Modelling of Lakes Entrance

Hydrodynamic modelling and field studies of the entrance to the Gippsland Lakes in Eastern Victoria have been undertaken. The purpose was to produce models that could be used to investigate the processes controlling sediment movement through the entrance and to identify and test possible management options. The entrance area comprises a single entrance to the ocean with four navigable channels within the lakes. Water level and velocity measurements were made over a series of tidal cycles to provide validation data for the models. Modelling has included investigations of the propagation of tides through the entrance and the impact of siltation on tidal exchange. A twodimensional model successfully reproduced measured water-level and volume exchanges and analysis of the velocity fields were consistent with the pattern of deposition observed in the entrance area. Analysis of tidal exchange quantified the impact of variations in the cross-sectional area of the entrance. The simulated effects on tidal constituents of changes in the entrance bathymetry before and following a major flood in 1998 indicate that there was very little change in tidal signal. It is also shown that dredging of the channel upstream of the entrance would have a limited impact on tidal exchange. The outcomes of these projects include calibrated one and two-dimensional models. These models were used to estimate sediment transport characteristics, and the effect of changes to the entrance on flushing.