304
R.H. Charlier and Chr. P. De Meyer
8 r
Berm
6
D
C
O.
- ~
--~
-
MLW
46
Fig. 37 : Effects of erosion
2
Impact of Existing Structures and Sites
The presence of a promontory, cape, presqu'isle slows down longshore transport,
results in deposition of carried material, and a change of direction of the current.
Evidently a beach will form on the updrift side, while the downdrift side will be
started. Logically thus any hard structure placed in the path of a longshore
current will have a similar effect. Groins, sea-walls, breakwaters, jetties are such
obstacles. But there are several other constructions not per se intended as coastal
protection which have similar, or milder effects. Drilling platforms, close to
shore, will deflect currents and slow down waves' shoreward progress. Artificial
islands will not only have an impact on shoreline morphology, they create erosion
problems of their own. An analysis of artificial islands implant and
environmental consequences has been recently published (R.H. Charlier and C.F.
De Meyer, 1992, Artificial Islands :lnt. J. Env. St. 40, 4, 244-265).