TY - GEN

T1 - Sediment concentration profiles and transport dynamics near the port of Brisbane, Moreton Bay, Queensland

AU - Beecroft, R.

AU - Perez, L.

AU - Grinham, A.

AU - Visscher, J.

AU - Hildebrandt, A.

AU - Cossu, R.

N1 - Publisher Copyright: © Australasian Coasts and Ports 2017 Conference. All rights reserved.

PY - 2017

Y1 - 2017

N2 - Dredge operations and relocation of dredge material are important to maintain navigable port facilities. However, the fate of dredge material after relocation is often unclear and requires intensive monitoring strategies. A LISST-100X instrument deployed at the dredge material placement area close to Mud Island (MI) within Moreton Bay, Queensland, reports suspended sediment concentration (SSC) and particle size distribution (PSD) in-situ between September-January, 2016-2017. Tidal driven SCC levels were monitored in the range of 10-35 μl/l with a preliminary analysis of wind-wave events showing no significant impact on SSC levels in the area during a 50km/h (West-Southwest) event. The LISST-100X has allowed for rapid profiling during a dredge dump event comprised of fluvial sediment (d50 = 15-30 μm) from within the Port of Brisbane (PoB). SSC levels 40-90 μl/l higher than those observed prior to the dredge placement are influenced by a bi-directional (Northwest-Southeast) tidal current velocity field on the 15th of November. Temporal and spatial monitoring of 5 sites close to MI indicate a predominant Northwest dispersion of the dredge plume during ebb tide, with its dispersion path hypothesised to intersect a neighbouring commercial shipping channel. These findings will have direct impact on current dredging strategies as well as longterm environmental management concepts in this highly active and sensitive embayment.

AB - Dredge operations and relocation of dredge material are important to maintain navigable port facilities. However, the fate of dredge material after relocation is often unclear and requires intensive monitoring strategies. A LISST-100X instrument deployed at the dredge material placement area close to Mud Island (MI) within Moreton Bay, Queensland, reports suspended sediment concentration (SSC) and particle size distribution (PSD) in-situ between September-January, 2016-2017. Tidal driven SCC levels were monitored in the range of 10-35 μl/l with a preliminary analysis of wind-wave events showing no significant impact on SSC levels in the area during a 50km/h (West-Southwest) event. The LISST-100X has allowed for rapid profiling during a dredge dump event comprised of fluvial sediment (d50 = 15-30 μm) from within the Port of Brisbane (PoB). SSC levels 40-90 μl/l higher than those observed prior to the dredge placement are influenced by a bi-directional (Northwest-Southeast) tidal current velocity field on the 15th of November. Temporal and spatial monitoring of 5 sites close to MI indicate a predominant Northwest dispersion of the dredge plume during ebb tide, with its dispersion path hypothesised to intersect a neighbouring commercial shipping channel. These findings will have direct impact on current dredging strategies as well as longterm environmental management concepts in this highly active and sensitive embayment.

KW - Coastal dynamics

KW - Dredge plume

KW - Sediment transport

KW - Suspended sediment concentration

UR - http://www.scopus.com/inward/record.url?scp=85055127560&partnerID=8YFLogxK

M3 - Conference contribution

SP - 68

EP - 74

BT - Australasian Coasts and Ports 2017 Conference

ER -