SEDIMENTATION DYNAMIC BASED ON GRAIN-SIZE SEDIMENT IN SUNGSANG ESTUARY, SOUTH SUMATRA

• Main Author: Krista S.P., Marcelia
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/74182
• Institution: Institut Teknologi Bandung

Sungsang Estuary in Southern Sumatra is a coastal areas in Indonesia, which is the estuary of two big rivers, Musi River and Banyuasin River that directly adjacent with Bangka Strait. Both of the rivers and the ocean current carries sediment into the estuary and settled to the bottom of the estuary. The carried sediment movement is influenced by the current speed and the size of the sediment grain. In this study, estimation of current velocity fluctuations was carried out based on the grain size of the sediment from the GC-601 and GC-703 core sediments taken by Balai Besar Survei dan Pemetaan Geologi Kelautan (BBSPGL) in 2021. With the help of the GRADISTAT v9.1 program and the Laser Particle Analyzer type Malvern Mastersizer 3000, the core sediments were analyzed for each depth layer. The results showed that the average grain diameter for core sediments GC-601 with sand sediment types was 40–170 m, and for core sediments GC–703 with silt sediment types, it was 8–32 m. Furthermore, based on the pattern of fluctuation changes, the grain diameter findings are separated into a number of sequences with various thicknesses. Two approaches, the Hjulström method and the Van Rijn method, were then used to compute the critical deposition velocity and critical erosion velocity from the grain diameter. The results then demonstrate that for core sediment GC-703, the critical erosion velocity range is 0.3–0.65 m/s and the critical deposition velocity range is 0.0005–0.0025 m/s, while for core sediment GC-601, the critical erosion velocity range is 0.32–0.44 m/s and the critical deposition velocity range is 0.005–0.0135 m/s. The study location which is in an estuary causes the sediment characteristics in core GC-601 and core GC-703 to be greatly influenced by river discharge activity and tidal currents