Spatial Analysis of Coastal Vulnerability Index to Sea Level Rise in Biak Numfor Regency (Indonesia)

Assessing the vulnerability of coastal areas is important in evaluating impact of sea level rise due to global climate change. This study aimed to spatially analyze and map the vulnerability level of the Biak Numfor Regency’s coastal area on Biak Island to the threat of sea level rise. The study area is limited to 500 m from the coastline and is divided into 383 grid cells. The Coastal Vulnerability Index (CVI) method was used to map the level of vulnerability of coastal areas based on four coastal geological variables (coastal elevation, coastal slope, geomorphology, and shoreline change) and three ocean physical process variables (tidal range, average significant wave height, and relative sea level rise). The results showed that the coastal areas of Biak Numfor Regency, belonging to the low, medium and high-risk vulnerability categories, were 77,685.63 km (32.18%), 159,084.38 km (65.74%), and 5,024.96 km (2.08%), respectively. The variables that contribute significantly to the level of vulnerability are coastal elevation, coastal slope, coastal geomorphology, and shoreline changes due to abrasion compared to tidal range, significant wave heights, and sea level rise rates. Vulnerability studies of other variables that can contribute to the vulnerability of coastal areas are needed, such as socio-economic variables and the impact of human activities on changes in the coastal environment, to obtain a comprehensive CVI value in supporting coastal mitigation planning efforts against sea level rise disasters so that they are more focused.