The sedimentation and shoreline change on the coast of Tanjung Kapal Cape, Rupat Island

Abstract

Tanjung Kapal is a cape area located on Rupat Island and is influenced by the oceanographic characteristics of the Rupat Strait. This research was conducted in June 2022 to provide information about the level of accretion on the coast of Tanjung Kapal from 2002 to 2020. The research was carried out through two steps : 1) processing of secondary data using Landsat Imagery Data, and 2) collection of sediment samples using a sediment grab, along with oceanographic observations (currents, tides, and waves) at the coast. Statistical calculations used to determine the accretion rate at Tanjung Kapal included EPR (End Point Rate) and NSM (Net Shoreline Movement), which are features of the DSAS (Digital Shoreline Analysis System). The results showed that the accretion rate on the coast of Tanjung Kapal ranged from 5.5 to 21.36 meters per year over the 18-year period. The waves at Tanjung Kapal have a height of 0.12 m with a period of 2 s, and current velocity of 0.16 m/s flowing towards the northwest. Accretion is thought to be due to a system of currents and waves flowing along the Tanjung Kapal beach, which carries sediment and then accumulates along the coast. Additionally, the coastal sediments, dominated by the gravel sand fraction with a sand percentage of 57.97%, are derived from the Rupat Strait by the current system.