The Swan River is a south-west Australian estuary which undergoes a distinct seasonal stratification cycle. The bottom topography of the estuary is dominated by two sills; a relatively deep basin separates a shallow (5m) sill close to the ocean entrance and a shallower (2m) secondary sill situated adjacent to the city of Perth. Due to the ever increasing nutrient loading of the system, algal blooms are being experienced. An intensive investigation into the hydrodynamics of the estuary was thus performed with the aim of understanding the physical processes which occur. The seasonal variability of the stratification has been documented with regular C-T-D-DO transects which were used to piece together an overview of the dynamics. The estuarine dynamics were classified into a gravitational overflow produced by the winter rains, a salt wedge condition governed by both discharge and topographic constraints, tidal dynamics which influences the degree of flushing, and the roles of the sills which control fluid exchange between the estuary and the ocean and control the propagation of the salt wedge and the gravitational overflow. The dynamics of the deep basin were documented in greater detail during intensive summer and winter experiments. Abroad variety of internal features including lee waves, undular bores, and basin scale seiching were observed over a tidal cycle. A one-dimensional, three layered analytical model was constructed to predict the basin response.
|Publication status||Unpublished - 1994|