Piers LarcombeRPS MetOcean

WAMSI Perth21st Feb 2013

5 mins

Shelf sediment transport in NW Australia over decades to centuries:

a knowledge gap for science, development & regulation

Marine ScientistsEnvironmental Regulators

Marine EngineersDevelopers & Operators

Marine developments:

• Design of structures• Assessment of environmental impacts

22

NW Australia has: much of ecological value

Key ecological features represented in the North-west Commonwealth Marine Reserves

Network

NW Australia has: many cyclones

NW Australia will have: bed sediment transport pathways

Scales = relevant to developments

>decades 10s-100s km

Ecology = f (sedimentology)

Engineering = f (sedimentology)

(NB – this is not transport AT the coast)

44

Belderson et al. (1982)

NW Australia has: major development projects

8 proposals requiring‘substantial’ dredging

Total ~200 M m3

Pilbara / W. Kimberley

Dredged channels, up to >30 km long

Durations >many decades

WA EPA (Oct. 2012)

Dredging volume >150 M m3

NW Australia has:

…knowledge gaps that WAMSI can help fill

to enhance: environmental

management& project design

66

Shelf Sedimentary Research To define the pathways’ location and extent e.g. Where are the critical regions?

Wrt removal (dredging) and addition (disposal) of sediment

At EIA stage - Improve assessment of pathways Many aspects, but esp. testing of directions

Bedforms, Deposits, Spatial gradients

Assess in-situ sediment production rates (biogenic sediment)