The Rehabilitation of North Breakwater of Nazaré Harbor, Portugal

Abstract

The north breakwater protecting the Nazaré harbor was severely damaged during the storms of the 2012-2013 and 2013-2014 winters, with the complete destruction of the structurés head, and about 30m of its body.This structure is founded in a sandy foundation, and quite near of Nazaré canyon. The head and the immediate part of the breakwater body were protected with a double layer of 40 ton tetrapods on a layer of 5-12ton rock blocks.A topographic survey of the nearby sea floor showed a change in a secondary branch of the underwater canyon; which could justify the destruction of the breakwater head, as the original design considered a maximum wave 9 m high; a new analysis indicate a correct value for the design wave should be now 14 m.Consequently the rehabilitation design considered then a 14 m design wave, and the protection of the breakwater head was redefined as a double layer of 50 ton antifer blocks, with a density of 70%. The protection of the reconstructed body considered the recovering and reutilization of the 40 ton tetrapods that were recovered.