Application of acoustic unmanned surface vehicle to submarine geomorphology survey in shallow water

Unmanned surface vehicle (USV) is an emerging platform for the oceanic survey. Small and medium-sized USVs have the advantages of the small draft, flexible maneuverability, safety, and efficiency, and increasingly become an important means for shallow water investigation. For the measurement and investigation of the shallow water environment that can not be reached by conventional ships and surveyors, USVs can play a significant role as an alternative to replace other facilities. This article is based on the C-Worker 4 USV platform, integrated with multi-beam sounding, side-scan sonar, sub-bottom profiler, and other acoustic equipment, using pulse delay time technology to acquire data simultaneously, aiming to improve the efficiency and optimize the program and save costs. In 2019, USV was applied in Chengmai Bay, Hainan Island to investigate submarine geomorphology in a shallow water environment with a water depth of 1.2～22 m. Data processing, analysis and evaluation showed that the data acquired by USV is highly reliable and can be used to identify the natural geomorphological units such as seabed reef, sand wave, sand ripple, buried channel, and the artificial geomorphology units such as waterway, channel filling deposits and submarine pipelines. The research in this paper confirms that the USV with a variety of acoustic equipment can provide precise, three-dimensional, and reliable basic data of submarine geomorphology, serving coastal geological surveys, resource exploration, engineering construction, maritime transportation, and national defense security.