ABSTRACT
In the low-lying coastal regions where inland elevations are lower than high sea water levels, coastal flood defence systems are important to protect the low-lying hinterland from sea flood. Typically, the system contains sea dikes, dunes, estuarine river levees, dams, sluices, etc. In principle, failure of any element will lead to flooding of the polders and may cause serious consequences. In order to have a better design solution over the recent years, considerable effort has been devoted to improving the knowledge of how to design the defence system to protect the low-lying region safely. Risk based design, with acceptable risk as the basic criteria for design, appears as a useful approach by considering the balance of the potential risk due to flooding and the characteristic value of the defence system and has been widely applied in the fields of water defences (Dantzig 1956, Vrijling et al. 1995).
