27.11.2015: In the current issue of Water Resources Research an international team led by Prof. Bruno Merz, Head of GFZ section Hydrology, analyses the problem of misinterpretations in flood risk management. Two causes for surprise with catastrophic consequences are identified: limits in predictability caused by complexity of flood extremes and biases  in human perception and decision making.

During the catastrophic Elbe river flood of 2002 more than 130 dikes broke, oil tanks that were not protected were flooded in great quantities, causing high overall damage. This event is an example for a scenario that was beyond perception of the involved parties. The team of Prof. Merz calls this misinterpretation of risk assessment the element of „surprise“. To reduce it the risk assessment should be extended by including not only what is likely but also what is possible. Assumptions should be systematically scrutinized concerning mistakes and uncertainties, as an integral part of risk assessment.

„To reduce surprise with catastrophic results, an awareness for the limits of knowledge and the vulnerability in regards of errors in reasoning is needed “, says Bruno Merz. It is possible to improve preparedness when risk experts and managers are better aware of the danger of misinterpretations and existing gaps of knowledge. Here a cooperation of scientists, engineers and social scientists is of great importance.

Merz, B., Vorogushyn, S., Lall, U., Viglione, A., Blöschl, G., 2015. Charting unknown waters – On the role of surprise in flood risk assessment and management. Water Resources Research 51 (8), 6399 – 6416, DOI: 10.1002/2015WR017464