THREE DIMENSIONAL METHOD FOR MONITORING DAMAGE TO DOLOS BREAKWATERS

Abstract

In order to extend the design life of breakwaters, regular damage investigations and timeous repairs are required. One of the important aspects is calculating the severity of damage to breakwaters. Traditionally, breakwater inspection has been done using aerial photographs and underwater imaging to accomplish these investigations. Breakwaters are systematically divided into inspection stations and photographs are taken to inspect and assess the damage. The photographs are then visually compared with the previous inspection photographs to identify changes. This is difficult to achieve as it is not always possible to get the helicopter exactly in the same position on every survey and highly dependent on the skill of the helicopter pilot. Another difficulty is taking underwater images near the breakwater due to poor visibility and wave breaking. The objective of this study is to test a 3D analysis method by evaluating the accuracy of using the LIDAR and multi-beam echo sounder data to quantify damage to dolos breakwaters above and below the water surface (including the inter-tidal zone). Thus, this comparison is aimed towards the development of the 3D eroded volume method (3D method).