Swath multibeam bathymetry surveys for Congo Submarine Canyon and Channel collected in 2019 and 2020, and changes in seabed elevation.

Swath multibeam surveys of seafloor bathymetry data were collected in two areas: Upper Congo Canyon in Angolan waters, and deeper-water channel in International waters between September 2019 and October 2020 using a Kongsberg EM122 (1 degree x 1 degree) system operating at 12 kHz. Higher resolution data was generated by setting the swath width to the narrowest setting (45 degrees from the nadir), and having large overlaps between adjacent swaths. Sound velocity profiles (SVPs) were taken through the water column at the start of most surveys, and a second SVP was performed halfway through some longer surveys. Multibeam sonar bathymetric data were processed in CARIS HIPS and SIPS and corrected for the ship's motion and for differences in sound velocity in the water column (using SVP data), before being gridded with a horizontal grid cell dimension of 5m (upper canyon in Angolan waters) or 15m (deep-water channel within international waters). Data were cleaned manually for obvious outliers in CARIS. A bathymetric difference map was then produced by subtracting October 2020 bathymetric data from September 2019 bathymetric data. This was done to document patterns of seabed erosion and deposition caused by turbidity currents between 2019 and 2020. Data were collected under NERC Grant references NE/R001952/1 and NE/R001960/1 lead by Professor Peter Talling at Durham University.