Year

2011

Degree Name

Bachelor of Environmental Science (Honours)

ANZSRC / FoR Code

05 ENVIRONMENTAL SCIENCES

Department

School of Earth & Environmental Sciences

Abstract

Changes in the morphology of Lady Robinsons Beach, Botany Bay, were determined using historical aerial photographs provided by the Rockdale City Council. Human induced changes to the bay, resulting from the construction of the Sydney Airport Parallel Runways and Port Botany, as well as dredging within the bay have altered the wave regime interacting with the beach. These changes cause refracted wave patterns and subsequent longshore sediment transport. Eleven rock rubble groynes were constructed in two separate stages (1997 and 2005) in an attempt to widen and stabilise the beach. The effectiveness of these groynes at maintaining a wide beachfront was determined by observing changes in the morphology of the beach since their construction, using aerial photographs. It was found that while, in many areas, the groynes have been successful at creating a wider beachfront, there are several areas where erosion and accretion is still taking place. Therefore it was concluded that the groynes are not entirely effective at solving the erosion problems experienced on Lady Robinsons Beach. Sediment samples were collected both on and offshore and particle size analysis was undertaken on these samples. There was found to be a significant difference in particle size of sediments on the southern point of the beach where there is a large accumulation of sediment. Analysis suggests that since the construction of the groynes this area has developed into a dune feature. This highlights the significant effects the groynes have had on Lady Robinsons Beach. It is clear that Lady Robinsons Beach has, and is still, undergoing significant morphological changes. It is likely that more protective measures are going to be put in place in order to protect the beach from irreversible damage.

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