Coastal protection and shoreline management in Darwin Harbour: understanding non-cohesive, sediment dynamics

Coastal protection and shoreline management in Darwin Harbour: understanding non-cohesive, sediment dynamics

Fri, 28/09/2012 - 09:30

Silvia Tonyes PhD Candidate


Venue

Charles Darwin University
Ellengowan Drive
Building Red 6.1.10
Casuarina NT 0810
Australia

Tropical coastal estuaries and shorelines, worldwide, face major anthropogenic impacts, including the ecological impacts of increased coastal development and also, the impacts of climate change (particularly sea-level rise and cyclone-induced, storm surges).  Shorelines are shaped by coastal erosion and accretion due to the interaction of sediments and coastal hydrodynamic processes.

While coastal erosion rates are determined by a range of factors, including coastal geomorphology, sediment characteristics, hydrodynamics, and coastal vegetation. In developing ‘soft engineering’ approaches to shoreline management, knowledge of the key processes of coastal dynamics of shorelines, on both spatial and temporal scales, is essential for managing coastal erosion. Sand, a loose and non-cohesive granular material, is a major component of beach sediments.

Understanding the characteristics, transport dynamics and the availability of sand are very important in coastal protection management.  Adjacent to the capital city of Darwin (Northern Territory, Australia), Darwin Harbour is a low-lying, macro-tidal embayment, subject to increasing human population pressure and also, a range of coastal and anthropogenic impacts, particularly from coastal development and climate change. The harbor is currently experiencing rapid urban and industrial development in the coastal zone, with resulting ecological impacts, including proposed large-scale dredging associated with port and infrastructure development.

Shoreline erosion currently occurs on several Darwin foreshores and cliffs. Situated in a cyclone-prone region, projected sea level rise and more intense cyclones and storm surges also have the potential to devastate the coastal zone and the city, particularly at high tides. While detailed hydrodynamic and modelling studies have been undertaken in Darwin Harbour, there remain fundamental gaps in our understanding of sediment dynamics within the harbor, particularly sediment pathways and net transport.

The presentation will outline a research program to investigate the sand characteristics, and sediment dynamics of the harbor (including sediment sources, sinks, transport pathways, sediment budget) - to assist future shoreline management and coastal protection management, and also, to assist future coastal development in Darwin Harbour.

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