Abstract :
Coastlines generally experience changes from time to time in line with nature, such as activity from waves, wind, tides, currents and shoreline sedimentation which also occurs due to disturbances in the coastal ecosystem such as the construction of embankments and canals as well as buildings around the coast. In this study, researchers are interested in examining changes in the coastline at Prapat Tunggal Beach, Bengkalis Regency. This research was carried out using terrestrial. After knowing the results of existing changes to the coastline, it is known that the smallest eroded area is in the P13-P14 segment with an area of 0.092 M2 and the largest eroded area is in the P12-13 segment with an area of 3.6416 M2. It can be concluded that Prapat beach is a single beach. As time goes by, the erosion will increase if coastal protection is not built.