Coastline changes and their effects on land use and cover in Subang, Indonesia

Indonesia is at high risk of coastal erosion. Therefore, is important to understand the current status over a large area in order to devise protection strategies. This study measured the coastline changes and examined the land use and cover affected by coastal changes in Subang, Indonesia, using Landsat images from 1990 and 2018. The modified normalized difference water index (MNDWI) was used to separate the water and non-water features of the images, and land use and cover were classified using object-based image analysis based on the red, green, and blue bands and normalized difference vegetation index (NDVI). The results revealed considerable coastal erosion in Legonkulon. In the most extreme case, the coastline had moved 2361.46 m inland, and the total area lost to erosion was 1012.25 ha. This area was mostly covered by fishponds (983.34 ha) in 1990. Given that the fishery sector is the main livelihood of communities in the study area, the disappearance of fishponds might have affected their income and worsened their poverty. We found marked coastal accretion in Blanakan. In the most extreme case, the coastline had moved 1695.61 m seaward from 1990 to 2018, adding a total area of 1856.62 ha. The new areas were used as fishponds (1738.95 ha) in 2018. Although the accretion exceeded the erosion, the distributions differed regionally. Therefore, a regional protection strategy is necessary.