SAFETY OF DIKES AND EMBANKMENTS IN THE NETHERLANDS WITH SPECIAL REFERENCE TO EARTHQUAKES

The protection against flooding is an important topic in the Netherlan ds. Based on statutorily defined sea and river levels which have to be withstood, safety is expressed as an acceptable annual probability of flooding for each area protected by water-retaining structures. This hazard assessment considers primarily the basic threat of extreme high water levels alone or in combination with (specific) storm conditions . However, combinations of high water levels with unrelated damaging e vents may also contribute to the total flooding hazard. This paper des cribes the general approach for the assessment of the possible combine d failure mechanism leading to the scenario 'flooding due to earthquak e-induced damage'. Based on the results of simplified slope stability calculations, the conclusion is drawn that the contribution of this sc enario to the total probability of flooding is exceedingly small for t he lower river region of the Netherlands.