Procedures for closing

The cost of depots and the procedures for closing a demountable flood defence means a great expense for society.

The cost
Although cost is not a direct aspect of the question of safety, in the case of Dutchdam it contributes very much to safety. After all, everything has to be paid for and, thanks to Dutchdam technology, within a fixed budget significantly more safety facilities can be provided.

The very fact that by using Dutchdam rather than demountable systems a saving can be made on development costs of 80% is not the only instance. In addition to that, the fact must be taken into consideration that in an emergency Dutchdam can soon be erected over a substantial distance by a few people. Compare this with what happens with demountable flood protection: a whole army of people, all of whom have to be available immediately, must be drummed up

In the diagram above the blue dotted line indicates a high water wave which over a period (3) rises above the fixed quay wall (4) or dike. This means launching a temporary elevation of a flood defence (2). With a demountable system (5) you can see the long time phase which is necessary for building it up (5a) and for dismantling it (5b).

But by using the Dutchdam the time-scale for erection and dismantling is much shorter (1a and 1b). With such a short reaction time many expenses are avoided, such as an unnecessary deployment of a demountable flood defence when the high water does not quite come over the fixed quay height. Dutchdam is able to offer the opportunity of unfolding at a much later point in time.