Numerical Modelling of Tidal Dynamic and Water Circulation at the Gold Coast Broadwater, Australia

MIRFENDERESK, H. and TOMLINSON, R., 2007. Numerical Modelling of Tidal Dynamic and Water Circulation at the Gold Coast Broadwater, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 277 – 281. Gold Coast, Australia, ISSN 0749.0208 The development of a vertically averaged numerical model of an estuary in the coastal region of the Pacific Ocean on the east coast of Australia is described. The primary objective of the study is to provide a detailed picture of the tidal characteristics in the study area to enable the simulation of the whole water circulation within the water body. A comprehensive data set is collected as part of this study to understand local dynamics and to calibrate and validate the model. Calibration and validation have been achieved through a comparison of computed tidal harmonics against those derived from harmonic analysis of the measured water level variations. Also a comparison was made between the measured discharges across seven cross sections at critical locations in the study area with the discharge obtained through modelling. Calculations show that tides become mixed, mainly semidiurnal in the estuary. The study shows that for lunar constituents (M2 and S2) dissipation mechanisms are dominant and their amplitudes decrease along the estuary. Solar constituents (O1 and K1) experience an increase in amplitude. However, the net result is a reduction of tidal amplitude, indicating the dominance of dissipation mechanisms.