Coastal Vulnerability Assessment Based on Multi-Hazardous Events. Case study: Northwestern Coastline of Guinea-Bissau (NC-GB)

Abstract

Guinea-Bissau coastlines are found highly vulnerable to coastal hazards, and this vulnerability will likely increase under future climate changes scenarios. In addition, the multi-hazardous assessment studies have not yet been conducted to clarify the status of vulnerability index to coastal hazards. Therefore, we integrated eight bio-geophysical parameters and elaborate a comprehensive Coastal Vulnerability Index to coastal hazards, stablish the rate of sea-level rise and determine the role of coastal habitats in protecting the shorelines in the Northwestern Coastline of Guinea-Bissau, by using the GIS and Coastal Vulnerability Index of InVEST Model. The study found that, out of 87 km of the studied coastlines, nearly 45 km lie in high to very-high vulnerability index. 17 km are found in a moderate vulnerability index and 25 km are found at low to very-low vulnerability index. The main responsible for high vulnerability registered in Zone-B were the wind and wave exposure, as this coastline is highly exposed to sea. The other reason was the storm surge and sea-level that rises 8.79/year, motivated by low coastal elevation. Mangrove ecosystem that are largely found in Zone-A, play very important role in protecting shoreline from coastal hazards with value 0.61, followed by forest and sand dune that are found mostly in Zone-C with 0.49 and 0.4 respectively, and saltmarsh that are relatively found in Zone-B with value 0.32. These findings can assist coastal managers in cost-effective adaptation plans, provide a scientific basis for sustainable coastal management and guidance for ecological conservation in coastal regions.