The Contribution of Drones to the Monitoring of Rubble-Mound Breakwaters

Abstract

Breakwaters are built to promote sheltered areas, for people, ships, and harbour activities. In the design of rubble-mound breakwaters, a common type of breakwater in many countries, including Portugal, it is assumed that damage may occur in certain stretches of the structures, and therefore maintenance and repair works will be quite certainly needed. To successfully carry out these interventions, in a timely and cost-effective manner, the structures must be observed and monitored systematically. This enables one to follow their structural behaviour and, through diagnosis analysis, to specify the most suitable timespan to undertake any necessary intervention. The severity of the sea on the Portuguese coasts justified the establishment, by the National Laboratory for Civil Engineering (LNEC), of a program of Systematic Observation of Maritime Works (OSOM) which, in 2018, was improved with the introduction of drones to monitor the structural present condition, evolution condition and risk condition of the structures, namely movements and falls of blocks in the armour layers. This communication presents some results of the application of OSOM+ program on breakwaters in Sines and Algarve (Faro-Olhão and Portimão) harbours, an activity that LNEC has developed for the APS – Ports of Sines and the Algarve Authority