Review of Tide and Wind Affect to Currents Pattern in Amurang Bay, North Sulawesi, Indonesia

Abstract

Winds, tides and river discharges largely drive coastal currents. The strength of tidal currents, river runoff, meteorological conditions, shoreline configuration, water depth and topography are the factors that affect coastal water circulation. Generally currents are the flowing of water mass caused by wind, difference of density or tide moving. The existence of currents direction to nearshore of Amurang Bay was studied with using computer model tools as the hydrodynamic model by determine currents speed and its direction.
The study took place in Amurang Bay as the province of North Sulawesi Indonesia with the geography position around 1012’16.16” N-124027’04.33” E to 1015’43.80” N-124032’01.06”E. The bathymetry and tide data used in this research from Indonesian Coastline Environmental map of year 1995 with scale 1:50.000 from BIG (Badan Informasi Geospasial) with a satellite data from Google earth of year 2018 and LANTAMAL Manado, the wind and current data was obtained from BMKG Bitung. Time simulations are taken from 25 November to 23 December 2016 as a wet season and 25 Mei to 23 Juni 2016 as a dry season. As analytical tools, MIKE3 hydrodynamic mode are used. The currents pattern play an important role in sediment transport process, so the study of the currents pattern become to be important as well.
The result of this study indicate that in the wet season the combination of tide wind in surface and bottom layer of sea the currents direction close to nearshore dominant to East with current speed average 0.18 m/s, in dry season the combination of tide wind in surface layer of sea the currents direction close to nearshore dominant to South-East with current speed 0.12-0.24 m/s, in bottom layer the currents direction dominant to South-East with current speed average 0.2 m/s. Some of interesting point in research’s area show that current by tide make the current direction seaward and landward, but tide combination wind change the direction of current. It can be said that the tide influenced to current make the currents direction seaward and landward follow the pattern of tide, but combination tide and wind change its direction.