Hydrographic survey HI634 by the RAN Australian Hydrographic Service at Davis, February 2020

The Australian Antarctic Division identified areas that required hydrographic surveying. (See map available in the download at \Plans and Instructions\HPS Supplied Data\davis_plan_2019_2020 version 5.1.pdf and a shapefile of the identified areas at FSD\ArcGIS\Pink V2\AOI_Unproject_wgs84.shp) A team from the Maritime Geospatial Warfare Unit, of the Australian Hydrographic Service, was at Davis in early February 2020. Single beam and side scanning survey data was collected on the water, beach profiles collected and rock data. Single beam and side scanning survey data Areas A, D, F, H, I, J and K were ice free. Area J was further broken down into four areas, J1, J2, J3 and J4. Areas A, D and F were thoroughly surveyed with 10m mainline spacing with 20m X-line spacing. Areas I, J3 and J4 were surveyed but due to time constraints were surveyed at approximately 40m line spacing to provide 200% sea floor coverage with the SSS to detect any features dangerous to navigation with one shoal detected in area I which is mentioned in Section I. Area H was too shallow to survey at any other time except high tide and it was decided to focus on other areas as the survey of this area would not value add to the required results of the survey. Area J1, J2 and K were not surveyed due to time constraints. RTK corrections or access to the CORS network couldn't be made to the CEESCOPE survey system. Instead positioning during the survey was recorded exclusively with the NovaTel GNSS 850 Antenna. No post processing was conducted. The team wasn't able to determine why the CEESCOPE was unable to connect to the CORS network or Base Station to gain RTK corrections, despite considerable effort spent problem solving and conducting a number of trials. Tide data collected was applied to the data and all tidal information is explained in section F of the report. A map showing the surveyed areas can be found in the report. Raw data in caris format is available from the Australian Hydrographic Office (AHO). Sounding data, stored as a shapefile, is available as a download file. Beach profiles Sites were also surveyed with 5m line spacing to maximise seafloor coverage, at 5 beach locations, 4 in area A and 1 in Area F. ArcGIS projects and PDF documents displaying the depth data and significant rocks are included in the download. Please note the ArcGIS projects do not include the AHO chart, due to distribution restrictions on digital charts. It is included in the PDF documents. These documents refer to images taken from the survey boat and spreadsheets displaying gradients data. Rock data A shapefile recording conspicuous rocks as well as photographs is available for downloading. Bench mark positions were reclaimed using Trimble R10 and post processed with AUSPOS. Abbreviations used in the download directories ROS = Report of Survey, FSD = Final Survey Data A detailed report can be found at /ROS/ Projection……..…...…...………….….……..Universal Transverse Mercator (UTM) Zone 43 South Horizontal Datum……………………………World Geodetic System 1984 (WGS84) Vertical Datum…………………………….....Approximated Lowest Astronomical Tide (LAT) Sounding Depths.……………………………Metres (m) Survey Date………………..………………….6th - 18th Feb 2020 Bathymetric Accuracy Horizontal……………± 0.8m Bathymetric Accuracy Vertical………………±0.46m Sounding Density……………………………..2m Surface Chart Reference………………………………AUS 451, 602​ ITRF 2014 and GRS80 were utilised for static observations of bench marks and levelling to the tide pole for establishment of approximate LAT. Hypack v19.1.11.0 which was used to gather all bathymetric data does not have the option to use the ITRF datum and the WGS84 Datum was used.