Coastal vulnerability assessment based on multi-hazards and bio-geophysical parameters. case study - northwestern coastline of Guinea-Bissau

Guinea-Bissau's coasts are considered highly vulnerable to coastal hazards, and this vulnerability is expected to increase under future climate change scenarios. Multi-hazards assessment studies have not been fully carried out to better understand the vulnerability index in the Northwestern Coastline of Guinea-Bissau. In this study, we coupled remote sensing data with the InVEST Model to develop a comprehensive coastal vulnerability index, establish the rate of sea-level rise, and determine the role of coastal habitats in protecting the shoreline from coastal hazards. The study area covered a coastline of 87 km that are classified in different levels of vulnerability. The results show that about 45 km of coastline are recorded in areas of high to very-high vulnerability index. 17 km are recorded in areas of moderate vulnerability, while 25 km are recorded in areas of low to very-low vulnerability index. The study concluded that, the very-high vulnerability index observed in Zone-B is mainly influenced by wind and wave exposure, as this zone is largely exposed to Atlantic Ocean. The low relief of less than 5 m and flat slope that vary between 0 and 5 degrees, made zone-A more vulnerable to storm surge and sea-level that rises by 8.79 mm/year, however, the coastal habitats of this zone play a vital role in protecting the shoreline from coastal hazards. The low vulnerability recorded in Zone-C is due to the relative high relief of above 10 m combined with coastal geomorphological structures and natural habitats. Zone-A and B, deserve special attention from the conservation bodies and coastal community. These findings can be a baseline to assist policymakers and coastal managers in sustainable coastal management and cost-effective mitigation plans for ecological restoration and conservation.