Abstract:
coastline appear to entail some disadvantages. An innovative and interesting way of protecting a local coastal zone
by means of multifunctional artificial reefs avoids some of them. A multifunctional artificial reef is a submerged
breakwater which, besides helping to protect the local coastline, can have other purposes; in particular it may enhance
the surfing possibilities and the environmental value of the local area. The structure has several positive side effects:
first, it provides an unimpaired visual amenity; second, it offers tourist and economic benefits by improving the surfing
conditions. A preliminary design, achieved step-by-step, is proposed for a multifunctional artificial reef making use of
the theory and state of the art multifunctional artificial reef design, a preliminary design, achieved step-by-step, a
priliminary design is proposed. The proposed reef geometry, together with numerical and physical tests, allows the
analysis of a multifunctional reef breakwater designed to protect a stretch of the northwestern coast of Portugal.
Taking into account the condition that the proposed geometry will only function properly on a sea slope bottom of
less than 1 : 50, the main choices are as follows: the upper part of the structure is delta shaped with an angle of 66
and a side slope of 1 : 10, and the lower part consists of a platform whose slopes are as steep as possible. The position
of the reef should be such that the distance from the apex of the structure to the undisturbed shoreline is greater
than 1.5 times the natural surf zone width.
