On the communication of statistical information about uncertainty in flood risk management

Uncertainty analysis is not typically performed in hydrological and hydraulic modelling. This is problematic because this may lead to inefficient decision making in water management. We therefore explored the role of statistical knowledge on uncertainty in decision-making processes in long term flood risk management within the context of regional water boards in the Netherlands. Research questions were: (1) in which parts of flood risk management statistical information about uncertainty is presented to professionals of district water boards, and in which forms?; (2) how is this information interpreted and used by these professionals, and how does this influence decision-making processes in district water boards?; and (3) how can communication about statistically quantified uncertainty be improved? To answer these questions we conducted interviews and surveys among professionals and board members of Dutch district water boards. Results suggest that statistical information on uncertainty is hard to interpret by professionals. The amount of statistical information on uncertainty strongly reduces during the decision making process, during which the information transforms from quantitative to qualitative. As a result the statistical information on uncertainty is not utilized to solve flood risk management decision problems. These decision problems are not formulated within statistical frameworks for decision making, and statistical information on uncertainty is not collected and presented with the purpose to be input of such frameworks. Practical recommendations for long term flood risk management are discussed.