Coves - artificial formation and use
Definition: A cove is a pocket beach suspended between two oblique coastal structures, see Fig 12.27.
27. Principle layout of a cove and photo of a cove constructed at the SW coast of Sri Lanka.
Method: The pocket beach will form by itself as soon as the structures have been built, however it is recommended to include initial beach fill in the design.
Functional characteristics: The formation and shape of the cove are fairly independent of the wave climate due to the relatively narrow opening. The cove concept is very similar to the pocket beaches, which are formed in the gaps of segmented breakwaters, with narrow gaps. It is important that there is a suitable distance from the coastline to the head of the structures in order to avoid dangerous currents, preferably this distance shall be larger than the width of the littoral zone.
Applicability: The cove concept is especially suited for coasts with a very oblique wave attack, i.e. type 3M and 3E coasts, and for locations with steep coastal profiles. This type of coast has a large littoral transport potential. This type of coast is often exposed to erosion and will therefore in many cases already have been protected. Traditionally, this type of coast is protected by revetments, as it is difficult to apply an optimal shore protection system. Long sections of accumulated material upstream of protruding coastal structures cannot be used in this situation due to the oblique wave attack. This type of coast is normally unsuitable for artificial nourishment as a stand-alone measure, as this will result in large maintenance requirements. Nor will beach fill in connection with structures work, as the structures can only hold a short beach section due to the oblique wave exposure.
The small cove shown above may change a small coastal section protected by a revetment into an attractive recreational environment. It is especially suited to provide a semi-protected beach at locations, which are too exposed for safe swimming. Such a semi-protected bay is also very suitable for beach-landing small fishing boats.
Although the cove concept is the optimal solution for type 3 coasts, the concept can also be used for all other types of coasts.
The opening to the cove should not be made too narrow, as this will reduce circulation and degrade the water quality.
The cove may trap seaweed and debris, but the smooth shape of the structures will normally reduce this problem.