Identification of the impacts of coastline dynamics on the Indonesian maritime zones

ABSTRACT The maritime zones of a state are influenced by the position of the baselines used. The position of the baseline will change along with coastline dynamics. Few causes of coastline dynamics are accretion and abrasion. The inventory method was used to gather findings in the shape of incongruencies on the Indonesian Nautical Chart. Comparative analyses were carried out using the Indonesian baseline map. The abrasion and accretion rate calculation using a Digital Shoreline Analysis System (DSAS) based on Otsu Thresholding was carried out on each incongruencies study area Siberut Island, Wunga Island, and South Kuta Regency. The case study results showed the coastal dynamics rate in Siberut Island of 7.41 metres/year, Wunga Island 12.08 metres/year, and South Kuta Regency 0.91 metres/year. This phenomenon caused changes in the maritime zone on Siberut Island to decrease by 15.78 km2, Wunga Island to increase by 23.04 km2, and South Kuta Regency to increase by 0.07 km2. The implication of the baseline incongruencies can affect the changes of Indonesia's maritime zones, becoming wider or smaller. It is suggested that basepoints and baselines in the unilateral maritime zones be maintained and updated regularly to match the actual conditions that can shift due to coastline dynamics.