Of course if your "2metre dyke" is a €100m dyke programme surrounding a significant area, it's probably cheaper and more efficient to bid for a couple of days on DestinE to check your calculations than to "just build it" and find it doesn't work because of a fundamental error in your design.
It would certainly be cheaper.
However going by the $70 billion damages caused by the flooding at New Orleans then i'd suggest that it would be safer to estimate the worst possible case (from previous historical patterns such as the once in two centuries 1953 storm) and then build taller "just in case" with a generous margins for error, subsidence and sea levels rising. And then with a bit more added in for paranoia's sake since better safe than squidgy.
In almost all cases I would expect that it's going to be cheaper to build the dyke higher than repair the damage and I doubt that the results of a computer program are going to come with an indemnity policy covering the potential damage, or even a guarantee that the people who recommended the wrong level would admit fault.
Biting the hand that feeds IT
