Coastline change detection using high-resolution satellite images: a case study in Amurang Coasts, South Minahasa, North Sulawesi

Abstract

Coastal dynamics have become an intriguing subject for observation due to their constant alteration. Coastline alteration involves natural factors and human interventions, including land reclamation. The land reclamation process can result in an extreme change in coastal dynamics in the area. Amurang, South Minahasa, is an example of coastal area exploitation. Amurang coasts have undergone physical changes in the last decade, which induced alteration in the coastal balance of erosion and accretion of the area. The primary purpose of this study was to determine the pattern of coastline changes in Amurang, South Minahasa, and North Sulawesi, Indonesia. Remote sensing methods using time series data of PlanetScope ortho-tile images have been involved in this study. The results revealed that from 2016 to 2022, the coastline changed with an erosion rate of 1.05 ha/year. Moreover, due to abrasion on June 15th, 2022, the Amurang coasts lost 3.97 ha of land. The construction of coastal protection (embankment) and land reclamation on the coasts has been observed in the study area. However, the embankment construction and land reclamation have altered coastal dynamics in Amurang, resulting in erosion in the east part. Therefore, coast construction requires accurate planning and calculation involving environmental impact assessment. Moreover, coastal protection cannot rely solely on the rigid structure. Coastal conservation involving the soft structure, such as mangrove vegetation and sediment nourishment by the river, should be considered. This study shows that inappropriate coastal construction can cause enormous damage and loss on the Amurang coasts.