MODELING SEA-LEVEL RISE VULNERABILITY OF COASTAL WETLANDS USING RANKED MANAGEMENT CONCERNS

Coastal strand and wetland habitats are intensively managed to restore and maintain populations of endangered species. However, sea-level rise (SLR) threatens the work of wetland and coastal managers because coastal erosion, salt-water intrusion, and flooding degrade critical habitats. Because habitat loss is a measure of the risk of extinction, managers are keen to receive guidelines and other tools to reduce the risk posed by SLR. Improving upon standard inundation mapping techniques we developed a spatial model and a used a geographic information system (GIS) to assesses wetland and coastal strand vulnerability to SLR at three coastal environments on the Hawaiian islands of Maui and Oahu. The model used five input parameters to characterize and map SLR vulnerability: 1. Type of inundation, 2. Time of inundation, 3. Soil type, 4. Habitat Importance, and 5. Infrastructure. For each input parameter we created a 2 m horizontal resolution raster and applied a vulnerability index that ranked SLR vulnerability from very low to very high. We estimate type and time of inundation using Vermeer and Rahmstorf’s (2009) SLR curves, LiDAR digital elevation models (DEMs), and the 8-sided hydrologic connectivity method. Poorly drained, high salinity hydric soils, endangered, native, and migrant species habitat, as well as infrastructure flooded by future SLR were also mapped. The assessed vulnerability of each study area was obtained by determining the weighted geometric mean of the input vulnerability scores. For example, areas with very high composite vulnerability scores are characterized by groundwater inundation after 2044, contain hydric soils, and are occupied by both endangered species and infrastructure. The SLR vulnerability maps created in this study can be used as a guide to rank threatened areas and initiate decision making by wetland and coastal managers.