State of the Art in the Design of Coastal Structures Contributions from MAST, PIANC and some national projects

Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives are sheltering of harbour basins and entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes and outfaHs. An overview is given in Fig. 1. In designing structures optinlization is wanted, both with respect to function and to economy seen over a structure service life time. F'unctional design is still very difficult when it involves structure-sediment interactions as for example for groynes in coastal protection schemes. As to optimal design of the structure itself it can be done today for smaller standard structures solely by the use of desk tools, provided that the sea state conditions are known. Howevcr, for largc-: and non-standard structures it is necessary to spend quite a lot of money and time on model tests which for some structures include the use of large scale test facilities. The art do not. allow conceptual design just based on available formulae and computer programs. The available sets of tools are not of generic nature as they do not provide the freedom of designing coastal structures which deviate significantly from the well proven and documented traditional design concepts.