The Bottom Surface Sediment Transport Changes in Bathymetry in the Rupat Strait, Riau Province, Indonesia

The Rupat Strait is located at the eastern coast of Sumatera Island, Riau Province,Indonesia, under the influence of the current system flowing from the Malacca Strait into the Strait.The primary purpose of this study is to identify the topographyof Rupat Strait prevailed by bathymetry changes, which was analyzed using oceanographic and satellite images.This study was conducted in the Rupat Strait in July 2018 through two steps of research: 1) oceanographic observation; 2) bathymetry measurement.The study of oceanographic observation was carried out along the coastal areas of Dumai City and Rupat Island. The depth of Rupat Strait (bathymetry) was measured using an echosounder at 60 stations in July 2018. The changes in the depth of the Strait were analyzed by comparing data between depth in 1990 by satellite images and the depth in 2018 by the measurement. The results of study indicate that dominantly, the depth of the Strait has increased by 1.5-2.7 meters for 28 years. The depth of the Rupat Strait, based on the interpretation of the satellite image data of MIKE C-MAP (1990) ranges from 0.9 to 29.4 meters, and of the measurement in 2018, ranging from 2.4 to 32.1 meters.The dominant factor causing the changes are the current system flowing from the Malacca Strait through the Strait during high and low tides, and the surface bottom sediments are transported out the Strait by the current, including the bottom current.

Study on Characteristics of Flow and Sediment for Xiaomiaohong Tide Inlet in Radial Sand Ridges

Based on the measured hydrological data and the established mathematical model of Xiaomiaohong channel, the current and sediment distribution characteristics are researched and analysed. Some conclusions are drawn as follows: (1) The maximum velocity and mean velocity of the measuring points in the groove were generally greater than those at points in the open waters; spring tide and neap tide strength difference is apparent, spring tide should play a major role in the beach evolution. (2) Suspended sediment concentration in the open sea is significantly lower than that in the tidal channel; the bottom sediment concentration is generally greater than surface, bottom surface sediment concentration is 1.12 ~ 1.66 times (3) Median particle diameter of suspension sediment is 0.005 ~ 0.017, mainly for fine silt and very fine sand.

Caracterização do Sedimentos de Fundo e Dinâmica Sedimentar da Enseada de Jurujuba (Baía de Guanabara), Niterói, RJ.

Sixty-four bottom surface sediment samples were collected in Jurujuba Bight using a Dietz LaFond grab sampler. They were analysed for grain size distribution, shape, mineralogy and geochemistry. From the association between the Bight bottom morphology and sediment characteristics, it was possible to establish the sedimentary dynamics. This allowed a division of the Bight into three sedimentary zones: an outer, sand-dominated zone of relatively high wave and current energy, an inner zone characterized by very calm conditions and clay/mud deposition and an intermediary zone of mixed sedimentary characteristics.