Multibeam Bathymetry

Multibeam echo sounders, for Bathymetric survey, use sonar pulses to measure the distance between the survey vessel and the seabed. This instrument collects point data at a resolution of 25cm or better, depending on water depth, vessel speed and bed topography and produces a high resolution elevation dataset of the underwater terrain. The Environment Agency's Multibeam Bathymetric data archive includes digital elevation data derived from bathymetric surveys carried out for a range of applications and locations where surveys have been previously commissioned. Multibeam data is available at 50cm resolution and supplied as an ESRI ASCII Raster which contains height, relative to Ordnance Survey Newlyn datum. Data is available in 5km download zip files for each year of survey. Within each downloaded zip file are ASCII files aligned to the Ordinance Survey grid. The size of each tile is dependant upon the spatial resolution of the data. Elevation values are presented in metres. Please refer to the metadata index catalgoues for the survey date captured and spatial resolution of the imagery.