Uncrewed bathymetric survey in UK waters: Testing CARIS Mira AI and globally-distributed Nippon Foundation/ GEBCO training program Alumni to produce data products

SEA-KIT USV Maxlimer successfully carried out a 22 day (24hrs per day), uncrewed survey operation offshore the United Kingdom in July-August 2020. The uncrewed vessel was controlled and manoeuvred from an operation room based in Essex, UK, while the data acquisition was performed by alumni of the Nippon Foundation/GEBCO Training Program, through the Map the Gaps NPO, spread across 10 countries. One of the main objectives of the trans-ocean survey was to test the remote survey capabilities through satellite communications, and also promote the contribution to seafloor mapping. CARIS Onboard, incorporating the new Sonar Noise Classifier tool via the CARIS Mira AI platform, was deployed to autonomously process the survey data in real-time, and provide products that could be streamed daily from SEA-KIT to ensure operations were successful and to help train the classifier as required. The data was post-processed with CARIS HIPS and SIPS using conventional and Ai techniques, and gridded at 10 m. The collected data size was 52.2 GB, surveyed area depth range from 57m to 1362 with 470m mean depth and around 900 km² was totally covered.  CARIS Mira AI with traditional QC approach reduced data processing time to 77% regarding the conventional path.

The high-resolution bathymetric dataset provided the first detailed picture of the Brenot Spur, adjacent to Dangeart Canyon. Three major submarine canyon systems can be identified, cross-cutting the continental shelf nearly perpendicularly. The main axis of the first canyon, located at the far northern part of the surveyed area, is oriented NE-SW and becomes wider downstream. Both of the flanks are highly carved by gullies and tributaries, especially along the northern flank, where a complex system is developed depicting well-developed amphitheatric heads, indicating retrogressive erosion. Moreover, this network shows a high degree of incision and narrow interfluves. The second major canyon trends ENE-WSW and is a multi-fed system consisting of three sub-canyons that coalesce at 1095 m water depth. Although tributaries bisect the flanks of this system, they are not mature and have not yet breached the continental shelf, but are mostly confined on the slope. The final canyon is narrower than the previous ones and its  thalweg is nearly N-S oriented. Additionally, the flanks of the later differ substantially when it comes to their morphology. The western flank is undulated by linear wall gullies and several landslides indicated by the crescent like rim of high slope values, while the eastern flank is smooth and featureless. Along the SW continental slope, evidence for several old landslide events can be identified. The major failure scars are located right at the edge of the shelf at 560 m water depth.