ABSTRACT
Deus mare, Friso litora fecit, a well known saying in the Netherlands, explains how a large part of the country was conquered from the sea. Another technology applied frequently in the Netherlands is the closure of estuaries. In many instances settlements grew at the mouth of rivers debouching into the sea. In the 19th century, large river floods occurred in the Netherlands in 1809, 1820, 1855 and 1861, inundating vast areas. This caused a lot of concern and controversy in Dutch society. The reasons for the relatively frequent flooding were well known among hydraulic engineers. The floods on the Rhine and the Meeuse in January–February 1995 made international headlines. In more floods, it was the uncertainty of the resistance of the dikes in the geotechnical failure modes of slides and sand boils, that was most threatening. Modern probabilistic analyses support this view, but once again political and financial constraints prohibit immediate action.
