THE COASTAL MACRO-VORTICES DYNAMICS: A CASE STUDY IN HONG KONG WATERS

Abstract

Coastal circulations are basic information when considering sediment transport and water quality in the oceanic environment, particularly the macro-vortices dynamics which greatly affected the mass transfer and extended the residence time (Hasegawa et al., 2009). Large-scale macro-vortices could be formed in the lee or around natural obstacles such as islands and headlands during the interaction between geographical features and coastal circulations induced by tides and winds. Pearl River is the second largest river in China considering discharge, delivering 3.26 × 1011 m3 freshwater every year into the South China Sea (SCS) through eight outlets (Wu et al., 2016). Hong Kong (HK) is located downstream of the Pearl River Estuary (PRE), acting as a bridge between the PRE and the SCS, as shown in Figure 1. HK possesses more than 200 islands as well as narrow channels and complex coastlines, which have a great impact on shaping local flow structures. In addition, prevailing southwest winds blow during the summer, while stronger northeast winds gust during the winter. Embracing tides from the SCS and river discharge from the PRE, HK waters is an energetic and interesting area and worth a detailed investigation.