Observations of a propagating vortex in a tidal current

While observing the hydrodynamics and geomorphology of the entrance to Burrill Lake, a small estuary on the south coast of New South Wales, Australia, a striking vortex phenomenon was observed. This vortex is described and interpreted

Appraisal of a one-dimensional model, field data and dimensionless parameters in a study of estuarine circulation

Parallel research programs encompassing the hydrodynamics and geochemistry have been undertaken in Oatley Bay, a small urban estuary that is a lower tributary to the Georges River in Southern Sydney Using field data and a simple numerical model, the regimes of flow effecting circulation in Oatley Bay have been determined. The efficiency of flushing and the subsequent fate of conservative pollutants are discussed. The field data comprised bathymetry, tides, drogue tracking and dye tests, the latter enabling the calibration of the model under different environmental conditions. With this model we have performed numerous runs and have characterised temporal and spatial patterns in the estuarine circulation. These results have been collated in terms of a simple dimensionless parameter – the estuary flushing parameter. This will allow generalization of the results for application to other similar estuaries

Application of a simple hydrodynamic model to estuary entrance management

Tidal inlets which link a tidal basin to the sea via a constricted entrance are common on the south-east Australian coast. Closure, or even significant constriction, raises water levels but restricts tidal range within the basin, while open entrances provide regular and significant tidal exchange with the ocean. A rapid assessment procedure with minimal data requirements has been shown to be informative for monitoring and a useful component of any Decision Support System set up as part of a management structure. Such a system is presented in this paper. It is based on one permanent water level gauge inside the inlet plus the use of a simple, first-order hydrodynamic model to relate the tide range, mean water level and river flow to the inlet cross sectional area. The method is tested against data from the Snowy River Estuary in south-eastern Australia but would be suitable over a range of estuaries. In addition, the framework presented can also provide a mechanism to explore conditions over the range of expected data, thus allowing better selection of model schematization and runs in estuarine systems where the use of 2 or 3D modeling can be justified