USING INSAR DATA TO MEASURE VERTICAL DISPLACEMENT IN COASTAL SOUTH CAROLINA

Increased flooding in southeastern US coastal cities is a primary infrastructural concern as relative sea-level rise (RSL) rates increase. Local conditions are not only influenced by the global eustatic sea-levels, but also local conditions including land displacement due to natural and anthropogenic factors, such as local tectonics, dissolution, and groundwater removal. Analysis and comparison of existing CORS GPS data, tidal gauges, and InSAR data over the past decade aids in understanding differential displacement along the Central South Carolina coast and indicates different areas of concern. Processing of multiple pairs of InSAR data (Sentinel-1) in the ESA Sentinel Application Platform (SNAP) allows for calculation of displacement at the millimeter scale. Processing of this data has revealed high coherence in urban areas as expected, but it has unexpectedly revealed high coherence in some marshes. Using downtown Charleston (SC) as an example, displacement is less than 1mm per year in some parts of the city, while in other areas data suggest land subsidence is occurring at rates over 3mm per year, matching observational and other short-term trends. Continued mapping of these findings will facilitate understanding of the relationship between sea-level rise and land deformation in South Carolina, supplying managers and municipalities data on which to base their decision-making processes.