Designing a Preliminary Multifunctional Artificial Reef to Protect the Portuguese Coast

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.