SQU dept workshop sheds light on sea-floor mapping technique

MUSCAT: The Department of Marine Science and Fisheries (MSF) at the College of Agricultural and Marine Sciences at SQU hosted a workshop to teach MSF faculty and staff how to use a side-scan sonar (SSS) to efficiently create images of large areas of the sea-floor.

The workshop was organised by Dr Alyssa Marshell (MSF) with funding received from His Majesty’s Trust Fund (HMTF) to purchase the new side-scan sonar equipment from Deep Vision Sonar Systems (deepvision.se). The owner of Deep Vision, Uffe Langstrom, with assistance from Dr Kaveh Samimi-Namin (Naturalis Biodiversity Center, Netherlands), taught MSF faculty and staff how to effectively use the side-scan sonar.

Day 1 of the workshop provided an introduction and background on how the sonar works. Day 2 was spent on the MSF department boat, Al Jamiah, to test the new equipment and learn how to practically use the sonar to conduct sea-floor surveys in the field. Day 3 focused on learning how to use the customised software to analyse the side-scan sonar data.

Side-scan sonars emit pulses down towards the sea-floor across a wide-angle while being towed from a boat. The sonar records the intensity of the acoustic reflections of the pulses from the sea-floor. When stitched together along the direction of motion, this data forms an image of the sea bottom within the coverage width of the pulse beam. Side-scan sonar is used to conduct surveys of the sea-floor, and in conjunction with sea-floor samples, it provides an understanding of the different types of materials and textures of the seabed.

Side-scan sonar imagery is also a commonly used tool to detect obstructions on the seafloor that may be hazardous to shipping, or for sea-floor installations by the oil and gas industry. Additionally, the status of pipelines and cables on the seafloor can be investigated using side-scan sonar. Side-scan data are recorded along with GPS and depth data, which provides a picture of the structure of the seabed. Side-scan sonar can also be used for fisheries research, dredging operations and environmental studies.

The MSF department plans to start fieldwork in January 2019 using the side-scan sonar to map artificial reef sites in the Al Batinah Governorate. These side-scan sonar maps of the artificial reef sites will help to assess the contribution of the sites to enhancing fisheries productivity in the governorate.