in Switzerland, a panel approach was used. Twenty-four semi-standardized questionnaires were completed at the beginning of the demonstration phase and 27 questionnaires were completed five months later. The results suggest that the platform was perceived as adding value to both situation analysis and decision making, and helped users to feel more confident about both. Interestingly, users' preference for receiving complex, primary information and forming their own impressions over receiving interpreted information and recommendations increased during the demonstration phase. However, no actual improvement in the quality of decisions was reported. (C) 2011 Elsevier B.V. All rights reserved.