The Effect of Coastal Dynamics on Changes in Normal Baselines and Their Implications on Weh Island, Nanggroe Aceh Darussalam Province, Indonesia

The United Nations Convention on the Law of the Sea (UNCLOS) 1982, gave archipelagic states the authority to set maritime boundaries that are based on such baselines. The baseline point is any point on the usual baseline. The base point must be set where the sea level and lowest tide on the beach coincide. The location of the base point will change if the terrain or sea level of the coastline changes as a result of physical land- and water-based causes. The reference used to establish marine limits will change if the base point changes.It is possible to discover deviations from the average baseline by combining multitemporal satellite imagery with remote sensing techniques. Using satellite images, the position of the shoreline is established according to the time of image acquisition. Utilizing tidal analysis data on changes in vertical position and the slope of the coastal topography, the position of the immediate coastline is then restored to the low water line/normal baseline. Using normal baseline data, the Digital Shoreline Analysis System (DSAS) method is utilized to calculate the rate and acceleration of temporal changes.According to calculations of the usual baseline's speed and acceleration on the eastern portion of Weh Island, which has a Base Point (TD) of 178, the baseline has drifted 21 meters seaward between 2017 and 2022, accelerating by ±5 meters every year. Consequently, coastal dynamics must be taken into account when calculating the base point if the location of TD 178 is updated in accordance with UNCLOS 1982 standards.