10 things you might not know about EurOtop


Overtopping and coastal flooding are a growing concern in the UK due to sea-level rise and possible increase in storminess associated with climate change. A key requirement for effective management of coastal defences is understanding future changes in flood risk from waves overtopping seawalls or other structures

To help understand the mechanisms of overtopping and develop overtopping prediction tools a guidance manual was produced called EurOtop.

EurOtop has been developed to both assist engineers concerned with existing defences as well as new schemes. The manual refers to best practice methods and data from worldwide research studies.

The latest edition of EurOtop (European Overtopping Manual) was released in October 2016 which provides improved guidance on nearly all aspects of wave overtopping.

Here are 10 things you might not know about EurOtop:

  • The original EurOtop (European Overtopping Manual) manual was published in 2007;
  • Wave overtopping is a hazard to which three levels of guidance are provided on tolerable overtopping discharges with respect to damage to defence structure(s), direct hazard to people immediately behind the defence, and damage to property, operation and / or infrastructure;
  • Two types of wave overtopping are discussed in the manual – ‘green water’ overtopping (where a continuous sheet of water passes over the defence) and the second type of overtopping is where waves break on the seaward face of the structure and produce ‘splash overtopping’ over the crest of the defence.
  • Four hydrodynamic parameters consisting of wave and water levels are required for overtopping calculations i.e. from model outputs;
  • It has been estimated that £150 billion of assets and 4 million people are currently at risk from coastal flooding in the UK [1];
  • At least 12 people have been killed in the UK by wave overtopping or related processes during 1999 to 2002, and approximately 60 people have been killed in Italy over the last 20 years [2];
  • EurOtop 2nd pre-release edition contained 7 chapters which address nearly all aspects of overtopping from calculations to the most relevant tool/software to use;
  • Tsunamis are not considered in EurOtop;
  • 9 authors were involved in developing the EurOtop 2nd Edition;
  • Original overtopping database included 10,000 overtopping simulations. The new database contains over 13,000.

For more information on our flood risk/ resilience knowledge go to http://www.abpmer.co.uk/services/flood-riskresilience/

Prepared by Alain Le Vieux, Coastal Process Specialist

1. Environment Agency, 2009. Flooding in England: A National Assessment of Flood Risk. Environment Agency report. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/292928/geho0609bqds-e-e.pdf
2. Allsop W, Report on hazard analysis. CLASH work package 6-report. http://www.clash-eu.org; 2004

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