According to UNESCO, floods are the most common and widespread of all natural disasters, besides fire. They are also the number one related killer. Flood disasters account for about a third of all natural disasters (by number and economic losses). The average death toll per year is approximately 7,000 people, the average number of people suffering flood damage is about 66 million.

Dikes and levees play a pivotal role in protection against flooding. Breaches in these protection systems can be devastating, depending on their location and the intensity of the event. The fact that scientists, engineers and decision makers recognise the importance of levees and their role in flood risk management is underpinned by an increasing attention to the topic through conferences and workshops in recent years. For example, GeoRisk 2011 (Atlanta), the 3rd International Symposium on Geotechnical Risk and Safety (ISGSR 2011, Munich) or the 2nd European Conference on Flood Risk Management (FLOODrisk 2012, Rotterdam) all held sessions particularly dedicated to levee and dam reliability as well as flood risk.

As a result of the general worldwide interest in the topic, Prof. G.A. Fenton (Dalhousie University, Managing Editor of Georisk for North America), who happened to be on sabbatical leave in the Netherlands in 2012, invited us to be guest editors for a special issue on the topic ‘Levee Reliability and Flood Risk’ in Georisk.

The resulting special issue, appearing as Vol. 7, Issue 2 (June 2013) of Georisk, contains invited contributions from Germany, Hong Kong and the Netherlands. The general topics are reliability analysis of levees (incl. the effects of heterogeneity), real-time safety assessments using fragility curves and code calibration as well as flood risk (system) analysis aspects with particular focus on the role of levee failure and the potential consequences.

The paper by Bachmann et al. entitled “Fragility curves in operational dike reliability assessment” is part of this special issue but was published in the previous issue of the journal (Vol. 7, Issue 1, 2013). Readers interested in this topic should also read Bachmann et al.‘s paper along with the papers in this issue.

We would like to express our gratitude to the contributing authors and reviewers of the articles in this special issue and to the editorial management of Georisk for supporting this effort. The papers are in alphabetical order of the first authors’ last names.@en