A review of spillway flood design standards in European countries, including freeboard margins and prior reservoir level

As a cornerstone to its review of the ICE guide to Floods and Reservoir Safety, the Working Party has surveyed European practice. This paper summarises the outcome of a questionnaire that focussed on the key parameters of Table 1 in that guide. Standards continually evolve as they adjust to operational experience and incidents inside and outside any one country. Given the varied number, type and mean age of dams coming under any single legislation, it is not surprising to find that coverage differs. There is no reason to think that UK guidelines need change fundamentally unless and until joint probability research into the relationship between the key parameters warrants it. However overseas experience of ice sheets, log jams and similar rare events needs to be drawn upon more widely in the United Kingdom. The concept of a Probable Maximum Flood has only limited acceptance in much of Europe but so has hazard categorisation.