EurOtop - Manual on wave overtopping of sea defences and related structures. An overtopping manual largely based on European research, but for worldwide application.

This Overtopping Manual gives guidance on analysis and/or prediction of wave overtopping for flood defences attacked by wave action. It is primarily, but not exclusively, intended to assist government, agencies, businesses and specialist advisors & consultants concerned with reducing flood risk. Methods and guidance described in the manual may also be helpful to designers or operators of breakwaters, reclamations, or inland lakes or reservoirs. Developments close to the shoreline (coastal, estuarial or lakefront) may be exposed to significant flood risk yet are often highly valued. Flood risks are anticipated to increase in the future driven by projected increases of sea levels, more intense rainfall and stronger wind speeds. This risk may also increase by increasing value of assets in flood risk areas or by increasing number of people in such areas. Levels of flood protection for housing, businesses or infrastructure are inherently variable. In the Netherlands, where two-thirds of the country is below storm surge level, large urban and rural areas may presently (2016) be defended to a flood probability of 1:10,000 years or even minimum of 1:100,000 years, with less densely populated areas protected to 1:1,000 years with a minimum of 1:300 years. In the UK, where low-lying areas are much smaller, new residential developments are required to be defended to 1:200 year return. Understanding future changes in flood risk from waves overtopping seawalls or other structures is a key requirement for effective management of coastal defences. Occurrences of economic damage or loss of life due to the hazardous nature of wave overtopping is more likely, and coastal managers and users are more aware of health and safety risks. Seawalls range from simple earth banks through to vertical concrete walls and more complex composite structures. Each of these require different methods to assess overtopping. Reduction of overtopping risk is therefore a key requirement for the design, management and adaptation of coastal structures, particularly as existing coastal infrastructure is assessed for future conditions. There are also needs to warn or safeguard individuals potentially to overtopping waves on coastal defences or seaside promenades, particularly as recent deaths in the UK suggest significant lack of awareness of potential dangers. The first edition of the EurOtop (2007) was well received in the coastal engineering community and has been used as code for many projects. Guidance on wave run-up and overtopping before 2007 have been provided by previous manuals in UK, Netherlands and Germany including the EA Overtopping Manual edited by Besley (EA, 1999); the TAW Technical Report on Wave run up and wave overtopping at dikes by Van der Meer (TAW, 2002); and the German Die Küste (EAK 2002). Significant new information was obtained from the EC CLASH project collecting data from several nations, and further advances from national and other European research projects. Since EurOtop (2007), new information was established on wave overtopping over very steep slopes up to vertical, on better formulae up to zero relative freeboard, on better understanding of wave overtopping over vertical structures; including the effect of foreshores and storm walls; and on individual overtopping wave volumes. Furthermore, insight can now be given by systematic videos on how a specific overtopping discharge looks like in reality. These videos can be found on the website. This Manual takes account of this new information and advances in current practice. In so doing, this manual will extend and/or revise advice on wave overtopping predictions given in the Rock Manual (2007), the Revetment Manual by McConnell (1998), British Standard BS6349, the US Coastal Engineering Manual (2006), and ISO TC98 (2003).