Authors / CoAuthors
Siwabessy, J.
Abstract
This dataset contains probability values of rocky/hard seabed (multibeam angular backscatter response derived product) from seabed mapping surveys in Darwin Harbour. The survey was undertaken during the period 24 June to 20 August 2011 by iXSurvey Australia Pty Ltd for the Department of Natural Resources, Environment, The Arts and Sport (NRETAS) in collaboration with Geoscience Australia (GA), the Darwin Port Corporation (DPC) and the Australian Institute of Marine Science (AIMS) using GA's Kongsberg EM3002D multibeam sonar system and DPC's vessel Matthew Flinders. The survey obtained detailed bathymetric map of Darwin Harbour. Refer to the GA record ' Mapping and Classification of Darwin Harbour Seabed' for further information on processing techniques applied (GeoCat: 79212; GA Record: 2015/xx)
Product Type
dataset
eCat Id
83950
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- Marine DataBackscatter Grid
- ( Theme )
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- backscatter
- ( Theme )
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- multibeam
- ( Theme )
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- marine survey
- ( Theme )
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- marine environmental baselines
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- AU-NT
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Marine Geoscience
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- Published_External
Publication Date
2015-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
asNeeded
Topic Category
environment
Series Information
Lineage
The backscatter data were processed using CMST-GA MB Process v10.10.17.0 software on the National Computational Infrastructure (NCI) supercomputer at the Australian National University. In the process of removing the angular dependence from the backscatter for a consistent backscatter strength across the swath in various incidence angles (for a homogeneous seafloor), the angular backscatter response was calculated in a 1° bin of incidence angle and averaged within the sliding window. The angular backscatter response is an intrinsic property of the seafloor, illustrating that the backscatter strength changes with the angle of incidence and is dependent on substrate type. The angular backscatter response curve data was analysed to produce a dataset indicating the probability of seabed hardness. The underwater video-derived hardness classifications were first used with existing seabed hardness data from DLRM to identify known areas of "rocky" seabed. The angular backscatter response curves were then extracted from the identified "rocky" areas and an average of the angular backscatter response curves was calculated. This was completed to determine a reference curve of "rocky" seabed. This curve was used as a reference and compared to all other angular backscatter response curves using the Kolmogorov-Smirnov goodness of fit test to estimate the probability of the "rocky" seabed (p-rock). Finally, the Inverse Distance Weighted interpolation technique was used to produce a continuous layer of the p rock for the whole study area.
Parent Information
Extents
[-12.59, -12.32, 130.69, 130.94]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Legacy product, source data not available. 130.69 130.94 -12.59 -12.32