09
AUG
2015

Sediment Distribution and Littoral Drift Direction for the Coastline between Batu Rakit and Setiu, Terengganu.

Sediment Distribution and Littoral Drift Direction for the Coastline between Batu Rakit and Setiu, Terengganu.

The main objective of this study is to determine the sediment distribution and investigate the net littoral drift direction from Batu Rakit to Kuala Setiu. The study is very important as a preliminary study to any coastal zone management decisions.  The study area is located on the East Coast, influenced by the Northeast monsoon season (November-March) that is characterised by strong currents and high-energy waves.

Sediment characteristics and beach profiles were studied from Kg. Batu Rakit to Kuala Setiu.  Beach sediment was found to be coarser during the Northeast monsoon season (November – March) and ranged between -0.33 to 1.91 phi.  The sediment was also poorly-sorted and negatively-skewed during this season.  For the beaches at Pantai Merangsediment transportation is interrupted by a breakwater resulting in a wider beach due to accumulation of sediment.

In general, beach slopes followed the normal relationship of wider beaches having gentler slopes while steeper slopes have narrower beaches.  Beach slope ranged from 0.01 (0.6°) to 0.51 (29.2°).  Beach width ranged from 60 m to 120 m with little-or-no definite pattern.

The littoral sediment transport rate at the study area is 64,757 cubic meters per year.  The littoral sediment transport rate was measured at 123,278 cubic meters per year during the Northeast monsoon season and 6,237 cubic meters per year during the non-monsoon season.

Littoral drift direction generated by longshore current and beach drift was determined to be from Southeast to the Northwest.  The littoral drift was interrupted by a breakwater at station P7 (Kg. Merang) resulting in less sediment source at the downdrift (Kg. Telaga Papan) and forming a sandbar.  In this study, the breakwater has been successfully used as a site-specific indicator for determination of net littoral drift direction at Merang coastline.  The littoral drift direction at Kg. Merang is heading to the Northwest; changes its direction to the Southwest causing sediment accretion at the entrance of the breakwater. The sandbar was created here in response to wave action and prograde in the direction of littoral drift.  The impacts to Kg. Telaga papan beach are coarser sand, poorly-sorted sediment types, steeper and narrower beach; and beach cusps formation in downdrift zone.

1-average mean size

Seasonal comparison of mean size value

2 - average sorting

Seasonal comparison of standard deviation (Sorting) value

3 - average skewness

Seasonal comparison of skewness value

 4 - station P7

Annual changes in beach profile – Station P7 (December 2003 – January 2005)

 5 - station P9

Annual changes in beach profile – Station P9 (December 2003 – January 2005)

6 - Shoreline changes

SPOT image map showing coastal changes at Kuala  Merang

7 - relationship between sediment size, beach slope and littoral drift direction

Relationships between sediment size, beach slope and littoral drift direction

8 - Full NSD

Net littoral drift direction at the study area

9 - sandbar

Sandbar image as taken from Google Map

10. jetty Merang 

Sedimentation closed the jetty entrance (taken from www.googleearth.com)

11 - electronic shaker

Electronic Shaker (Retsch-Germany)

12 - Malvern PSA

Malvern Particle Size Analyser (UK)

 13 - Sokkia Transit

Transit SOKKIA C410 (Japan)

Biodata of the Author

Azam-baru-2-150x150

 Mohd Azam bin Mat Yaacob
– Sciencer Officer at Institute of Oceanography and Environment (INOS), Universiti Malaysia Terengganu (UMT).
– B. Sc. degree in Marine Science (2002) Universiti Putra Malaysia Terengganu (UPMT).
– Master of Science Oceanography (Coastal Processes) (2010) Universiti Malaysia Terengganu.