Detached breakwaters’ effects on a microtidal Mediterranean Coast, case of the Hammam-Lif littoral (North-East of Tunisia)

Abstract

The Hammam Lif shoreline, which is part of the Gulf of Tunis (North-East of Tunisia), suffered from a dramatic erosion event during a storm in 1981. Therefore, eight successive and detached breakwaters were built to protect it. The effect of these protection works on the evolution of this coastline is assessed using aerial photographs geo-referenced by digital photogrammetric methods. Results show that a general accretion has developed behind the detached breakwaters, with the formation of seven tombolos and one salient. The response of the coastline depends on the characteristics of the protective works (length, distance to coast, and spacing). Detached breakwaters which are short, far from the coastline and distant from each other, give rise to very small tombolos or salients. On the other hand, longer breakwaters which are near the coastline and closely spaced, give rise to more developed tombolos, showing that these structures are the most efficient.