Modelling of the Bar System at Lakes Entrance, Victoria

Lakes Entrance is an artificial entrance into the Gippsland Lakes of eastern Victoria. The entrance has training walls and a large bar system has formed necessitating continuous dredging to allow the large local fishing fleet safe passage. The entrance is on the Ninety Mile Beach facing Bass Strait and the Tasman Sea and experiences a bi-directional wave climate with sediment transport in both directions along the beach. An analysis of aerial photography allowed the development of an understanding of the behaviour of the bar and entrance channel. Modelling of the bar, the entrance and the resulting sediment transport was undertaken using the Delft3D MOR system. This includes coupled models of the hydrodynamics, the waves, including feed-back into the hydrodynamics to generate wavedriven currents, sediment transport and bed level modification. The model allows simulation of the bar generation and its behaviour under a range of wave conditions. The model results have been used to understand the bar behaviour and provide guidance in the management of the bar and development of dredging options for the long-term management of the entrance. The model setup, validation and results will be described.