Coastal Vulnerability Assessment and Disaster Risk Management of the Betahwalang Conservation Area, Demak, Indonesia

Abstract

Low-lying coastal regions worldwide face escalating threats from sea-level rise, land subsidence, coastal erosion, and recurrent tidal flooding, underscoring the urgent need for effective disaster management informed by spatial vulnerability assessments. This study evaluates temporal changes in coastal vulnerability within Betahwalang Waters, Demak Regency, Indonesia, over the period 2015–2025, applying the Coastal Vulnerability Index (CVI) integrated with Geographic Information Systems (GIS). Primary data were obtained through field surveys, whereas secondary data comprised Sentinel-2 satellite imagery, digital elevation and bathymetric datasets, and tidal records. Coastal vulnerability was analyzed using a GIS-based weighted overlay approach that combined and quantified multiple physical, geological, and environmental parameters. The results reveal that approximately 69% of the study area falls within the high to very high vulnerability categories, with geomorphology and coastal slope emerging as the two dominant contributing factors, each accounting for 20% of the overall index. A comparison with the 2015 BNPB coastal hazard assessment indicates a pronounced spatial expansion of high-vulnerability coastal zones over the past decade, primarily driven by tidal inundation, aquaculture expansion, and progressive mangrove degradation. This study contributes to coastal disaster management by demonstrating the value of integrating field observations, remote sensing, and GIS for monitoring long-term vulnerability dynamics. The findings offer a robust scientific basis for disaster risk reduction, vulnerability-based spatial planning, and ecosystem-based coastal management. Collectively, they provide a practical and transferable framework for strengthening the resilience of tropical deltaic coasts confronting intensifying climate-related hazards in similarly vulnerable low-lying coastal environments worldwide.