Numerical Study of the Wet-season Hydrodynamics of a Macrotidally forced Bay with Complex Topography: Collier Bay, Kimberley, Western Australia

摘要

The Regional Ocean Modeling System (ROMS) was employed tostudy the wet season hydrodynamics of Collier Bay in theKimberley region of Western Australia. Hydrodynamics of thissemi-enclosed estuary is characterized by complex topography,macro-tides and highly seasonal freshwater inflow pulses.Freshwater inflows result in both horizontal and vertical densitystratification. Tidally forced residual currents are much strongeraround the islands and reefs, which is consistent with thecomplex topography. To study the interactive role of tides andfreshwater inflows in determining the mass exchange in CollierBay, Eulerian salt-flux decomposition and isohaline salt-fluxdecomposition are applied to a group of cross-sections distributedlongitudinally from the river mouth to the open ocean. TheEulerian method decomposes the salt flux into three componentsto demonstrate the contribution of advection, exchange flow andtide-correlated flow to the net salt fluxes; the isohaline methodprovides more details about the salinity ranges of thedowngradient and the upgradient components. Results show thatbathymetric variation in different directions has different impactson the interaction between tides and freshwater inflow in shapingsalt fluxes and thus the horizontal mass exchange, which ishelpful regarding a better understanding of the sediment andnutrient transport processes in this area.