Sea Level Rise: Vulnerability Assessment of Coastal Roadway Subgrades in North Carolina

The need to identify vulnerable sections of roadways has increased in central coastal North Carolina (NC) due to rising groundwater table levels and nuisance flooding resulting from sea level rise (SLR). These events, in turn, adversely affect surface transportation's social, ecological, and technical dimensions. Therefore, this study aims to identify vulnerable roadway subgrades sections in Beaufort County, NC, using the most recent groundwater levels. Our study focuses on US and NC routes as they serve as potential evacuation routes in the event of flooding. Based on relevant spatiotemporal scales of the roadways, a geodatabase was built using the Geographic Information System software ArcGIS Pro 2.9.5. Different geoprocessing and geostatistical tools were utilized in the spatial analysis of roadways, and the extent of the vulnerable road sections was determined based on the criterion for potential loss of subgrade soil stiffness susceptibility. Preliminary results show that 25% of the roadways are currently vulnerable. These findings are essential in improving predictions of vulnerable roadway sections since, currently, nuisance flooding happens 5-8 days annually in Beaufort and is likely to happen 70-100 days annually by 2050, as per NOAA's SLR predictions.