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

Abstract

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.

Socio-hydrological modelling: a review asking "why, what and how?"

“…Uncertainty in socio-hydrology could certainly be the subject of a paper on its own, and so while this paper outlines some of the aspects of uncertainty which have particular significance for modelling, some aspects are not covered in full detail. For more detailed coverage of uncertainty in a socio- Merz et al (2015).…”

Prediction in a socio-hydrological world

“…The same cannot, however, be said about extreme social disruptions such as wars, pandemics, natural disasters, new technologies or social movements that transform the fabric of society in fundamental ways. These so-called "black swan" events (Taleb 2007) are external to water systems; yet if they do occur, they can be expected to permanently alter the trajectories of the water systems (Merz et al 2015, Di Baldassarre et al 2016. While black swan events are inherently unpredictable, we can nevertheless "stress test" predictive models to assess system robustness.…”

Integrating human behaviour dynamics into flood disaster risk assessment

“…52 In reality, adaptation dynamics are largely determined by the behavior and perception of the aforementioned stakeholders, influencing both the risk and each other's decisions, sometimes in unpredictable ways. 53 For example, cognitive biases have played a pivotal role in past flood disasters and have catalyzed adaptation. 54 In most situations in which significant steps were taken to reduce flood risk, these steps were triggered by experiences from previous disasters.…”