Dynamics of the Swan River Estuary: The seasonal variability

Abstract

The Swan River is a south-westem Australian estuary that undergoes a distinct seasonal stratification cycle. Motivated by the increasing nutrient loading of the estuarine system, an intensive investigation into the hydrodynamics was performed with the aim of understanding the physical processes responsible for transport within the estuary. The seasonal variability of the stratification was documented with regular conductivity-temperature-depth-dissolved oxygen transects that 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 that influence the degree of flushing, and the roles of two sills that control fluid exchange between the estuary and the ocean and control the propagation of the salt wedge and the gravitational overflow.