Quantification of the Coastal Exposure Index (CEI) in the Kangean Islands using GIS Based Modelling

Abstract

Climate change has become an important issue in recent years, especially in the context of threats to small islands. This phenomenon causes a rise in sea surface and surface temperatures that endanger coastal ecosystems. Therefore, studies related to the calculation of coastal exposure levels are very important in an effort to mitigate and reduce these impacts. In this study, the calculation of Coastal Exposure Index (CEI) was carried out on the entire coastal area of the Kangean Islands, both large and small islands. We quantified the CEI using Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Modeling. Parameters used in this analysis include coastal topography, bathymetry, waves, surges, natural habitats (mangrove, coral, and seagrass), geomorphology, and sea level rise. The results of the analysis were then classified into fives categories using natural break point as very low, low, moderate, high, and very high. The results show that about 9.76% (58.03 km) of the coastline has a very high vulnerability level, 19.18% is categorized as high (114.04 km), and about 144.85 km or 24.37%, is a moderate category. Locations with very high and high vulnerability level dominate the northern part of Kangean Island. This area is more exposed to the open ocean and has relatively low natural habitat cover and high exposure of wave and surge potential. While the southern part of the island is dominated by mangrove cover, which is protected from exposure in the open ocean area. This condition is probably causing this area to dominantly have low and moderate CEI categories. In the Sepanjang Island area, areas with coral reef and seagrass cover have a lower CEI. The existence of natural habitats is one of the important components of coastal area exposure and reduces the level of vulnerability. The results of this study can be used as a reference in the Kangean Islands management programme as a response to climate change disasters.