The purpose of this study is to determine the rate of shoreline change and the level of abrasion in Bukit Batu District, Bengkalis Regency, Riau Province based on several physical variables in the coastal area. End Point Rate (EPR) is a method that can be used to calculate the rate of shoreline change by displaying transects according to their category (high abrasion, medium abrasion, low abrasion, stable, and accretion). From 1991-2021 there was an abrasion of ±139.71 meters equivalent to ±4.65 m/year which mostly occurred in Sukajadi Village and Pangkalan Jambi Village, while accretion of ±27.51 meters equivalent to ±1.58 m/year mostly occurred in Pakning Asal Village and Sejangat Village. Moderate abrasion is the predominant type. Sukajadi and Pangkalan Jambi are villages that have experienced high levels of abrasion. The area affected by abrasion has moderate and fast currents as well as coastal protection in the form of mangroves, most of which have been damaged and require repairs. Therefore, the main factors causing the abrasion are thought to be the lack of coastal protection and high-speed currents and waves flowing from the Malacca Strait.

Rhu Bay is located in Rupat Island, Bengkalis Regency, Riau Province, Indonesia, under influence of the Malacca Strait. The main purpose of this study is to analyze shoreline changes in the Rhu Bay Coastal Area for 18 years, from 2012 to 2022 based on characterstics of sediment and physical Oceanography. Analysis of shoreline changes using Google Earth (Landsat Copernicus) covering the entire Rhu Bay area in 2002, 2008, 2014 and 2020. This research was carried out in Rhu Bay in June 2022 through two research stages:1) processing of secondary data in using Lansat Imagery Data and 2) the sediment samples were collected using sediment grab and oceanographic observation (currents, tides and waves) was also carried out at the coast. Digital Shoreline Analysis System (DSAS) is empowered in processing spatial data to calculate the rate of abrasion and accretion in Rhu Bay, using the methods applied of Net Shoreline Movement (NSM) and End Point Rate (EPR). The results of the study show that the coastline changes dominantly in Rhu Bay experiencing abrasion of 7.87 - 11.24 meters/year in a period of 18 years. The oceanographic parameters in Rhu Bay showed that the waves had a height of 0.2 m with a period of 3 second, current velocity of 0.36 m/s to the northwest. The change in shoreline is thought to be due to the current that flows from the Malacca Strait at high and low tide, as well as the transport of coastal sediment (dominated by medium sand fraction) towards the Malacca Strait by the currents.