Unmanned aerial vehicles based on rotary wings (multi-rotor), namely the so-called UAV have been widely spread in recent years. They are expected to be applied to surveys on the coastal and port structures for more enhancement of quickness, reasonability, safety and accuracy in the surveys. As a typical example with targeting a detached breakwater, the UAV-based survey can cut landing on the breakwater by a ship to promptly grasp the detailed positions of the structures. However, in order to achieve it, highly precise positioning-data of the UAV and a highly accurate photogrammetry method, which are insufficiently studied in the coastal and port engineering field, are required. To resolve the problem, this study examines the survey methods in disaster area.
Firstly, the GNSS systems on UAV are compared. It is shown that surveying with single-positioning GNSS system mounting on a UAV has about 30m error. And it can be suppressed with 0.174m error by GCP (Grand Control Pint) corrections within the image analysis. Moreover, by using UAV with RTK-GNSS and PPK-GNSS systems, the error are further suppressed with 2.1cm and 8.9m, respectively. This implies that the UAV with highly-accurate GNSS systems can cut the landing surveys on the target breakwater.
Second, as a practical trial of the UAV-based survey in the disaster area, the Port and Airport Research Institute is targeted. This location had a damage by high waves and a high-tide due to a typhoon in 2017. From the traces of the inundation in the photos, the detailed inundation height and depth are spatially estimated. Moreover, additional practical UAV-based survey is conducted with targeting Kobe city including a large container terminal, which was damaged by a typhoon in 2018. Considering the result, the practical operation method and important notice for UAV-based survey are examined.

Key Words: UAV, Wave dissipating block, Typhoon, High tide, high wave, Survey