Chapter 15 Merging scales in models of water circulation: perspectives from the great barrier reef

Abstract

This chapter describes the technique chosen to include the effect of the oceanic circulation in a 2-D model of the large-scale circulation on the continental shelf. This circulation is found to be modulated at an intermediate spatial scale by the interaction of the tidal circulation with individual reefs, and this process is modeled by merging large-scale and reef-scale 2-D circulation models. The oceanography of the Great Barrier Reef (GBR) is made particularly complex by the extraordinary complex bathymetry. In the GBR, the obstruction of the flow by the presence of reefs steers and modifies, even at these large scales, the oceanic inflow and the longshore currents. Obstruction by large reefs or a reef matrix steers prevailing currents toward areas of low reef density. This provides the modeler the challenge to merge the large-scale oceanic circulation with the shelf-scale general distribution of reefs over the shelf. The resulting currents through a reef matrix, and the deflection of the prevailing currents around a reef matrix, are modulated by the tides.