Darwin Harbour Habitat Mapping Program: Wave derived seabed shear stress (0°, 90°, 140°, 270° and 315°)

Full description

This resource contains wave derived seabed shear stress grids (0°, 90°, 140°, 270° and 315°) 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 wave derived seabed shear stress grids (0°, 90°, 140°, 270° and 315°) 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.

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Maintenance and Update Frequency: asNeeded

Statement: Wave propagation within Beagle Gulf, Darwin and Bynoe Harbours was modelled with the SWAN shallow water wave model (Ris et al.1999). SWAN is a third generation spectral model that contains implicit shallow water routines to allow for shoaling, frictional dissipation, wave breaking and refraction. The model grid was a regular, rectilinear mesh with 100m spatial resolution, with bathymetry at model grid points interpolated from a 10m bathymetric survey grid compiled from both previously reported (e.g. digitised nautical charts) and new survey data. Surface wave simulations were performed with wind forcing of at 10 m/s from directions of 0, 90, 140, 270 and 315 degrees. From these, grids of wave-derived bed orbital velocity and wave bed shear stress were calculated.