The design and application of scour anticipated designs in river related and coastal structures in various countries and their effectiveness

Keynote lecture at the ICSE2006. Various types of scour can confront the engineer, who has to design and construct a hydraulic structure in a marine environment. The engineer is interested in the magnitude of the scour to be expected and its development in time. He hopes that such information, if at all available, is accurate and that he can base his design and construction method on such information without meeting any unexpected hydraulic response. In principle the engineer can react differently, according to the situation: 1 he accepts that scour will develop after completion of the structure and, given its extent and rate of development, he takes measures to prevent (or limit) damage to the structure and loss of stability; 2 he tries to prevent the scour or, in any case, takes measures to keep it away from the structure; 3 he is aware of the possibility that the works will be only exposed to scour during construction and he takes temporary measures to limit the damage; 4 he completely under-estimates or is not aware of any danger of scour and must repair the damage afterwards against high cost. In the paper is elaborated the said situations, as encountered by my colleagues and myself, by presenting five case histories. They will be presented in chronological order as one learns always from mistakes. Moreover, one starts usually by having responsibility for small projects and ends up doing large project