Authors / CoAuthors
Williams, D. | Brinkman, R.
Abstract
This resource contains tidal current derived seabed shear stress grids (50th and 75th percentile) 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 tidal current derived seabed shear stress grids (50th and 75th percentile) were 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.
Product Type
dataset
eCat Id
127200
Contact for the resource
Point of contact for the resource
Point of contact
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- Hydrodynamic
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- Marine Environmental Baselines
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- Marine Survey
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- Exclusive Economic Zone
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- Published_External
Publication Date
2020-01-15T03:40:00
Creation Date
Security Constraints
Legal Constraints
Status
completed
Purpose
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
A numerical model of the broader study region was established using the RMA-2 hydrodynamic modelling software to simulate tidal currents and water levels. RMA-2 is a two-dimensional depth averaged finite element hydrodynamic numerical model (King 2016). It computes water surface elevations and horizontal velocity components for subcritical, free-surface two-dimensional flow fields. RMA-2 computes a finite element solution of the Reynolds and Navier-Stokes equations for turbulent flows, solving the depth-integrated equations of fluid mass and momentum conservation in two horizontal directions. Friction is calculated with the Manning’s or Chezy equation, and eddy viscosity coefficients are used to define turbulence characteristics. The underpinning bathymetry for the model grid was derived from a 10m bathymetric survey grid compiled from both previously reported (e.g. digitised nautical charts) and new survey data. The model was run for a 30 day period to capture a characteristic spring-neap tidal cycle. At each model element, tidal velocities were calculated and analysed to provide maps of tidal velocity percentiles and accompanying percentiles of tidal bed shear stress.
Parent Information
Extents
[-12.77, -12.1, 130.25, 131]
Reference System
WGS 84 / UTM zone 52S (EPSG:32752)
Spatial Resolution
100m
Service Information
Associations
Source Information