Mapping gravel beds combining multibeam bathymetry, underwater video, and grab samples with continuous spatial modeling by random forest

<p>In this study, high-resolution (1 m) multibeam echosounder system (MBES) bathymetry data and derivatives, optical images by underwater video drop-frame, and Hamon grab sediment samples, all acquired within 170 km2 of seafloor in offshore Belgian Waters, were integrated to produce a random forest spatial model targeting the prediction of the continuous surficial distribution of gravel %, i.e., a substrate category whose known detailed distribution is central to the environmental stewardship of natural gravel bed habitat. MBES bathymetry reveals explicit details of the seafloor topography, allowing the derivation of geomorphometric variables that are important in the classification process. Underwater video and grab samples provide the means to directly observe the nature and distribution of the response variable. The model output is presented along with a protocol of error and uncertainty estimation, providing detailed information of the gravel spatial distribution that would otherwise remain undetected by categorical-type classifications, focused on predefined habitat classification schemes. Targeting the methodological improvement of this mapping approach, an overview of the limitations identified at the various steps of the acoustic seafloor classification (ASC) pipeline is presented.</p>

Review : Bathymetry Mapping Using Underwater Acoustic Technology

The bathymetry mapping using underwater acoustic technology very important in Indonesia waters. Bathymetry is the result of measuring the height of the seabed so that the bathymetric map provides information about the seabed, where this information can provide benefits to several fields related to the seabed. In bathymetry mapping uses underwater acoustic technology where among them is using Single beam echosounder and MBES (Multibeam Echosounder System), and multibeam echosounder (MBES) is acoustic equipment that is intensively used frequently in basic waters mapping. The advantage of using underwater acoustic technology is the acquisition and processing of data in real time, high accuracy and precision (correction of the bathymetry data was carried out with reference to the 2008 International Hydrographic Organization (IHO), and cannot be a threat or damage to objects. Retrieval of bathymetry data must use parallel patterns, namely: patterns with perpendicular sounding directions and tend to be parallel to longitudinal lines or in accordance with parallel sounding patterns.