Charting unknown waters-On the role of surprise in flood risk assessment and management

• Published in: Water resources research 2015-08, Vol.51 (8), p.6399-6416
• Main Authors: Merz, B., Vorogushyn, S., Lall, U., Viglione, A., Blöschl, G.
• Format: Article
• Language: English
• Subjects: cognitive biases; deep uncertainty; Environmental risk; Flood control; Flood insurance; flood risk; Floods; predictability; Risk assessment; Risk management
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1002/2015WR017464

Unexpected incidents, failures, and disasters are abundant in the history of flooding events. In this paper, we introduce the metaphors of terra incognita and terra maligna to illustrate unknown and wicked flood situations, respectively. We argue that surprise is a neglected element in flood risk assessment and management. Two sources of surprise are identified: (1) the complexity of flood risk systems, represented by nonlinearities, interdependencies, and nonstationarities and (2) cognitive biases in human perception and decision making. Flood risk assessment and management are particularly prone to cognitive biases due to the rarity and uniqueness of extremes, and the nature of human risk perception. We reflect on possible approaches to better understanding and reducing the potential for surprise and its adverse consequences which may be supported by conceptually charting maps that separate terra incognita from terra cognita, and terra maligna from terra benigna. We conclude that flood risk assessment and management should account for the potential for surprise and devastating consequences which will require a shift in thinking. Key Points: Surprise is a neglected element in flood risk assessment and management Limits of predictability and cognitive biases need closer attention Approaches for reducing surprise and its malicious consequences are discussed