ABSTRACT
As a result of these technical or so-called structural measures, the frequency of flooding is reduced. But sediment deposition is confined to the area between the dikes and water levels gradually start to rise. This is the start of a vicious circle, in which population and investments in the protected areas increase, and ask for better protection (i.e. higher dikes). As a consequence, water levels increase between the rising embankments. Currently, in many places in the world (Japan, China, USA, Hungary, The Netherlands) design flood levels may be up to 10 m above ground level. In these situations, the frequency of flooding may be reduced to 1/100 or even 1/1000 or 1/10,000 per year, but the damage caused by such a rare event will be dramatic. It is estimated that flooding of the central part of The Netherlands, including cities like Amsterdam, the Hague and Rotterdam, may cause more that 100,000 casualties and a damage of more than €100 billion (i.e 16% of GDP) (Brinke & Bannink, 2004). If this happens it would ruin the country.
