Influence of wind magnitude and direction to the variability of Pahang River plume distribution

Abstract

Degradation of coastal water quality has become an issue as far as the fishery sector is concerned. River discharge is one of the environmental threats in coastal area. River discharge induces river plume containing high concentrations of suspended matter, various phytoplankton pigments and coloured dissolved organic matter. The distribution of river plume in coastal environment varies widely over time and space. Variations in plume events will be affected by a number of factors including magnitude and direction of wind stress, storm and seasonal cycle, bathymetry and exit angle. The objective of this research is to examine the effects of the magnitude and direction of wind stress on the variability of Pahang River plume. The results showed that the wind speed is highly variable throughout the six years study period. The lowest wind speed was observed at 2.00 ms−1 in June 2005 and the highest at 5.20 ms−1 in January 2010 with average annual wind speed for the six years was 2.90 ms−1. In this study there were five directions of wind at South China Sea: the east, west, northeast, south and southwest. These wind directions cause the variability in plume direction. The plume pattern tends to move to the south by the north and northeast wind directions during Northeast monsoon (November-March), plume propagates to the north by the south and southwest winds during Southwest monsoon. During inter-monsoon (April and October), the plume tends to move the plume across shelf direction affected by west wind direction. These indicate that wind direction and magnitude influence the plume movement at the study area.