Etude " in situ " du fonctionnement des brise-lames de protection du littoral sud du petit golfe de Tunis (Tunisie)

"In situ" study of the operation of breakwaters protecting the South coast of the Gulf of Tunis

¹ Direction des Ports Maritimes, Tunis
² Laboratoire d'études et de recherches en géotechnique et géophysique appliquée, Université de Bordeaux I

Abstract

The current estimations of essential factors of coastal dynamics in the smallerGulf of Tunis relate erosion of the coasts, substantial as of the 50's, and strongly accelerating since then, to human action on the continent. The localized disappearance of beaches followed by the attack of coastal infrastructures by swell, led to the installing of defense installations. More particularly, along the South coast beaches, 17 breakwaters, isolated or in series, form a natural laboratory. The position of these installations, all above water, was studied as of the installation: origin of the trapped sand, influence of artificial refill, formation and evolution of sand spits and sometimes tombolos. The influence of conventional waterbreak characteristic dimensions ( length, distance to the shore, spacing of any) on their efficiency led to a proposal to optimize dimensioning in order to satisfy a triple requirement of protection of the beaches around the Gulf of Tunis: to retain as much sand as possible, but without the formation of tombolo, white preventing erosion along the bank lines due to the installations.