Darwin Harbour Habitat Mapping Program: High resolution bathymetry grid

Brief description

This resource contains a multibeam bathymetry grid for the greater Darwin Harbour region as part of a baseline seabed mapping program of Darwin Harbour and Bynoe Harbour. This project was funded through offset funds provided by an INPEX-led Ichthys LNG Project to the Northern Territory Government’s Department of Environment and Natural Resources (NTG-DENR) with co-investment from Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS). The intent of this program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps and information to underpin marine resource management decisions. The bathymetry grid was derived from a compilation of multiple surveys undertaken by GA, AIMS and NTG-DENR between 2011 and 2017, including GA0333 (Siwabessy et al., 2015), GA0341 (Siwabessy et al., 2015), GA0351/SOL6187 (Siwabessy et al., 2016), GA4452/SOL6432 (Siwabessy et al., 2017), GA0356 (Radke et al., 2017), and GA0358 and GA0359 (Radke et al., 2018), adding to those from previous surveys GA4425 and GA0333 collected by GA, AIMS, NTG-DENR and Darwin Port Authority.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: This bathymetry composed of multibeam sonar data from multiple surveys GA4425 in 2010, GA0333 in 2011, GA0351/SOL6187 in 2015, GA4452/SOL6432 in 2016, GA0361 in 2017 and GA0362 in 2017 and 2018. The first two surveys were acquired by Geoscience Australia (GA), Australian Institute of Marine Science (AIMS), Northern Territory Government’s Department of Environment and Natural Resources (NTG-DENR) and Darwin Port Authority using GA’s Kongsberg EM3002D multibeam echosounder from aboard MV Matthew Flinders and the last four surveys by GA, AIMS and NTG-DENR using GA’s Kongsberg EM2040C Dual multibeam echosounder from aboard RV Solander for the first two and using GA’s Kongsberg EM3002D from aboard MV Reelax and RV Capricornus for the last two respectively. CARIS HIPS & SIPS and QIMERA were used to process multibeam bathymetry data and to produce multibeam bathymetry grids. Multiple grids were produced by CARIS and QIMERA and were combined in ArcGIS. The processing steps included: i) the application of algorithms that corrected for tide and vessel pitch, roll and heave; ii) the use of software filters and a visual inspection of each swath line to remove any remaining artefacts and noisy data (e.g. nadir noise and data outliers). To provide more accurate motion compensated data for all surveys, including GPS tide, attitude data was acquired separately by an Applanix POS MV motion reference unit and post-processed using POSPac software. The GPS tide was used to reduce the bathymetry to the mean sea level using EGM 2008 geoid height model (http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/egm08_gis.html) with a small vertical refinement, adjusted with previously surveyed data to take into account of variation of local mean sea level (MSL).