J. K. Raj

Bio: J. K. Raj is an academic researcher. The author has contributed to research in topics: Longshore drift. The author has an hindex of 1, co-authored 1 publications receiving 17 citations.

Grain-size distribution and subsurface mapping at the Setiu wetlands, Setiu, Terengganu

Abstract: A study was carried out around the lagoon and coastal area of Setiu wetlands to determine the general characteristics and grain-size distribution of their sediments. Sediment samples were collected from 39 stations of the lagoon area and 8 stations of the coastal area, and were analyzed for their sedimentological characteristics (mean, sorting, skewness and kurtosis). The sediment mean size ranged between 0.06–2.52 and 2.12–2.69 phi (O) for both lagoon and coastal sea-bottom sediments, respectively. Generally, the sediments in the study area consist mostly of coarse to fine particles. The major portions of the sediment are negatively skewed. This indicates that the study area is under the influence of the rather strong wave and current action. The study also encompassed the geophysical survey that was conducted near the coastal zone of the study area. The high-resolution seismic sub-bottom profiling technique is the standard method employed to map geological features and locate structures below the surface of the seafloor. Data obtained from seismic records were used to interpret the seismic reflectors. Three main reflectors (layers), which consist of the seabed and the seabed multiple, were traced using Sonar Web Pro software, and the results showed a uniform distribution pattern for all stations surveyed. It is envisaged that this method could be an effective way to image the marine subsurface structures; thus, its use is anticipated in the higher degrees of sedimentary research and marine resource exploration.

Beach Erosion Variabiltiy during a Northeast Monsoon: The Kuala Setiu Coastline, Terengganu, Malaysia

Abstract: It is widely accepted that beach erosion occuning along the coastline of the east coast states of Peninsular Malaysia is caused solely by the large waves of the northeast monsoon seasons. However, this study, which monitored 9 beach profile stations before and after a NE monsoon along a 25-km stretch of the Kuala Setiu coastline showed that only 2 of the 9 stations -located on both sides of the Setiu estuary river mouth - were eroded. The others showed accretion or negligible changes. Thus the assumption that the monsoon waves are the sole cause of beach erosion cannot be applied to all eroding coastlines. For some coastlines, theassumption may be only partly true. Wave refraction analyses show that, beside the large monsoon waves, the offshore bottom bathymetry and island shelters act as si~ specific factors either to help focus or disperse the energy of the monsoon waves to cause localized erosion or accretion. It is thus imperative that the modifYing effect of bottom topography and island shelters on monsoonal waves be considered if proper beach management policies and erosion mitigation measures are to be effective.

Holocene sea level changes in Kelang and Kuantan, Peninsular Malaysia

Abstract: A proper methodological approach of investigating Holocene sea level changes is a prerequisite in order that the sea-level index points can be useful and significant. This requires the correct identification of the indicative meaning. The indicative meaning of the sea level indicator is defined as the altitudinal relationship of the local environment in which it accumulated to the contemporaneous reference tide level. This study identifies the index points using the litho-, bio-, and chrono-stratigraphic approach. The sea level indicator is derived from the regressive contact of the intercalated peat and marine clastic sequence, while the indicative meaning is estimated based upon the relationship with the contemporary samples. The study was carried out at two contrasting coastal locations, the fossil sites from Meru and Mardi in Kelang in the west and Penur (north and south transects) in Kuantan in the east, while the contemporary sites are from various ecological environments from both areas. Microfossil analysis of pollen and diatoms indicates that the former are more applicable, and defined the changing microfossil assemblages within the regressive contact of the sea level indicator samples. Seven sea level index points are identified. The finding agrees to the general assumptions of high mid-Holocene sea level history in peninsular Malaysia. A relative sea level difference between the west and east coast is indicated, but the significance, if any, is dealt with caution. The explanations of presumed differential crustal movement or sheer age/altitude variability of the index points are suggested.