ABSTRACT
The interface of land and water has always played an important role in human activities; settlements are often located at coasts, river banks or deltas. Bed protection is necessary where bottom erosion could endanger structures, like bridge piers, abutments, in- or outlet sluices or any other structures that let water pass through. The same holds for flow in a river, through a tidal closure or an outlet sluice, when it comes to protecting the bed or the bank. A bank, eroding due to wave action, can be protected by making a revetment or by constructing a wave reductor in front of the bank. Shore protection structures include seawalls, revetments, dikes and groynes. A design that combines effectiveness and efficiency can be said to be "value for money". A hydraulic jump and the roller of a broken wave are very much the same. The same similarity exists between a fixed object in flowing water and a ship sailing in still water.
