Water circulation in Darvel Bay, Sabah, Malaysia

Darvel Bay, located on the east coast of Sabah and facing the Sulawesi Sea, is the largest semi-enclosed bay in the east coast of North Borneo. In Sulawesi Sea, strong surface winds and corresponding ocean response occur during the southwest and northeast monsoon periods. The area consists of many islands and complex bathymetry contributing to its unique marine environment, which is considered as one of the most biologically diverse marine environment in the world. Water circulation and mixing play an important role on distribution of marine ecosystem components and the survival rate of marine organisms. This paper covers a study on water current velocities and water circulation patterns in Darvel Bay, under different tidal conditions and monsoonal variations, through field investigations and model calculations. Field measurements were conducted using two holey sock drogues tracking and Aquadrop Profiler current meter at the tip of Sakar Island. Hydrodynamic model calculations were conducted using MIKE 21 HD Model. The computational results were calibrated and verified using field measurement data. Based on the hydrodynamic simulations data, time series of current velocity at three location points were randomly selected around the bay to compare changes in current velocity during ebb and flood tides. Findings of this study can be used for different aquaculture activities, coastal developments and integrated coastal zone management planning in the study area.